Take precautions against this contagious disease.
Strangles is a respiratory infection caused by the bacteria Streptococcus equi. It causes the lymph nodes around the head and neck to abscess, and the abscesses can become soft and rupture. Affected horses usually become dull, develop a fever, and stop eating. Many horses develop a creamy nasal discharge and sometimes a mild cough.
Strangles is a highly contagious disease transmitted by direct contact with nasal secretions or saliva. All horses can be affected, but young horses, very old horses, and horses under stressful conditions, such as shipping, are especially susceptible. Anything that comes into contact with the secretions can transmit the disease. This could include shoes, hands, clothing, gloves, lead ropes, blankets, and buckets. Once a horse is exposed, it takes 3 to 14 days for them to show symptoms. The bacteria can survive in water for 3 to 4 weeks and can also survive freezing and become infective once thawed. Some healthy horses intermittently shed the bacteria for years.
The goal of treatment is to keep the horse comfortable by administering anti-inflammatories such as phenylbutazone and Banamine TM while the disease runs its course. Other therapies such as hot packs and surgical lancing are directed towards helping the abscesses erupt and drain. Antibiotics may actually be counter-productive and are prescribed only if the horse remains off-feed, has a persistent fever greater than 104° F, or if the swellings are interfering with the horse's breathing. Pneumonia, abdominal abscesses, guttural pouch infection, immune mediated vasculitis, and muscle damage are all complications that can follow a strangles infection.
Prevention of this disease is paramount. All new horses coming into a barn should be isolated for at least two weeks. During this period their temperatures should be taken daily, and they should be screened for signs of disease. A swab of the back of the throat can be taken to pick up non-clinical carriers. If strangles is suspected on a farm, all horse movement on or off that farm must stop to help prevent the spread of the disease.
A live intranasal vaccine is available. It does not give complete protection but may reduce the number of horses affected and the severity of symptoms. Vaccine use itself can have some complications, so we recommend that you discuss the pros and cons with your veterinarian on a case-by-case basis. Vaccination during an outbreak is not done as it can complicate the disease.