Botulism

Botulism is a progressive, often fatal, neuromuscular disease that affects chickens worldwide. It is caused by ingestion of the toxin produced by Clostridium botulinum, which is the most lethal bacterial toxin known. The toxin is extremely potent, and acts by interfering with nerve function, resulting in respiratory and musculoskeletal paralysis. There are several different strains of C. botulinum which produce different types of toxins. Chickens are most often affected by Type A.

Affected chickens are often found recumbent and unable to move (characterized as "crawling" by some chicken owners), flaccid paralysis of the legs, wings, and neck. The most common classic symptom of botulism is chickens the inability for them to hold their necks up, as a result of flaccid paralysis. Sometimes the chickens are found dead, from accidentally drowning in the water they were trying to drink. Other, less frequently observed signs include diarrhea with excess urates (increased whiteness) and respiratory difficulty.

Transmission
C. botulinum is found widespread in the soil. It produces toxins during periods of warm weather, exposure to an anaerobic (no oxygen) environment, and protein source available to consume (decaying vegetation/feed materials or rotting carcasses). Chickens become infected by eating particles of contaminated soil or water, rotten food (such as that found in composts), or from ingestion of maggots which recently fed on decaying materials containing the toxin.

Incubation period
Clinical signs of botulism start to appear within a few hours if high doses were ingested and for low doses, it can take up to a few days.