What you need to know about this common horse disease.

What you need to know about this common horse disease.

Swollen lymph nodes can be an indicator of strangles.
Swollen lymph nodes are a symptom of strangles, a disease that often affects young horses.

From the American Association of Equine Practitioners, an AQHA educational marketing alliance partner

Strangles is caused by bacterial infection with Streptococcus equi subspecies equi (referred to as S. equi). The bacteria typically infect the upper airway and lymph nodes of the head and neck. The disease was first reported in 1251. The infection is highly contagious in horse populations, particularly affecting young horses, and can recur on farms with previous outbreaks of the disease.

It is one of the most commonly diagnosed contagious diseases of horses worldwide. The bacteria can survive on water troughs for more than a month, but the primary source of recurrent infections is most likely asymptomatic carrier horses that can shed the bacteria to other horses for months and years.

Strangles isn’t the only horse disease that’s highly treatable. Learn more about Equine Viral Arteritis with our FREE EVA: A Manageable Problem report. Download your copy today!

Clinical Signs of Disease

Historically, strangles got its name because affected horses were sometimes suffocated from large, infected lymph nodes that obstructed the upper airway or trachea. The hallmark clinical signs of infection are fever (a temperature of greater than 101.5 F), nasal discharge and enlarged lymph nodes in the space between the lower jaw bones, which ultimately abscess.

Pus-filled nasal discharge is typically present, although it may initially be clear. The lymph nodes in the area behind the throat latch can also become enlarged and abscess.

The lymph nodes will sometime drain into the guttural pouches, which are air-filled spaces within the head that are an expansion of the Eustachian tubes.

Though strangles is highly contagious and can affect many horses on a farm, most horses with infection recover without complication. Complications from the infection include spread of the infection to lymph nodes other than the head and neck, immune-mediated disease, muscle disease and pain, and lack of milk production. Horses that develop a complicated infection typically require antibiotics and additional therapies based on veterinary examination.


Antibiotic therapy remains controversial for the treatment of strangles. Complicated cases generally require antibiotic and other supportive therapies.

There is some evidence that treatment with antibiotics (such as penicillin) at the first sign of fever and in horses with no lymph node enlargement might prevent infection. However, early antibiotic treatment will also prevent these cases from developing immunity to the infection and subsequently makes them susceptible to reinfection sooner.

Management of an Outbreak

The first and most important thing to remember in a suspected outbreak of strangles is to involve your vet right away to determine the diagnosis and the best control practices for your particular farm.

Strangles is a reportable disease in some states, and the state veterinarian might need to be notified as well. Movement of any horses on or off the farm should be stopped, and new horses should not be introduced. Take the temperature of all horses on the farm twice daily (normal rectal temperature is 99 to 101.5 F).

Monitoring the rectal temperature and isolating horses at the first sign of fever is one of the most effective ways to stop the spread of infection. Infected horses can transmit the bacteria to healthy horses one to two days after they develop a fever.

An isolated area should be set up for horses with fever and any other signs of illness. Extreme care should be taken not to mix infected or exposed horses to unexposed horses.

Your horse’s health is important to you. That’s why it’s good to be as informed as possible. Learn all about Equine Viral Arteritis with our FREE EVA: A Manageable Problem report.

Ideally, three groups of horses should be created:

  • Infected horses
  • Horses that have been exposed to or been in contact with infected horses
  • Clean horses with no exposure

Unexposed horses should be kept in a clean area and ideally should have separate caretakers, cleaning equipment, grooming equipment, water troughs and pasture. People and equipment can transfer the infection from horse to horse. Extreme care, hand washing and disinfection of supplies must be observed by everyone involved. If different individuals cannot care for infected and healthy horses, the healthy horses should always be handled first

Additional Preventive Measures

Here are some additional suggestions for reducing your risk:

  • Require a current health certificate for new horse arrivals on the farm.
  • Ask owners of new horses about a history of strangles and consider testing new horses to see if they are shedding the bacteria.
  • If feasible, quarantine new arrivals for two to three weeks and monitor their temperature.
  • All horses should have individual water buckets that are routinely disinfected.
  • When traveling to shows, minimize your horse‚Äôs exposure by bringing your own feed, buckets and equipment. Minimize use of shared stalls or pastures at show grounds.
  • If horses are pastured together, group them according to their age and risk level.

6 thoughts on “Strangles”

  1. Is strangles a reportable disease in the state of Pennsylvania? I know of a boarding and riding facilty there that is not following normal protocal which you state in this article. What would be the best approach to handle this problem. To date it has infected 20 horses and I am concerned for the re-occurance.

  2. I am from Michigan and recently took on a horse from a horse rescue facilitiy in my area. The horse broke out with strangles 14 days later. With a little research from local vets and other people that had bought horses from the same place I am finding that strangles is on that farm and it is now spreading all over the area.

    I feel that the rescue facility is helping horses, but I do not see where it is helping to control the dieses or educate the buyers of these horses. Its a very sad situation.

    It is also my understanding that there are not any requlations or anything that can be done in Michigan or to non-profit organizations.

    Question 2 is how do you go about finding out if a horse is a carrier? After 54 days of seperation I am having another outbreak. This was in a clean non exposed area, but the horses did have contact with the previoulsy infected horse through the fence,after 54 days. The infected horse had light stangles for 7 days than I kept her seperated for an additional 47 days. I would not think that she could still spread it, but I quess sometimes they can.

    I also pastured 2 horses with her after her 30 days of being clean from strangles and they are showing no signs of strangles and are fine approx 70 days later.

    I am now letting all 6 horse have contact to each other so that hopefully they get it and get over it so that I do not continue to have sporatic outbreaks. This disese seems not to follow any simple pattern. All cases seem different. Luckily my horses are getting a little nasal discharge, slight temperaturess and then are fine in about 1 week.

    Question 3 When is it safe to take a horse to a show or to another farm after an outbreak? Should you have have them tested to see if they are harboring the disease after all symptoms are gone?

  3. This was a problem at a local boarding facility which housed over 50 horses. My horse came down with it as a two year old and became quite ill but recovered just fine. We used bute to treat temperature when it was over 104 and hot packed the abcess using a wash rag soaked with hot water to encourage to abcesses to burst and drain, in some cases a mild betadine/water solution was flushed through the opening where the abcess had drained. Anti-biotics should be avoided if possible (aside from horses with bastard strangles) since they slow the rate of bacterial reproduction, ultimately slowing how quickly the abcess will burst. A recovered horse will usually be immune for up to five years, but can become a carrier horse. A vet can test for carrier animals and if you desire to keep a confirmed carrier the vet can flush their guttural pouch, where the bacteria can remain even in otherwise heathy horses and infect other horses.

  4. If the enlarged lymph nodes drain into the gutural pouches of the horse, the horse can get gutural pouch empyma, which comes with its own problems. One main side affect of the gutural pouch empyma is that the bacteria can survive and persist for months to even years, without showing any other signs or symptoms of illness. This can be very problematic because in these cases the horses are carriers of the bacteria for a prolonged period of time.

  5. I just recently adopted a horse through a rescue in PA, she had been on Auction circuit and broker lot. She was shipped in a 6 Horse Slant that was Beyond disgusting. Not the Truck or Trailer advertised in their ad. Anyways she was immediately QT away from all the other horses, and is separated quite away’s from the others with no way to contact at all. Her case is not confirmed but most likely as she has all the symptoms. Should my other horses be safe after 30 days or should I keep her there 60 days to make sure.

  6. My horse was infected with strangles and had a lighter case of it, we turned her out with the others after quarantine for a month. We now have another horse that broke out with the disease.

    Is it okay to take mine to a show now? Its been a little over a month and she is fine, no symptoms.

Leave a Reply

Your email address will not be published. Required fields are marked *