November 2007

This fact sheet discusses the general basics of poultry disease management and prevention.  Diseases common in more than one poultry species are also discussed.

Sanitation

Appropriate sanitation and disinfection measures will help to prevent disease transfer from the old flock to the new one.

One of the key preventative measures for poultry diseases is proper sanitation.  It is important to thoroughly clean empty rooms between flocks and remove any visible manure and dirt.  All feeding, watering, and ventilation equipment should also be cleaned.

Following cleaning and prior to chick placement, the grow-out area should be treated with a disinfectant.  Disinfectants are most effective when used on clean surfaces free of organic material such as straw and manure.  Disinfectants can be obtained by consulting a veterinarian clinic or agricultural supply centre.  Leaving the chicken house empty for about two to three weeks will also help eliminate or reduce the population of infectious organisms. 

If outdoor runs are used, they also should be kept clean.  Disinfection is difficult, but it is beneficial to allow the area to dry thoroughly prior to bird placement.  It is also important to keep the area as dry as possible when birds are present.  This can be accomplished by alternating runs.

Isolation

Isolating poultry flocks from other animals reduces the opportunity for disease transmission.  Young birds should be isolated from older birds if more than one age group is present on the farm.  Steps should be taken to keep wild birds, rodents, insects and pets away from poultry.  Humans can also transmit diseases from pet birds to a poultry flock.

Any dead birds should be removed and disposed of promptly according to provincial regulations.  If a poultry disease is suspected, birds should be submitted to a provincial diagnostics lab.  Prairie Diagnostic Services has offices in Regina, phone (306) 787-6435, and Saskatoon, phone (306) 966-7316.

Vaccination

If birds are being kept for an extended period of time, it may be appropriate to vaccinate for various infectious diseases.  Vaccination introduces an organism, either live or dead, which will stimulate an immune response in the bird.  If successful, a bird that is later challenged with the disease will be able to resist it. 

A local veterinarian may be consulted for information regarding diseases that may be present in your area.  All chickens kept longer than six weeks of age should be vaccinated for Marek's disease at the hatchery.  Marek's disease is caused by a virus and is characterized by nervous disorders and tumours in the major internal organs.  There is usually a high incidence of death and condemnations at slaughter.

For more information about bird health, and the prevention and detection of disease, see the Canadian Food Inspection Agency website at

www.inspection.gc.ca/english/anima/heasan/disemala/avflu/bacdoc/floelee.shtml.

Medications

Caution must be exercised when using any medication, as medications effective for one species may cause mortality in another species. For example, a medication used to treat poultry may kill dogs and horses, and medication effective for broilers may be harmful to ducks and geese.  Withdrawal times prior to slaughter or product ingestion must be respected.  Consult the feed supplier or veterinarian for instructions or check the feed bag for information regarding withdrawal times.

Brooding

Good brooding management and adequate placement of feed and water will reduce the number of young birds that die of starvation or dehydration in the first few days.  Feed and water must be placed at a level accessible to the birds.  Room temperature is also important.  Young birds should not be over-heated or chilled during transport or during the first few weeks of brooding.  Information on brooding and rearing is available in the General Brooding and Rearing Poultry Fact Sheet.

Air Quality

Maintaining consistently good air quality will help to prevent respiratory diseases and can be accomplished by proper ventilation of the poultry building.  Fans or open windows are needed to remove excess moisture, reduce ammonia levels, and reduce the amount of dust in the air.  High levels of ammonia and dust can damage lung tissue, thereby increasing susceptibility to respiratory disease.  At approximately 10 to 15 parts per million (ppm), a person can detect ammonia.   Levels over 20 ppm will cause eyes to water, and, as the ammonia concentration increases (>25 ppm), it can adversely affect birds.

Nutrition 

Balanced diets that contain adequate nutrients are important in disease prevention.  Nutrient deficiencies can cause disease or make birds more susceptible to infectious and non-infectious diseases.  Nutrient deficiency problems in small flocks are commonly related to imbalances in protein, vitamin A, vitamin D, calcium, and phosphorus.  Examples of nutrient deficient conditions are rickets and vitamin A deficiency.

Rickets

Rickets can occur in young birds due to insufficient vitamin D₃, calcium and/or phosphorus.  Commercial feeds and supplements provide these nutrients, but if they are diluted or mixed inappropriately on farm, deficiencies may occur.

A deficiency of vitamin D₃, calcium and/or phosphorus may also lead to problems with egg laying birds.  Egg production may be reduced and/or the quality of the egg shell may be poor.  In severe cases, hens may be affected with a disease called cage-layer fatigue, also called brittle-bone disease or osteoporosis, which is not usually found in birds raised on floors.

Vitamin A Deficiency

Vitamin A deficiency is a common nutritional deficiency in small flocks.  Vitamin A is normally ingested with greenfeed in the summer and is also stored for short periods of time in the liver.  Once summer greenfeed is unavailable, birds become deficient unless they are given a vitamin supplement.  Deficiencies are most prevalent in the fall if the birds have been grain fed only and/or not allowed to forage. 

Symptoms of vitamin A deficiency include staggering, thinness, paleness and blindness.  Blood spots may also be seen in the eggs of laying birds.  If diagnosed early, birds will respond to vitamin supplementation.

For more information, refer to the General Nutrition Poultry Fact Sheet.

Poison Access 

Care should be taken to remove or prevent access to poisons located in areas that the birds can access.  Poisonous substances include insecticides, pesticides, anti-freeze (ethylene glycol), lead, and misused medications.  Mouldy feed can also cause problems due to the mycotoxins produced by the mould.

Parasites are organisms that grow and feed on birds.  Common parasitic conditions affecting poultry are coccidiosis, histomoniasis, mites and lice.

Coccidiosis

Coccidiosis is a parasitic infection (protozoan) common to birds which have access to their own litter.  Once coccidiosis is present, it is difficult to eradicate, but the infection will be less severe if litter is kept reasonably dry.

Coccidiosis causes a reduction in bird growth and/or production because the parasite invades intestinal tissue and interferes with nutrient digestion and absorption.  Diarrhoea and/or bloody droppings may be seen, depending on the causative organism.  However, these symptoms may also be related to other diseases.  Severe coccidial infections can cause mortality. 

Medication (coccidiostats) can be added to feed to prevent coccidiosis.  If birds are to be kept for an extended period of time, it may be beneficial to gradually induce immunity to coccidiosis.  Developing immunity is especially important for egg-production birds because eggs cannot be eaten for a period of time after laying hens are fed a diet containing coccidiostats.  Developing immunity is also more economical compared to the cost of treating a coccidiosis outbreak. 

The process of inducing immunity begins by using lower-strength coccidiostats in the starter feed, and then eliminating them altogether.  The birds become mildly infected with coccidiosis and gradually develop natural immunity.  The birds should be watched carefully once the medication is removed just in case a severe infection develops.  If symptoms such as diarrhoea, droopiness, ruffled feathers, and listlessness are observed, a mild medication can be provided in the water to combat the infection.

Histomoniasis

Histomoniasis, also referred to as Blackhead, is a parasitic infection (protozoan) which attacks the digestive tract and liver of turkeys and causes considerable mortality.  The organism survives by living in caecal worms in the birds and/or in earthworms in the soil.  Chickens can also be carriers of the organism, but do not get sick.  Therefore, raising turkeys where there were or are chickens should be avoided.  Once the organism infects a farm, it is difficult to eradicate. 

Affected birds appear sick and depressed.  Their heads are dark, and droppings are yellow and frothy.  Severe cases will cause substantial mortality.

There is no medication available in Canada to treat Blackhead in meat producing turkeys.  However, if it is known to be present on the farm, preventative drugs called histomonastats can be prescribed for the feed.

Mites

There are two common mites that infest poultry: the northern fowl mite and the red mite. Northern fowl mites are small, black, blood-sucking insects.  The red poultry mite is similar to the northern fowl mite, but resides only on the birds while feeding and is more likely found in crevasses on perches or nest boxes. 

If mite infestation is extensive, birds become anemic and may die.  Generally, infestation is more likely to result in reduced egg production in laying hens.  Mites can infest wild birds other than poultry.  The mites do not survive long without a host bird, so leaving the chicken house empty between flocks is an effective procedure for eradicating mites.  Insecticides can also be used.

Birds can be checked for mites by examining areas under the wings and around the vent.  Another method is to ruffle feathers over a piece of white paper.  Mites falling onto the paper will look like mobile specks of pepper.

Lice

Lice are not as common as mites.  They feed on skin follicles and their egg clusters show up as white spots at the base of wing feather follicles.  Lice may cause a drop in production.  As with mites, they can be controlled by leaving the house empty or using insecticides.

Cannibalism occurs when birds peck at the feathers, toes, heads, and vents of other birds.  Cannibalism can even lead to the pulling out of the intestines (pick-outs).  If there is bleeding and further pecking, cannibalism may result in the death of the bird.

Vent picking occurs often in laying hens and young turkeys.  Young hens, especially if they are overweight, are susceptible to prolapses, where the oviduct does not retract after the egg is laid.  The visible prolapse induces pecking in the vent area. 

Cannibalism occurs more often in egg-type than meat-type chickens, and may be caused by dietary insufficiencies such as salt, vitamins, or amino acids (protein components).  Another causative factor includes stress from feed deprivation, over-crowding, over-heating, inadequate ventilation and bright lighting.  Eliminating these stressors can prevent or reduce cannibalism.  If possible, injured or cannibalized birds should be removed from the flock to allow for healing.  Leaving cannibalized birds in the flock will stimulate further pecking.

Another method of preventing or controlling cannibalism is through light manipulation.  Reducing the light intensity and/or the duration of light in a day can help to alleviate cannibalism.  The use of red lights is also thought to help.  The length of light exposure each day should not be reduced for laying hens.

Another preventative measure is to trim the beaks of day-old birds at the hatchery, or to trim beaks of birds later in life if a cannibalism problem arises.  A small portion of the sharp tips of the beaks can be removed using nail trimmers or electric beak trimming machines.  This will make the beaks less dangerous to the other birds, but will not interfere with eating and drinking.

Metabolic diseases affect internal body metabolism and development, and cause a large portion of mortality in both commercial and back-yard poultry flocks.  The birds of main concern are turkeys and broiler chickens, due to their rapid growth rate.

Examples of metabolic diseases include chronic and acute heart failure, and leg problems.  These metabolic disorders can be reduced significantly by slowing early growth rate.  A slower rate of growth can be achieved by mild feed restriction, or by providing a longer dark period.  For more information, refer to the section on lighting in the General Brooding and Rearing Poultry Fact Sheet.

Sudden Death Syndrome (acute death syndrome, flips, flipovers)

Chickens and turkeys that die of sudden death syndrome are most often found lying on their backs with their legs and necks extended, although, occasionally, they are positioned on their front side.  Other than convulsions observed immediately before death, affected birds do not appear to be sick prior to dying.  The affected birds are usually large, and are most often males.

Sudden death syndrome is a cardiovascular disorder caused by a heart arrhythmia, meaning the birds die of a heart attack.  Mortality can occur in birds as early as one week of age, and normally peaks around three weeks of age.  A fast rate of growth is the major causative factor.  The methods described earlier in this section to slow growth rate will help to reduce the number of birds dying from this condition.

Ascites (water-belly, congestive heart failure)

Ascites occurs due to stress on the cardiopulmonary system, and is characterized by a build-up of fluid in the abdomen of the bird.  In severe cases, affected birds will have a bluish appearance on their combs and feet.  In addition, their breathing sounds laboured and gaspy, and they may be observed crouching with ruffled feathers.  Birds may also die without any obvious symptoms.  Birds that do not die from the disease are considered inedible.

There are many factors thought to affect the development of ascites.  The disease is stimulated by rapid growth, cold temperatures during brooding, high altitudes, excess dietary salt levels and/or genetic factors. 

Preventative measures include slowing early growth, ensuring a comfortable and consistent brooding temperature to prevent chilling, and checking water quality for sodium content.  It is also important to adequately ventilate the bird housing area, as dust and ammonia can damage lung tissue and may be a causative factor of ascites.

Leg Problems (cripples, leg weakness, lameness)

All birds can be affected by leg problems, but they are seen more often in meat-type birds.  The problem may become severe enough that the bird cannot move easily to obtain adequate feed or water and, therefore, becomes emaciated. 

Rapid growth early in life is one of the main factors related to the leg disorders and poor mobility in broiler chickens and in turkeys.  It has been demonstrated that slowing early growth through lighting programs or mild feed restriction reduces the incidence of leg problems.  Examples of these methods are described in the metabolic disease section of this article.

If the floor of the brooding area is not covered with a sufficient amount of bedding, young birds may lose their footing.  Slipping can cause leg problems, particularly in young turkeys and waterfowl.

Nutritional deficiencies or imbalances can affect leg development and cause abnormalities.  Deficiences of vitamins or minerals, such as manganese, zinc, selenium, vitamin E, choline, biotin, niacin, folic acid, riboflavin, and pyridoxine, can cause twisted legs or angular deformities in broiler chickens and turkeys.

Leg problems can also be caused by microbial infections.  The birds will be reluctant to move and their joints may or may not be swollen.  The prevention of microbial infections can be achieved by reducing stress caused by crowding and by chilling, especially at night; by maintaining dry litter; and by practising good preventative disease measures.

Reportable diseases are diseases outlined in the federal Health of Animals Act and Health of Animals Regulations and are usually of significant importance to human and animal health as well as the Canadian economy.

Poultry owners, veterinarians and laboratories are required to immediately report the presence of a bird that has or is suspected of having one of these diseases to a CFIA district veterinarian. 

Avian Influenza

Avian influenza (AI) is a contagious viral infection caused by the influenza virus Type A, which can affect several species of food producing birds, such as chickens, turkeys, quails, and guinea fowl, as well as pet birds and wild birds.

AI viruses can be classified into two categories: low pathogenic (LPAI) and high pathogenic (HPAI) forms.  These classifications are based on the severity of the illness caused in birds, with HPAI causing the greatest number of deaths in birds.  

Most AI viruses are low pathogenic, and they typically cause little or no clinical signs in infected birds.  However, some low pathogenic viruses are capable of mutating into high pathogenic viruses.  

There are many influenza subtypes, two of which include H5 and H7.  Historically, only the H5 and H7 subtypes are known to have become high pathogenic in avian species.

Some or all of the following clinical signs are evident in AI infected birds:

• quietness and extreme depression;
• sudden drop in the production of eggs, many of which will be soft-shelled or shell-less;
• wattles and combs become swollen and congested;
• swelling of the skin under the eyes;
• coughing, sneezing and signs of nervousness;
• diarrhea;
• haemorrhages on the hock;
• death. A few deaths may occur over several days, followed by a rapid rise in mortality resulting in the death of the majority of the flock.

Wild birds, especially waterfowl, are natural reservoirs for the influenza viruses.  Wild birds are not generally affected by the disease, but can still transmit the disease to domestic birds.

The disease can also spread to birds through contact with infected poultry and poultry products, and through manure and litter containing high concentrations of the virus.  For example, the disease can spread through contaminated clothing and footwear, vehicles and equipment, and feed and water.

Wild bird populations are beyond producers' control. Therefore, it is essential for poultry producers to maintain strict biosecurity practices to prevent introduction of the virus in their flock.

This information was provided by the Canadian Food Inspection Agency (CFIA).  More information is available from the CFIA's website at:

www.inspection.gc.ca/english/anima/heasan/disemala/avflu/avflufse.shtml

Exotic Newcastle Disease (END)

Exotic Newcastle Disease (END) is a contagious and fatal viral disease affecting all species of birds, but is of particular concern for poultry flocks.  

END is probably one of the most infectious diseases of poultry in the world.  Death rates of 100 per cent can occur in unvaccinated flocks, and even vaccinated flocks can experience infections and deaths.

END, also known as velogenic viscerotropic Newcastle disease, is one of several types of Newcastle disease.  The severity of the disease depends on the type of Newcastle disease virus.

END affects the respiratory, nervous and digestive systems of birds.  The incubation period ranges from two to 15 days.  

An infected bird may exhibit the following signs:

• sneezing, gasping for air, nasal discharge, coughing;
• greenish, watery diarrhea;
• depression, muscular tremors, drooping wings, twisting of head and neck, circling, complete paralysis;
• partial to complete drop in egg production;
• production of thin-shelled eggs;
• swelling of the tissues around the eyes and in the neck; and
• sudden death.

The flock will experience an increase in sudden deaths.

The transmission of infection is mainly by direct contact with diseased or carrier birds.  It can spread rapidly among birds in close confinement, such as birds in commercial flocks.  

As there is a high concentration of the virus in birds' bodily discharges, the disease can also be spread unintentionally through human activity.  For example, poultry material bearing the virus such as feathers and manure, could become attached to people's shoes or clothing, and carried from an infected area to a healthy flock.  The virus is often spread by people working in the poultry industry, such as manure haulers, truck drivers, poultry buyers, and feed delivery services.  Even non-industry visitors to poultry operations could become the unwitting sources of transmission.

There have not been any cases of END in domestic poultry in Canada since 1973.  Sporadic cases have been recorded in migratory birds.  END occurs in Central and South America, the Middle East and most of Europe, Africa and Asia.  Outbreaks of END have occurred periodically in the Western United States.

This information was provided by the CFIA, and can be found on the CFIA website at:

www.inspection.gc.ca/english/anima/heasan/disemala/newcastle/newcastlefse.shtml

Fowl Typhoid (Salmonella gallinarum infection)

Salmonella gallinarum infection is a disease with high mortality and morbidity that affects adult birds more often than young birds.  In chicks and poults, most of the clinical features are similar to Pullorum Disease.

In adult birds, fowl typhoid may go unnoticed, but if clinical signs do occur, they may include:

• sulphur-coloured diarrhoea;
• listlessness;
• decreased appetite;
• depression;
• dehydration;
• weight loss;
• ruffled feathers; and
• pale and shrunken combs and wattles.

Bird-to-bird transmission of fowl typhoid can occur through infected droppings, dead bird carcasses, and infected clothing, shoes, utensils and other vectors.

Pullorum Disease (Salmonella pullorum infection)

Pullorum Disease is caused by the bacteria Salmonella pullorum and is transmitted by infected breeder hens through their eggs.  Chicks and poults that hatch from infected eggs will have white diarrhea, pasty vents and high mortality.  Infected chicks can infect other chicks via droppings.  Most acute outbreaks occur in birds that are under three weeks of age.  Death may occur soon after hatching without any observable signs.  Mortality may approach 90 per cent and survivors are usually stunted and unthrifty.

Clinical signs of a bird infected with Salmonella pullorum include:

• droopiness, birds may appear sleepy or weak;
• ruffled feathers;
• a chilled appearance with birds huddling near a source of heat;
• laboured breathing;
• presence of a white diarrhea with a "pasted-down" appearance around the vent;
• decreased appetite; and
• shrill chirping.

Adult birds infected with Salmonella pullorum usually have no signs of disease, but may sometimes appear unthrifty.  Infected hens will have internal lesions in the ovary, and may or may not be productive layers.  The eggs of infected birds may have reduced hatchability.

The information on Fowl Typhoid and Pullorum Disease was referenced from:
Important Poultry Diseases, Intervet International BV, and
Descriptions of Significant Poultry Diseases, NB Poultry Disease Emergency Response Plan

Infectious Bronchitis Virus (IBV)

Infectious bronchitis is an acute, highly contagious respiratory disease occurring in chickens of all ages.  Symptoms include coughing, sneezing and nasal discharge.

The major economic loss in mature chickens is the reduction in egg production and inferior egg quality.  In younger birds, there may be a high death rate with a loss in weight gain and feed efficiency due to secondary bacterial infection.  IBV is highly transmissible, and is a potential hazard when the virus is present for unvaccinated flocks.

More information on Infectious Bronchitis is available on the Canadian Poultry Consultants Ltd. website at www.canadianpoultry.ca/infectious_bronchitis_virus_(ibv).htm.

Infectious Laryngotracheitis (ILT)

Infectious Laryngotracheitis is an acute respiratory disease of chickens caused by a herpes virus. 

Symptoms in its milder form include watery eyes (conjunctivitis), swollen sinuses and persistent nasal discharge.  There can be a five to 15 per cent reduction in egg production, with no apparent eggshell abnormality.  Great economic losses can occur in broilers, due to decreased growth rate. 

Symptoms in its severe form include:

• gasping and coughing;
• bloody discharge from the trachea or windpipe during gasping and coughing;
• the trachea is often partially blocked with blood, so the neck is extended during violent coughing efforts;
• beaks, faces or feathers of birds may be bloody; and
• blood can be found on walls or cages.

Severe ILT may result in 10 to 20 per cent mortality.  The disease persists in flocks for as long as two to six weeks, a course longer than that of most respiratory viral diseases of chickens. 

More information on ILT is available from the websites of the Canadian Poultry Consultants Ltd. found at  www.canadianpoultry.ca/ilt.htm, and the Alberta Agriculture, Food and Rural Development website at

www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex2216?opendocument.

Prepared by Amanda Beutler, M.Sc.
Department of Animal and Poultry Science
College of Agriculture and Bioresources
University of Saskatchewan
51 Campus Drive
Saskatoon, Saskatchewan, S7N 5A8