Protect Your Horse from Strangles

Strangles is an upper respiratory tract infection caused by the bacteria Streptococcus equi (Strep. Equi).  It can affect horses of any age although young horses (age 5 and under) tend to be more susceptible.

This contagious disease has many forms, the most common of which is the form responsible for abscess formation in the lymph nodes in the head.  These nodes are located between the mandibles of the jaw and in the throatlatch area.  The swelling can be severe and result in respiratory distress, hence the name "strangles."  Affected horses also run a fever > 102, are anorexic, may exhibit dysphagia (difficulty swallowing), have a cough and a thick nasal discharge.

Another form of the disease is called "bastard strangles" in which internal lymph nodes are involved.  This can lead to pneumonia, weight loss, or colic. This can be difficult to treat but is not a common problem.

Purpura hemorrhagica is another serious complication.  The horse's immune response to the disease results in small hemorrhages in the mucosa, and mild to severe swelling of the head, limbs and abdomen.

Strangles is very contagious and may affect up to 100% of the horses in a barn if strict quarantine procedures are not in place. Infection is by ingestion or droplet inhalation.  So the horse with a cough or drainage from the nose or lymph nodes is most contagious and can infect neighboring horses, or persons working with them who may then carry the organism to another animal if they are careless in their hygiene. Affected barns are quarantined to prevent the spread of the disease.  The length of quarantine is dependent on the course of the disease in the barn.

Fortunately there are many things you can do to protect your horse:

  • Ideally, new horses coming into a barn should be isolated from the rest of the population for two weeks.  If they are carrying the disease, it should be obvious by that time.  This may not always be possible, but there may be ways to minimize any contact to the new horse.
  • When traveling in a trailer and going into a new stall, take a few minutes to mop down all surfaces with a disinfectant solution.  The bacteria is easily killed by this method.
  • When there is a known sick horse, handle that horse last, or designate a single person to care for that animal and go through a disinfecting process after handling. 
    For me, I visit these horses last during my day, I take a complete change of clothes, bag the "dirty" stuff which then goes directly into the washer with chlorhexidine solution and dried on hot.  Boots are covered in plastic and then still disinfected 2-3 times, long plastic sleeves and double gloves are worn.  No equipment enters the barn unless necessary and that too is completely disinfected.  Lots of Lysol, Clorox wipes, etc.!

    Being diligent means going the extra mile to prevent any spread of disease. Conversations with our local state veterinarian lead me to believe this is an extremely effective method of control - and no it won't travel by car tires, etc.!

  • Vaccinations are also available. There is an intramuscular form as well as an intranasal form. I see advantages and disadvantages to each and so when counseling clients I try to advise them fully of their options.

I hope this helps to answer some of your questions, or maybe now you have new ones.... Remember that preventive medicine works best when taking into account all the different factors affecting your horse: age, use, nutritional status and feeding program, exposure risk, management and veterinary care.

Lets work together to keep our horses healthy!

Jeanne Best, DVM
Royalton Equine Veterinary Services, P. C.


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