By Jennifer Copley (Last Updated 14 January 2011)
Fevers are caused by disease processes that trigger the release of pyrogens into the bloodstream. These pyrogens travel to the animal’s brain and reset the body’s thermostat to a higher temperature. Fevers can help the body fight infection, as many viruses and bacteria don’t do well in overly hot environments.
Causes of Fever in Cats and Dogs
Fevers in pets may be caused by:
- Infection (either internal illness or an infected wound)
- Certain medications
- Metabolic illnesses
- Consumption of toxic substances such as macadamia nuts or human antidepressants
Some animals may also run low-grade fevers for one to two days after receiving vaccinations.
How to Tell if Your Cat or Dog Has a Fever
The most common symptoms of fever are lethargy and loss of appetite. Some animals with fevers may also become cranky, stop or reduce drinking, shiver, breathe rapidly, stop grooming, or hide. In addition, if a cat or dog has lumps, swellings, or open wounds, or infection symptoms such as coughing, sneezing, runny nose, or eye discharge, there is an increased likelihood of fever.
Although it’s commonly believed that a feverish animal always has a hot dry nose whereas a healthy pet will have a cold wet nose, there are many factors that affect nose temperature and moisture, including hydration and environmental temperature. A pet may also sleep curled up in a tight ball, which can warm its nose up.
Hot ears often indicate a fever, but the only way to know for sure is to take the animal’s temperature using a rectal thermometer specifically designed for a cat or dog (or a pediatric rectal thermometer).
How to Take a Pet’s Temperature
Ideally there will be two people for this job – one to hold the animal and the other to insert the thermometer. To take a cat’s or dog’s temperature, lubricate the thermometer with petroleum jelly, insert it one inch into the rectum, and leave it in for two minutes (or until it beeps, in the case of a digital thermometer). After using the thermometer, clean it with lukewarm soapy water, rinse thoroughly, and wipe it down with alcohol to sterilize.
The normal body temperature for cats and dogs is between 100.5 and 102.5°F. However, hot environments, intense exercise, and stress can cause an animal’s body temperature to rise above normal – up to 103.5°F. For this reason, veterinarians tend not to be concerned unless the temperature reaches 104°F or higher, or there are worrisome additional symptoms.
How to Treat Fever in Cats and Dogs
Assuming that there are no other serious symptoms, a mild fever may be left to run its course, as it will help to destroy invading microorganisms. In the case of a higher fever, a veterinarian may use medications such as Ketoprofen to bring it under control. If the fever has caused the pet to become dehydrated, the veterinarian may administer fluids as well.
If there is no obvious cause and your veterinarian suspects a bacterial illness, he or she may try a course of antibiotics. If the antibiotics don’t improve the situation or the fever recurs after the course is completed, diagnostic tests may be undertaken. Treatment will vary depending on which illness is diagnosed.
If caring for a fevered cat or dog at home, place a bowl of fresh water near the pet to encourage drinking and take its temperature regularly. Consult your veterinarian immediately if the temperature rises beyond 104°F. In addition, you should watch for additional symptoms such as:
- Straining to urinate
- Blood in the urine
- Breathing difficulties
- Sneezing/nasal discharge
- Skin lumps
- Runny eyes
- Appetite loss/weight loss
Can You Give Cats and Dogs Aspirin® or Tylenol® for Fever?
Never give cats or dogs any fever medications designed for humans without first consulting a veterinarian. Acetylsalicylic acid and acetaminophen, commonly found in popular medication brands such as Aspirin® and Tylenol® respectively, can be extremely dangerous for pets.
It takes only a very small dose of either acetylsalicylic acid or acetaminophen to induce fatal illness in a cat. Although dogs tolerate these medications better, many dogs have also been sickened or killed by well-meaning owners who gave them what seemed like relatively small doses.
How to Prevent Fevers in Dogs and Cats
To reduce the likelihood of fever, limit or prevent your pet’s exposure to sick animals and don’t allow animals to fight. Keeping cats indoors and having male pets neutered significantly reduces the likelihood of injury-related fevers (contrary to popular belief, spay-neuter surgery does not adversely affect a pet’s personality).
This article is provided for informational purposes only and is not intended as a substitute for veterinary consultation and care.
- Drs. Foster & Smith. (2011). “ The Causes of a Fever in Pets.” PetEducation.com.
- Manning, A.M., Dr. (2010). “Acetaminophen (Tylenol) Toxicity in Cats.” PetPlace.com.
- Papich, M., Dr. (2010). “Acetylsalicylic Acid (Aspirin).” PetPlace.com.
- Petplace Veterinarians. (2010). “Fever in Dogs” and “Fever in Cats.” PetPlace.com.
- WebMD. (Reviewed by Audrey Cook, BVM&S, August 31, 2009). “High Fever in Dogs.” Pets.WebMD.com.
- Wexler-Mitchell, E., DVM. (2003). “Does Your Cat Have a Fever?” CatChannel.com.