POULTRY DISEASES Flashcards
Many chickens on a poultry farm are affected by one of two syndromes. Some chicken develop nodules and scabs that are most prominent on the comb, wattles, feet, and vent. Other chickens develop a diphtheritic membrane in the mouth and pharynx. What is the best treatment for this flock?
Avian fowl pox
What is the treatment for avian fowl pox
Control mosquito populations and vaccinate chicks or replacement chickens with a single immunization against the suspected disease
What causes cervical lordosis, a shortened axial skeleton, and subcutaneous emphysema in embryo?
These deformities are associated with organophosphate insecticides, particularly parathion, which can cause several vertebral and long bone abnormalities as well as generalized stunting of embryonic development. PCBs are mixtures of compounds released in combustion. They cause reproductive toxicity in avians by binding to estrogen receptors and altering thyroid and adrenal homeostasis. They do not cause specific fetal abnormalities.
How do you treat Coccidia in turkeys?
he condition described is coccidiosis and the cause is Eimeria based on the fecal findings. There are many different Eimeria species that can infect poultry. Different species of Eimeria typically parasitize different regions of the intestine. Coccidiosis in turkeys can be treated with Amprolium or Sulphonamides (ie Sulphaquinoxaline). Salinomycin is a coccidiostat but is toxic to turkeys, even at low doses. Ionophores such as lasalocid and monensin are coccidiostats that are used for prevention of coccidiosis in turkey growers.
What is the causative agent of turkey coryza?
The correct answer is Bordetella avium. Turkey coryza or avian bordetellosis is an acute respiratory disease of turkeys with high morbidity and low mortality. Clinical signs include nasal discharge, foamy eyes, and cough. Diagnosis is via isolation on MacConkey agar or serology. A vaccine is available but has mixed results. Antimicrobial therapy is usually unrewarding.
Most of the chickens on a farm are coughing and sneezing and many have facial swelling. You necropsy several and find mucoid exudate in the bronchi and thickened air sacs. You suspect that this may be an outbreak of infectious bronchitis. Which of following would be most helpful in confirming a diagnosis?
Infectious bronchitis is caused by a coronavirus. It is spread by aerosol and ingestion and usually affects all exposed birds. The clinical signs and necropsy findings are as described in the question. The disease can be clinically indistinguishable from mild forms of Newcastle disease, laryngotracheitis, and infectious coryza.
Virus isolation after 3-5 passages in chick embryo is needed to obtain a definitive diagnosis. Other techniques including PCR and monoclonal antibody serotyping may also be helpful.
Gomori methenamine silver stain is generally performed to identify fungal organisms and India ink is to aid in identification of Cryptococcus.
Which of the following is the causative agent of fowl cholera?
The correct answer is Pasteurella multocida. The bacterium is a gram negative rod. It causes fever, mucoid discharge from the mouth, diarrhea, petechia, ecchymoses, increased pericardial and peritoneal fluid, and death. The chronic form of the disease usually causes localized disease. Diagnosis is based on identifying the organism from samples in conjunction with clinical signs. Vaccines are available for prevention of the disease. Sulfa antibiotics are used for treatment.
Drastic changes in the feed of chickens should be avoided to prevent which of the following conditions?
The correct answer is necrotic enteritis (Clostridium perfringens). C. perfringens A and C can cause acute enterotoxemia with sudden onset explosive mortality due to necrosis of the mucosa of the small intestine. This usually occurs when intestinal microecology is disturbed (due to changes in feed or damage from other pathogens or toxins). Diagnosis is made by finding large numbers of short, thick, gram positive rods in mucosal scrapings.
Turkeys and chickens should not be housed together in order to prevent transmission of __________ to __________.
The correct answer is Histomonas meleagridis to turkeys. This protozoan parasite, also called blackhead or infectious enterohepatitis, is fatal to turkeys but less pathogenic to chickens. It causes extensive necrosis of the liver and cecum. For this reason, chickens and turkeys should not be housed together and turkeys should not be housed in areas where chickens were previously housed.
Several turkeys recently moved to new housing, which previously housed chickens, have died. One is brought to you for necropsy and you find marked inflammatory changes, cecal wall thickening and ulcerations. There are also rounded necrotic lesions present on the liver. What is the most likely diagnosis?
The correct answer is Histomonas meleagridis. Heterakis gallinarum is the parasite which hosts the protozoan Histomonas meleagridis which causes clinical disease. Clinical signs include drooping wings, unkempt feathers, sulfur colored droppings, listlessness, and death. The liver and cecal lesions are considered pathognomonic for Histomonas meleagridis. This is must know information for boards.
You are examining a turkey flock that has been experiencing significant losses recently. Birds have been dying suddenly after exhibiting ataxia and weakness. Necropsy reveals diffuse darkening of the skin and enlarged and friable livers and spleens in affected animals. You perform an impression smear of the spleen and identify Gram-positive, slender, pleomorphic rods. What is the most appropriate treatment for birds in this flock?
The key to identifying the disease is the Gram-positive, slender, pleomorphic rods in the liver which suggest this is Erysipelas. Otherwise, other differentials such as Pasteurella, E. coli, salmonellosis, Newcastle disease and others could present similarly.
The treatment of choice for Erysipelas is a rapid-acting penicillin simultaneously with erysipelas bacterin. Oral oxytetracycline is not thought to be effective. Amprolium is used for coccidia and copper sulfate and vinegar is sometimes used in poultry to treat crop mycosis or thrush.
Several of the 1-3 week-old broiler chicks on a small chicken farm are exhibiting stunted growth. On examination, you find that they also have decreased pigmentation of the skin, feet, and beak and many broken or twisted feathers. You perform a post-mortem examination of a few chicks and find that they have orange mucus in the small intestine, an enlarged proventriculus, a small gizzard and an atrophied pancreas. How should you treat the flock?
The condition described is known as malabsorption syndrome, also known as runting-stunting syndrome or pale-bird syndrome. It is mainly seen in 1-3 week old chickens and appears to have a complex or multifactorial etiology related to numerous enteric viruses as well as possible mycotoxins.
Key clinical signs include the poor growth and feathering in birds of the appropriate age as well as abnormal feathers and pale feet and skin. Orange intestinal contents or feces is also a common finding.
There is no treatment and daily cull of affected birds in the appropriate age range is appropriate. Improved hygiene and sanitation, good nutrition and egg selection are also important management steps to minimize the damage from this condition. As no single specific cause is identified, the benefit of vaccination is unclear. There are vaccines against avian reovirus available but these are not given in-ovo.
Marek’s disease is caused by what type of agent?
The correct answer is herpesvirus. Marek’s disease is one of the most ubiquitous avian infections. It is highly contagious and can survive for months in the environment.
Turkeys and chickens should not be housed together in order to prevent transmission of __________ to __________.
Histomonas meleagridis, Turkeys
