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 occasion, can become so severe that it “strangles” the horse. While most exposed horses will develop the disease, few will die.
Who gets Strangles: Horses less than five years of age, or those that are unvaccinated. 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, other wise known as fomites. Fomites include unwashed hands, boots, brushes, water buckets, and stall walls, just to name a few. Horses may also carry Steptococus equi in the pharynx and be infective to other horses up to 90 days after resolution of clinical signs.
Rarely, strangles can become endemic on a farm, such that susceptible horses brought onto the premise contract strangles even following adequate disinfection.
Clinical Signs: Clinical signs usually appear 3-10 days following exposure. They include the following:
- Fever of 102-107° F (normal is 100° F +/- 1° F)
- Decreased appetite, also known as anorexia
- Yellowish nasal discharge from both nostrils
- Cough that may or may not be productive, and varies in intensity
- Difficulty breathing, also known as dyspnea
- Swelling and/or abscessation 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 usually made based on clinical signs. Although rarely performed, swabs of the pharynx or nasal discharge can be taken in order to make a definite diagnosis. 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, on a case-by-case basis.
In addition to good nursing care, we also recommend feeding your horse on the ground to facilitate drainage of nasal discharge and abscesses. Applying a warm compress to the enlarged lymphnodes 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. If antibiotics are used, it needs to be for a long period of time.
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. A tracheosotomy is when 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 gutteral pouch empyema, or pus accumulation in the gutteral pouches. Abscesses can also form else where in the body, also known as bastard strangles. Finally, horses can develop Purpura hemorrhagica or cellulitis involving the entire body, especially the legs.
Control: The best method of control is prevention. We recommend yearly vaccination, especially for animals under five years of age or those at high risk. We may recommend more frequent vaccination depending on the circumstances, especially if there is a history of strangles on the farm.
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 another animal or 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 though contaminated clothes, brushes, etc. This is accomplished by one of two ways, one person treating the infected horse and another care for the healthy animals or abiding by the following:
Tips for caring for a horse with Strangles:
- Care for healthy horses first wearing clean boots /clothes
- Enter isolation area and care for the infected horse wearing rubber exam gloves
- When leaving the isolated area, wash your hands and arms with warm soapy water, step in a footbath that contains bleach to clean your boots, and change your clothes.
- Clean all items exposed to the infected horse with a 10% bleach solution, including stall walls, water buckets, tack, etc.
We hope this will provide some insight into the cause, treatment, and transmission of strangles. If you have any questions, or if you suspect your horse may have strangles, please contact us at (913) 533-2370.
Jessica R. Newberry