Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose


Synonyms: Woolsorter's Disease, Cumberland Disease, Maladi Charbon, Malignant Pustule, Malignant Carbuncle, Mizbrand, Splenic Fever


Anthrax is a rare disease in horses, and more common in food animals. It is a rapidly fatal blood disease caused by a spore-forming bacterium (Bacillus anthracis), which is typically found in warm geographic areas with moist, alkaline soil that favors the organism.

The spores are extremely resistant to temperature extremes and most disinfectants. They can survive in the environment for decades. Horses usually develop Anthrax after eating the spores in the soil, and die within 2-8 days.

Anthrax is a zoonotic disease, meaning that it can be transferred from an infected horse to humans. If you have been exposed to a horse with (or suspected of having) anthrax you should contact your doctor immediately. For this reason, post-mortem examination is potentially dangerous and should NOT BE DONE.

Anthrax is a reportable disease, meaning that if a horse has or is suspected of having this disease, vets are required to report it to agricultural authorities (usually the State Veterinarian). These authorities may investigate the case as part of a larger effort to monitor equine health and coordinate with other States and the USDA APHIS in preventing the spread of illness or disease on a national and international level.

my vet's role


Guarded if caught early and treated aggressively. Early treatment with penicillin is said to be effective if the disease is promptly diagnosed.

my role


I might observe

You might make these observations when a horse has this condition.

Very Common
Less Common
more observations

Questions To Ask Your Vet:
  • What measures can we take to prevent infection in my other horses?
  • How can I disinfect my barn & tack, given the difficulty of decontamination?

There is a vaccine licensed to protect against this disease in horses. Unfortunately, it has a fairly high adverse reaction rate. It should be considered in areas where the risk of this disease is relatively high.

further reading & resources

Related References:

Lavoie JP, Hinchcliff KW eds. Blackwell's 5 Minute Vet Consult: Equine. 2nd Ed. Ames: Wiley Blackwell 2008.

Author: Doug Thal DVM Dipl. ABVP