How to Determine if Your Dog Has a Fever

That warm, clammy forehead. The endless back-and-forth feeling of being dunked in ice water then plopped in a pool of lava. Those pangs of exhaustion that hit hard even though all you’re doing is laying in bed.

You know all too well when you have a fever — the signs are pretty tough to ignore. And it’s usually pretty easy to tell when someone else has a fever just by looking at them and feeling their forehead for the fever’s trademark heat.

But what about your dog?

He’s covered in hair that’s thicker and denser than any hair on your body, so the old forehead trick won’t work. And since he can only speak dog, he can’t tell you, “Hey, I’m burning up! Help me!”

A tan chihuahua lying on a couch

Fever is a symptom of a canine illness that shouldn’t be ignored, but how can you tell if your dog has one? And just what, exactly, constitutes a fever in dogs?

Follow our guide to find out if your dog has a fever and what to do about it. No need to get hot-headed — it’s easier than you might think!

What Are the Symptoms of Fever in Dogs?

Observing your dog’s behavior won’t tell you conclusively whether he has a fever, but it’s a great place to start.

Fever itself is a symptom of a more significant illness that could have many other symptoms. Depending on what he’s come down with, your dog could exhibit some of the following symptoms. Please consider that all the ones listed are commonly seen alongside fever.

So if you notice any of the following symptoms in your dog, and there’s no environmental or situational explanation for them, there’s a good chance he’s got a fever too.

Hot, Dry Nose

This isn’t a definitive way of telling if your dog has a fever, but it’s a decent starting point and the closest method we have to the old hand-on-forehead trick.

A dog’s nose should normally be wet and cool to the touch. It’s like that to help him utilize his superb sense of smell — and, of course, to startle you when he sneaks up behind you and rubs it on your bare skin.

But if your dog’s nose is hot and dry, that’s a good indication that something’s wrong. Dry noses are often due to dehydration, which is a typical result of high fever.

A short coated brown dog

Dogs with fevers can have wet noses, and healthy dogs can have dry noses, so this isn’t the smoking gun that solves the fever mystery. But if your dog’s hot, dry nose is accompanied by any of the following symptoms, he could very well have a fever.

Loss of Appetite

We can certainly relate to this symptom — it’s tough to eat when you’ve got a fever. You feel so tired, achy, and uncomfortable that chowing down is the last thing on your mind.

And it’s much the same with dogs. If your normally ravenous pup suddenly shows little interest in the sound of his kibble hitting the bowl, he may have a fever that’s contributing to appetite loss.

The old adage “feed a cold, starve a fever” would seem to suggest that this is a good thing. Unfortunately, it’s simply not true — whether he’s got a cold, a fever, or anything else, your dog needs to eat when he’s sick to get well.

Sudden appetite loss can indicate anything from bacterial infection to influenza to cancer, all of which can also cause fever. So if you notice your pup’s appetite decreasing and suspect a fever, call a vet as soon as possible.

Depression and Exhaustion

Dog in depression

It can be tough to tell whether your dog is having a lazy day simply because he feels like it or because he’s exhausted from illness. But if he usually can’t wait to go for a walk yet won’t even walk to the door today, he could very well have a fever.

Most canine illnesses can cause a loss of energy, a reluctance to move, and a depressed demeanor. A sick dog’s body can’t afford to expend energy on unnecessary movement — it needs every bit it can get to fight off the illness. This results in a dog who literally can’t move.

And since dogs are usually big balls of energy covered in hair, it’s no wonder that they get depressed when they’re too exhausted to be active.

Many causes of exhaustion in dogs don’t cause fever. However, it’s still wise to check your dog’s temperature if you notice him behaving sluggishly or acting down in the dumps.

Vomiting and Diarrhea

You don’t ever want liquid coming out either end of your dog, be it vomit or diarrhea. Both of these unpleasant bodily emissions are signs of illness, and more often than not, they’re accompanied by fever.

Food poisoning, bacterial infection, parasitic infection, GI disease, and many chronic illnesses can all cause fever along with vomiting and/or diarrhea. It’s never normal for your dog to experience vomiting or diarrhea, so if you observe them, take his temperature and get to a vet as soon as possible.

How Do I Take My Dog’s Temperature?

The only way to know for sure if your dog has a fever is to take his temperature with a thermometer. It’s not fun for either of you, but it’s a necessary part of diagnosing a sick dog.

A Dog’s Normal Body Temperature

Dog's Normal Body Temperature

First things first, though: you need to know what your dog’s normal body temperature is. The best way to do this is to take it when you know he’s healthy to establish a baseline, but if you haven’t done that, there are some rough guidelines you can follow.

A dog’s normal body temperature is higher than a human’s: while ours ranges from 97.6 to 99.6 degrees Fahrenheit, a dog’s ranges from 100.5 to 102.5 degrees Fahrenheit.

Your dog’s body temperature will fluctuate based on his activity level, air temperature, humidity, and time of day. You’ll need to consider these factors when analyzing your thermometer reading: if it’s hot out, a temperature of 102.7 is probably acceptable, but if it’s blizzarding outside, 102.7 likely indicates a fever.

Using a Dog Thermometer

Thermometers meant for humans aren’t accurate when used on dogs. You’ll need to purchase a thermometer explicitly intended for rectal use in dogs.

Yes, unfortunately, rectal thermometers remain the best way to take your dog’s temperature. Thankfully, modern rectal thermometers are super-accurate, easy to read, and display results in under 30 seconds.

Make sure the thermometer is sterilized, and your hands are clean. You may want to wear disposable gloves and/or use disposable thermometer covers.

Lubricate the tip of the thermometer with petroleum jelly, baby oil, or a medical lubricant. This will reduce the discomfort your dog feels at having something in his butt.

Then slowly and gently insert the thermometer into your dog’s rectum, taking care not to move it around too much. For small dogs, only insert it about an inch deep; for larger dogs, a depth of two to three inches will suffice.

Try to keep your dog still and talk to him in a calm voice, petting him if he’ll allow it. You can remove the thermometer as soon as you get a reading.

Interpreting Your Dog’s Temperature

Cute dog has a fever

Any thermometer reading over 103 degrees, regardless of external factors, indicates a fever. Low-grade fevers like this often resolve themselves within a day or so. Still, if a fever of 103 persists for longer than 24 hours, a vet visit is needed.

It’s best to be proactive if your dog has any fever, even a low-grade one. Call your vet and explain your dog’s symptoms to determine if you should seek medical attention or simply wait it out.

However, if you get a reading of 104 degrees or higher, get to the vet right away. High fevers not only indicate a severe illness, but they’re also dangerous in and of themselves.

Regardless of the grade of your dog’s fever, it’s critical to keep him hydrated. Fevers deplete the body of water and electrolytes, which in turn reduces your dog’s ability to fight off the illness and reduce the fever.

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