Horse Health


August 4, 2011

Should your horse be vaccinated against strangles?

From AQHA Corporate Partner Pfizer Animal Health

horse strangles

Strangles is a highly contagious disease that localizes in a horse’s lymph nodes in the upper respiratory tract. Journal photo.

Show season is in full swing, and many owners are traveling with their American Quarter Horses to events across the country. Keeping horses healthy when traveling can present some challenges. Contagious diseases, such as strangles, can have severe consequences on a facility or surrounding area, according to a press release from AQHA Corporate Partner Pfizer Animal Health.

Strangles, caused by the bacterium Streptococcus equi, is a highly contagious disease that localizes in a horse’s lymph nodes in the upper respiratory tract. The disease obtained its name from the strangling breathing sounds made by affected horses, caused by enlarged lymph nodes in the throat. Strangles may also be referred to as distemper.

Horses with strangles will usually first show signs of high fever, poor appetite and depression. Horses will excrete a thin, watery discharge from their nostrils, which will quickly turn thick and yellow. The horse’s upper respiratory lymph nodes can become enlarged and may abscess, most noticeably the ones at the throat latch area and between the jawbones.

Once a horse is exposed to the bacteria, it can begin to show symptoms in two to six days. If left untreated, it can often develop abscessed lymph nodes within one to two weeks after the onset of the illness. The abscessed lymph nodes can rupture and drain, and the drainage is highly contagious. Most horses will recover, but approximately 10 percent of untreated horses may die, usually from a secondary pneumonia.

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Strangles can affect horses of any age but most commonly infects those between weanling and 5 years of age. The disease is usually acquired after exposure to another horse that is shedding the Streptococcus equi bacteria, either during or after its own bout with the illness. Infectious horses can spread the bacteria even when they are no longer showing signs of the disease. Around 20 percent of horses remain contagious for four to six weeks after all symptoms vanish.

Direct contact between horses is the most common way that strangles is spread. However, it can also be spread by contaminated equipment. Proper biosecurity practices are necessary to help reduce the spread of disease from contaminated equipment such as shared buckets, stalls, tack, halters and lead ropes. Be sure to follow proper sanitation and disinfection techniques and follow label directions. There are a number of commercially available disinfectants, such as ROCCAL D Plus or NOLVASAN Solution, that are effective for killing bacteria. Before disinfecting, remove all excess debris or dirt from the item and wash with a detergent such as laundry or dish soap. Follow this washing by dipping the item in disinfectant. Disinfection can be completed on items such as nylon halters, bits, lip chains, grooming equipment, shovels, pitchforks and even shoes. Be sure to rinse the disinfectant off completely, using clean water two to three times before using the item.

Vaccination can help in the prevention of strangles. Although vaccinated horses may still contract the disease, they tend to experience a less severe illness. Horses cannot contract strangles from the vaccine itself.

Pfizer Animal Health offers PINNACLE IN, an intranasal Streptococcus equi vaccine. The modified-live intranasal vaccine has shown to stimulate a high level of immunity against the disease. The vaccine must reach the pharyngeal and lingual tonsils in sufficient numbers to help trigger a protective response. Therefore, accurate vaccination delivery by a veterinarian is critical to vaccine efficacy.

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According to the American Association of Equine Practitioners, the incidence of strangles varies regionally, as well as from farm to farm. Therefore, it is listed in AAEP’s guidelines as a “risk-based” disease. Risk-based vaccinations differ from core vaccinations in that they help protect against diseases that are endemic to a region and that have potential public health significance.  Core diseases include eastern equine encephalitis, western equine encephalitis, rabies and tetanus. Due to these variations, it is important to consult a veterinarian when developing a vaccination program.

If you suspect that a horse has strangles, notify a veterinarian to confirm the disease. The sooner a positive diagnosis is reached, the sooner the horse can be isolated and treated.