Poultry production not only occurs in large commercial flocks, it is also finding a resurgence among small-scale farmers and backyard producers. No matter where or how the birds are raised, common poultry diseases are a concern. Knowing the signs and symptoms, and collecting samples to make a positive diagnosis, can go a long way in insuring poultry health.
Dr. Mahamed El-Gazzar, Assistant Professor and Poultry Extension Veterinarian, The Ohio State University, presented a webinar designed to assist producers with the proper identification and control of poultry disease. Whether conventional or organic, preventing the spread of illness is of the utmost importance, so proper treatment is vital, he said.
Poultry diseases are “one of the major challenges that poultry producers in both the conventional and organic” markets face today, El-Gazzar said.
As backyard poultry production increases, the availability of trained poultry veterinarians is a concern. Producers themselves should have the knowledge to recognize signs and symptoms of illness, and to properly take samples and prepare specimens for laboratory diagnostic testing, he said.
The primary diseases of concern in poultry fall into four groups: respiratory; digestive; musculoskeletal; neurological. No matter which group is causing problems, knowing how to perform post-mortem necropsy is a vital link in proper diagnosis, treatment and prevention. Dr. El-Gazzar recommends the video, a joint production of Cornell University and the United States Department of Agriculture, available for purchase at www.partnersah.vet.cornell.edu/veterinarians/avian-necropsy-examination
The primary means of laboratory diagnosis depends upon the collection of blood from live birds, using the wing vein. Post-mortem swabs and tissue samples are taken from organs to assist with the diagnosis of bacterial and viral pathogens. Sterile collection techniques, including using formaldehyde to preserve samples as needed, is vital.
“It’s very, very important to collect the right samples,” El-Gazzar explained. “More often than not, you will have only one chance of collecting the sample.”
In the respiratory group of diseases, symptoms typically show as coughing and sneezing, fever and lethargy, nasal or ocular discharge, anorexia and inflamed eyelids. Post-mortem examination of the head, including nasal and eye, will show inflammation. Air sacs will be inflamed. Inflammation will be present throughout the body cavity.
Possible diseases, which must be ruled out, include those originating from viruses, such as Newcastle and avian influenza. Bacterial concerns include mycoplasmosis and escherichia coli, while aspergillosis could be a fungal cause. Worms could also cause respiratory symptoms.
“By collecting the right samples, the lab should be able to tell you the difference,” El-Gazzar said.
Viral causes of disease are often preventable via vaccinations, which is the most efficient tool available in offering protection and control of poultry disease, he said. Other supplementary treatments, such as vitamins in the water, or slightly increasing the temperature of the poultry housing when fever is present, can help. Using a disinfecting agent in the water can help decrease the spread of disease, as can appropriate biosecurity. If bacteria are a causative agent, antibiotics are needed.
“Sometimes we have no choice,” if birds are suffering and dying, he said.
Digestive disease symptoms include dehydration, diarrhea, anorexia and death. Upon death, the intestinal mucosa must be examined within a 10-minute time frame, and will show obvious changes from its normal appearance.
Lesions on the intestine are “very suggestive to a viral infection,” El-Gazzar said. “Turkeys are much more susceptible to viral infections in the gastrointestinal tract than chickens.”
Protozoan issues can be seen by scraping the surface of the mucosa. Coccidia will be evident if that was the cause of disease, and tapeworms would also be easily diagnosed.
“Coccidiosis is the most common protozoan present that we see.” It causes mortality and economic loss. Vaccines are “very successful in controlling coccidia infections,” he said. Amprolium is used for prevention and control.
Parasites are not only intestinal, but can be found in the liver, as with Blackhead, another protozoan disease. Gapeworm, a parasitic nematode, presents in the trachea and causes suffocation. External parasites, such as mites or lice, require treatment with powders or sprays, reapplied after seven days as treatments are not effective on the eggs.
Musculoskeletal diseases of poultry exhibit as decreased motion. Lameness, paralysis, and lack of standing are all signs. Nerve and joint inflammation, footpad infection, bone deformities and soft bones occur. Diseases such as Marek’s disease, which is viral and causes nerve inflammation, or bacterial causes of joint inflammation such as E. coli, staphylococcus aureus and mycoplasma synoviea, need to be ruled out.
Many causes of bone weakness are “primarily due to nutritional deficiencies.” Calcium deficits will cause rickets in young birds, or osteoporosis in older layers. Ionophore toxicity is another reason for bone issues.
Neurological disease shows as paralysis, torticollis (neck twisting) or tremors. Taking a brain tissue sample for analysis is important for diagnosis. Marek’s disease, E. coli, or influenza are some causes.
Other diseases fall outside of the primary groups of concern. Vitamin E deficiency results in one of three forms of disease. Pox virus comes in dry and wet forms, where either the wattle and exposed skin will show symptoms, or the upper respiratory system will be impacted. Wet pox virus is hard to distinguish from other causes of concern based on symptoms, but a pathologist can readily diagnosis pox virus, El-Gazzar said.
Tumor viruses infect the birds and produce tumors. They are a part of the HIV family of diseases.
While most often egg production declines due to concerns with lighting, water consumption or nutritional issues, diseases can be a cause. Lack of egg laying production can be caused by egg peritonitis, where over-ovulation causes the yolk to be absorbed into the abdominal cavity. Bacterial infection then occurs, causing death.
Avian Influenza is thought to have spread through overlapping migratory flyways of various bird species. Farm-to-farm transit occurs via human transport of the disease, and close proximity of poultry houses has assisted in the spread. The spread of H5 Highly Pathogenic Avian Influenza (HPAI) has “really shown the gaps of biosecurity we have in the United States.”
Biosecurity is “the practices that we use to prevent infectious agents from having access to our poultry,” El-Gazzer said. Biosecurity measures are “a barrier to prevent the disease from taking the transmission route and reaching our poultry population.”
Diseases can be transmitted directly, or indirectly, such as through environmental contamination on clothing or surfaces. Humans, wild animals, domestic animals or other poultry can transmit disease. Using disposable clothing when in contact with the poultry or their environment, preventing animal access to the poultry, and quarantining any new poultry or any poultry returning to the farm from an exhibit can be effective biosecurity measures.
“Biosecurity and vaccines are very, very useful tools.”