The disease is transmitted from horse to horse by inhaling or ingesting the bacteria that is shed by the discharge from infected horses, carrier horses, buckets, waterers, bedding, grooming equipment, tack, or people handling multiple horses. The incubation period is three to fourteen days. initially a sore throat infection can quickly spread to the local lymph nodes where the abscess occurs. The accumulation of infectious streptococcus organism and the body’s white blood cells continue to grow until it ruptures and drains. This is bad enough but around 20% of the cases result in bastard strangles. This term is used to describe an infection that has spread from the lymph nodes under the jaw to any other part of the body.

This infection should be taken seriously and the horses involved need to be isolated from other horses so that no nose to nose contact occurs. The strangles horse should have his own water and feed bucket and the person handling the horse should wear coveralls and boots that are worn only in that stall. This will help to keep the bacteria localized to one area that can be properly sanitized once the horse has recovered. The recovery in many cases can last up to four weeks and that is when treatment goes will.

Treatment protocols vary depending on many circumstances and some controversy exists here. In our practice area we have a lot of horse and a lot of young horses which tend to lead to a lot of strangles. Our recommendations to treat are as follows:

1. If the horse shows signs of lymph node abscessation but the abscess hasn’t ruptured we will try to get the abscessed drained by lancing it or hot packing it unit it can be drained or it ruptures on its own. Once we have it drained properly we will wash it out daily and apply an antiseptic solution to it. Once drained we will start the horse on Penicillin twice daily. All horses are treated in isolation.

2. If horses exhibit signs of the strangles infections (high fever, depressed or off feed) but no signs of abcessation; we will start the horse on Penicillin to arrest the infection before an abscess forms.

3. Horses exposed to strep equi but showing no signs of infection can be started on Penicillin to prevent the bacterial from infecting the horse. We also recommend intranasal vaccination for these horses if they have not been previously vaccinated. This is a case by case decision that should be decided upon with your veterinarian.

Prevention of strangles by vaccination can be frustrating but we feel that with proper vaccinations we can decrease the incidence and the severity of the sickness. We prefer to use the intranasal form as this route more closely resembles natural infection. There is also an added immune barrier by using this modified live vaccine. Our recommendation is to vaccinate at three months of age and repeats every month for three treatments. annual vaccination there after have provided reasonable protection. Remember not to use this vaccine while your horse is on antibiotics for another reason as the antibiotic may interfere with the vaccines ability to stimulate protection. We occasionally see older horses that react to the vaccine adversely; run high temperatures, do not feet good for a few days; in these horses we discontinue the annual vaccination. If a horse has gone through strangles the resulting immunity can be quite long; we usually do not vaccinate these horses except for special circumstances.