This is a test of commonsense. Complete the next sentence:

How to detect common signs of illness in cats 
Look for problems on your cat's coat. 
There are a variety of health problems that can show up on your cat's coat. Make sure the cat's coat is shiny and thick, that there are no patches of missing fur, and that your cat is keeping it nice and clean.
Areas of missing fur could signal injuries, like those created during cat fights, that need veterinary treatment. They could also signal allergies or some other autoimmune or skin problem that also needs veterinary treatment.