my cat has developed matts all over her fur on her back and sides.?

It would be best to take her to a groomer. These mats are painful as they are pulling at the skin. The areas are most likely red and tender in spots. If this is a senior cat, it sometimes happens as they can no longer groom themselves correctly. Since she is not doing it herself, you will need to keep the fur near hind quarters short and brush her several times a week.

You need to take her to the vet or a groomer to have her professionally shaved. Depending on how calm she is, she may have to be sedated. Once the matts are gone you will need to get into a routine of brushing her several times a week to prevent matts from forming again.

I think you have to have her shaved...that's going to be much easier and faster than cutting out each matt. I'm not sure if she would have to be doped up in order to shave her...call your vet and check.

Shaving is the best option. As her hair grows out, train her to accept daily brushing.

You need to get the cat to a vet or take her to a professional groomer!