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The take home message for this article is this: Strangles is a highly contagious disease, and strangles is rarely fatal. This disease is caused by a specific type of bacteria called Streptococcus equi. It is spread by direct horse to horse contact or by transfer from horse to horse on contaminated tack, water troughs, feed buckets and human hands. The organism does not blow across the countryside. Remember: direct contact.
Most of the time, in most horses, the characteristic signs include a sudden onset of fever, loss of appetite, cough and difficulty in swallowing. Over the next couple of days you will likely see an enlargement of the glands under the jaw and in the throatlatch area. A clear to yellowish nasal discharge may develop, the swollen glands will continue to enlarge and will likely rupture and drain a thick yellow pus. If the abscess glands fail to rupture on their own or the enlarged glands constrict breathing; they must be lanced by a veterinarian.
The organism is normally sensitive to penicillin but the general consensus is that initiation of treatment should be delayed until the lymph node abscesses have ruptured. There is concern that treating too early may predispose to bastard strangles, a condition where the bacteria spread to internal lymph nodes. Bastard strangles can be very serious and internal abscess rupture can lead to death. Occasionally, recovered horses can develop a condition know as purpura hemorrhagica. This is an immune reaction to the bacteria and can lead to swelling of the legs and head and small areas of petechia (bleeding) in the mouth.
In the majority of cases the disease runs its course over a couple of weeks and the affected horses will have natural immunity for several years. We now understand that some horses can become symptomless carriers of the disease. The organism can become an inhabitant of the nasal passage and guttural pouch. In certain instances where the disease does not seem to run its course and persists, trying to identify and treat these carrier horses is very important. The organism does not persist long term in the soil or even feed troughs and waterers, it is the carrier animal that is the culprit.
Prevention of the disease mostly involves common sense, good horsemanship and in some cases vaccination. New horses to your property, especially those coming from a public sale or where they have been directly commingled with horses of unknown background, should be isolated for 2-3 weeks. Be a good citizen; do not take any horse with a cough, fever or nasal discharge to any public horse event. Isolate any sick horse and advise others in your barn to institute good housekeeping practices to avoid possible spread to other horses. If you have an outbreak do not start moving horses to different properties, that can only increase the likelihood of spread to other farms. After an outbreak disinfection of all equipment, stalls, trailers etc. is advised. Vaccination is useful but not 100% effective. If you are in a high risk area or come in contact with horses of unknown background, vaccination may be warranted. Vaccination in the face of an outbreak within a barn is generally not recommended especially if your horse has already been exposed to the disease. Talk to your veterinarian about the risk factors for your horses.
This is not a reportable disease and an outbreak does not involve the government. Voluntary quarantine of infected properties, staying calm and following the guidelines set out by your veterinarian will go a long way in clearing up the problem and preventing further spread.
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