Strangles is a contagious upper respiratory disease caused by the bacteria Streptococcus equi. It earns its name by causing enlargement of the lymph nodes around the throat that, on rare occasions, can become so severe that it “strangles” the horse. While most exposed horses will develop the disease, few will die. Horses that are stressed, such as those in training, will be more susceptible.

Transmission: Strangles is highly contagious and is transmitted through contact with infected nasal secretions. This contact could be direct or via items that have the secretion on them, otherwise known as fomites. Fomites include unwashed hands, boots, brushes, water buckets and stall walls, just to name a few. Horses may also carry Streptococcus equi in the pharynx and be infectious to other horses after resolution of clinical signs.

Clinical Signs: Clinical signs usually appear 3-10 days following exposure.

  • Fever (anything higher than 101.5)
  • Decreased appetite (anorexia)
  • Nasal discharge from both nostrils
  • Cough that may or may not be productive and varies in intensity
  • Difficulty breathing (dyspnea)
  • Swelling of lymph nodes around the neck and below the jaw
  • Enlarged lymph nodes may break open, or abscess, within 7-10 days

Diagnosis: Diagnosis is initially made based on clinical signs. A nasopharyngeal wash can be done to a fluid sample from both nostrils. This sample will be submitted for strangles PCR and culture. An endoscopic exam of both guttural pouches is another option that can be done. A lavage of the guttural pouches can be done to collect samples. Due to the highly contagious nature of the disease, we will treat a horse as if it does have strangles until results are obtained.

Treatment: The mainstay of treatment for strangles is good nursing care. This includes rest, minimizing stress and offering a good palatable diet. Our goal is to support the horse while their immune system fights off the bacteria and the disease runs its course. We may also suggest the use of non-steroidal antiinflammatories (NSAIDs), such as phenylbutazone (Bute) or flunixin (Banamine), on a case-by-case basis. Applying a warm compress to the enlarged lymph nodes for 5-10 minutes once or twice a day will also help them open and drain. The use of antibiotics is controversial and we usually suggest not using antibiotics for most cases.

Complications: Most cases resolve without complications, however they do occur. These may include, severe lymph node enlargement that occludes the airway and necessitates a tracheostomy, an opening is made in the trachea so that air can enter it directly without having to pass through the throat.
Other possible complications include guttural pouch empyema or pus accumulation in the guttural pouches.

Abscesses can also form elsewhere in the body, also known as bastard strangles. Finally, horses can develop purpura hemorrhagica or cellulitis involving the entire body, especially the legs. Some of these complications can be fatal.

Control: The best method of control is prevention. We recommend yearly vaccination, especially for horses in large boarding facilities and those that travel frequently.

Biosecurity: It is also important to prevent exposure. Isolating any infected animals and practicing good hygiene can accomplish this. When isolating a horse, they should not be able to touch noses with other horses, ideally be at least 20 feet away. Since strangles is transmitted through nasal secretions, it is also important to prevent the spread of the disease through contaminated buckets, clothes, brushes, etc.

Isolation Protocols:

  •  Assign one person to treat the infected horses and another to care for the healthy horses
  • Care for healthy horses first wearing clean boots and clothes
  • Enter isolation area and care for the infected horses wearing exam gloves
  • When leaving the isolated area, wash your hands and arms with warm soapy water. Step in a foot bath that contains bleach to clean your boots. Change your clothes.
  • Clean all items exposed to the infected horses with a 10% bleach solution, including stall walls,water buckets, tack, etc.

For more information or any specific questions about your horse please do not hesitate to contact our office.