Strangles

by Sarah Probst

"In terms of human disease, strangles is like a bad case of strep throat," says Dr. Thomas Goetz, veterinarian in equine medicine and surgery at the University of Illinois Veterinary Medicine Teaching Hospital in Urbana. "In horses it's a highly contagious streptococcal infection. The infected horse has a fever and appears not to feel well. Eventually discharge may come from the horse's nose, and its lymph nodes may swell."

Treatment
Depending on the case's severity, Dr. Goetz suggests three treatment options:

1. For a mild case, don't do anything; let the disease run its course. Lymph nodes may swell, burst, and drain. If the lymph nodes do not drain on their own, ask a veterinarian to lance them. Do not lance them yourself or you run the risk of severing vital nerves or vessels.
   
   
2. A horse that becomes more clinically ill and stops eating and drinking requires supportive care. Take measures to lower the fever and reduce the pain, but don't give antibiotics.
   
   
3. If the horse develops complications, antibiotics may be needed. "Refrigerator-cold injections once or twice a day for 21 days are going to give this horse a sore neck and sore leg," says Dr. Goetz. "The horse may have trouble putting its neck down to eat, and other problems may develop from treatment. Despite these negative aspects, antibiotics may be necessary to save the horse's life." Horses with complications may get a guttural pouch infection, abdominal lymph node infection (bastard strangles), vascular inflammation (purpura hemorragica), and even skin sloughing, but these complications are rare.

Because strangles is highly infective, risk of an outbreak is always present, especially with young horses. The disease may be spread when puss from the nose or burst abscesses gets on water troughs, feed buckets, brushes, driving lines, other equipment, or you.

In the event of an outbreak, Dr. Goetz prefers treatment options 1 and 2, but has resorted to antibiotics. "In a large outbreak you could separate the less severe cases and treat them with the first two options, or you could bite the bullet and treat them all. Quite a few years back a 30-pony farm had an outbreak of strangles. At first I worried we'd be treating them for 2 to 3 months. We decided to use antibiotics and in 3 weeks it was over and done with. Herd treatment, considering your manpower and financial resources, may be the best way to contain the infection and end the disease without having all your horses go through the breakage and drainage of lymph nodes and having the disease perhaps linger for several months."

Most horses are not infectious 30 days after the disease has run its course, but some horses may continue to be infective up to 6 months later. If you are concerned about whether a horse is still shedding the bacteria, ask a veterinarian to culture the horse's guttural pouch.

Cleaning the environment is difficult. Wash everything with soap and a 3:1 mixture of water and bleach. Control pests that spread disease, including flies, rats, and mice.

Prevention
Preventing strangles is also a challenge. If your horse is often exposed to other horses—such as, for example, you enjoy going on wagon trains or entering plowing matches—Dr. R. Dean Coggins, University of Illinois Extension veterinarian recommends the new intra-nasal vaccine. "It is a live-vaccine spray, so you have to be careful to give all necessary injections before using the spray. If some of the intra-nasal spray gets airborne, injection sites could get contaminated and form abscesses." Dr. Scoggins adds that you'll need an annual booster if you use intra-nasal live vaccine.

Sarah Probst is an information specialist at the University of Illinois, Urbana, College of Veterinary Medicine and a frequent contributor to Rural Heritage.