Strangles: Dispelling the Myths

Strangles. Even the common name for this bacterial disease—caused by the sinister Streptococcus equi—sounds like something of legend, a cautionary tale inscribed by medieval monks.

 

The abscesses and pus-laden nasal discharge common to the condition can seem like something from a mythical plague. However, strangles is very much an actuality in today’s horse world, a real respiratory disease with a real, mundane bacterial cause.

 

Though the disease has been recognized in horses since it was first reported in 1251, myth and misunderstanding persist even today. But before launching into the realm of myth, let’s take a quick look at the basic facts of the disease.

 

Cause Streptococcus equi spp equi (frequently referred to as S. equi) inhabits the respiratory tract of sick horses and carriers—those horses that might not be obviously sick. 

 

Clinical signs Ashley Boyle, DVM, Dipl. ACVIM, assistant professor at the University of Pennsylvania School of Veterinary Medicine, says the first sign of strangles is often (though not always) a sudden fever spike. In a 2011 article in Compendium: Continuing Education for Veterinarians, Boyle lists other signs of the disease, including “lethargy, depression, bilateral mucopurulent nasal discharge, lymphadenopathy, and abscessation of the retropharyngeal and mandibular lymph nodes.” Translation: If your horse has strangles, he might seem very tired and have thick snot made up of mucus and pus streaming from both nostrils, swollen lymph nodes, and abscesses under the jaw and at the throatlatch.

 

Disease spread Sick horses shed S. equi  via these nasal secretions and when the abscesses drain pus. Chronic carrier horses that appear healthy can shed bacteria trapped in their guttural pouches through their pharynx (more on this phenomenon in a moment). Horses can become infected through direct contact with diseased horses; contact with people, equipment, or surfaces that have recently touched diseased horses or their secretions/pus; or common water sources shared by sick or carrier horses.