Strangles: Corral a Common Threat to Horse Health

Using an intranasal vaccine can help prevent this complicated disease.

From AQHA Corporate Partner Zoetis

Horses with a persistent strangles infection are one of the primary causes of strangles outbreaks, even in well-managed horse herds. Journal photo

Here’s a situation no horse owner wants: diagnosing a disease that shows no symptoms. In the case of strangles, that’s exactly what you might be facing.

The disease caused by Streptococcus equi, more commonly known as strangles, is a highly contagious upper respiratory infection most common to young horses.

Symptoms can include fever, difficulty swallowing, abnormal breathing, nasal discharge, swelling and/or abscesses of the lymph nodes.1 The disease can spread quickly and is easily transmitted through direct animal-to-animal contact or by objects - buckets, bridles or human hands - that may have come in contact with infected horses.

“Commonly, a horse with strangles will have profuse nasal discharge and swollen submandibular lymph nodes,” says Dr. Kevin Hankins, senior

veterinarian, Equine Technical Services, Zoetis. “Unfortunately, with strangles, about 10 percent of horses that recover from the disease don’t fully recover and then can become persistent carriers.2 Even worse, persistent carrier horses don’t show the outward clinical signs that the sick horses do.”

Horses can have a variety of health risks whether it's strangles, colic or West Nile. Another issue is genetic: HYPP. Learn how to manage a horse with HYPP by downloading AQHA's FREE HYPP Survival Guide.

Identification and Treatment

Horses with a persistent strangles infection are one of the primary causes of strangles outbreaks, even in well-managed horse herds.Once you have a persistent carrier on your farm, the only way to help eliminate the risk of disease outbreaks is to identify the persistent carrier and initiate appropriate methods for isolation and treatment.

 “If a persistent carrier or infected horse is suspected, get a veterinarian involved immediately,” Dr. Hankins says. “From there, a surveillance diagnostic test on every horse on the farm will render the most reliable results to identify persistent carriers.”

Diagnostic testing to identify persistent carriers can include endoscopic examination of the guttural pouches and nasal pharyngeal washes. Results of these tests will help the veterinarian determine an appropriate treatment program, he says.

Help Protect Your Horse

Vaccination is one of the key components of good management practices that will help protect your horses from becoming infected with strangles, help reduce their risk of becoming a persistent carrier and help you avoid expensive diagnostic and treatment protocols. Yet 40 percent of horse owners have reported that their horses have never been vaccinated for strangles.3

To help protect your horse against strangles, owners can look to an intranasal vaccine such as PINNACLE® I.N. It is the only two-dose, modified-live bacterial vaccine developed to help prevent strangles caused by S. equi and is available through your veterinarian.

Strangles is not the only health problem horses can be at risk for. A genetic condition that affects many horses is HYPP. Download AQHA's FREE HYPP Survival Guide to learn how to handle a horse with this condition.

“Strangles is classified as a risk-based disease1, so if you have a traveling horse that is frequently exposed to unfamiliar horses, you should strongly consider helping protect your horse against this costly disease,” Dr. Hankins says.

For more information on PINNACLE I.N., contact your veterinarian or visit Learn more about other Zoetis equine products at

1 American Association of Equine Practitioners. Strangles (Streptococcus equi). 2008. Available at: Accessed September 5, 2015.
2 Sweeney CR, Timoney JF, Newton JR, Hines MT. Streptococcus equi Infections in Horses: Guidelines for Treatment, Control, and Prevention of Strangles. J Vet Intern Med 2005;19(1):123-134.
3 Stowe JC. 2012 AHP Equine Industry Survey. Available at: Accessed September 5, 2015.
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