Disease Information
Current information on infectious diseases of horses is listed here. More information may be available at the office of your state veterinarian.
To learn more about how certain diseases are transmitted, see
Iatrogenic vs Natural Transmission
Domestic Diseases
Anthrax (Bacillus anthracis)
Overview of Anthrax, Merck Vet Manual
Blastomycosis (Blastomyces dermatitidis)
Systemic blastomycosis in a horse, Journal of Veterinary Diagnostic Investigation
Botulism (Clostridium botulinum, types A, B, C, D)
Botulism: A Deadly Disease That Can Affect Your Horse, UKY
Brucellosis (Brucella abortus)
Brucellosis in the Horse, Bell Equine
Clostridial Enteritis (Clostridium perfringens, Clostridium difficile)
Clostridial Diarrhea in Adult Horses, AAEP
Coronavirus
Equine Coronavirus and COVID-19
Dermatophilosis or Streptothricosis (Dermatophilus congolensis)
Overview of Dermatophytosis, Merck Vet Manual
Eastern Equine Encephalitis (Eastern equine encephalomyelitis)
USDA/APHIS Annual Report: EEE 2015
USDA/APHIS Annual Report: EEE 2016
Equine herpesvirus 1 & 4 related diseases (equine herpesvirus 1 & 4, equine rhinopneumonitis virus)
EHM Owner Factsheet (EHV neurologic disease)
Equine Herpesvirus Resources, AAEP
Equine Herpesvirus 1 & 4 Related Diseases, AAEP
IDOHC EHM Guidance Document, USAHA
Equine infectious anemia (Equine infectious anemia virus)
Equine Infectious Anemia (EIA) Factsheet, APHIS
USDA/APHIS Annual Report: EIA 2018
Equine influenza (A/Equine/1/Prague 56 [H7N7] and A/Equine/2/Miami 63 [H3N8]
Equine Influenza Owner Factsheet
Equine piroplasmosis (Theileria equi, Babesia caballi, T. haneyi)
Equine Piroplasmosis Factsheet, APHIS
Equine Protozoal Myeloencephalitis (Sarcocystis neurona)
Overview of Equine Protozoal Myeloencephalitis, Merck Vet Manual
Equine pythiosis (Pythium insidiosum)
Equine viral arteritis (equine arteritis virus)
Leishmaniasis (Leishmania siamensis)
Leptospirosis
Leptospirosis in Horses, Merck Vet Manual
Mange (Demodex equi, Psoroptes equi)
Mange in Horses, Merck Vet Manual
Pigeon Fever (Ulcerative lymphangitis)
Potomac Horse Fever or Equine Neorickettsiosis
Potomac Horse Fever, AAEP
Rabies (Rabies virus)
Overview of Rabies, Merck Vet Manual
Rhodococcus equi
Ringworm (Microsporum equinum, M. gypseum, T. equinum)
Overview of Dermatophytoses, Merck
Salmonellosis (various Group A, B, and C salmonellae)
Strangles (Streptococcus equi var. equi)
Streptococcus equi var. equi, AAEP
Vesicular stomatitis (Vesicular stomatitis virus, subtypes New Jersey and Indiana)
West Nile encephalitis (West Nile virus)
Western Equine Encephalomyelitis (Western equine encephalomyelitis virus)
Foreign Diseases
African horse sickness (African horse sickness virus)
Contagious Equine Metritis (Taylorella equigenitalis)
Dourine (Trypanosoma equiperdum)
Equine piroplasmosis (T. equi, B. caballi, T. haneyi)
Glanders (Burkholderia mallei)
Hendra (Equine Morbilivirus)
Surra (Trypanosoma evansi)
Venezuelan equine encephalomyelitis (virus subtypes 1AB, 1C, 1E)
