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.
I hope this helps. Good luck!
Dr. Clayton Greenway
