Cat losing hair?

This question is about one of my moms cats. my mom doesn't seem bothered by this but it really bugs me. my moms DLH cat has been losing its hair off and on mostly from mid back to all around tail and butt, anyone have any ideas on what could be causing this? my first thought is maybe a food allergy my mom feeds her cats what ever is on sale right now she has Alley Cat food for them What else could cause this?

How old is the cat? The quality of food would show up in skin and fur but this sounds more extreme. It could be a skin disease. Does it lose the fur in patches, or does it just thin out?

is the cat being treated for fleas? the cat could have a flea allergy if not.

How old is the cat? The quality of food would show up in skin and fur but this sounds more extreme. It could be a skin disease. Does it lose the fur in patches, or does it just thin out?
She is probably about 8 it isn't really patch almost like her butt area and part way up her back and tail is shaved there really isn't marks there about a year ago there were blisters/sores but they are no longer there and were only there for a short time. Her fur is really ruff/dry I am not fond of petting her All her other cats are fine it is just this one
is the cat being treated for fleas? the cat could have a flea allergy if not.
I do not think she is I know my mom had bought some flea stuff but I can't remember when it was or what stuff it was.

If she bought the $4 flea control, that could be the problem. It could also be the cat has fleas, because $4 flea control does not work. She probably has a skin infection, or a flea allergy and needs to be treated with antibiotics and advantage, frontline, or revolution.

Could she be overgrooming herself, i.e. licking her hair off?

I've had that with 2 of my cats. One was an allergy to fleas and the other was an allergy to one of my dogs. Sometimes this can be caused by stress. If it is allergy related, you need to go thru a long, drawn out process of eliminating one thing at a time from their environment to see what is causing it. In the case of Stumpy being allergic to my dog, we didn't find out what it was until the dog crossed and his hair grew back within a month (he was half bald for 7 years and we couldn't find the source in that time). Allergies can be maddening.

With my long haired cat Clover we had sever occasions where patches of fur was missing like it was shaved (no irritation, scratches, etc). It would worry me but the fur always grew back. This dosen't sound the same though if its a consistant problem.

It does sound like possible allergy. But... If the fur is relaly dry and corse then I would suggest adding some salmon oil to the cats diet. This is full of omega 3&6's (just like its healthy for humans to take fish oil). Over time this could have a huge impact on the vibrance of the coat and skin. However, if there is an underlying medical problem then it wouldn't hurt things but it may not help.

Vet fist
diet second food and supplement