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Fowl Cholera (Pasteurellosis)

Other Names: Pasteurellosis

Fowl cholera (FC) is a highly contagious bacterial disease caused by Pasteurella multocida. There are many serotypes of P. multocida with differing pathogenicity. FC is seen in both wild and domestic birds, including mammals. Young, growing birds are most susceptible.

The disease most frequently presents in birds as an acute septicaemia, where death may be the first sign observed. However, a more chronic and asymptomatic form of the disease can also occur. When clinical signs do develop, the most frequent include diarrhea, ruffled feathers increased respiratory rate, depression, and bluish to purplish color comb (cyanosis) immediately prior to death.

Sometimes chickens may recover or develop a chronic infection. Chronic FC occurs generally as a localized infection of a particular region of the body--specifically in the hock or wing joints, footpad, tendon sheath, ear, sinuses, wattles, or sternal bursae. When chronic infections involve the ear, it is usually relating to the middle ear and cranial bones, resulting in torticollis.


FC is spread a number of different ways:
  • Direct contact with infected birds: Secretions made from infected birds, requiring close contact with one another.
  • Ingestion: Most common route, involving contamination of the environment, feed, or water with feces from infected birds. Chronically infected birds may shed the virus in their droppings even following recovery.
  • Predator attacks: Non-fatal predator attacks from wild or domestic animals (dogs, cats, and raccoons are known to be carriers of high amounts of the bacterium in their oral cavities). Any chicken that has been in a predator's mouth or mouthed by a predator should be treated immediately with appropriate antibiotics.
  • Fomites: Contamination of equipment, clothing, cages, feeders, etc.
  • Aerosol form
P. multocida can persist in the environment for weeks after an outbreak. Chronically infected carriers play a major role in the spread of this disease, and infected birds can remain carriers for life.

Confirmed Cases of Fowl Cholera

AffectedHistoryDiagnostic FindingsTests usedRef
18-week old turkeysHistory of difficulty walking, recumbency, and increased mortality, with no respiratory signs.Severe keel bursitis and synovitis of the hock joints, where P. multocida was isolated.Necropsy; bacterial cultureCAHFS Connection, October 2016
Eight adult Rhode Island Red laying hens from a small commercial free range flockHistory of listlessness and deathFbrinous coelomitis, perioophoritis, multifocal hepatitis and splenitis. Isolation of P. multocida.Necropsy; bacterial cultureCAHFS Connection, August 2015
Multiple 10-week-old turkeys Presence of airsacculitis, pneumonia, splenitis, and arthritis. P. multocida was isolated from multiple tissues.Necropsy; bacterial cultureCAHFS Connection, January 2017
18-week-old chukar partridge flock5-7% mortality for 3 consective days.Mild splenomegaly with multiple pale foci and subtle hepatitis. Large numbers of P. multocida isolated from the liver, kidney, and spleen. Necropsy; histopathology; bacterial cultureCAHFS Connection, October 2013
10-week-old pheasantsClinical signs of swollen legs and hocks. History of increased mortality in the flock.Septicemia; swollen and mottled spleen, dark red and mottled liver, dark red lungs, caseous exudate in the bursa of Fabricius, and dark red and edematous testes were seen in some birds. P. multocida was isolated from the hock, spleen, and liver.Necropsy; histopathology; bacterial cultureCAHFS Connection, February 2013
Flock of 12-week-old crossbred commerical laying hensIncreased mortalityNecropsy revealed marked pericarditis and oophoritis, with mild enlargement of the spleen. P. multocida was cultured from the ova, pericardium, and liver. Enrichment culture for Salmonella was negative.Necropsy; bacterial cultureNew Zealand Veterinary Journal, Quarterly review of diagnostic cases, January to March 2016
Adult laying hens on a free-range farmHistory of recent flooding of the paddock. Clinical signs consisted of sudden death, and increased mortality rate.All hens were laying but the developing ovules were large and flaccid with empty oviducts. The lungs were normal in the majority of the birds but in one they were slightly larger, very congested and haemorrhagic. Cultures of the lung from this bird and from the bone marrow and liver in the other birds revealed the presence of P. multocida.Necropsy; bacterial cultureNew Zealand Veterinary Journal, Quarterly review of diagnostic cases, January to March 2016
44-week-old brown laying hens from a commerical flockIncreased mortality over a one-week period and decreased egg production.Necropsy revealed evidence of coalescing regions of splenic necrosis, multifocal to coalescing hepatic necrosis, and bacterial endocarditis. Culture of the spleen revealed the presence of P. multocida.Necropsy; bacterial cultureNew Zealand Veterinary Journal, Quarterly review of diagnostic cases, July to Sept 2016

Clinical Signs

Ruffled feathers
Pasty or yellow diarrhea
Mucous discharge from the mouth
Nasal discharge
Increased respiratory rate
Swollen wattles
Darkened head and comb


  • History
  • Clinical signs
  • Bacterial Culture
  • Gram-stained impression smears
  • Pasteurella multocida ELISA
  • Necropsy


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
AntibioticsSulfamethazine, Norfloxacin, Penicillins, Oxytetracycline, Doxycycline



  • Attenuated live vaccines administered in drinking water
  • Prevent rodents, wild birds, and other animals from accessing or dropping their feces within coops and outdoor enclosures
  • Minimize contact with cats and dogs or with environments that they live in
  • Purchase cholera free birds
  • Biosecurity

Scientific References

Good Overviews

Age Range

Fowl cholera occurs most commonly in chickens over 16 weeks of age

Risk Factors

  • Wild bird feeders
  • Rodent populations
  • Survivor of a recent predator attack (especially from cats or dogs)
  • Introduction of a new bird to the flock