Fowl cholera (FC), also referred to as avian cholera or pasteurellosis, is a significant disease of wild and domestic birds worldwide. FC is caused by infection with the Gram-negative bacterium, Pasteurella multocida
. The disease can occur in two forms--acute or chronic. In ducks, FC most frequently occurs as an acute septicemic infection, often with many acute deaths. Incidences of chronic and asymptomatic infections have also been reported in ducks, however less frequently. Ducks that are four-weeks of age and older are more susceptible to developing FC than ducks younger than 4-weeks old.
Clinical signs of acute FC are usually only observed for a short period (sometimes a matter of a few hours) prior to death. Often, unless clinical signs are witnessed the duck's keeper, FC appears as sudden death of the bird. When signs do occur, they usually include:
- Fever: Presents as loss of appetite, ruffled feathers, and increased respiratory rate
- Changes in droppings appearance: Includes diarrhea that is initially watery and whitish that later changes to a greenish mucus.
- Mucus discharge from the mouth
- Cyanosis (bluish bill and/or skin), just prior to death
is primarily spread through domestic flocks of poultry through chronic carriers (domestic birds that have become infected and recovered or had subclinical infections in which they displayed no clinical signs of illness). P. multocida
most often enters the duck through inhalation or ingestion, but can also enter through the conjunctiva or cutaneous wounds. The spread of P. multocida
through a flock is primarily through excretions from the mouth, nostrils, and conjunctiva of infected birds, or even humans and other animals, that contaminate their environment, particularly the feed and water. Raccoons, domestic dogs, both domestic and feral cats are known carriers of P. multocida
in their mouths. Any attacks or attack attempts made by any of these species can cause FC in ducks.