How to Tell a Dog Has Fever Without a Thermometer

The most accurate way to tell if a dog has a fever is to take their rectal temperature. This task can often be complicated because not all dogs will react to this process in the same way, making a temperature reading difficult or even dangerous.

It may also be that you suspect your dog has a fever, but you don’t have a thermometer at hand. There are a series of symptoms that appear when a dog is in a febrile state.

By identifying them in your dog, you can better assert whether the animal has an increase in body temperature due to fever. Today, I'll explain how to tell if a dog has a fever without a thermometer by looking at the common causes and symptoms of fever in dogs.

Causes of Fever in Dogs

1. Heat Stroke

Heat stroke does not cause fever due to an internal process, but it does cause an elevated body temperature due to external factors.

This is severe when they reach 106°F or 41.1°C or higher. They will experience nervousness, rapid panting, hypersalivation, and increased heart rate.

2. Infections

Viruses, bacteria, and fungi are capable of infecting your dog and resulting in disease. In these cases, vomiting, diarrhea, or a runny nose may appear.

3. Vaccine Reactions

Sometimes, your dog may have a mild fever after vaccination. It's a totally normal response of their body reacting to the vaccine. In these cases, it usually lasts between 24 and 48 hours.

4. Poisoning

If your dog has been poisoned, it’s possible that fever may appear as a result. Vomiting, apathy, tremors, dilated pupils, disorientation, or paralysis may also occur.

5. Inflammation

If your dog has an inflammatory process, it’s likely the fever is a result of their immune response. Depending on the inflammation type, they may experience pain, refusal to be touched, and lameness.

6. Tumors

Malignant tumors can also cause fever.

Symptoms of Fever in Dogs

The appearance of tremors is a very common symptom when a dog has advanced fever. They may also feel more tired, so you may notice they sleep more and move less than normal. You may also notice a loss of appetite and an increase in heart and respiratory rates.

Their stool may look more solid and dry due to dehydration. The ears and belly are usually warmer than normal, although this may be due to other causes such as exposure to the sun. Their nose may feel dry and hot.

What Should I Do if My Dog Has a Fever?

To start, apply cold cloths or compresses to their abdomen. Do not shock them by putting ice or anything too cold. Wet their paw pads and ears with cold water as well—this usually helps reduce the fever.

They need to drink water in small amounts to prevent dehydration, especially if they are vomiting. Wet their entire body progressively with fresh water. Keep the dog in a cool and quiet place.

Under no circumstances should you give them medication, much less human medicine, as this could cause more serious problems.

If the fever lasts a day or less, there should be no need to worry, but it may be advisable to go to the vet to rule out any illness. If your dog has had a fever for two or more days or the temperature is above 41°C, do not hesitate to go to the vet as the underlying cause could be very serious.

Final Thoughts

Taking care of a dog’s health means being attentive to subtle changes that may signal issues, such as a fever. While the best way to confirm a fever is with a thermometer, recognizing symptoms can help you act quickly and ensure your dog’s comfort and safety.