How to Tell if Dog Has Fever?

As a dog owner, you want to ensure your furry friend is happy and healthy. One of the most common health issues dogs face is fever. A fever indicates something is wrong, and your dog’s body attempts to fight it off. But dogs can’t tell us they feel under the weather like humans can. So, how do you know if your dog has a fever?

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What is a Fever in Dogs?

What is a Fever in Dogs?

A fever is defined as an elevated body temperature above the normal range. For dogs, a fever is typically considered to be:

  • Over 102.5°F for most breeds
  • Over 103°F for giant breeds like Great Danes

An average body temperature for a dog ranges between 101-102.5°F. Factors like time of day, exercise, and excitement can all impact your dog’s temperature slightly. But a reading over 102.5°F that persists indicates fever.

Fever helps enhance your dog’s immune response to fight infection. So, in most cases, fever is the body’s natural defense against invaders like viruses and bacteria. However, fevers can also be caused by non-infectious issues like cancer or autoimmune disease. Identifying a fever is essential to determine the underlying cause and get your dog treatment.

Checking Your Dog’s Temperature

The most accurate way to check for fever in dogs is by taking their rectal temperature. Unlike humans with consistent oral temperatures, a dog’s mouth temperature can easily be thrown off by drinking, eating, or panting.

Here’s how to properly take your dog’s rectal temperature:

Supplies Needed

  • Pet thermometer – Digital rectal thermometers designed specifically for dogs or cats provide the most accurate readings. Never use a human thermometer.
  • Lubricant – Such as petroleum jelly or KY jelly to help insert the thermometer.
  • Treats – Have your dog’s favorite treats on hand to reward them and keep them still.

Steps to Take a Dog’s Temperature

  1. Apply a small amount of lubricant to the tip of the thermometer.
  2. Have your dog either stand or lie down and gently lift their tail.
  3. Gently insert the thermometer about 1 inch into your dog’s rectum. Please do not force it.
  4. Hold the thermometer until you hear the “beep” that indicates it’s finished reading, usually within 60 seconds.
  5. Check the reading on the display. Normal is 101-102.5°F.
  6. Reward your dog with treats and praise for standing still!
  7. Be sure to clean the thermometer thoroughly between uses with soap and water. Disinfectants can also be used.

Taking your dog’s temperature rectally provides the most accurate reading to check for fever. However, if you are uncomfortable doing this, vets can get a decent temperature reading by feeling the dog’s belly or groin area. The following tips can help indicate fever:

  • Wet nose and gums – If your dog’s nose and gums feel dry or tacky, it could signal fever.
  • Warm belly or groin – Place your hand under their belly to feel if it’s hot. Check the groin area, too.
  • Warm ears – Feel your dog’s ears for excess warmth, as fever can cause vasodilation.

While these areas aren’t as precise as a rectal reading, they can give you an idea of body temperature. If you suspect fever, get an accurate rectal temperature.

Signs Your Dog May Have a Fever

Signs Your Dog May Have a Fever

Aside from checking body temperature directly, there are many signs your dog may be running a fever. Be on the lookout for these common symptoms:

1. Lethargy

Dogs with fever often have less energy and may seem tired and listless. They may sleep more or move slower on walks. Loss of appetite frequently accompanies fever, too.

2. Shivering

The chills are another common fever symptom. Your dog may shake or shiver even when they don’t seem cold.

3. Warm and Dry Nose

As mentioned, a warm, dry nose instead of a cool, wet one can indicate fever. But remember dogs pant and breathe through their mouths, which dries out the nose.

4. Red or Glassy Eyes

Fever can cause eyes to look red or glassy. There also may be discharge or goop coming from the eyes.

5. Vomiting or Diarrhea

Gastrointestinal upset like vomiting or diarrhea can sometimes happen with fever. However, these symptoms alone aren’t always fever-related.

6. Whining or Restlessness

Dogs that don’t feel well may whine, pace, or seem anxious when running a temperature. Pay attention to any unusual vocalizations.

Monitor your dog closely if it exhibits any of these fever symptoms in combination with an elevated body temperature. Fever usually indicates an underlying illness that requires veterinary attention.

Common Causes of Fever in Dogs

There are many possible causes of fever in dogs, including:


Bacterial and viral infections are the most common cause of elevated temperatures and dog illness. This includes:

  • Upper respiratory infections
  • Pneumonia
  • Urinary tract infections
  • Parvovirus
  • Distemper
  • Pyometra (uterine infection)

Infections require prescription antibiotics or antivirals to treat. Prompt vet care is critical.

Immunization Reactions

It’s normal for a dog to develop a mild fever after getting vaccinations. This is the immune system ramping up. Fevers above 103°F or those that last over 48 hours warrant a call to the vet.

Inflammation & Injuries

Inflammation from joint pain or injuries can cause fever by releasing pyrogens into the bloodstream. Causes include:

  • Arthritis
  • Soft tissue injury or trauma
  • Bite wounds
  • Ingesting toxins or poison


Cancers like lymphoma, leukemia, and hemangiosarcoma are unfortunately common in older dogs. Fever is one early symptom as the body reacts to cancer cells.

Autoimmune Disease

Autoimmune conditions in which the body attacks itself, such as Cushing’s disease, Addison’s disease, and immune-mediated hemolytic anemia, can all kickstart fevers.

Other Causes

Less common causes of elevated temperature in dogs include:

  • Heat stroke
  • Certain medications/drugs
  • Blood transfusion reaction
  • Dental infection or abscess
  • Brain tumor or encephalitis

No matter the underlying cause, it is vital to identify fever quickly and get veterinary attention. A persistent high fever can even cause seizures in dogs. Left untreated, many conditions will continue to worsen.

What to Do If Your Dog Has a Fever

What to Do If Your Dog Has a Fever

Follow these steps if you suspect or confirm your dog has an elevated temperature:

  • Call your vet – Alert your veterinarian if your dog’s temperature is over 102.5°F. Describe all symptoms in detail. The vet will advise on the next steps.
  • Come into the vet ER immediately if your temperature is over 104°F and symptoms include vomiting, diarrhea, lethargy, or trouble breathing. These issues can be life-threatening.
  • To help lower body temperature, place cool, wet towels around high-blood-flow areas like the neck, groin, and paws. Avoid cold baths.
  • Offer fresh water to prevent dehydration. Broths can encourage eating. But don’t force food.
  • Limit activity & stress – Keep your dog calm and confined to prevent overexertion until fever passes.
  • Give any medications, such as pain relievers, as directed by your vet. Never give human fever reducers like Tylenol.
  • Monitor temperature and symptoms. Track any changes and report them to the vet. A worsening fever can indicate complications.

If left untreated, severe fever can lead to brain and organ damage in dogs. So, time is of the essence. Veterinary care is crucial to getting your dog diagnosed and treated promptly.


How long can a dog’s fever last?

Fevers can last anywhere from 24 hours to several days. If they persist for more than 2 days without improving, visit the vet.

Is a temperature of 103°F dangerous for a dog?

Once a dog reaches 103°F, it is considered a significant fever, and a vet visit is recommended. Temperatures over 104°F can be life-threatening if not addressed quickly.

When should you go to the ER vet for a dog fever?

Take your dog to the emergency vet immediately if their temperature is over 104°F, along with lethargy, trouble breathing, or other severe symptoms. These cases can be critical.

Conclusion: Identifying and Treating Fever in Dogs

Fevers in dogs should never be ignored, as they are signs of an underlying illness needing treatment. Know the normal temperature range for dogs and how to take their rectal temperature accurately. Be alert for common fever symptoms like lethargy, shivering, warm nose and ears, vomiting or diarrhea, and whining.

Seek prompt veterinary care if you suspect a fever or have confirmation with a high-temperature reading. It is crucial to address the root cause, whether it be infection, cancer, or something else. If your dog has stopped eating dry food, it could be a sign of discomfort or illness; follow your vet’s treatment plan closely to manage any fever and support your dog’s recovery, as fevers, while scary, are the body’s natural defense against disease. With attentive care and a visit to the vet, your beloved pup will be back to total health in no time!