Diagnosis of Cat Hair Loss

by Linda Santos
(Pahoa, Hawaii)

Reader Question: What conditions can cause cat hair loss?

I have two black cats who both suffer from hair loss. The older cat has loss mostly on her fat belly. The younger one has various spots. They do not interact even though the younger one wants to.

Is there anything that I can put on them to treat it? I flea comb both of them, the older one had dry, sometimes flaky skin. The younger guy had a bad reaction to flea drops (5 days at vet) so I use a natural flea spray on him.

Suggestion from our Veterinarian for how to diagnose cat hair loss


The list of conditions that could be causing your cats’ hair loss is quite long. If they were my patients, I would start their work-up with a physical exam and complete health history, and unless their diagnosis was obvious (e.g., a flea infestation), then move on to a few simple laboratory tests.

In cases like these, I usually start with skin scrapings to look for mange mites, skin cytology to rule out yeast or bacterial infections, and fungal cultures for ringworm. It can take up to two weeks to get the results of a fungal culture, so in the meantime I treat for anything that I found (e.g., a skin infection), sometimes prescribe a broad spectrum parasiticide like Revolution to deal the mites that can be hard to find on skin scrapings, and pursue any other leads that I might have.

If the fungal cultures came back negative and your cats were still not better, we’d have to consider additional diagnostic tests like skin biopsies, a hypoallergenic food trial, or environmental allergy testing.

Best of luck,

Jennifer Coates, DVM

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