A normal temperature for an adult horse ranges from 99.0-101.5 degrees Fahrenheit, therefore, anything over 101.5*F is considered a fever. There are a multitude of reasons why horses develop fevers and each is managed a little differently. Any temperature over 105.0 degrees Fahrenheit is considered a high-grade fever and requires IMMEDIATE medical attention. Lower grade fevers may not warrant an emergency visit but should always elicit a medical consultation with your veterinarian. Prior to contacting your veterinarian, it is important to note your horse’s attitude and demeanor, appetite, water intake, and manure and urine output. It is also important to note if there are other horses on the property having similar symptoms or running a fever.
The most common cause for a fever is an infection which can be in any of your horse’s body systems:
- Respiratory
- Gastrointestinal
- Dermatologic (skin)
- Circulatory (heart and vessels)
- Musculoskeletal
Other causes of increased temperature in your horse are less common but need to be considered:
- Genetic (malignant hyperthermia)
- Heat exhaustion (overworking in warm temperatures)
- Immune response (after vaccination)
Prior to consultation with or arrival of your veterinarian, isolate your horse from other horses on the property. Thoroughly sanitize your hands and ideally change your boots and clothes before handling other horses on the property and do not share equipment (brushes, tack, etc.).
Once your veterinarian has arrived, they will begin with a thorough physical examination to look for the source of the fever. Depending on this examination they may recommend further diagnostics such as bloodwork, imaging (ultrasound), and respiratory or fecal diagnostic panels. Pending diagnostics, your veterinarian will determine the best course of action for you and your horse.
Following your veterinarian’s visit to the farm, it is important to keep your horse isolated from others while they continue to display symptoms; follow veterinarian instructions on re-introducing your horse to the herd. Your veterinarian may also ask you to monitor your horse’s temperature once to twice daily. This can be done using a human thermometer, however, is important to ensure the thermometer is thoroughly inserted into the rectum to obtain an accurate temperature (generally 1-2 inches of the thermometer should be inserted). Tipping the butt end of the thermometer down while inserted will allow the tip to touch the surface of the rectum and will provide a more accurate reading.
Most fevers can be treated effectively on the farm, however, if your horse’s case is complicated/advanced or there is not resolution of clinical signs after a period of time your veterinarian may recommend referral to hospital facility for more advanced diagnostics, monitoring, and treatment.