High Fever in Dogs

You may have heard that you can tell whether your dog has a fever by feeling his nose -- cool and wet is good, hot and dry means fever -- but it’s not that simple. In fact, dog fever often goes unrecognized or undetected.

One reason it can be difficult to detect fevers in dogs is that their normal body temperature is naturally higher than in humans.

What Is a Dog Fever?

The normal body temperature for dogs is between 101 and 102.5 F, compared to 97.6 to 99.6 F for humans. This means your dog may feel feverish to you even when his temperature is completely normal.

The word “fever” is typically used to describe elevated body temperature caused by infection or inflammation. A temperature of more than 103 F is considered a dog fever.

When dogs have high temperatures that are the result of hot external temperatures or excessive exercise in humid conditions, the condition is referred to as hyperthermia or heat stroke. When temperatures reach 106 F, serious and fatal complications can occur.

Dog Fever Symptoms

Although there are no definite signs, some symptoms that might indicate illness and fever in dogs include:

  • Lethargy
  • Depressed mood
  • Shivering
  • Loss of appetite
  • Vomiting
  • Coughing
  • Nasal discharge

The only accurate way to tell if your dog has an increased body temperature is to take his rectal temperature. Experts recommend using a digital thermometer specifically designed for rectal use in dogs. Most thermometers intended for use in human ears do not work well for this purpose.

To take your dog’s temperature, first coat the thermometer with a lubricant such as petroleum gel or baby oil. Next, gently insert the thermometer about one inch into your dog’s anus and wait for results. Most thermometers sold for this purpose will take less than 60 seconds to register.

Causes of Dog Fever

A variety of illnesses and conditions may make your dog run a fever. These include:

  • Infection. This may have any number of causes, including bacterial, fungal, and viral diseases. Infection may be anywhere in the body, such as the lungs (pneumonia), the kidneys (pyelonephritis), the brain (encephalitis), or even the skin. The symptoms you see will depend on where the infection is focused and the underlying cause. Some infections, such as fungal diseases, can affect several areas of the body at the same time.
  • Vaccination. A low-grade fever for 24 to 48 hours after vaccination is not uncommon and results from the interaction between the injection and the dog’s immune system.
  • Toxins. Consuming substances that are poisonous to dogs, including macadamia nuts and some human antidepressants, can result in increased body temperature.

There are times when the cause of dog fever cannot be readily determined; this is called "fever of unknown origin," or FUO. The most likely causes for dog fever of unknown origin are disorders of the immune system, bone marrow problems, undiagnosed infections, and cancer.

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Home Care and When to Call the Vet

If your dog has a temperature greater than 103 F, you should call your veterinarian. Fevers above 106 F are emergencies that must be treated promptly.

If your dog has a temperature above 105 F, you can help bring his body temperature down by applying cool water to his fur, especially around the ears and feet. Using a fan on the damp fur will help lower the temperature. Be sure to monitor your dog’s rectal temperature as you do this, and stop the cooling procedure once it reaches 103 F. You don’t want to bring down the temperature too fast.

If your dog has a fever, try to see that he drinks small amounts of water on a regular basis to stay hydrated, but don’t force it. And never give your dog any human medicines intended to lower fever, such as acetaminophen or ibuprofen, as they can be poisonous to dogs and cause severe injury or death.

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