Common signs of fever in cats include increased body temperature (higher than 103.5°F/39.7°C); loss of appetite; lethargy; excessive grooming and/or licking; dehydration; coughing or sneezing; runny eyes or nose; shivering or trembling; panting; vomiting and/or diarrhea. If you see any of these signs, be sure to take your cat to the vet as soon as possible.