How to Tell If a Cat Has a Fever
Normal temperature in cats, why the classic nose test does not work, how to measure properly and when a fever needs treating.
Is this an emergency?
A temperature above 39.5 C, or below 37 C, needs veterinary attention. If fever comes with lethargy and loss of appetite, do not wait.
Above 39.5 or below 37 needs a vet without waiting.
A cat’s normal body temperature is higher than ours: 38.0 to 39.2 degrees Celsius. Anything above 39.5 is a fever. Anything below 37 is hypothermia, and that is just as serious.
The nose test does not work
Feeling whether the nose is warm and dry is the most repeated piece of advice about cats and one of the least reliable. A cat’s nose changes temperature and moisture through the day with the room, with sleep and with grooming. A cat with a fever can have a cool wet nose, and a healthy cat can have a warm dry one.
The only way to know is to measure.
Measuring properly
Temperature is taken rectally. Use a digital thermometer, lubricate the tip, insert it about one to two centimetres and hold it until it reads.
It helps to have a second person to hold the cat, wrapped in a towel with only the back end out. Work quickly and calmly, and stop if the cat is becoming distressed. An accurate reading is not worth being bitten for.
Ear thermometers made for animals exist and are less accurate, but a reading is better than none if the cat will not tolerate the rectal route.
If your cat will not allow it, come in. We would rather measure it than have you injured trying.
Signs that suggest fever
Lethargy and sleeping more than usual. Loss of appetite. Hiding away. Reduced grooming and a scruffy coat. Faster breathing. Shivering. Warm ears and paws. Reluctance to be touched.
None of these are specific, which is why the number matters.
What causes fever
Bacterial and viral infection, abscesses from bite wounds, dental disease, pancreatitis, immune mediated disease and tumours.
Abscesses deserve a mention because they are so common in cats that go outdoors. A cat bite seals over quickly and the infection develops underneath, so the fever appears several days after a fight that may not have been noticed.
What not to do
Never give human fever medication. Paracetamol kills cats. Ibuprofen and aspirin cause stomach ulceration and kidney failure. This is the single most important sentence on this page.
Do not put the cat in cold water or apply ice. Do not withhold water.
What you can do
Keep the room cool and quiet. Keep water within reach. Offer warmed, strongly scented food. Let the cat rest.
When to come in
A temperature over 39.5, or under 37. Fever lasting more than a day. Fever with lethargy, refusal to eat, vomiting, laboured breathing, or a painful swelling anywhere on the body. Or any fever at all in a kitten or an older cat.