A dog's normal body temperature is higher than a person's, typically about 101 to 102.5°F (38.3 to 39.2°C).1 Some references put the lower limit nearer 99.5°F, and excitement, exercise and warm weather can push a healthy dog's reading up a little.2,3 A temperature above about 102.5 to 103°F is higher than normal.3,4 It may be a true fever, which is the body's response to infection or inflammation, or overheating such as heatstroke, which is an emergency and is handled differently.5,6 This guide explains how to take your dog's temperature, the signs and causes of fever, when it's an emergency, and why you shouldn't treat a fever at home.
Call your vet now, or go to an emergency vet, if your dog's temperature is:
What the Research and Guidelines Say
- Rectal readings are the most accurate. In a study of 50 dogs, ear thermometer readings differed from rectal readings by 0.6°C (about 1°F) on average and up to 2.2°C. Armpit readings were off by up to 4°C.8 A larger study of 300 dogs called the ear-to-rectal differences "clinically unacceptable."9
- Unexplained fevers often have a non-infectious cause. In one study of 50 dogs with a fever of unknown origin, 48% had an inflammatory or immune condition, 18% an infection and 6% cancer. No cause was found in 28%.10
- Cool first, then drive. In a UK study, of the dogs whose cooling was recorded, only about 1 in 5 had been cooled before reaching the vet. Dogs cooled first arrived with much lower temperatures, and the authors note that earlier research links prompt cooling to better survival.7
What Is a Normal Temperature for a Dog?
| Reading | What it usually means |
|---|---|
| Below about 99°F (37.2°C) | Too low. Keep warm and see a vet now.1 |
| 101 to 102.5°F (38.3 to 39.2°C) | Typical normal range.1 |
| Above 102.5 to 103°F (39.2 to 39.4°C) | Higher than normal. Call your vet, especially if your dog seems unwell.3,4 |
| 104°F (40°C) or higher | Call your vet now.3 |
| 105 to 106°F (40.6 to 41.1°C) or higher | Emergency. Readings of 106°F (41.1°C) or more are usually overheating, such as heatstroke, rather than fever.4,5,6 |
How to Take Your Dog's Temperature
The only reliable home method is a digital thermometer in the rectum.11,4
- Use a digital thermometer kept just for your dog, and coat the tip with a lubricant.4
- Have a helper hold your dog gently, lift the tail and slide the thermometer about 1 inch into the rectum. Hold it in place until it beeps.4,3
- Clean the thermometer afterward. Stop if your dog is in pain or becomes aggressive and call your vet instead.
Ear thermometers made for pets are easier but less accurate, so confirm a worrying reading rectally. Forehead thermometers are usually inaccurate.4,8 A warm, dry nose doesn't mean a fever, and a cold, wet nose doesn't mean a dog is well.4 For a routine check, wait until your dog has rested, because activity and excitement can raise the reading.3,4 If you suspect heatstroke, don't wait: start cooling and head to the vet (see below).
Signs of Fever in Dogs
- Lethargy and low energy. See lethargic dog.3
- Loss of appetite3
- Shivering3
- Vomiting or diarrhea3
- Dehydration5
These signs aren't specific to fever, so a thermometer reading is the only way to know.4
What Causes a Fever in Dogs?
- Infections from bacteria, viruses or fungi.5,3
- Tick-borne diseases. Anaplasmosis, for example, can cause fever 1 to 2 weeks after a tick bite.12 See Lyme disease symptoms.
- Inflammation and immune conditions, in which the immune system attacks the dog's own joints, blood cells or other tissues.5,10
- Cancer.5,10
- Vaccines. A mild fever for a day or two after vaccines is common.3,13
When a fever lasts and the cause isn't obvious after the usual tests, it is called a fever of unknown origin.5
Fever or Heatstroke?
In a true fever, the brain resets the body's thermostat higher to fight an illness. In heatstroke, the body simply can't get rid of heat fast enough after exercise or time in a hot place, and the temperature often climbs above 106°F.5,6 The two are handled differently:
- Heatstroke: cool first, then go to the vet. Move your dog somewhere cool, pour cool or cold tap water (not iced) over the body, keeping it away from the nose and mouth, and use a fan. Don't cover your dog with wet towels, which trap heat. Go straight to a vet and keep cooling on the way if you can, but stop active cooling once the temperature reaches about 103°F (39.4°C) or your dog shows signs of recovery, to avoid overcooling.6,14,7 See dog panting.
- Fever: don't cool or medicate at home. Cooling a dog with a true fever works against the body, and there is no safe home treatment. See your vet to find and treat the cause.5,3
Can I Give My Dog Something for a Fever?
No. Never give human fever reducers or pain relievers unless your vet tells you to. Some damage a dog's liver and red blood cells, and others cause stomach ulcers and kidney damage. Dogs are more sensitive than people to the anti-inflammatory type.3,15,16,17 Human medicines are one of the most common causes of pet poisoning calls.18 If your dog has swallowed one, call your vet or a pet poison helpline right away.18
What Your Vet Will Do
Your vet will ask about vaccines, travel, ticks and medicines, examine your dog closely, and usually run blood tests and a urine test, often with X-rays. If the cause still isn't clear, the next steps may include ultrasound, joint fluid samples, other samples or biopsies, and more specialized imaging.10,5 Trying treatments before a diagnosis can hide the cause and carries risks, so finding the cause comes first when possible.10
Frequently Asked Questions
What is a normal temperature for a dog?
Typically about 101 to 102.5°F (38.3 to 39.2°C).
How can I tell if my dog has a fever without a thermometer?
You can't reliably. Lethargy, shivering and poor appetite are clues, but a rectal reading is the only way to know.
Can a dog's fever go away on its own?
A mild fever in the day or two after vaccines usually does.13 Call your vet about any other fever, or a post-vaccine fever that lasts more than about 48 hours or comes with other signs.
How do I bring my dog's fever down?
Don't try at home. See your vet. Only cool your dog at home for suspected heatstroke.
Is 103°F a fever in a dog?
It is above normal. Call your vet, especially if your dog seems unwell.
Ask Our Team a Question
Help Others by Sharing Your Dog Story or Question!
Have a Question, Request or Want to Share a Story that could help others? Our team will answer questions for free!
Please include information such as your dog's medical history, age, sex, breed, symptoms, diet, changes in behavior and medications. Providing pictures by uploading them below can also be of help.
We will do our best to get back to you quickly (it depends on how many questions we receive each day). If you do require an immediate response we suggest using this online dog veterinary service that is available now.
What Other Visitors Have Asked and Answers From Our Team
Click below to see contributions from other visitors to this page...
A 6-Year-Old Lab Cross With a Fever No One Could Explain Not rated yet
Reader Question Two weeks ago Kenzie, my 6-year-old Yellow Lab/Golden Retriever cross, quit eating. The vet at the emergency clinic found she had a …
Sources and further reading
This article was written and fact-checked on October 19, 2026 against current veterinary references and specialist guidelines:
- Coates J, DVM; reviewed by Higgs V, DVM. Hypothermia in Dogs. PetMD, updated January 23, 2026.
- Merck Veterinary Manual (adapted from Robertshaw D, Dukes' Physiology of Domestic Animals, 12th ed.). Table: Normal Rectal Temperature Ranges. Merck Veterinary Manual, undated table.
- Meeks C, MS, DVM, DACVIM; reviewed by Kearley M, DVM. Fever in Dogs: Signs, Symptoms, and Treatment. PetMD, updated December 18, 2024.
- Boldan M, DVM. How to Take a Dog’s Temperature. PetMD, June 1, 2023.
- Allen AJ. Fever of Unknown Origin in Dogs. Merck Veterinary Manual (pet owner version), full review June 2018, last updated September 2024.
- Weir M, DVM, MSc, MPH; Williams K, BSc, DVM, CCRP; Ward E, DVM. Heat Stroke in Dogs. VCA Animal Hospitals, last updated July 10, 2025.
- Hall EJ, Carter AJ, Bradbury J, Beard S, Gilbert S, Barfield D, O’Neill DG. Cooling Methods Used to Manage Heat-Related Illness in Dogs Presented to Primary Care Veterinary Practices during 2016–2018 in the UK. Veterinary Sciences 10(7):465, 2023.
- Journal of the American Animal Hospital Association. Comparison of rectal, axillary and auricular temperature measurement in healthy adult dogs (DOI 10.5326/JAAHA-MS-6500). J Am Anim Hosp Assoc 53(6):291–296, November 2017.
- Tierärztliche Praxis K. Comparison of auricular and rectal temperature measurement in normothermic, hypothermic, and hyperthermic dogs. Tierärztl Prax Ausg K Kleintiere Heimtiere 42(1):13–19, 2014 (PubMed abstract).
- Lunn KF. Fever of Unknown Origin in Animals. Merck Veterinary Manual (professional version), full review August 2022, last updated September 2024.
- Hohenhaus A, DVM. Taking Your Pet’s Temperature. Animal Medical Center (New York), July 19, 2017.
- Cornell University College of Veterinary Medicine. Anaplasmosis (Riney Canine Health Center). Cornell University, undated.
- Long C (with Stokes J, DVM). Vaccine Reactions. MSPCA-Angell, August 7, 2026.
- PDSA vets and vet nurses. Heatstroke in Dogs. PDSA Pet Health Hub, September 2023.
- Schmid R, DVM, DABVT, DABT; Brutlag A, DVM, MS, DABT, DABVT; Downing R, DVM. Acetaminophen Poisoning in Dogs. VCA Animal Hospitals, last updated May 2026.
- Morrison BJ, DVM. NSAID Toxicity in Dogs. PetMD, September 14, 2022.
- Mueller B (quoting Wismer T, DVM, ASPCA APCC). Keep Your Medications Away from Pets. University of Illinois College of Veterinary Medicine, March 4, 2019.
- ASPCA. Protecting Your Pets from Poisons: What You Need to Know. ASPCA, March 19, 2019.
About this article
Last updated : new page, written using Merck Veterinary Manual, PetMD, VCA, PDSA and Animal Medical Center guidance and published research on thermometers and heatstroke cooling in dogs.
This page is for general information and is not a substitute for an exam by your veterinarian.
