PET TALK: Reining in the facts on equine strangles

Since the first vaccine was invented in 1796, the practice of immunization has transformed how we view infectious diseases, taking many pathogenic invaders from being deadly threats to easily preventable maladies. For humans and animals alike, vaccines are important healthcare tools.

Dr. Leslie Easterwood, a clinical assistant professor at the Texas A&M College of Veterinary Medicine & Biomedical Sciences, says the equine strangles vaccine is one that is of particular importance for horse owners in protecting their animal.

“Strangles is the common term for the bacterial respiratory disease caused by Streptococcus equi, subspecies equi,” Easterwood said. “Strangles infections most commonly present as an upper respiratory infection that primarily involves the lymph nodes in a horse’s jaw. Symptoms include high fevers, thick nasal discharge, depression, and a lack of appetite.”

The bacteria that causes strangles in horses may sound familiar to their human owners; a cousin of this bacteria, called Streptococcus pyogenes, causes strep throat in people. Though these bacteria are genetically similar and cause upper respiratory symptoms in both species, horses with strangles cannot infect humans, and humans with strep throat cannot infect horses.

“Strangles is spread via respiratory secretions from infected horses,” Easterwood said. “It is highly contagious from horse to horse and is pretty common.”

Since strangles is easily transmitted between horses, vaccination is an important tool for minimizing the spread of this disease.

“Although the disease rarely results in a fatality, it will make horses sick and can lead to loss of production, decreased performance, and quarantine, in some circumstances,” Easterwood said. “Vaccination does not provide complete protection, as with all vaccinations, but it can help to decrease the chance of contracting the disease in susceptible populations.”

Since horses are often kept in groups—grazing together at pasture, sharing pens, or neighbored in stalls—contagious diseases can quickly work their way through a herd. As such, vaccination remains an essential tool for both individual and herd health.

Ultimately, the decision of whether to vaccinate an animal comes down to the owner, Easterwood says, although there might be situations during which a third party takes interest in a horse’s vaccination records.

“There are no governmentally mandated vaccinations in horses,” Easterwood said. “Some boarding and breeding facilities will require vaccination to board at their location, but that is not a legal requirement.”

Even if no legal requirement enforces the vaccination of horses, owners should still consider consulting with their veterinarian to determine what care is best for maintaining the health of their animal.Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. Stories can be viewed on the web at Suggestions for future topics may be directed to

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