Cat Fever Symptoms: How to Tell If Your Cat Has a Fever & What to Do 2026

Cat fever symptoms include lethargy, loss of appetite, shivering, rapid breathing, warm ears, and hiding behavior. A cat’s normal body temperature is 100.5–102.5°F (38–39.2°C) — anything above 103°F (39.4°C) is considered a fever. Fevers in cats are always a sign that something is medically wrong and warrant prompt veterinary attention.

This guide is for informational purposes only. A rectal temperature reading requires a thermometer and is the only reliable way to confirm fever. Call your vet immediately if you suspect your cat has a fever.

Normal Cat Temperature

A cat’s normal body temperature ranges from 100.5°F to 102.5°F (38°C to 39.2°C). Anything above 103°F (39.4°C) is considered a low-grade fever. Above 104°F (40°C) is a significant fever requiring veterinary care. Temperatures above 106°F (41.1°C) are life-threatening and constitute an emergency.

Source: Cornell Feline Health Center; Merck Veterinary Manual 2025

Signs of Fever in Cats

Since you can’t ask your cat how they feel, watch for these behavioral and physical signs:

• Lethargy and weakness: Sleeping more than usual, reluctance to move
• Loss of appetite: Refusing favorite foods or eating significantly less
• Hiding: Withdrawing to unusual spots or avoiding contact (instinct to hide when vulnerable)
• Shivering or shaking: Trembling even when the environment is warm
• Warm ears: Consistently hotter than usual ears (though this alone is not diagnostic)
• Rapid breathing or panting: Abnormal in cats — a sign of significant illness
• Dehydration: Dry gums, skin that doesn’t snap back when gently pinched
• Grooming changes: Either stopped grooming (looks unkempt) or over-grooming
• Rapid heart rate
• Watery eyes or nasal discharge

Common Causes of Cat Fever

Cats develop fevers as an immune response to infection, inflammation, or disease. The medical term for fever of unknown origin is pyrexia. Common causes include:

• Bacterial infections: Bite wounds, urinary tract infections, respiratory infections
• Viral infections: Feline herpesvirus, calicivirus, feline leukemia virus (FeLV), feline infectious peritonitis (FIP)
• Fungal infections: Cryptococcosis, histoplasmosis
• Parasites: Toxoplasmosis, other parasitic infections
• Immune-mediated disease: Lupus, inflammatory bowel disease
• Cancer
• Medication reactions: Some vaccinations cause a short-term low fever (usually resolves in 24–48 hours)
• Trauma or internal injury

How to Check Your Cat’s Temperature

The only accurate way to check a cat’s temperature is rectally with a digital thermometer:

1. Use a digital rectal thermometer designated for pet use
2. Lubricate the tip with petroleum jelly or water-based lubricant
3. With a helper restraining your cat gently, insert the thermometer 1 inch into the rectum
4. Hold it in place for 60 seconds or until it beeps
5. Normal range: 100.5–102.5°F

Note: Ear thermometers designed for pets can be used but are less accurate than rectal measurement. Touching a cat’s ears, nose, or forehead does not reliably indicate fever.

Treatment Options

Treatment depends entirely on the underlying cause, which requires veterinary diagnosis. Your vet may:

• Run blood work, urinalysis, or imaging to identify the cause
• Prescribe antibiotics for bacterial infections
• Prescribe antivirals or antiparasitics as appropriate
• Provide IV fluids to treat dehydration
• Recommend supportive care at home for mild cases after diagnosis

At home (after vet visit), you can support your cat by: keeping them warm, encouraging fluid intake, offering strong-smelling foods to stimulate appetite, and reducing stress.

Medications Never to Give Cats

This is critical: never give your cat human fever medications. The following are highly toxic to cats:

• Acetaminophen (Tylenol): Rapidly fatal to cats — destroys red blood cells. Even a single tablet can kill a cat.
• Ibuprofen (Advil, Motrin): Causes severe kidney failure and gastrointestinal ulcers in cats
• Aspirin: Cats metabolize aspirin very slowly — toxic even in small doses. Never give without specific veterinary guidance.
• Naproxen (Aleve): Highly toxic to cats; causes kidney failure

When Is Cat Fever an Emergency?

Go to an emergency vet immediately if your cat:

• Has a temperature above 106°F (41.1°C)
• Is completely unresponsive or collapses
• Has difficulty breathing or is breathing with an open mouth
• Has not eaten for more than 24 hours
• Shows signs of extreme dehydration (sunken eyes, sticky gums)
• Is a kitten under 12 weeks (fevers in very young kittens are especially dangerous)

Find a veterinary clinic near you through HeiBob’s directory of trusted pet care providers.