Treatments

Medication Practices for Poultry

Veterinary medicine is the branch of medicine that deals with the following:

Prevention
Control
Diagnosis
Treatment of disease
Disorder
Injury in animals

Medication practices also deal with the following:

Animal rearing
Husbandry breeding
Research on nutrition
Product development

Vaccination and drug administration are part of poultry medications. The reason why vaccines are applied to chickens is thus to build their immune system against an impending disease. Therefore, the best way to control poultry disease is via vaccination.

Furthermore, in poultry production (broiler production, turkey production, ostrich production and layer production) an animal health flock plan includes a vaccination programme should always be included in the medicine chart.

Vaccines are used for prevention, while drugs are used for treatment. Vaccination is periodic, drugs are administered at any particular time and only provided when the chicken or other poultry species are unhealthy.

Vaccines are commonly administered even when your flock is healthy therefore it is to compliment and build resistance against deleterious diseases that distort the healthy living of the bird in the future. When chickens show symptoms of disease, record, monitor, evaluate and notify your animal health representative to consult with the veterinarian for diagnosis and treatment.

Farmers and breeders are always advised to strictly follow the vaccination schedules to ensure the chickens benefit from the vaccines when due. Failure to administer the vaccines when due, may prone the chickens to future outbreaks of a particular disease.

A. The Difference Between Preventative and Therapeutic Medications

Preventative medication: Medications used to prevent certain conditions from developing or from coming back.

Therapeutic medications: A branch of medicines specifically for the treatment of diseases. Therapeutic drugs are used to relieve symptoms, and treat infection.

Preventative medications include the use of ANTIBIOTICS which plays a role in poultry production medications. An ANTIBIOTIC is a drug that inhibits or kills the growth of pathogenic bacteria within the chicken. Antibiotics are used to treat diseases and respiratory infections that could be caused by bacteria.

Therapeutic medication is the branch of medicine concerned specifically with the treatment of diseases. The therapeutic dose of a drug is the amount needed to treat a disease. Drugs should only be administered where permitted by law.

Specific rates of addition to feed and water may vary according to the concentrations of the active compound in the commercial presentations.

Printed label directions should be followed:

Comply with species and age restrictions.
Observe withdrawal periods of egg-producing and poultry meat flocks.
Select drugs on a cost-effective basis advised by your veterinarian.
Monitor clinical response where practical compared with untreated exposed controls.

B. Methods for the Administration of Medication

The route of administration is normally demoted with abbreviations on the label of certain drugs.

These abbreviations are:

I/V: This means INTRAVENOUS that the drug must be given to the animal through the vein. This method is used for early or acute emergencies of an infection or disease.
I/M: This means INTRAMUSCULAR that the drug must be administered to the animal through the muscle. This method is common in all livestock species.
S/C: This means SUBCUTANEOUS that the drug must be administered to the animal through the skin of the animal.
Topical: This means that the drug must be applied through rubbing on the skin of the animal. This method is common in farm animals to treat skin infections.
Oral: This means that the drugs are administered through drinking water or mixing with feed. This method is a common route in poultry production.
LA: This means LONG-ACTING, that the drugs will stay longer in the animal’s system.

These codes are embedded by the manufacturer of the vaccine or drug to aid the medications.

Poultry medications have certain rules and regulations. Vaccines or drugs meant for chickens have withdrawal periods. The withdrawal period is the period when these chickens are unproductive not because they do not produce, but because their by-products such as eggs and meat cannot be consumed during these medications when given. During the withdrawal period, the by-product (eggs and meat) can be terminated and should be eaten by humans after medications. Drugs administered to poultry have residue in the chickens within the withdrawal period.

Consuming chicken eggs or meat while on drugs or other medications is highly detrimental to human health. The threatening diseases affecting humans today are a result of the indiscriminate consumption of animals and their by-products at any period.

Figure 16.35 Angles for inserting injections Angles for inserting injections

C. Adhering to the Medication Procedures

It is of utmost importance to diagnose your flock’s disease as accurately as you can learn about effective treatments and learn about specific instructions for all medications. All medication prescribed by a qualified veterinarian should be applied strictly in accordance with the manufacturer’s instructions unless otherwise advised by the veterinarian concerned.

D. The Role of Vaccinations in the Control of Poultry Diseases

The role of vaccinations is to prepare the flock against disease challenges caused by specific pathogens that are exposed to all birds in the form of infectious organisms.

Vaccines act as insurance against the risk of disease, but like insurance, they have a cost associated with them. The price of the vaccine, time involved in scheduling and administering vaccines, as well as losses or reactions associated with the vaccine itself. Vaccines are normally used to prevent or reduce problems that can occur if a flock is exposed to the field strain of a particular disease.

E. Function of the Vaccine

Veterinary vaccines are to improve the health and welfare of all animals and thus cost-effectively increase the production of livestock. To prevent animal-to-human transmission from both companion animals through to wildlife. The vaccines are intended to stimulate the immune mechanisms of an animal to produce antibodies which will inactivate pathogens and produce minimal effects. The vaccine is a protective measure against the outbreak of contagious and infectious diseases which plays a vital role in preserving animal health in poultry. The function of a vaccine is for the active immunisation of chickens to reduce infection, and to reduce clinical signs and effects of the disease caused by the virus.

F. Why More Than One Vaccination is Often Necessary

Many vaccinations will not cover and protect your bird for life so boosters may be needed. The immune system cells, circulating antibody levels can decline over time and drop to a low level which will result in the immune system taking longer to respond to an antigen entering the body.

In some cases, the birds’ immune system requires frequent boosting to be effective against an antigen, while in other cases, less frequent stimulation is required. In some situations, it is possible to depend on natural infection to trigger the immune system to produce the antibodies. To ensure a quick response to an invader antigen high levels of circulating antibodies are necessary and the frequent refreshing of the memory immune cells will ensure a quick response.

A virus with a short incubation time will require a more rapid immune response than a virus with a longer incubation time. If the disease progresses very rapidly, the immune system’s memory response antibodies generated after a previous infection or vaccination may not be able to respond quickly enough to prevent infection unless they’ve been “reminded”

The mild vaccine is followed by a more virulent strain of the virus, to achieve effective levels of immunity.

A mild or inactivated vaccine can serve as a method to “introduce” the antigen to the immune system for the first time. This approach is most commonly used for rapidly spreading viruses that do not allow for the immune system to respond fast enough to prevent the disease. A mild vaccine will allow the immune system to produce enough immune cells that will circulate in the body and generate high levels of memory immune cells that will shorten the response time to eliminate the antigen before causing the disease.

G. Methods of Administering Vaccines

There are six main methods used to vaccinate poultry, these are via:

Drinking water
Sprays
Drops or squirts
Scarification
Injection
In-ovo

Drinking water:

Vaccination through the water system to vaccinate a flock of birds without needing to handle individual birds. This should be carried out early in the morning with cool water used for vaccination. Check that all the drinkers are working effectively. The drinker system should be drained of water so that the vaccine is not diluted when added.

There are times that vaccination can be delayed for 1 to 1.5 hours depending on the weather conditions to ensure that the birds are thirsty when vaccinated. The nipple lines or bell drinkers should be raised above bird height when filling with water containing the vaccine when the lines or drinkers are lowered. Allow for the water to drain out of the end of the nipple lines.

Sprays:

Coarse droplet sprays are mainly administered in the hatchery. With this method, the vaccine is sprayed onto the chickens (or into the air above the chickens) using a suitable atomiser spray. The vaccine then falls onto the chickens and enters the bodies of other chickens as they pick at the shiny droplets of the vaccine. A small quantity may be inhaled as well.

Drops or squirts:

Applied in the eye or nasally.

Ocular (eyes): This method involves the vaccine being put into one of the bird’s eyes. From here the vaccine makes its way into the respiratory tract via the lacrimal duct. The vaccine is delivered through an eyedropper and care must be taken to ensure that the dropper delivers the recommended dose. If it is too little, the level of immunity may be inadequate, while if too much, the vaccine may not treat the total flock but will run out beforehand.
Nasal: This method involves introducing the vaccine into the birds’ nostrils either as dust or as a drop. Always ensure that the applicator delivers the correct dose for the vaccine being used.

Scarification of the wing web, comb, thigh or wing-web stab:

Skin scarification involves a scarifying needle being dipped into the vaccine mixture. The scarifying needle is then used to vaccinate the bird by puncturing the wing web (for chicks) or the comb (for older birds).

Injection:

Intramuscular: This method involves the use of a hypodermic needle or similar equipment to introduce the vaccine into the muscle (usually the breast muscle) of the bird. The task is sped up greatly by the use of an automatic syringe which makes the technique relatively easy and doesn’t harm the bird. Care must be taken to ensure that the correct dose is administered to each chicken and the equipment should be checked regularly to ensure this. Care must be taken to ensure that the needle does not pass through into a key organ and that other unwanted organisms are not administered to the bird at the same time by contaminated vaccine or equipment. Contamination can be prevented by good hygiene and vaccine-handling procedures.
Subcutaneous: This method involves the use of similar equipment to that used for the intramuscular technique. The main difference between the two techniques is that, in this case, the vaccine is injected under the skin, usually at the back of the neck, and not into the muscle. Care must be taken to ensure that the vaccine is injected into the bird and not just into the feathers or fluff in the case of very young chickens. The dose being administered should be checked for accuracy frequently. Maintain good hygiene practices to limit the introduction of contaminating organisms during the procedure.

In-ovo (in the hatchery):

Vaccines can be injected into fertile eggs during day 18 of incubation. The eggs can be vaccinated as they pass through an automated machine or manually by a vaccinator.

Reasons for using different methods to administer vaccines:

Vaccination methods vary according to veterinary advice. Vaccination is an effective means to prevent and reduce the adverse effects of specific diseases that can cause problems within your poultry operation. In the case of some vaccines, an important part of the procedure is to ascertain whether the vaccine has worked, or “taken”. A good example of this is the fowl pox vaccine, which is administered by wing stab.

Within 7 to 10 days after vaccination, a “take” should appear at the vaccination site. This is in the form of a small pimple one-half to one centimetre in diameter. If the take is larger and has a cheesy core, it indicates that contaminants have been introduced either with the vaccine or with dirty vaccinating equipment. A check for takes would involve inspecting approximately 100 birds for every 10,000 vaccinated.

Another example of whether the birds are reacting satisfactorily to the vaccination is the systemic reaction found in chickens vaccinated against infectious bronchitis disease. In many cases, the birds react approximately 5 to 7 days after vaccination by showing signs of ill health such as a slight cough, a higher temperature and lethargy. In cases where there are no obvious signs of success, blood samples may be taken and sent to the laboratory for examination. The usual test is for the presence of an adequate number of the appropriate antibodies (called the titre) in the blood. If the vaccination has been unsuccessful, it may be necessary to re-vaccinate to obtain the desired protection.

Failure to find evidence of success could be because of:

Faulty technique resulting in the vaccine not being introduced into the vaccination site.
Faulty vaccine – too old or not stored or mixed correctly. It would be unusual but not impossible for the vaccine to be faulty from the manufacturer.
The birds are already immune, meaning the immune system has already been triggered as a result of parental (passive) immunity, previous vaccination or other exposure to the causal organism.

H. Guidelines for Vaccine Preparation and Administration

Vaccine preparation must be on a clean surface (disposable kitchen roll or clean newspaper on a clean table top is suitable).
Disposable gloves must be worn for the entire procedure.
Chlorine neutralisation solutions must be made up of low-volume stock solutions (5-10 litres) and then mixed through the larger volume of water for vaccination. Leave for 20 minutes to neutralise any chlorine which may be in the water.
Remove the metal caps from the vaccine bottles.
Put approximately one to two litres of chlorine-neutralised water in a small container. Submerge the vaccine bottle into the solution and remove the rubber bung.
Ensure that the pellet has dissolved.
Gently but thoroughly stir the solution to mix and then add to the rest of the water (calculated from the previous day’s intake during a 1½ – 2 hour period after feeding, plus 5%) for vaccination.
Thoroughly mix the solution with the rest of the water in the water tank and stir it with a plastic stick or place the solution under the proportioned, submerging suction tube.
Allow all drinkers to fill with vaccine-containing water before lowering them to bird level. In the case of nipples take a bucket to the far end of the nipple line and drain off the existing untreated water. As a rough guide, one litre of water should be removed from each three-metre length of the nipple line. Repeat this for each line in the building until coloured vaccine water appears. Once drained, nipples should be lowered to the normal height for the birds.
Walk the flock at least twice during the vaccination process to encourage uniform consumption and make sure that the vaccine is flowing to all the drinkers.
Observe the drinking behaviour and ensure to your satisfaction that all the birds are drinking and are receiving a dose of vaccine.
Monitor the consumption rate of the vaccine to ensure your calculations are correct and that the vaccination solution will be consumed over two hours. Note: the vaccination solution will be consumed quite quickly at the start of the process.
Only when the vaccine water in the drinkers is finished should the mains water be turned back on. The vaccine must not be diluted by the addition of mains water.
All equipment must be clean, but the vaccine must not come in contact with disinfectant.

Cleaning and storage of vaccine equipment:

Wash vaccine equipment with clean water. No detergents or disinfectants are to be used.
Store all equipment in a sealed plastic bag and store it in a clean area of the farm.
The water system should be sanitised.

I. Vaccination Timetable

Before the day of vaccination, a vaccination timetable should be drawn up. Where multiple sheds are to be vaccinated on the same day a timetable for each shed must be prepared and vaccination only performed when it is practical to keep to the correct timings to ensure the correct vaccination of each shed.

Below is an example of a vaccine timetable for one house:

00 a.m.: Feed and water.
45 a.m.: Turn the water off and let birds drink the remaining water in drinkers (20 minutes approximately).
05 a.m.: Raise drinkers or lines out of the reach of the birds.
05 a.m.: Water withdrawal time. Prepare the vaccine to dose the volume of water that will be drunk in about 1½ – 2 hours.
10 a.m.: Drain residual water from each line or bell (1 litre/3 metres of line) until milky or white-coloured water appears and then lower lines or bells to the birds.
10 a.m.: Vaccination period. Walk flock twice during vaccination, and check the flow of vaccine along all water lines and to all drinkers.
10 p.m.: Turn on mains water after vaccination. Clean water.

J. Evaluation of Drinking Water Vaccination

It is important to assess the efficiency of vaccination once it has been completed. This can be done by using a commercially available dying product which stains the tongue. It is advisable to use dye tablets at least once per flock to assess the vaccination technique. There are several products available. The blue intensity on the tongue of the birds after vaccination varies between products and decreases with time after exposure.

The manufacturer’s instructions should be followed carefully when assessing the efficiency of vaccination using this technique.

One hundred birds from at least three different locations in the house should be examined for tongue colour to see if the blue colour of the tongue corresponds approximately to a dose of vaccine. If the vaccination technique has been successful at least 90% of the birds examined will have well-stained tongues in accordance with the manufacturer’s guidelines.

If there is any doubt about how well the flock has been vaccinated, then the line manager or veterinary surgeon responsible for the flock should be informed.

Infectious Respiratory Diseases and Treatments

Infectious respiratory diseases in poultry, their clinical signs and management.

Disease name	Clinical signs	Control	Treatment or products
Aspergillosis	Infected chickens are depressed, thirsty, gasping, and breathing rapidly.	There is no specific treatment for infected birds. The best option is to remove and destroy affected birds. Strict hygiene in breeders (hatching eggs) and hatchery management is necessary. The choice and quality of litter are also important to prevent spore-bearing. Wood shavings or straws are used. Hatchery control with anti-fungal disinfectant may be critical to cleaning and disinfection procedures to control fungus infection.	None. Use disinfectant to clean out poultry houses.
Avian influenza (AI)	Mild symptoms include coughing, sneezing, wet eyes, nasal discharge, depression, lethargy and limited intake of feed. A drop in egg production will be prevalent, but the mortality rate is low.	Vaccination is generally done with inactivated AI vaccines based on the strain H-type causing the outbreaks.	There is no treatment for avian influenza. Antibiotics will help to control secondary bacterial infections. Doxycycline antibiotic.
Avian metapneumovirus	Occurs in both turkeys and chickens. In young birds, the respiratory clinical signs include snicking, rales, sneezing, nasal discharge, foamy conjunctivitis, and swollen infraorbital and periorbital sinus (swollen head). When birds become older, head shaking and coughing can be seen. In adult laying hens, there may be a drop in egg production up to 70% with an increased incidence of poor shell quality.	Vaccination is the most effective prevention method. Over the years live and inactivated vaccines have been developed and are very effective in controlling infections. Short-living birds will only be vaccinated with a live vaccine(s). Long-living birds are advised to be primed with live- and boosted with inactivated vaccines. In this way, the birds will have long-lasting local and systemic protection.	There is no treatment for AMPV infections. Treatment with antibiotics can be given to control secondary bacterial infections. Doxycycline antibiotic.
Infectious bronchitis (IB)	In young chickens the respiratory form appears with gasping, sneezing, tracheal rales and nasal discharge. Generally, chicks are depressed and show reduced feed consumption.	Vaccination with strain-specific or cross-protective live vaccines, and for layers and breeders the addition of inactivated vaccines at the point of lay to induce long-lasting systemic immunity. BI-VAC 1 water treatment vaccine.	There is no treatment for IB. Antibiotics are used to control secondary bacterial infections. Doxycycline antibiotic.
Infectious coryza The eyes of a chicken with infectious coryza.	The main clinical signs are due to an acute inflammation around the eyes and upper respiratory tract. Signs include a serous to mucoid discharge in the nasal passage and sinuses, facial oedema and conjunctivitis. Feed and water consumption will decrease, resulting in loss of weight gain and loss of egg production (10-40%) in laying birds. In affected breeders, the hatchability and day-old chick quality might decline. Mortality will vary with the virulence of the infection but is generally low.	Vaccination is the preferred control method and is standard in most Vaccination with multi-serotype inactivated vaccines during the rearing period will reduce clinical signs and control infectious coryza. Cori-vac 3 vaccine.	Treatment with various antibiotics (erythromycin and tetracycline are Relapse often occurs after treatment is discontinued and recovered birds will remain carriers. Because of the noted drug resistance of Avibacterium paragallinarum, an antimicrobial sensitivity test is recommended. Oxytet FG200 25 kg. Betamin 1 litre.
Infectious laryngotracheitis	An acute respiratory disease with nasal discharge and moist rales followed by gasping marked respiratory distress, and expectoration of blood-stained mucus in laying birds. Egg production can drop 10 to 50% but will return to normal after 3-4 weeks. Mortality can vary from 5 -70%. Spreading through a chicken house is slower compared to IB and ND.	In many countries, vaccination is the preferred control method. However, in some countries, it is not allowed to be vaccinated (or only under restriction). The existing Live Conventional CEO ILT vaccines are effective in controlling clinical problems but have the risk of spreading and reversion to virulence after multiple passages through chickens. Recent outbreaks show often the relation to the live vaccine strains used in an area. Therefore, the new generation of recombinant vector vaccines is more suitable for the control and prevention of ILT. Recombinant vaccines based on HVT-vector carrying inserts of important immunogenic ILT proteins show good efficacy and do not spread and cannot revert to virulence because there is not a full ILT virus involved.	There is no treatment for ILT; emergency vaccination in the early stage of an infected flock may reduce the spread and limit the outbreak.
Mycoplasma gallicepticum (MG)	Young chickens (broilers or layer pullets) will show respiratory distress. The birds frequently show a lack of appetite, decreased weight gain and increased feed conversion ratios. In adult birds the most common signs are sneezing and general respiratory distress. In laying birds a drop in egg production between 20-30 % can occur. In breeders, hatchability can be affected and day-old chick quality produced from hatching eggs coming from infected flocks will be reduced. MG does not normally cause an alarming number of deaths. The effect is more of a chronic nature causing reduced weight gain and higher feed conversion ratios in broilers and lower egg production in breeders and layers. In this way, the overall economic losses can be very high.	Prevention by monitoring and vaccination has become a more effective method of combating the disease, especially in layers. Economic losses in commercial layers can be reduced by the proper use of mg vaccines. Eradication programs (first in breeder flocks) based on stringent monitoring and culling are preferred in breeders to prevent vertical transmission. This is only economically possible when prevalence is low.	Treatment of infected chickens or turkeys with suitable antibiotics or chemotherapeutics is of economic value but will not eliminate mg from the flock. Aivlosin FG or WS.
*Mycoplasma synoviae* The feet of a chicken infected with mycoplasma synovia.	The first recognised signs are pale comb, lameness, retarded growth and, as the disease progresses, ruffled feathers, swelling of joints and breast blisters. Respiratory involvement is generally asymptomatic but is possible; usually, 90-100% of the birds will be infected. Clinical synovitis varies around 5-15% in an infected flock. Mortality is low (around 1%, but up to 10%). More recent strains induced a drop in egg production and/or misshapen eggs (so-called “glass window eggs”).	Prevention by monitoring and vaccination has become a more effective method of combating the disease, especially in layers. Economic losses in commercial layers can be reduced by the proper use of MS vaccines. Eradication programs (first in breeder flocks), based on stringent monitoring and culling, are preferred in breeders to prevent vertical transmission and are only economically possible when prevalence is low.	Mycoplasma synoviae is susceptible to several antibiotics. Antibiotic treatment will diminish clinical signs but not eliminate MS from a flock. Strict biosecurity. Aivlosin and Supadox 50.
Newcastle Disease (ND) The twisted neck of a chicken infected with Newcastle Disease.	Highly pathogenic strains (velogenic) of ND cause high mortality with depression and death within 3 to 5 days. Affected chickens do not always exhibit respiratory or nervous signs. Mesogenic strains cause typical signs of respiratory distress. Laboured breathing with wheezing and gurgling, accompanied by nervous signs, such as paralysis or twisted necks (torticollis) are the main signs. A 30 to 50% drop in egg production, and returning to normal levels in about 2-3 weeks is observed. Eggshell quality will also be affected (thin and loose). In well-vaccinated chicken flocks, clinical signs may be difficult to find.	Vaccination has proven to be a reliable control method. ND is a notifiable disease, and in many countries, the control is based on a combination of obliged vaccination and stamping out in case of outbreaks. A wide range of live and inactivated vaccines are used in vaccination programs to prevent ND. The new generation of live recombinant HVT-vector vaccines allows early hatchery vaccination and can be used to replace conventional ND vaccination, eliminating vaccination reactions and inducing lifelong protection. Bio-vac NDC 6/10 vaccine.	There is no specific treatment for ND; antibiotic treatment of secondary bacterial infections (such as E. coli) will reduce the losses. Supadox 50.

Disease name

Clinical signs

Control

Treatment or products

Aspergillosis

Infected chickens are depressed, thirsty, gasping, and breathing rapidly.

There is no specific treatment for infected birds. The best option is to remove and destroy affected birds.

Strict hygiene in breeders (hatching eggs) and hatchery management is necessary. The choice and quality of litter are also important to prevent spore-bearing. Wood shavings or straws are used.

Hatchery control with anti-fungal disinfectant may be critical to cleaning and disinfection procedures to control fungus infection.

None.

Use disinfectant to clean out poultry houses.

Avian influenza (AI)

Mild symptoms include coughing, sneezing, wet eyes, nasal discharge, depression, lethargy and limited intake of feed. A drop in egg production will be prevalent, but the mortality rate is low.

Vaccination is generally done with inactivated AI vaccines based on the strain H-type causing the outbreaks.

There is no treatment for avian influenza. Antibiotics will help to control secondary bacterial infections.

Doxycycline antibiotic.

Avian metapneumovirus

Occurs in both turkeys and chickens. In young birds, the respiratory clinical signs include snicking, rales, sneezing, nasal discharge, foamy conjunctivitis, and swollen infraorbital and periorbital sinus (swollen head). When birds become older, head shaking and coughing can be seen. In adult laying hens, there may be a drop in egg production up to 70% with an increased incidence of poor shell quality.

Vaccination is the most effective prevention method. Over the years live and inactivated vaccines have been developed and are very effective in controlling infections. Short-living birds will only be vaccinated with a live vaccine(s). Long-living birds are advised to be primed with live- and boosted with inactivated vaccines. In this way, the birds will have long-lasting local and systemic protection.

There is no treatment for AMPV infections. Treatment with antibiotics can be given to control secondary bacterial infections.

Doxycycline antibiotic.

Infectious bronchitis (IB)

In young chickens the respiratory form appears with gasping, sneezing, tracheal rales and nasal discharge. Generally, chicks are depressed and show reduced feed consumption.

Vaccination with strain-specific or cross-protective live vaccines, and for layers and breeders the addition of inactivated vaccines at the point of lay to induce long-lasting systemic immunity.

BI-VAC 1 water treatment vaccine.

There is no treatment for IB.

Antibiotics are used to control secondary bacterial infections.

Doxycycline antibiotic.

Infectious coryza

The eyes of a chicken with infectious coryza.

The main clinical signs are due to an acute inflammation around the eyes and upper respiratory tract. Signs include a serous to mucoid discharge in the nasal passage and sinuses, facial oedema and conjunctivitis. Feed and water consumption will decrease, resulting in loss of weight gain and loss of egg production (10-40%) in laying birds. In affected breeders, the hatchability and day-old chick quality might decline. Mortality will vary with the virulence of the infection but is generally low.

Vaccination is the preferred control method and is standard in most

Vaccination with multi-serotype inactivated vaccines during the rearing period will reduce clinical signs and control infectious coryza.

Cori-vac 3 vaccine.

Treatment with various antibiotics (erythromycin and tetracycline are

Relapse often occurs after treatment is discontinued and recovered birds will remain carriers. Because of the noted drug resistance of Avibacterium paragallinarum, an antimicrobial sensitivity test is recommended.

Oxytet FG200 25 kg.

Betamin 1 litre.

Infectious laryngotracheitis

An acute respiratory disease with nasal discharge and moist rales followed by gasping marked respiratory distress, and expectoration of blood-stained mucus in laying birds. Egg production can drop 10 to 50% but will return to normal after 3-4 weeks. Mortality can vary from 5 -70%. Spreading through a chicken house is slower compared to IB and ND.

In many countries, vaccination is the preferred control method. However, in some countries, it is not allowed to be vaccinated (or only under restriction).

The existing Live Conventional CEO ILT vaccines are effective in controlling clinical problems but have the risk of spreading and reversion to virulence after multiple passages through chickens.

Recent outbreaks show often the relation to the live vaccine strains used in an area. Therefore, the new generation of recombinant vector vaccines is more suitable for the control and prevention of ILT. Recombinant vaccines based on HVT-vector carrying inserts of important immunogenic ILT proteins show good efficacy and do not spread and cannot revert to virulence because there is not a full ILT virus involved.

There is no treatment for ILT; emergency vaccination in the early stage of an infected flock may reduce the spread and limit the outbreak.

Mycoplasma gallicepticum (MG)

Young chickens (broilers or layer pullets) will show respiratory distress. The birds frequently show a lack of appetite, decreased weight gain and increased feed conversion ratios.

In adult birds the most common signs are sneezing and general respiratory distress. In laying birds a drop in egg production between 20-30 % can occur. In breeders, hatchability can be affected and day-old chick quality produced from hatching eggs coming from infected flocks will be reduced. MG does not normally cause an alarming number of deaths. The effect is more of a chronic nature causing reduced weight gain and higher feed conversion ratios in broilers and lower egg production in breeders and layers. In this way, the overall economic losses can be very high.

Prevention by monitoring and vaccination has become a more effective method of combating the disease, especially in layers. Economic losses in commercial layers can be reduced by the proper use of mg vaccines.

Eradication programs (first in breeder flocks) based on stringent monitoring and culling are preferred in breeders to prevent vertical transmission. This is only economically possible when prevalence is low.

Treatment of infected chickens or turkeys with suitable antibiotics or chemotherapeutics is of economic value but will not eliminate mg from the flock.

Aivlosin FG or WS.

Mycoplasma synoviae

The feet of a chicken infected with mycoplasma synovia.

The first recognised signs are pale comb, lameness, retarded growth and, as the disease progresses, ruffled feathers, swelling of joints and breast blisters.

Respiratory involvement is generally asymptomatic but is possible; usually, 90-100% of the birds will be infected.

Clinical synovitis varies around 5-15% in an infected flock. Mortality is low (around 1%, but up to 10%). More recent strains induced a drop in egg production and/or misshapen eggs (so-called “glass

window eggs”).

Eradication programs (first in breeder flocks), based on stringent monitoring and culling, are preferred in breeders to prevent vertical transmission and are only economically possible when prevalence is low.

Mycoplasma synoviae is susceptible to several antibiotics. Antibiotic treatment will diminish clinical signs but not eliminate MS from a flock.

Strict biosecurity.

Aivlosin and Supadox 50.

Newcastle Disease (ND)

The twisted neck of a chicken infected with Newcastle Disease.

Highly pathogenic strains (velogenic) of ND cause high mortality with depression and death within 3 to 5 days. Affected chickens do not always exhibit respiratory or nervous signs. Mesogenic strains cause typical signs of respiratory distress.

Laboured breathing with wheezing and gurgling, accompanied by nervous signs, such as paralysis or twisted necks (torticollis) are the main signs. A 30 to 50% drop in egg production, and returning to normal levels in about 2-3 weeks is observed. Eggshell quality will also be affected (thin and loose). In well-vaccinated chicken flocks, clinical signs may be difficult to find.

Vaccination has proven to be a reliable control method. ND is a notifiable disease, and in many countries, the control is based on a combination of obliged vaccination and stamping out in case of outbreaks. A wide range of live and inactivated vaccines are used in vaccination programs to prevent ND.

The new generation of live recombinant HVT-vector vaccines allows early hatchery vaccination and can be used to replace conventional ND vaccination, eliminating vaccination reactions and inducing lifelong protection.

Bio-vac NDC 6/10 vaccine.

There is no specific treatment for ND; antibiotic treatment of secondary bacterial infections (such as E. coli) will reduce the losses.

Supadox 50.

Other Infectious Diseases and Treatments

Other infectious diseases of poultry and their treatment.

Disease name	Clinical signs	Control	Treatment or products
Lymphoid leucosis (big liver disease, visceral leucosis) Lymphoid leucosis (big liver disease visceral leucosis).	Visceral tumours are the main feature of lymphoid leucosis. They can be found in the liver, spleen, kidneys, and bursa of birds that are in general older than 25 weeks. In affected layer flocks a lower egg production can be observed.		No treatment is known. The best control method is the laboratory detection of infected breeders. Eradication of the virus from primary breeding stock is the most effective way of controlling infections in chickens.
Marek’s Disease (MD) Mareks Disease in a chicken.	Infected birds show weight loss or may exhibit some form of paralysis. The classical form of neurolymphomatosis (paralysis) with leg nerve involvement causes a bird to lie on its side with one leg stretched forward and the other backwards. When the gizzard nerve is involved, the birds will have a very small gizzard and intestines and will waste away. Acute Marek’s disease is an epidemic in susceptible or unvaccinated flocks causing depression, paralysis, mortality and lymphomatous infiltrations or tumours in multiple organs. Subclinical infections result in impaired immune responses as MDV causes a lytic infection in lymphocytes. Mortality usually occurs between 10 and 20 weeks of age and can reach up to 50% in unvaccinated flocks.	Vaccination is an effective means of control. It has been demonstrated that the MD vaccine only prevents the appearance of MD tumours and paralysis. It does not prevent the birds from becoming infected with the MD virus. It is therefore of major importance to maintain high hygienic and sanitary measures by good management to avoid early exposure of young chickens. Vaccination against MD is performed in the hatchery. There are two routes of application: in-ovo injection into the18-day embryonated eggs or injection in day-old chickens. For this purpose, different MD vaccines exist. Most used are the Rispens (serotype-1), SB1 (serotype-2) and HVT vaccine strains (serotype-3). The choice of the strains for MD vaccination will depend on the virulence of the strains present in the field.	There is no effective treatment for affected flocks.
Egg Drop Syndrome (EDS) Egg drop syndrome.	EDS affects only layers and breeders at the start of or during their egg production. Affected flocks show a failure to reach peak egg production or a drop in egg production accompanied by an inferior eggshell quality and in the case of brown eggs, a loss of shell colour. Affected birds may also appear to be anaemic, may show transient diarrhoea and sometimes the food intake may be reduced. No increased mortality or other symptoms are observed.	Vaccination with an inactivated vaccine before the point of lay is the only available, effective method for the control of EDS.	There is no treatment against egg drop syndrome.
Inclusion body hepatitis hydropericardium-hepatitis syndrome (HHS) Internal lesions caused by HHS.	Chickens with inclusion body hepatitis are affected at usually 5 to 7 weeks of age. The birds are listless, with ruffled feathers. Mortality is usually quite severe: up to 25 % in the first 10 days of the disease. Internal lesions: affected chickens have enlarged and mottled livers, many with pinpoint necrotic and haemorrhagic spots. Pale bone marrow and, in some cases in the presence of infectious anaemia, gangrenous dermatitis can be seen. Kidneys are pale.	The preferred way of control in endemic areas is to give the breeders a controlled exposure before the onset of lay by using inactivated vaccines related to the appropriate serotype of adenovirus to match the challenge. IBA-vac vaccine.	No treatment exists. Antibiotics can be used to prevent and control secondary bacterial infection and possible gangrenous dermatitis. The best method of control is to ensure adequate immunity against other immune-suppressive diseases (such as infectious bursal disease). Supadox 50.
Avian encephalomyelitis (AE or epidemic tremor) Avian encephalomyelitis in young chickens.	Clinical tremors and increased mortality in young chickens, with a drop in production and hatchability in the breeders or egg production drop in layers are signs related to AE. The disease is mainly seen in young chickens between 1 and 3 weeks of age. Affected chickens sit on their hocks, do not move well, and many fall on their sides. A fine, rapid trembling of the head and neck can be seen, but especially felt when affected chickens are held in the hand. In laying and breeding flocks, AE virus infection causes a marked drop in egg production which returns to normal in about 2-3 weeks. Mortality in naturally infected chickens varies and can be as high as 75%.	Preventive vaccination of breeder pullets and layer pullets with live AE vaccine before egg production is the only effective means of AE control. If a breeder flock has been inadequately or not vaccinated against AE and an outbreak occurs, it is advisable to stop hatching eggs from the flock for several weeks until the breeders have acquired immunity and no longer transmit the AE virus through their eggs.	There is no effective treatment for AE.
Chicken anaemia virus (CAV or blue wing disease) Chicken anaemia virus causes blue wings in poultry.	CAV causes a syndrome in young chicks up to approximately 3 weeks old. Adult birds may get infected but will not develop clinical signs. The disease is characterised by depressed birds, increased mortality and anaemia (pale birds, low haematocrit) and retarded growth. Lesions: thymus atrophy, bone marrow atrophy, and subcutaneous and intramuscular haemorrhages can be found accompanied by atrophy of The lymphoid system: affected birds may show focal skin lesions often complicated by bacterial infection (also known as blue wing disease). Mortality rates vary but generally do not exceed 30%.	Vaccination of breeders with live attenuated CAV vaccine will induce high and uniform maternal derived antibodies (MDA’s) levels and prevent vertical transmission. MDAs will protect the progeny during the susceptible period of life.	No treatment is available for chicken infectious anaemia.
Fowl pox (avian pox, avian diphtheria) Avian pox.	The lesions of fowl pox can be external (mainly on the head) or internal (“wet pox”) in the oral cavity, oesophagus and/or trachea; they can also be found on other parts of the body (skin of legs, cloaca and so forth). The lesions on the head, combs, and wattles are usually wart-like in appearance, and yellow to dark brown in colour. The internal lesions (diphtheria) in the mouth, oesophagus and/or trachea are yellow-white and cheesy in appearance. Affected birds will be depressed, lack appetite and when “wet pox” is present they breathe laboriously. Mortality is variable, from a low 1 to 2%, when slight head lesions are present, to over 40% when the diphtheritic form (“wet pox”) is more prevalent. Reduced egg production can be observed in laying birds, this will return to normal in a few weeks.	Preventive vaccination using a live vaccine is by far the most successful control method. Even when an outbreak of fowl pox has been diagnosed, it is advisable to vaccinate the flock immediately (emergency vaccination) to stop further spreading of the infection.	There is no effective treatment.
Infectious bursal disease (IBD, gumboro disease) Infectious bursal disease.	Clinical IBD occurs usually between 3 and 8 weeks of age depending on maternal antibody levels. Affected birds are listless and depressed, pale, huddling producing watery white diarrhoea. Mortality varies. Usually, new cases of IBD have a mortality rate of about 5 to 10% but can be as high as 60% depending on the pathogenicity of the strain involved. Highly pathogenic strains are called “very virulent” IBD resulting in high mortality. Subclinical IBD occurs with infections before 3 weeks of age. Early IBD infection results in permanent immunosuppression without mortality. Immunosuppression is economically important due to increased susceptibility to secondary infections especially in the respiratory tract. Gumboro disease-related diseases such as inclusion body hepatitis are also more frequent in these birds. In broilers this form of the disease results in bad performance with lower weight gains and higher feed conversion ratios.	Vaccination of breeders and young chicks is the best means of control. The induction of a high maternal immunity in the progeny of Vaccinated breeders, together with the vaccination of the offspring are the most effective approaches to successful IBD control. A variety of live and inactivated vaccines have been developed to enhance the control of classical, variant and IBD challenges. Recently a new generation of recombinant vector vaccines based on HVT-vector carrying an insert of the VP2 part of the IBD-virus entered the market for the control of IBD. normal chicken (IBA-vac vaccine).	No treatment is available for IBD.
Malabsorption syndrome (MAS, runting, stunting syndrome) Malabsorption syndrome.	The disease is mainly observed in broiler flocks. Poor performance, increased FCR, retarded growth and uneven flocks. Many affected broiler flocks have a history of diarrhoea, beginning as early as a few days of age and lasting until 10-14 days of age. Light or dark brown, foamy droppings can be found with undigested food particles. Several Affected broilers in a flock may exhibit malpositioned feathers, especially on the wings. Early rickets with extreme paleness of legs and heads can be observed. Encephalomalacia is also regularly found. Later an important effect is the delayed growth of the affected birds. Mortality is variable and in general as low as 4%	Vaccination against reovirus in the breeders helps to reduce problems in the progeny. Strict hygienic and sanitary measures will reduce the incidence of the disease.	No treatment is available.
Reovirus infections (viral arthritis, tenosynovitis) Reovirus infections.	In young meat-type chickens: increased mortality, arthritis or tenosynovitis, and disuniform flocks resulting in loss of performance and economic losses. The first signs of reovirus infection can be observed in broiler-type chickens between 2 and 10 weeks of age. The birds are reluctant to walk and when forced up have a painful, trembling gait. A distinct swelling of the tendons of the shanks and also above the hock joint can be observed. Affected birds have malpositioned feathers, especially on the wings and are called “helicopter chickens”. Internal lesions: the hock joint may be somewhat swollen, but usually not as severely as with mycoplasma synoviae (MS) or staphylococcus infections. The tendons usually appear discoloured, brown or Blood-tinged, with straw-coloured fluid between them. Ruptured tendons may occur and, in older broiler breeders (29-30 weeks old), one may feel a hard knot in the tendon above the hock joint. When the infection is complicated by mycoplasma synoviae or staphylococcus the fluid may appear yellow and creamy. In layer-type breeders, the disease is not as common as in broiler breeders and broilers.	Besides biosecurity, cleaning and disinfection between the cycles of vaccination of broiler breeders is a must for reovirus control. A good reovirus vaccination programme consists of live (priming) followed by one or two boosting injections with inactivated reovirus vaccines during the rearing period. The goal is to prevent vertical transmission and induce high and Uniform “maternal derived antibodies” (MDA) in the breeders will be passed, via the egg, to the progeny to protect the progeny during the most susceptible period of life.	Reovirus infection cannot be treated successfully, but antibodies are of help in preventing secondary bacterial infections, particularly staphylococcal infections.
Colibacillosis Colibacillosis.	Clinical signs vary depending on specific diseases induced by E. coli. From very mild cellulitis to severe disease, lameness, retarded growth, increased mortality, reduced feed and water intake. Lesions: colisepticemia in combination with polyserositis, salpingitis, osteomyelitis or synovitis, enteritis, meningitis and young birds with omphalitis. Both morbidity and mortality are very variable.	Hygiene management, hatching egg management, E. coli vaccination and vaccination against primary causes like respiratory viruses, coccidiosis, IBD, and CAV.	Antibiotics based on antibiotic sensitivity test.
Fowl cholera (avian cholera, pasteurellosis, Avian haemorrhagic septicaemia) Fowl cholera.	Affected birds are depressed and have decreased appetite. Egg production will drop 5-15 % and mortality will be high in acute fowl cholera. Birds that die from acute fowl cholera frequently have bluish combs and wattles. Chronic fowl cholera will not cause high mortality, although there will be an increase in deaths. Swollen wattles are a feature of chronic fowl cholera. Lesions, acute phase septicaemia, vascular changes in abdominal viscera, haemorrhages, liver swelling with focal necrosis, ovaries appear flaccid and haemorrhagic and show ruptured yolks. Chronic phase: localised infections in the conjunctiva, facial oedema, middle ear infection resulting in torticollis, and meningeal infection.	Hygiene management and rodent control to eliminate possible sources of Pasteurella multocida. Vaccination can be considered in areas where Pasteurella multocida is prevalent. Both live and inactivated vaccines are available.	Antibiotics based on antibiotic sensitivity tests, the earlier the diagnosis, the better chance of a positive effect of an antibiotic treatment. Chlortet 200g.
Infectious synovitis Infectious synovitis.	Staphylococcus aureus is ubiquitous and infections can manifest after the breakdown of the natural defence mechanisms such as wounds, inflammation, and haematogenous dissemination. Signs vary with the site of entry. The most frequently affected tissues are bone, tendon sheaths and joints. The clinical picture includes lameness in one or both legs, ruffled feathers, swollen joints, fever and increased mortality. Lesions, swollen joints, arthritis, peri-arthritis and synovitis, osteomyelitis.	Prevent damage to natural host defence mechanisms. Good litter quality, prevent wounds, hatchery management and sanitation. So far vaccination has not been successful.	Antibiotic treatment based on sensitivity test. Success is not guaranteed. Aivlosin WS.
Necrotic enteritis (NE, clostridial enteritis, enterotoxaemia) Necrotic enteritis.	There are 2 forms of necrotic enteritis (NE), the acute clinical form and the subclinical form. Although it can be seen at any age, the acute clinical form is primarily a disease in young chickens, showing severe depression, reluctance to move, diarrhoea, ruffled feathers and sudden death. The subclinical form produces no outward signs but has a big impact on performance (weight loss, reduced weight gain and impaired FCR). Lesions: necrosis of the mucosa of the small intestine. In the clinical form, the necrosis might progress into a fibrinonectoric enteritis forming a diphtheritic membrane. In the mild form, focal areas of intestinal mucosal necrosis without further clinical signs can be found.	Vaccination of breeders with inactivated vaccines based on toxins inducing active and passive immunity has shown to offer good protection. Maintain microflora balance with management of all related factors: management, coccidiosis control and nutritional factors.	Antibiotic: Tyleco FG 100.
Ornithobacterium rhinotracheale (OR, ORT) Ornithobacterium rhinotracheale.	Or may cause a respiratory disease in turkeys, usually between 2-6 and 12-20 weeks of age. The birds may show respiratory disease with watery eyes and swelling of the sinus infra orbitalis. Broilers may also show respiratory signs after infection around 4 weeks of age. A severe purulent pneumonia, accompanied by airsaculitis and pericarditis may be found in broilers as well as in turkeys. Affected birds also show growth retardation. Concomitant viral infections may intensify the severity of the lesions.	An inactivated vaccine for broiler breeders is available to prevent the disease in the vaccinated birds and provide maternal antibodies to the Offspring of the vaccinated breeders.	Infections are normally treated with broad-spectrum antibiotics with variable degrees of success. Resistance building might force us to perform an antibiotic sensitivity test. Chlortet 200g 25 kg.
Pullorum disease and fowl typhoid Pullorum disease and fowl typhoid.	Birds hatched from S. Pullorum or S. Gallinarum infected eggs appear moribund or dead in the hatching trays and the young birds will show weakness, depressed appetite, poor growth and increased mortality. Older birds show depression. Diarrhoea, ruffled feathers, pale shrunken combs and drop in egg production and increased mortality will be observed. Morbidity and mortality can be highly variable (mortality can reach 25-60%) Lesions, acute phase septicaemia-enlarged and congested liver, spleen and kidneys, pericarditis. Haemorrhages. Livers may show white foci. In adult birds, atrophic ovarian follicles may be found.	Monitoring and eradication in breeders are the preferred control method. For layers, vaccination against fowl typhoid with a special S. Gallinarum (9R strain) has been practised in several countries.	Treatment with antibiotics for pullorum or fowl typhoid disease will not cure but reduce clinical signs and is undesirable from a standpoint of Eradication. It is far more practical to control the disease by eliminating infected carrier breeder hens. Blood testing (monitoring) of breeder Chickens by the serum plate or tube agglutination test with suitable S. Pullorum antigen will detect infected carrier birds which can then be culled. Such control measures will stop the incidence of egg-transmitted Pullorum disease or fowl typhoid. If hatching eggs from tested Pullorum-free breeders are kept free from contamination through Infected eggs from infected breeders or through contaminated equipment, chickens can remain carriers after treatment.
Black head (Histomoniasis, enterohepatitis) Black head.	Affected birds are depressed, stand or sit with ruffled feathers, and have yellowish diarrhoea. Darkening of head parts, especially in turkeys, gave the name to the disease (black head). Gross lesions include circular necrotic areas in livers with a crater-like centre and cheesy cores in the caeca. Blackhead can cause high mortality, particularly in young turkey poults, but the disease can also affect older birds. In chickens, the mortality from blackhead infection is usually lower, young chickens being the most susceptible.		Treatment with protozoan chemotherapeutics is usually effective. Such drugs can also be given at preventive levels in turkey starter and grower feed. Growing turkeys on wire and indoors can reduce the incidence of blackhead to a large extent, but even so, strict hygiene and elimination of caecal worms are important control measures.
Coccidiosis Coccidiosis.	Clinical signs vary by the species infecting the flock. Some species, such as E. Acervulina and E. Maxima have a severe negative effect on weight gain and feed conversion, particularly E. Maxima, these species do not cause obvious morbidity unless the infection is moderately severe. Mortality in field cases of these species is rare unless complicated by secondary infection with clostridium perfringens (necrotic enteritis). Other species such as E. Tenella, E. Necatrix and E. Brunetti can induce sick and listless birds in combination with high mortality.	Anticoccidial chemicals effectively suppress sensitive Eimeria spp. populations, but complete resistance to these drugs develops very quickly sometimes during a single broiler flock cycle. Therefore, most coccidiosis control programs do not rely on chemical anticoccidials. Chemicals, particularly in liquid preparations, are largely used for the treatment of clinical outbreaks. Most effective coccidiosis prevention and control programs depend upon flock immunity. One method to develop controlled immunity is via feed medication with ionophore antibiotics. The ionophores reduce coccidiosis multiplication, allowing natural immunity to develop while preventing clinical outbreaks. Over time, the Eimeria field populations become less sensitive to these medications, resulting in subclinical coccidiosis or even clinical outbreaks before complete immunity can develop. To slow the loss of sensitivity, broiler producers employ shuttle medication programs (a chemical in the starter feed followed by an ionophore in the remaining feeds) and rotational programs (changing the feed medications to slow the loss of sensitivity to a single medication). This strategy was most effective when new medications were periodically introduced. Unfortunately, since the year 2000, no new medications have been introduced to the market and sensitivity to medications has declined. Another method to develop controlled immunity is coccidiosis vaccination with live attenuated or naturally selected strain sporulated oocyst vaccines. Vaccination is already used almost exclusively for coccidiosis control in long-life birds such as breeding and egg-laying populations. Routine vaccination of broilers against coccidiosis is increasing and may eventually replace controlled immunity via feed medication.	Good management skills and proper biosecurity programs must be in place. Sulfamethazine 16% and give Modulin aves 100g treats 10 k birds. 1 g/100 broilers in water

Disease name

Clinical signs

Control

Treatment or products

Lymphoid leucosis (big liver disease, visceral leucosis)

Lymphoid leucosis (big liver disease visceral leucosis).

Visceral tumours are the main feature of lymphoid leucosis. They can be found in the liver, spleen, kidneys, and bursa of birds that are in general older than 25 weeks. In affected layer flocks a lower egg production can be observed.

No treatment is known. The best control method is the laboratory detection of infected breeders. Eradication of the virus from primary breeding stock is the most effective way of controlling infections in chickens.

Marek’s Disease

(MD)

Mareks Disease in a chicken.

Infected birds show weight loss or may exhibit some form of paralysis.

The classical form of neurolymphomatosis (paralysis) with leg nerve involvement causes a bird to lie on its side with one leg stretched forward and the other backwards. When the gizzard nerve is involved, the birds will have a very small gizzard and intestines and will waste away.

Acute Marek’s disease is an epidemic in susceptible or unvaccinated flocks causing depression, paralysis, mortality and lymphomatous infiltrations or tumours in multiple organs. Subclinical infections result in impaired immune responses as MDV causes a lytic infection in lymphocytes.

Mortality usually occurs between 10 and 20 weeks of age and can reach up to 50% in unvaccinated flocks.

Vaccination is an effective means of control. It has been demonstrated that the MD vaccine only prevents the appearance of MD tumours and paralysis. It does not prevent the birds from becoming infected with the MD virus. It is therefore of major importance to maintain high hygienic and sanitary measures by good management to avoid early exposure of young chickens.

Vaccination against MD is performed in the hatchery. There are two routes of application: in-ovo injection into the18-day embryonated eggs or injection in day-old chickens.

For this purpose, different MD vaccines exist. Most used are the Rispens (serotype-1), SB1 (serotype-2) and HVT vaccine strains (serotype-3).

The choice of the strains for MD vaccination will depend on the virulence of the strains present in the field.

There is no effective treatment for affected flocks.

Egg Drop Syndrome (EDS)

Egg drop syndrome.

EDS affects only layers and breeders at the start of or during their egg production. Affected flocks show a failure to reach peak egg production or a drop in egg production accompanied by an inferior eggshell quality and in the case of brown eggs, a loss of shell colour.

Affected birds may also appear to be anaemic, may show transient diarrhoea and sometimes the food intake may be reduced. No increased mortality or other symptoms are observed.

Vaccination with an inactivated vaccine before the point of lay is the only available, effective method for the control of EDS.

There is no treatment against egg drop syndrome.

Inclusion body hepatitis hydropericardium-hepatitis syndrome (HHS)

Internal lesions caused by HHS.

Chickens with inclusion body hepatitis are affected at usually 5 to 7 weeks of age. The birds are listless, with ruffled feathers. Mortality is usually quite severe: up to 25 % in the first 10 days of the disease.

Internal lesions: affected chickens have enlarged and mottled livers, many with pinpoint necrotic and haemorrhagic spots. Pale bone marrow and, in some cases in the presence of infectious anaemia, gangrenous dermatitis can be seen. Kidneys are pale.

The preferred way of control in endemic areas is to give the breeders a controlled exposure before the onset of lay by using inactivated vaccines related to the appropriate serotype of adenovirus to match the challenge.

IBA-vac vaccine.

No treatment exists. Antibiotics can be used to prevent and control secondary bacterial infection and possible gangrenous dermatitis.

The best method of control is to ensure adequate immunity against other immune-suppressive diseases (such as infectious bursal disease).

Supadox 50.

Avian encephalomyelitis (AE or epidemic tremor)

Avian encephalomyelitis in young chickens.

Clinical tremors and increased mortality in young chickens, with a drop in production and hatchability in the breeders or egg production drop in layers are signs related to AE.

The disease is mainly seen in young chickens between 1 and 3 weeks of age. Affected chickens sit on their hocks, do not move well, and many fall on their sides. A fine, rapid trembling of the head and neck can be seen, but especially felt when affected chickens are held in the hand. In laying and breeding flocks, AE virus infection causes a marked drop in egg production which returns to normal in about 2-3 weeks. Mortality in naturally infected chickens varies and can be as high as 75%.

Preventive vaccination of breeder pullets and layer pullets with live AE vaccine before egg production is the only effective means of AE control. If a breeder flock has been inadequately or not vaccinated against AE and an outbreak occurs, it is advisable to stop hatching eggs from the flock for several weeks until the breeders have acquired immunity and no longer transmit the AE virus through their eggs.

There is no effective treatment for AE.

Chicken anaemia virus (CAV or blue wing disease)

Chicken anaemia virus causes blue wings in poultry.

CAV causes a syndrome in young chicks up to approximately 3 weeks old. Adult birds may get infected but will not develop clinical signs.

The disease is characterised by depressed birds, increased mortality and anaemia (pale birds, low haematocrit) and retarded growth.

Lesions: thymus atrophy, bone marrow atrophy, and subcutaneous and intramuscular haemorrhages can be found accompanied by atrophy of

The lymphoid system: affected birds may show focal skin lesions often complicated by bacterial infection (also known as blue wing disease).

Mortality rates vary but generally do not exceed 30%.

Vaccination of breeders with live attenuated CAV vaccine will induce high and uniform maternal derived antibodies (MDA’s) levels and prevent vertical transmission.

MDAs will protect the progeny during the susceptible period of life.

No treatment is available for chicken infectious anaemia.

Fowl pox (avian pox, avian diphtheria)

Avian pox.

The lesions of fowl pox can be external (mainly on the head) or internal (“wet pox”) in the oral cavity, oesophagus and/or trachea; they can also be found on other parts of the body (skin of legs, cloaca and so forth). The lesions on the head, combs, and wattles are usually wart-like in appearance, and yellow to dark brown in colour. The internal lesions (diphtheria) in the mouth, oesophagus and/or trachea are yellow-white and cheesy in appearance. Affected birds will be depressed, lack appetite and when “wet pox” is present they breathe laboriously.

Mortality is variable, from a low 1 to 2%, when slight head lesions are present, to over 40% when the diphtheritic form (“wet pox”) is more prevalent. Reduced egg production can be observed in laying birds, this will return to normal in a few weeks.

Preventive vaccination using a live vaccine is by far the most successful control method. Even when an outbreak of fowl pox has been diagnosed, it is advisable to vaccinate the flock immediately (emergency vaccination) to stop further spreading of the infection.

There is no effective treatment.

Infectious bursal disease (IBD, gumboro disease)

Infectious bursal disease.

Clinical IBD occurs usually between 3 and 8 weeks of age depending on maternal antibody levels. Affected birds are listless and depressed, pale, huddling producing watery white diarrhoea. Mortality varies.

Usually, new cases of IBD have a mortality rate of about 5 to 10% but can be as high as 60% depending on the pathogenicity of the strain involved. Highly pathogenic strains are called “very virulent” IBD resulting in high mortality.

Subclinical IBD occurs with infections before 3 weeks of age. Early IBD infection results in permanent immunosuppression without mortality.

Immunosuppression is economically important due to increased susceptibility to secondary infections especially in the respiratory tract.

Gumboro disease-related diseases such as inclusion body hepatitis are also more frequent in these birds. In broilers this form of the disease results in bad performance with lower weight gains and higher feed conversion ratios.

Vaccination of breeders and young chicks is the best means of control.

The induction of a high maternal immunity in the progeny of

Vaccinated breeders, together with the vaccination of the offspring are the most effective approaches to successful IBD control. A variety of live and inactivated vaccines have been developed to enhance the control of classical, variant and IBD challenges.

Recently a new generation of recombinant vector vaccines based on

HVT-vector carrying an insert of the VP2 part of the IBD-virus entered the market for the control of IBD. normal chicken (IBA-vac vaccine).

No treatment is available for IBD.

Malabsorption syndrome (MAS, runting, stunting syndrome)

Malabsorption syndrome.

The disease is mainly observed in broiler flocks. Poor performance, increased FCR, retarded growth and uneven flocks. Many affected broiler flocks have a history of diarrhoea, beginning as early as a few days of age and lasting until 10-14 days of age. Light or dark brown, foamy droppings can be found with undigested food particles. Several

Affected broilers in a flock may exhibit malpositioned feathers, especially on the wings. Early rickets with extreme paleness of legs and heads can be observed. Encephalomalacia is also regularly found. Later an important effect is the delayed growth of the affected birds. Mortality is variable and in general as low as 4%

Vaccination against reovirus in the breeders helps to reduce problems in the progeny.

Strict hygienic and sanitary measures will reduce the incidence of the disease.

No treatment is available.

Reovirus infections (viral arthritis, tenosynovitis)

Reovirus infections.

In young meat-type chickens: increased mortality, arthritis or tenosynovitis, and disuniform flocks resulting in loss of performance and economic losses.

The first signs of reovirus infection can be observed in broiler-type chickens between 2 and 10 weeks of age. The birds are reluctant to walk and when forced up have a painful, trembling gait. A distinct swelling of the tendons of the shanks and also above the hock joint can be observed. Affected birds have malpositioned feathers, especially on the wings and are called “helicopter chickens”.

Internal lesions: the hock joint may be somewhat swollen, but usually not as severely as with mycoplasma synoviae (MS) or staphylococcus infections. The tendons usually appear discoloured, brown or

Blood-tinged, with straw-coloured fluid between them. Ruptured tendons may occur and, in older broiler breeders (29-30 weeks old), one may feel a hard knot in the tendon above the hock joint.

When the infection is complicated by mycoplasma synoviae or staphylococcus the fluid may appear yellow and creamy. In layer-type breeders, the disease is not as common as in broiler breeders and broilers.

Besides biosecurity, cleaning and disinfection between the cycles of vaccination of broiler breeders is a must for reovirus control. A good reovirus vaccination programme consists of live (priming) followed by one or two boosting injections with inactivated reovirus vaccines during the rearing period. The goal is to prevent vertical transmission and induce high and

Uniform “maternal derived antibodies” (MDA) in the breeders will be passed, via the egg, to the progeny to protect the progeny during the most susceptible period of life.

Reovirus infection cannot be treated successfully, but antibodies are of help in preventing secondary bacterial infections, particularly staphylococcal infections.

Colibacillosis

Colibacillosis.

Clinical signs vary depending on specific diseases induced by E. coli.

From very mild cellulitis to severe disease, lameness, retarded growth, increased mortality, reduced feed and water intake.

Lesions: colisepticemia in combination with polyserositis, salpingitis, osteomyelitis or synovitis, enteritis, meningitis and young birds with omphalitis.

Both morbidity and mortality are very variable.

Hygiene management, hatching egg management, E. coli vaccination and vaccination against primary causes like respiratory viruses, coccidiosis, IBD, and CAV.

Antibiotics based on antibiotic sensitivity test.

Fowl cholera (avian cholera, pasteurellosis, Avian haemorrhagic septicaemia)

Fowl cholera.

Affected birds are depressed and have decreased appetite. Egg production will drop 5-15 % and mortality will be high in acute fowl cholera. Birds that die from acute fowl cholera frequently have bluish combs and wattles. Chronic fowl cholera will not cause high mortality, although there will be an increase in deaths. Swollen wattles are a feature of chronic fowl cholera.

Lesions, acute phase septicaemia, vascular changes in abdominal viscera, haemorrhages, liver swelling with focal necrosis, ovaries appear flaccid and haemorrhagic and show ruptured yolks.

Chronic phase: localised infections in the conjunctiva, facial oedema, middle ear infection resulting in torticollis, and meningeal infection.

Hygiene management and rodent control to eliminate possible sources of Pasteurella multocida.

Vaccination can be considered in areas where Pasteurella multocida is prevalent. Both live and inactivated vaccines are available.

Antibiotics based on antibiotic sensitivity tests, the earlier the diagnosis, the better chance of a positive effect of an antibiotic treatment.

Chlortet 200g.

Infectious synovitis

Infectious synovitis.

Staphylococcus aureus is ubiquitous and infections can manifest after the breakdown of the natural defence mechanisms such as wounds, inflammation, and haematogenous dissemination.

Signs vary with the site of entry. The most frequently affected tissues are bone, tendon sheaths and joints.

The clinical picture includes lameness in one or both legs, ruffled feathers, swollen joints, fever and increased mortality. Lesions, swollen joints, arthritis, peri-arthritis and synovitis, osteomyelitis.

Prevent damage to natural host defence mechanisms. Good litter quality, prevent wounds, hatchery management and sanitation.

So far vaccination has not been successful.

Antibiotic treatment based on sensitivity test. Success is not guaranteed.

Aivlosin WS.

Necrotic enteritis (NE, clostridial enteritis, enterotoxaemia)

Necrotic enteritis.

There are 2 forms of necrotic enteritis (NE), the acute clinical form and the subclinical form.

Although it can be seen at any age, the acute clinical form is primarily a disease in young chickens, showing severe depression, reluctance to move, diarrhoea, ruffled feathers and sudden death. The subclinical form produces no outward signs but has a big impact on performance (weight loss, reduced weight gain and impaired FCR).

Lesions: necrosis of the mucosa of the small intestine. In the clinical form, the necrosis might progress into a fibrinonectoric enteritis forming a diphtheritic membrane.

In the mild form, focal areas of intestinal mucosal necrosis without further clinical signs can be found.

Vaccination of breeders with inactivated vaccines based on toxins inducing active and passive immunity has shown to offer good protection.

Maintain microflora balance with management of all related factors: management, coccidiosis control and nutritional factors.

Antibiotic:

Tyleco FG 100.

Ornithobacterium rhinotracheale (OR, ORT)

Ornithobacterium rhinotracheale.

Or may cause a respiratory disease in turkeys, usually between 2-6 and 12-20 weeks of age. The birds may show respiratory disease with watery eyes and swelling of the sinus infra orbitalis. Broilers may also show respiratory signs after infection around 4 weeks of age.

A severe purulent pneumonia, accompanied by airsaculitis and pericarditis may be found in broilers as well as in turkeys. Affected birds also show growth retardation. Concomitant viral infections may intensify the severity of the lesions.

An inactivated vaccine for broiler breeders is available to prevent the disease in the vaccinated birds and provide maternal antibodies to the

Offspring of the vaccinated breeders.

Infections are normally treated with broad-spectrum antibiotics with variable degrees of success.

Resistance building might force us to perform an antibiotic sensitivity test.

Chlortet 200g 25 kg.

Pullorum disease and fowl typhoid

Pullorum disease and fowl typhoid.

Birds hatched from S. Pullorum or S. Gallinarum infected eggs appear moribund or dead in the hatching trays and the young birds will show weakness, depressed appetite, poor growth and increased mortality.

Older birds show depression. Diarrhoea, ruffled feathers, pale shrunken combs and drop in egg production and increased mortality will be observed. Morbidity and mortality can be highly variable (mortality can reach 25-60%)

Lesions, acute phase septicaemia-enlarged and congested liver, spleen and kidneys, pericarditis.

Haemorrhages. Livers may show white foci. In adult birds, atrophic ovarian follicles may be found.

Monitoring and eradication in breeders are the preferred control method.

For layers, vaccination against fowl typhoid with a special S. Gallinarum (9R strain) has been practised in several countries.

Treatment with antibiotics for pullorum or fowl typhoid disease will not cure but reduce clinical signs and is undesirable from a standpoint of

Eradication. It is far more practical to control the disease by eliminating infected carrier breeder hens. Blood testing (monitoring) of breeder

Chickens by the serum plate or tube agglutination test with suitable

S. Pullorum antigen will detect infected carrier birds which can then be culled.

Such control measures will stop the incidence of egg-transmitted Pullorum disease or fowl typhoid. If hatching eggs from tested Pullorum-free breeders are kept free from contamination through

Infected eggs from infected breeders or through contaminated equipment, chickens can remain carriers after treatment.

Black head (Histomoniasis, enterohepatitis)

Black head.

Affected birds are depressed, stand or sit with ruffled feathers, and have yellowish diarrhoea. Darkening of head parts, especially in turkeys, gave the name to the disease (black head). Gross lesions include circular necrotic areas in livers with a crater-like centre and cheesy cores in the caeca. Blackhead can cause high mortality, particularly in young turkey poults, but the disease can also affect older birds. In chickens, the mortality from blackhead infection is usually lower, young chickens being the most susceptible.

Treatment with protozoan chemotherapeutics is usually effective.

Such drugs can also be given at preventive levels in turkey starter and grower feed. Growing turkeys on wire and indoors can reduce the incidence of blackhead to a large extent, but even so, strict hygiene and elimination of caecal worms are important control measures.

Coccidiosis

Coccidiosis.

Clinical signs vary by the species infecting the flock. Some species, such as E. Acervulina and E. Maxima have a severe negative effect on weight gain and feed conversion, particularly E. Maxima, these species do not cause obvious morbidity unless the infection is moderately severe. Mortality in field cases of these species is rare unless complicated by secondary infection with clostridium perfringens (necrotic enteritis). Other species such as

E. Tenella, E. Necatrix and E. Brunetti can induce sick and listless birds in combination with high mortality.

Anticoccidial chemicals effectively suppress sensitive Eimeria spp. populations, but complete resistance to these drugs develops very quickly sometimes during a single broiler flock cycle. Therefore, most coccidiosis control programs do not rely on chemical anticoccidials. Chemicals, particularly in liquid preparations, are largely used for the treatment of clinical outbreaks.

Most effective coccidiosis prevention and control programs depend upon flock immunity.

One method to develop controlled immunity is via feed medication with ionophore antibiotics. The ionophores reduce coccidiosis multiplication, allowing natural immunity to develop while preventing clinical outbreaks. Over time, the Eimeria field populations become less sensitive to these medications, resulting in subclinical coccidiosis or even clinical outbreaks before complete immunity can develop.

To slow the loss of sensitivity, broiler producers employ shuttle medication programs (a chemical in the starter feed followed by an ionophore in the remaining feeds) and rotational programs (changing the feed medications to slow the loss of sensitivity to a single medication). This strategy was most effective when new medications were periodically introduced. Unfortunately, since the year 2000, no new medications have been introduced to the market and sensitivity to medications has declined.

Another method to develop controlled immunity is coccidiosis vaccination with live attenuated or naturally selected strain sporulated oocyst vaccines. Vaccination is already used almost exclusively for coccidiosis control in long-life birds such as breeding and egg-laying populations. Routine vaccination of broilers against coccidiosis is increasing and may eventually replace controlled immunity via feed medication.

Good management skills and proper biosecurity programs must be in place.

Sulfamethazine 16% and give Modulin aves 100g treats 10 k birds.

1 g/100 broilers in water

Parasites and Treatments

Parasites in poultry and their treatment.

Disease name

Clinical signs

Control

Treatment or products

Red mite

Red mites on poultry.

Blood loss leading to anaemia, irritation and stress due to disturbed sleep, and increased feed intake are signs of red mites.

Blood spots on eggs result in egg downgrading. Higher infestations lead to lowered egg production. Red mites can act as vectors for bacterial and viral diseases. In humans, skin irritations and itching allergies may appear.

Poultry house hygiene and whole flock replacement rather than partial culling. Cleaning thoroughly after removing the previous flock, avoid bringing in new mites: via egg cases, egg trays, egg containers, transport equipment, passive transmission by people, vaccination crew, rodents or wild birds.

Insecticides, some products can be used in populated poultry houses against Dermanyssus gallinae, some are only allowed after cleaning in an empty farm. Resistance of red mites to used products can be a problem.

Worms

Worms which infect poultry.

Mature roundworms are not a major cause of disease, but the larvae can damage the intestinal lining, causing enteritis, anaemia, decreased egg production and some eggs with pale yolks. Capillaria causes more damage to the intestinal lining and can cause enteritis and anaemia with decreased egg production and the appearance of pale egg yolks (“platinum yolks”). Caecal worms are found in the caeca and do not cause serious damage, except that their eggs can transmit blackhead (histomonas) –mainly in turkeys.

Tapeworms are infrequently found and do not cause serious damage, except that they use the nutrients of the host chicken affecting economic performance.

Prevent egg loading by strategic deworming and removing infected litter after each cycle.

Roundworms and caecal worm infections can be treated with anthelmintics (piperazine and fenbendazole). Piperazine is not effective against tapeworms and capillaria for which other anthelmintics are required.

Eradiworm concentrate.
Ostridose.
Eradiworm plus.
Eradiworm+ tape.

Vitamin Deficiency Diseases and Treatments

Vitamin deficiency diseases in poultry and their treatment.

Disease name	Clinical signs	Control	Treatment or products
Riboflavin (vitamin B2) deficiency (curly toe disease) Riboflavin deficiency causes curly toe disease.	Young chicks, as early as 1 week old, exhibit curling of the toes, inability to walk and sometimes diarrhoea.	Administering vitamin B preparations brings a rapid cure. Only in advanced cases will birds be dehydrated and emaciated, requiring further treatment. It is important to ensure adequate vitamin B levels not only in starter and grower diets but also in the diet of parent breeders.	Afrivit-p. Flaveco-80 20 kg. Betmint 1 litre.
Vitamin D3 deficiency (rickets, “rubber legs”) Vitamin D3 deficiency.	Young chickens 2 to 5 weeks of age with vitamin D3 deficiency are unable to stand and have very soft, pliable, legs and beaks. The rib joints are swollen like beads and curved inward, and the breastbone is often twisted. In layer chickens, vitamin D3 deficiency causes soft-shelled eggs and a drop in production.	Vitamin D3 can be given as treatment, usually in combination with calcium and phosphorus.	Afrivit-p. Flaveco 80 20 kg.
Vitamin E deficiency (crazy chick disease, encephalomalacia) Vitamin E deficiency.	Vitamin E deficiency in chickens affects the brain, causing degeneration, oedema and haemorrhage, especially in the small brain (cerebellum). Affected young chicks appear unable to walk, they fall on their sides or stand with their heads between their legs. The cerebellum shows gross swelling, with yellow or brown discoloration and pinpoint haemorrhages may be observed. Encephalomalacia can also be found in mature chickens.	Adequate levels of vitamin E and selenium in the diet of chickens and their parent breeders are of prime importance. Treatment of affected birds with vitamin E preparations (alpha-tocopherol) is effective if the condition is not too advanced.	Afrivit-p. Flaveco 80 20 kg.

Vaccination Programme for Broilers

Vaccination programme for broilers.

Age (days)	Disease	Route	Vaccine	Notes
0-1 Day	Infectious Bronchitis	Coarse spray or drinking water	BI-VAC 1	Water treatment
0-1 Day	New Castle Disease	Coarse spray or drinking water	BIO-VAC NDV 6/10	Water treatment
Day 14	Infectious Bursal Disease (Gumboro, IBD)	Drinking water	IBA-VAC	Water treatment
Day 14	New Castle Disease	Drinking water	BIO-VAC NDV 6/10	Water treatment
Day 18	Infectious Bursal Disease (Gumboro, IBD)	Drinking water	IBA-VAC	Water treatment
Day 25	New Castle Disease	Drinking water	BIO-VAC NDV 6/10	Water treatment

Vaccination Programme for Layers

Vaccination programme for layers.

Age	Vaccine, medication or action	Fatro vaccines	Route and dose	Monitoring	Supplier
Hatch Day 0	MAREK-VAC BIVALENT FROZEN	Frozen live bivalent vaccine against Mareks Disease.	0.2 ml sub cut at hatchery		Afrivet
	BIO-VAC NDV 6/10	Freeze-dried live vaccine against New Castle Disease	Coarse spray (mix)		Afrivet
	BI-VAC 1°	Freeze-dried live vaccine against Infectious Bronchitis	Coarse spray (mix)		Afrivet
Day 1 (only if no Marek’s vaccine was given at Hatchery)	BIO-MAREK HVT	Freeze-dried live vaccine against Marek’s disease FC-126 strain	0.2 ml subcutaneous		Afrivet
Day 1	Immucox	Vaccination against Coccidiosis	Spray		Ceva
Day 14	IBA-VAC	Freeze-dried live vaccine against Infectious Bursal Disease (Gumboro)	Drinking water (mix)		Afrivet
Day 14	BI-VAC 1° and BIO-VAC NDV 6/10	Freeze-dried live vaccine against Infectious Bronchitis and New Castle Disease	Drinking water (mix)		Afrivet
Day 21	IBA-VAC	Freeze-dried live vaccine against Infectious Bursal disease (Gumboro disease)	Drinking water (mix)		Afrivet
Day 28	Poulvac E. coli		Spray (mix)		Zoetis
Day 28	Nobis MA5+ Clone 30		Spray (mix)		MSD
5 weeks 35 days	BIO-VAC SGP695	Live attenuated vaccine against Fowl Typhoid Ms Gallinarium or pullorum)	Drinking water		Afrivet
6 weeks 42 days	Vaxsafe MS		Eye drop (mix)		MSD
	LTI Vax ASL		Eye drop (mix)		MSD
	Poulvac AE+ Pox		Wingstab		Zoetis
8 weeks 56 days	BIO-VAC NDV 6/10	Freeze-dried live vaccine against Infectious Bronchitis and New Castle Disease	Spray		Afrivet
	Poulvac IB GX		Spray (mix)		Zoetis
	Poulvac E. coli		Spray (mix)		Zoetis
10 weeks 70 days	SET-VAC	Inactivated Salmonella enteritis and Salmonella Myphimurium)	0.5 ml intramuscular	0.5 ml	Afrivet
10 weeks 70 days	OLVAC B+HG	Inactivated vaccine against NCD/IB and IC (A1 and C2)	0.5 ml intramuscular	0.5 ml	Afrivet
12 weeks 84 days	Avipro MGF		Eye drop (mix)		Elanco
	LTIVax ASL		Eye drop (mix)		MSD
	Volvac AC P		0.5 ml intramuscular	0.5 ml	Boehringer
15 weeks 105 days	BIO-VAC LA SOTA	Freeze-dried live vaccine against Newcastle disease	Spray		Afrivet
	Nobilis IB		Spray (mix)		MSD
	Poulvac E. coli		Spray		Zoetis
	CORI-VAC	Inactivated vaccine against Infectious Coryza	0.3 ml intramuscular	0.3 ml	Afrivet
18 weeks 125 days	BIO-VAC SGP 695	Inactivated vaccine against Fowl Typhoid	Drinking water		Afrivet