My cat is losing hair. What is the cause and treatment?

Original Question: On the top of my cats head by his left ear he has a patch of fur missing with a little bit of redness. He is an indoor cat and has no interaction with other animals. Would this be ringworm? And if so how would he have contracted it? Thank you. - Isabell

Jun 17, 2018

Hi Isabell,

Thanks for your question.

It’s important that we perform diagnostics that identify causes of hair loss in cats. I would recommend you first have your veterinarian perform a ‘skin scraping’. This is a quick and inexpensive ‘in clinic’ test that looks for entities such as parasites, bacteria and yeast on the skin. A fungal culture for ringworm would be ideal as well as this is known to cause semi-circular areas of hair loss. If these tests don’t reveal the answer, you would have to move to a skin biopsy to determine the exact cause. Before going to this level, you could ask your veterinarian about a treatment trial or some topical ointment in case the previous testing was falsely negative. A treatment like this is not always ideal because you don’t have a confirmed diagnosis, but most clients prefer this route before going to an expensive and invasive test like a biopsy. An ointment with an antibacterial and anti-inflammatory agent in it could be attempted but only do this under the guidance of your veterinarian. I highly recommend the ringworm test for cats as the treatment I just mentioned would not resolve a fungal infection if it was present.