Monthly Doctor’s Blog: Hair Loss in Cats

Dr. Brodie Morris

When cats develop hair loss, it can be associated with obvious scratching and self-trauma (often seen as redness, crusting, swelling, and hair loss around the face, ears, belly, or back) or it can simply show up as patches of missing hair with completely normal looking skin and no obvious scratching behavior.

In both cases, even when the skin looks normal and no scratching has been observed, itching is the most common reason for the hair loss. Stress is another potential cause and is often suspected when the cat hasn’t been visibly scratching, but in one study of 21 cats referred to a behaviorist to discuss suspected stress-related overgrooming, only two of them had no itchiness after a complete evaluation. Several cats did have both an underlying itchiness and a behavioral problem, as sometimes a medical cause of itching can lead to an overgrooming behavior that then becomes a separate issue. Correctly sorting out exactly what is going on can be quite complicated.

If itching is the underlying problem, it can be broken down into a few general categories. The first is some kind of skin parasite, for example fleas or mites. This is much more common in young cats or cats who spend a significant time outdoors. The second is an infection, such as ringworm or a type of bacteria. This is more common in young cats a well, although most bacterial infections in cats are caused by itching and scratching rather than being the cause of the itching in the first place. The third category is that of miscellaneous diseases, including drug reactions, hyperthyroidism, and certain cancers. It’s less common for these to be the root cause of hair loss, but when they are it is mostly in older cats.

The final large category is allergies, which are very common. Allergies themselves can be broken down into multiple common types, including to food, environmental factors (for example pollen, dust, and cleaning products), and sometimes to parasites (some cats will be incredibly itchy after getting bit by a flea for weeks to over a month even if the fleas are immediately treated and eliminated).

If you do notice hair loss, it’s a good idea to come in for an appointment to discuss potential diagnostic and management strategies, although sometimes very mild symptoms can be monitored rather than requiring immediate treatment.