Ok thank you for that information. So there are several reasons why we see hairloss, specifically on the abdomen. One can be fleas, usually you will see scratching or biting that causes the hair to be broken. Another reason would be allergies, whether that is food or environmental is a little harder to determine. Usually we look for other clues to suggest environmental (like skin problems too). The last possible cause is behavioral, usually stress/anxiety related. We can see these usually in multicat homes due to stress from another cat, but sometimes we can see it in a single cat home due to other reasons.
It may possibly be diet related, but would be to the food too, not just the treats. If we were going to pursue the diet we typically put them on a prescription diet for 6-8 weeks giving them nothing else and see if the excessive grooming or hair loss improved. If we think it is anxiety related then we try to reduce the stress in the home and start on an anti anxiety med. If we are thinking environmental then we typically try a course of steroids to see if we respond, or consider starting atopica which is a medication that helps the immune system to not respond as much to the allergens.
There are definitely other possibilities (depending on what the skin looks like) such as ringworm
, bacterial infection, etc.
I think it may be time to see the vet so we can get a good physical and check out the skin/fur and get the best course of treatment started.
Does that answer your questions? Is there anything else I can answer for you?