Fever in Horses: How to Check

Fever is one of the most common signs that your horse is fighting an infection or dealing with an illness. As a horse owner or caretaker, knowing how to accurately check your horse’s temperature and recognize the early signs of fever can help you catch health problems before they become serious. A fever is your horse’s natural immune response to infection, inflammation, or illness, but it also signals that veterinary attention may be needed. This guide walks you through the process of taking your horse’s temperature, interpreting the results, and understanding when fever demands immediate professional care.

Checking your horse’s temperature is a simple skill that every horse owner should master. Unlike humans, horses cannot tell us when they feel unwell, so we must rely on physical examination and vital signs to assess their health. Temperature is one of the four critical vital signs for horses, alongside heart rate, respiratory rate, and capillary refill time. By learning to take your horse’s temperature correctly and knowing what readings mean, you will be better equipped to work with your veterinarian to keep your horse healthy and catch illness early.

What is a Normal Temperature in Horses?

The normal body temperature for an adult horse ranges from 99.0 to 101.5 degrees Fahrenheit (37.2 to 38.6 degrees Celsius). Some horses naturally run slightly cooler or warmer than others, so it is helpful to know your own horse’s baseline temperature when healthy. Take your horse’s temperature on several calm occasions and record the results to establish what is normal for that individual animal.

Young foals have slightly higher normal temperatures than adult horses. Foals typically have a normal temperature range of 100.5 to 102.5 degrees Fahrenheit (38.1 to 39.2 degrees Celsius). This is normal and does not indicate fever. Temperature can also vary based on the time of day, environmental temperature, exercise level, and stress. A horse that has just finished work or is anxious may have a temporarily elevated temperature that drops back to normal within 30 minutes of rest.

How to Take Your Horse’s Temperature

Tools You Will Need

• A digital or traditional mercury thermometer designed for horses or livestock
• Lubricant such as petroleum jelly or water-soluble gel
• Clean cloth or paper towel
• A helper to hold or calm your horse if needed

Step-by-Step Instructions

1. Prepare your horse. Move your horse to a calm, quiet location. Have your helper stand at the horse’s head to keep the animal still and relaxed. A nervous or stressed horse may have an artificially elevated temperature.
2. Gather your supplies. Have your thermometer and lubricant ready before you begin. Digital thermometers are faster and easier to read than mercury ones, typically taking 10 to 15 seconds to register a reading.
3. Position yourself safely. Stand to the side of your horse’s rear end, not directly behind. This position keeps you safer in case the horse moves suddenly.
4. Lubricate the thermometer. Apply a generous amount of lubricant to the bulb or sensor end of the thermometer. This reduces discomfort and makes insertion easier.
5. Insert the thermometer. Gently lift the horse’s tail and carefully insert the thermometer into the rectum. Insert it only 2 to 3 inches for safety and comfort. Do not force it.
6. Wait for the reading. Hold the thermometer steady for the time specified by the manufacturer. For digital thermometers, this is usually 10 to 15 seconds. The device will beep or show a signal when the reading is complete.
7. Remove and read. Carefully withdraw the thermometer and note the temperature reading. Wipe the thermometer clean with a cloth or paper towel before putting it away.

Tips for Success

• Choose a quiet time when your horse is calm and not fresh from exercise or stress.
• Use a digital thermometer for faster, easier readings.
• Have someone hold your horse to keep the animal still.
• Be gentle and patient; rough handling can raise heart rate and temperature.
• Record the time and temperature in a notebook or on your phone for reference during vet calls.

Signs Your Horse May Have a Fever

A fever is confirmed by a rectal temperature above 101.5 degrees Fahrenheit in an adult horse at rest. However, fever often comes with other signs that alert you to check your horse’s temperature. Learn to recognize these symptoms:

• Lethargy or depression: The horse appears unusually quiet, stands with head down, or shows no interest in food or activity.
• Loss of appetite: The horse refuses grain, hay, or both, or eats less than normal.
• Increased heart rate: You may feel a faster pulse, especially when the horse is at rest.
• Rapid breathing: The horse breathes faster than the normal rate of 12 to 20 breaths per minute at rest.
• Sweating: The horse sweats without exertion or in cool weather.
• Shivering or chills: The horse shivers or trembles as if cold, despite warm weather.
• Nasal discharge: Clear, cloudy, or yellowish discharge from the nostrils.
• Cough: A new or persistent cough, especially when accompanied by nasal discharge.
• Watery eyes or swollen eyelids: The eyes may appear irritated or teary.
• Dull coat: The horse’s hair coat appears rough or lacks its usual shine.

Understanding Fever Severity

Temperature Range (Fahrenheit)	Category	Severity	Recommended Action
99.0 to 101.5	Normal	No concern	Continue normal care and monitoring
101.6 to 102.5	Low fever	Mild	Monitor closely; call vet if persists beyond 24 hours or worsens
102.6 to 103.5	Moderate fever	Moderate	Call veterinarian same day for evaluation
103.6 to 104.5	High fever	Serious	Call veterinarian immediately or within 1 to 2 hours
Above 104.5	Very high fever	Emergency	Call equine veterinarian or emergency clinic right away

When to Call Your Equine Veterinarian

Contact your veterinarian immediately in these situations:

• Temperature above 103 degrees Fahrenheit in an adult horse.
• A fever of 101.6 to 102.5 degrees that lasts longer than 24 hours.
• Fever accompanied by severe lethargy, inability to stand, or collapse.
• Fever with signs of colic, such as pain, rolling, or disinterest in food.
• Fever with difficulty breathing or severe respiratory distress.
• Fever with signs of lameness, swelling, or joint pain that developed suddenly.
• Fever with profuse sweating, shivering, or signs of shock.
• Any fever in a very young foal, elderly horse, or horse with a known health condition.

This article is for educational purposes and is not a substitute for veterinary diagnosis, treatment, or professional advice. Always consult your equine veterinarian regarding your horse’s health concerns.

Fever Management at Home

While waiting for veterinary care or in cases of mild fever under veterinary guidance, you can support your horse’s comfort and recovery:

• Provide clean, fresh water at all times. Fever increases fluid loss, so hydration is critical.
• Offer soft, palatable feed such as bran mash, soaked hay pellets, or grass hay if your horse will eat.
• Keep your horse in a comfortable, well-ventilated stall or shelter. Avoid extreme heat or cold.
• Remove blankets and rugs to allow body heat to dissipate if the horse is sweating.
• Do not exercise or work your horse while feverish.
• Monitor temperature every 4 to 6 hours and record the readings.
• Watch for changes in breathing, heart rate, appetite, and behavior.

Common Causes of Fever in Horses

Understanding what causes fever can help you recognize when your horse needs help. Common causes include:

• Viral infections: Equine influenza, equine herpesvirus, and other respiratory viruses.
• Bacterial infections: Strep throat, respiratory tract infections, and abscesses.
• Strangles: A highly contagious bacterial infection of the lymph nodes.
• Abscess: Localized infection anywhere on the body, including internal abscesses.
• Pneumonia: Inflammation of the lungs, often from viral or bacterial infection.
• Dental disease: Tooth infections and severe gum disease can cause fever.
• Wound infection: Cuts, punctures, or other injuries that become infected.
• Inflammatory conditions: Joint disease, tendinitis, or other inflammatory problems.
• Vaccination response: A mild fever within 24 to 48 hours of vaccination is normal.
• Heat stress: Extreme heat can raise body temperature, though this differs from true fever.

Frequently Asked Questions

How do I know if my horse has a fever without a thermometer?

While a thermometer is the only way to confirm fever, signs such as lethargy, loss of appetite, rapid breathing, and a dry muzzle (the horse’s nose feels hot and dry) suggest fever may be present. However, you should obtain a thermometer and take your horse’s temperature rather than relying on observation alone. A rectal temperature is the gold standard for diagnosis.

Is it normal for a horse’s temperature to be higher in summer or after exercise?

Yes. Environmental temperature and exercise raise body temperature temporarily. Always take your horse’s temperature when the animal is calm and at rest, after at least 30 minutes of rest if the horse has been exercised. Hot weather can raise resting temperature by 0.5 to 1 degree Fahrenheit, which is normal and not a true fever.

Can I use a human thermometer on my horse?

Human digital thermometers can work in an emergency, but horse-specific or livestock thermometers are more reliable and easier to use safely. Equine thermometers are designed for the task and typically cost between 10 and 30 dollars. Keep one on hand as part of your first-aid supplies.

How long does it usually take for a fever to go away after veterinary treatment?

This varies depending on the cause and severity of illness. Some horses show improvement within 24 to 48 hours of starting treatment, while others may take a week or longer to return to normal temperature. Your veterinarian can advise on the expected timeline based on your horse’s specific diagnosis and treatment plan.

Should I give my horse medications to lower fever at home?

Do not give any medications without veterinary guidance. Never self-treat with over-the-counter pain relievers or fever reducers. Fever is a symptom, not a disease itself, and the underlying cause must be identified and treated by a veterinarian. Some fever-reducing drugs can mask serious illness or cause complications. Always consult your veterinarian before giving any medication.

Key Takeaways

• Normal temperature for adult horses is 99.0 to 101.5 degrees Fahrenheit. Foals run slightly higher at 100.5 to 102.5 degrees Fahrenheit.
• Check your horse’s temperature using a lubricated digital or livestock thermometer inserted gently 2 to 3 inches into the rectum.
• Fever often comes with signs such as lethargy, loss of appetite, rapid breathing, and sweating.
• Temperatures above 101.5 degrees in an adult horse at rest indicate fever and warrant close monitoring or veterinary care depending on severity.
• Call your veterinarian immediately for temperatures above 103 degrees, fever lasting longer than 24 hours, or fever accompanied by severe signs.
• Support a feverish horse with fresh water, soft feed, rest, and comfortable shelter while awaiting or following veterinary guidance.
• Never give fever-reducing medications without veterinary approval. Fever is a sign of underlying illness that requires professional diagnosis and treatment.