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Strangles: Fighting an age-old disease

It was described in veterinary literature as far back as 1251, more than 750 years ago, yet it remains one of the most commonly diagnosed infectious diseases in horses worldwide. It's called strangles because symptomatic lymph-node enlargement can compress the pharynx, larynx or trachea of infected horses, causing them literally to strangle and die from asphyxia. In today's environment, careful attention and proper management of the disease can help more horses than ever to survive. Farm operators who pay special attention to testing and isolating asymptomatic carriers eventually can reintroduce those horses back into the general population.

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 Equine Strangles: Management and Prevention

The incubation period for strangles ranges from three to 14 days. A horse usually develops fever a day or two prior to lymph node enlargement or shedding of large numbers of the organism. S. equi is highly contagious, causing infection in the upper airway and in lymph nodes around the head and neck. There is a potential for it to become more serious and metastasize to form internal abscesses, called bastard strangles.

 Hard Work And Dedication Got Us Through A Strangles Outbreak

Strangles is an infectious and highly contagious bacterial disease caused by Streptococcus equi. The bacterium enters the lymph glands via the respiratory tract and most commonly takes up residence in the guttural pouch (just behind the cheekbone). The extreme swelling of the lymph nodes causes the horse to sound as if he is being strangled, hence the name.

 Strangles in equines: An overview

Strangles is an extremely infectious and serious disease infecting the upper respiratory pathway of horses and other equines. It is caused by a spherical, gram-positive, pyogenic and β-haemolytic bacterium Streptococcus equi subsp. equi which is a member of Lancefield group C. The bacterium is extremely contagious and causes high morbidity, but low mortality in previously disease free but vulnerable populations.

Articles of Interest

Should I vaccinate my horse against Strangles?

The Strangles vaccination provides the best possible protection against Strangles and although it does not completely prevent Strangles it does markedly reduce the clinical signs your horse will have. If a horse comes into contact with Strangles 50% of vaccinated horses will show no clinical signs, others will just show very mild signs such as a mild temperature and slight cough and the resolution of disease will be much quicker than an unvaccinated horse.

A Herd Outbreak of Equine Strangles

Strangles is most commonly spread by horses harboring the organism in their guttural pouch. It is important to test horses following an outbreak to prevent further spread of this frustrating disease. Testing recommendations for carrier horses include repeated (3) nasopharyngeal washes or guttural pouch lavage (considered the best place to sample from and only 1 wash is necessary). Samples should be submitted for culture and PCR for S. equi, as this organism can be difficult to culture. Prevention of bringing strangles into the herd, can also be accomplished by quarantining any new additions to a herd for four weeks and then testing (nasopharyngeal or guttural pouch lavage).

Are you and your horse at risk of Strangles?

Our animation takes a light-hearted look at some serious situations in which your horse could easily become infected... Thanks to some fantastic research, funded by our friends at the Horse Trust, we can now link Strangles outbreaks not only in different counties, but in different countries!!

Equine Strangles: Management and Prevention

Strangles is a disease caused by bacterial infection with Streptococcus equi subspecies equi (also referred to as S. equi). Strangles is one of the most commonly diagnosed contagious diseases in horses worldwide, and was first reported in 1251. The bacteria typically infect the upper airway and lymphoid tissues of the head and neck, causing enlarged lymph nodes, nasal drainage, and abscess formation. Strangles is highly contagious in horse populations and can cause outbreaks

Speak out on strangles!

Strangles is the most commonly diagnosed equine infectious disease in the world. Because it is contagious, it is widely feared by owners and many feel they will be ostracized by others on their yard if they suspect their horse has the disease. This hinders a quick

Strangles (Distemper) in Horses

Although strangles is a bacterial infection, there are pros and cons to using antibiotics to treat it. Most researchers agree that antibiotic therapy will provide temporary improvement in fever and depression; however, it may also prolong the course of the disease by delaying maturation and drainage of the abscesses.

Strangles: What's the Deal?

It is important NOT to vaccinate your horse during an outbreak as elevation of the horses’ antibody levels if they’ve already been exposed is dangerous too and can lead to an immune mediated vasculitis called Purpura Hemorrhagica where your horse may slough skin over its limbs or have other organs affected (kidney failure, pneumonia, cardiac arrhythmias) and even lead to death.

Streptococcus equi Infectious Disease Guidelines

The upper respiratory disease commonly referred to as strangles is caused by Streptococcus equi subsp equi. Less commonly, the bacteria affect lymph nodes in the thorax and/or abdomen, causing a syndrome known as metastatic or “bastard strangles”. Clinical signs are age and immune status dependent, with older horses typically exhibiting milder signs of shorter duration. Vaccinated animals may show mild signs. Every horse is at risk of disease when challenged with substantial pathogen dose and frequency.

Understanding Strangles: A Guide for Horse Owners

Strangles is a serious concern for horse owners due to its highly contagious nature and potential complications. The disease can spread rapidly through direct contact with infected horses or indirectly via contaminated equipment, water, feed, and even human handlers. Horses of all ages are susceptible, but younger horses tend to be more severely affected. Complications can include abscesses in internal organs, known as "bastard strangles," and purpura hemorrhagica, an immune-mediated condition that can be fatal.

What Horse Owners Need to Know About Equine Strangles

“It’s usually probably three to four weeks total for a horse to clear the infection, and during that time, they can give it to a whole lot of other horses,” says Dr. Kate Hepworth, an assistant professor of equine medicine at the NC State College of Veterinary Medicine. “It can be a very prolonged disease course that can stop people from traveling, going to horse shows, and doing many of the things that people enjoy doing with their horses.”

Resources

7 Facts About Strangles You Need to Know

If you’ve owned or been around horses, you have most likely heard of strangles. Recognized most for its signature symptom—swollen lymph nodes in the throat—it is a bacterial infection similar to strep throat in humans. But are you familiar with how to spot less-obvious symptoms, treat, and prevent the spread of strangles?

Strangles vaccination

Many horse owners will be aware that a vaccine against Streptococcus equi equi, the bacterium that causes strangles, called Strangvac, became available in 2022. We now have the benefit of three years’ experience of its use in about 10,000 horses throughout Europe, along with a scientific review published in the Equine Veterinary Journal in 2024.

Strangvac

Strangvac is an intramuscular vaccine against the highly contagious respiratory disease strangles. Strangvac is indicated to reduce the clinical signs and the number of abscesses within submandibular and retropharyngeal lymph nodes in horses during the acute stage of strangles.

Strepvax® II

Contains a purified antigenic protein of S. equi extracted through an exclusive process and is essentially free of the toxic and irritating substances present in whole cell bacterins

UC Davis

In most cases, strangles is treated with rest and supportive care. Horses are monitored closely to ensure pain management and adequate consumption of food and water. If not treated with antibiotics, 75% of horses mount a sufficient immune response to develop long-term immunity to strangles.