All Cooped Up: Fowl Cholera
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All Cooped Up is a new feature, profiling poultry diseases and how to prevent/treat them, written as a collaboration between medical professional Lacey Hughett and University of Pennsylvania poultry specialist Dr. Sherrill Davison.
What is it? A highly contagious bacterial disease.
Causative Agent: A gram-negative rod-shaped bacteria called Pasteurella multocida.
Incubation period: 5-8 days.
Disease duration: Acute: A very short duration usually ending in death of the bird. Chronic: This is a lasting disease, affecting the bird for the rest of their life.
Morbidity: Can be very high, up to 100%.
Mortality: Very high.
Signs: Acute: anorexia, depression, cyanosis, rough breath sounds, mucous discharge, and white or green diarrhea. Chronic: Joint, wattle, foot, or tendon swelling, wry neck, or fluid and pus in the eyes or sinuses. Post-mortem: There may be hemorrhages on the heart, serous membranes, abdominal fat, or gizzard. The liver may be enlarged with necrotic spots.
Diagnosis: Post-mortem exam and culture by a veterinarian.
Treatment: Antibiotics obtained through a veterinarian, usually sulfa drugs, tetracyclines, erythromycin, streptomycin, and penicillin.
Fowl cholera is a highly contagious bacterial infection that affects multiple species of wild and domestic birds. Turkeys and waterfowl are more susceptible than chickens, and older birds are more susceptible than younger ones. Onset is sudden, with a high mortality and morbidity rate. Chronic infections can also exist and are more likely to be asymptomatic. Fowl cholera is found worldwide.
P. multocida is spread from the excretions of the mouth, nose, and eyes of an infected bird. The largest carriers of the bacteria are chronically infected birds and those who are asymptomatic, but home flocks can also become infected from wild birds as well.
These bacteria can survive on most surfaces and can live long enough to infect birds from exposed feed bags, shoes, crates, or equipment, so excellent biosecurity is a must for disease prevention. Additionally, mammals such as rodents or pets may carry the disease into the living space of the chickens and potentially infecting them. The bacteria can be killed by most disinfectants, heat, sunlight, and drying.
Unfortunately, one of the first signs of fowl cholera is a deceased bird. Frequently, owners will not notice any other proceeding signs of infection, and the mortality of the flock increases rapidly. As more birds contract the disease, signs may start to become more obvious.
Signs to look for in surviving birds are fatigue, ruffled feathers, diarrhea, anorexia, discharge from the nose and mouth, and a rapid respiration rate. Chronic infections of P. multocida happen later but include additional signs of swollen wattles, feet, and tendons, and wry neck related to infection in the middle ear and cranial bones.
A post-mortem assessment will reveal different signs, dependent on the course of the infection. For the birds who die with an acute infection, the liver and spleen may be enlarged, and bloody hemorrhages may be seen throughout the mucosal lining of the internal cavity. In subacute infections, the liver may have some necrotic lesion spots as well.
The chronic infection presents as widespread, pus-filled lesions, including in locations such as the respiratory tract, eyes, wattles, and face. The lung infection may cause the lungs to become consolidate or hard to the touch. The oviduct and body cavity will be inflamed and full of fluid. Inflammation and arthritis are found in the joints, feet, and tendons.
Although it is possible to make a preliminary diagnosis of fowl cholera based on age, history of illness, and clinical manifestations, it is still essential to isolate and identify the bacteria for conformation. There are several avian bacterial infections that can produce lesions similar to fowl cholera, and correct diagnosis will help with the treatment and management of the flock.
Prevention of the disease can be done in healthy, large scale flocks in the form of attenuated vaccines. Turkeys can receive the vaccine in drinking water, and chickens from wing web inoculation. The vaccinations have a high success rate but should only be administered if there is a certainty that the birds are healthy and not suffering from any underlying conditions. Unfortunately, vaccines are not available for small flocks. The isolates need to be typed to determine if the vaccine will be effective. There are limited types of vaccines available and are chosen based on the typing of the specific isolate.
If a flock does contract fowl cholera, there are several drugs that help manage the disease. These drugs do not eradicate the bacteria, so if they are stopped it is possible that the infection will break out again. The flock will always carry the disease, so the only way to fully stop the cycle of infection is to cull the remaining chickens, disinfect the living area, and wait a few weeks before adding new birds.
If owners do not intend on selling birds or buying new ones, they can use sulfa drugs in the feed to help lower mortality. Tetracycline in the feed, in high amounts, can help manage the infection. Penicillin can be used for strains that have become resistant to sulfa drugs. Prior to any antibiotic use, contact your local veterinarian. Incorrect dosing or drug usage can lead to resistance, making future infections harder to fight.
All information in this article has been vetted for accuracy by Dr. Sherrill Davison, Poultry Specialist at University of Pennsylvania School of Veterinary Medicine.
Originally published in the February/March 2020 issue of Backyard Poultry and regularly vetted for accuracy.