Adult birds in a flock of chickens have firm cutaneous nodules or papules, some of which are pustular, coalescing, and crusting.
Which infection transmitted by biting insects is most likely responsible?
Fowlpox virus infection
Which organisms causes fowl typhoid and fowl cholera?
- Fowl typhoid: Salmonella gallinarum
- Fowl cholera: Pasteurella multocida
Post-mortem exam of a turkey with a history of anorexia, depression, and sulfur-yellow droppings shows pathognomonic focal, round, pale liver lesions.
What is the diagnosis?
Histomoniasis
(“blackhead”)
This is caused by the protozoan Histomonas meleagridis.
Which is FALSE regarding avian influenza?
- A. Broilers: signs may include severe depression, facial/neck edema, torticollis, ataxia, death
- B. Mature chickens: wattles often swollen and cyanotic
- C. Incubation period is up to 7 days
- D. Low pathogenic form does not mutate to high pathogenic form
D. Low pathogenic form does not mutate to high pathogenic form is false
The low pathogenic form of the virus does mutate to the highly pathogenic form. A common characteristic of influenza viruses is their propensity to mutate.
What are three differential diagnoses for lameness in chickens, excluding trauma?
- Rickets (vitamin D deficiency)
- Osteomyelitis
- Marek disease
- Synovitis
- Femoral head necrosis
This coronaviral of chickens produces respiratory signs, often followed by renal disorders (with pale, swollen kidneys) and reproductive dysfunction.
Infectious bronchitis
In a mixed-bird flock, only chickens are showing depression, anorexia, diarrhea, and sometimes death. On necropsy there are petechiae in muscle and prominent swelling and inflammation of the bursa of Fabricius.
Which acute disease is most likely?
Acute (very virulent) infectious bursal disease
The presence of eosinophilic intranuclear inclusions in respiratory and conjunctival epithelium is pathognomonic for which disease of chickens?
Infectious laryngotracheitis
What is the most common species of coccidia found in poultry?
Eimeria spp.
Most often seen in young birds, causing diarrhea and weight loss.
Blackhead disease in turkeys is transmitted by which nematode paratenic host?
Heterakis gallinarum
(the cecal nematode)
Mortality rate in turkeys is up to 100%, though chickens are usually subclinical carriers.
A paralyzed chicken is euthanized, and necropsy reveals thickening of the sciatic nerve.
Which infectious disease is most likely?
Marek disease
(oncogenic herpesviral disease)
Other classic findings are: enlarged feather follicles, change in eye color due to lymphoid infiltration (rare), and diffuse or nodular lymphoid tumors in organs.
Newly hatched chicks with “clubbed” down (failure of feathers to rupture their sheaths), chicks with curled toe paralysis, and reduced egg production in hens are all signs of deficiency of which vitamin in poultry?
Riboflavin (vitamin B2) deficiency
What are ratites?
Family of flightless birds
(includes ostriches, emus, cassowaries, and kiwi)
This infectious disease of chickens produces upper respiratory infection due to a tropism for ciliated cells by the causative bacterium, Avibacterium paragallinarum.
What is the name of the disease?
Infectious coryza
It is a disorder that produces high morbidity (highly contagious, spread via aerosolization) and low mortality.
Name three possible causes of abnormally soft-shelled (or shelless) eggs in laying hens.
- Birds coming into lay
- Newcastle disease/paramyxovirus
- Infectous bronchitis
- Egg drop syndrome ‘76
- Avian rhinotracheitis
- Treatment with sulfa-class antibiotics
- Calcium, phosphorous, or vitamin D imbalances
Which organism is responsible for necrotic enteritis, a disease of chickens characterized by liquefactive necrosis of the intestine?
Clostridium perfringens
(types A and C)
Primarily seen in young broilers and laying hens.
Which family of etiologic agents causes duck virus enteritis, infectious laryngotracheitis of chickens, Pacheco disease, and Marek disease?
Herpesviridae
What is the most common vector of avian poxviruses?
The mosquito
Poxviruses require an injury such as a mosquito bite wound to enter the body.
Exotic Newcastle disease virus is shed through which body systems in infected birds?
- Respiratory
- Gastrointestinal (feces)
Of all the avian species, quail are classically susceptible to this disease, caused by Clostridium colinum.
Ulcerative enteritis
Can cause sudden death (up to 100%) without premonitory signs in quail; or causes hemorrhagic/watery diarrhea, anorexia, and lethargy. Rapidly contagious.
Exudative diathesis (with extravascular leakage of plasma and blood), nutritional muscular dystrophy, and encephalomalacia (“crazy chick” disease) are recognized syndromes caused by deficiency of which vitamin in poultry?
Vitamin E deficiency
Chickens in a crowded, poorly ventilated henhouse show respiratory signs. Necropsy reveals pneumonia, pleuritis, sequestered necrotic lung lesions, and caseous arthritis.
What is the most likely diagnosis?
Fowl cholera
(Pasteurella multocida infection)
You suspect a chicken died of either lymphoid leukosis or Marek disease. There are no tumors of the bursa, but the spleen has diffuse tumors, whose cytology show an assortment of lymphoblasts and lymphocytes of various sizes.
Which of the two diagnoses is more likely?
Marek disease
(MD)
MD presents with diffuse splenic tumors, variable cytology, and usually spares the bursa. vs. lymphoid leukosis (LL) is characterized by bursal tumors, focal splenic lesions, and cytologically uniform lymphoblasts.
Which organism causes disease in turkeys classically characterized by vertebral lesions (“crooked neck”) and tarsometatarsal deformities?
Mycoplasma meleagridis
Control programs have eradicated it from all turkey primary breeders and many commercial flocks worldwide.
