"Strangles" is a layman’s term for Streptococcus equi infection. It is an extremely contagious bacterial infection which is contracted through the mucous membranes your horse’s nasal/ oral passages.

Strangles can be fatal, but this is rare. Usually, infection remains localized within the upper respiratory system. Because bacterial inoculation occurs in the mucous membranes of the nasal and oral passages, it occasionally "seeds" in the intermandibular lymph nodes, which often become swollen and painful. "Bastard strangles" is a layman’s term which describes mobilization of the bacteria from the intermandibular lymph nodes to other parts of the body. Depending on where (and how many places) bacteria end up, the disease may become life-threatening.

Antibiotic therapy in the form of Penicillin can be used to alleviate clinical signs in severe cases. However, because strangles is caused by a tough, gram-positive bacteria, indiscriminate use of antibiotics can cause the disease to linger in horses for extended periods of time. Therefore, it is generally better to let the infection run its course and treat only when necessary…it will resolve much quicker.

Once the first horse exhibits clinical signs of strangles, one should assume that EVERY horse in the barn has been exposed. All horses should have their temperatures taken twice a day, since a rise in body temperature of 1.5°F over normal is an indicator that the horse might contract the disease. Horses with fever should be isolated immediately.

Since normal-appearing horses may be incubating the disease, we highly recommend not moving horses around, to, or from the premises. If possible, visibly affected horses should be strictly isolated to allow for more intensive care and discourage direct transmission to other horses.

Factors that facilitate transmission of strangles infection include human hands, shoes, clothing, towels, grooming equipment, flies, and anything else that touches discharge from a sick horse, then lands on a healthy horse’s nose. The bacteria can persist in the environment for a variable amount of time, especially when protected by discharge material. Contaminated bedding should be disposed of properly and not spread on pastures, since it also can be a source of contamination.

In regard to vaccination, the intranasal preparation is by far the best to use, because it elicits a local (and dramatic) immune response within the mucous membranes of the oral and nasal passages (where the disease is contracted) rather than a general systemic response (which occurs pursuant to intramuscular vaccination). However, we would not expect any strangles vaccine to provide complete protection. This is because…

  1. Vaccines are generally designed to prevent VIRAL infection. Viral antigens are extremely specific and consistent from one animal to another. Vaccinating against rabies, for example, pretty much assures that rabies infection won’t occur. Bacteria, on the other hand, have many strains. Although you may elicit a general (broad spectrum) response against a certain type of bacteria, the response is not nearly as specific for any one strain.
  2. During an epidemic, your horses have (undoubtedly) already been exposed to strangles. Vaccinating now will not elicit enough of an immune response to provide much (if any) protection.

Nevertheless, we recommend vaccinating all potentially-exposed horses (with the intranasal preparation) including the pregnant mares. Because the vaccine contains live bacteria, care must be taken in terms of administration. The vaccination process should be the very last thing that is done on the farm that day. Hands should be washed in between every horse. DO NOT administer any intramuscular injections to horses that have been vaccinated within the past 24 hours. Your clothes, shoes, and body should be washed thoroughly after handling horses with strangles.

There is no disinfectant that can be safely used on pastures. Water and feed buckets should be daily cleaned with a detergent and disinfected with a phenolic disinfectant, then thoroughly rinsed prior to use.

We highly encourage you not move any horses off or onto the grounds until AT LEAST 30 days AFTER THE LAST HORSE’S SYMPTOMS HAVE COMPLETELY RESOLVED. This sounds like a long time, but the infection can linger in asymptomatic horses for many months. Prior to moving horses, EVERYTHING the horses come in contact with in the barn (bridles, halters, stalls, aisle ways, etc.) should be disinfected with bleach solution. Let dry for 24 hours.

Contributed By: http://www.atlantaequine.com/