Most of the time we want to rule out a flea infestation first. Depending on the cat’s lifestyle and the area of the country in which it lives, this may be more or less likely; however, it’s quick, easy, and cheap to treat for fleas.
We’d hate to embark on a complicated and expensive diagnostic effort only to find out the cat had fleas all along, so it’s usually the first thing we try.
Cats that have been exposed to other cats recently are more likely to have diseases they can catch from them, such as mange and ringworm. Mange is an itchy skin disease caused by a mite infestation. Ringworm is actually a fungus, not a worm, and it also comes from other cats or dogs. There are special tests to diagnose these infections.
If we can’t find fleas, mites, or ringworm, the most likely cause of itching in cats is allergies. Allergies can be caused by exposure to a specific ingredient in the food, like fish or chicken, or to something in the environment, such as pollen or dust. Successfully treating allergies means stopping the immune reaction that’s causing the itchiness, which usually means changing foods or using prescription medications and supplements like fish oil.