Need ideals for grooming matted cat. Tranquilizers?

A little background. My cat has never been the most prolific groomer and every couple of years she gets terribly matted despite my daily brushing.. Over the last 5 or 6 years, I have taken her to the vet to have her groomed, but because she is terrified of vets she has to be anesthetized. Because of this, it's considered a surgical procedure and it typically costs me $300+$50 for pre-op blood work.. I can't really afford that and she is 17 years old so the vet is reluctant to put her under. Other than thyroid problems, which are controlled, she is in good health. 

Does anyone know of another option like a strong tranquilizer or sleeping aid that would just put her out for 30 minutes or so, so that I could give a quick trim with clippers? I've asked the vet, but they didn't recommend anything other than doing blood work and anesthesia and offering to relieve me of $350. 

Thanks in advance

Wow, that sounds like a really awful situation. How bad are the mats? What breed of cat is it, and is it a long-haired cat?

A few suggestions....

1) You need a different grooming device, since your brush isn't working. Try several, starting with a comb like this one:


2) I wouldn't want to put any cat let alone a 17 year old under anesthesia for this either. Have you tried taking her to a professional groomer?

3) Small mats can be tackled one a time by pulling them apart with your fingers, and then using the comb as a pick to pull apart the rest....GENTLY, and holding the fur by the root so you're not tugging on the cat's skin. Sort of like how you'd comb tangles out of a little girl's hair. For larger mats, you want to shave them off with a clipper like this one:


4) Try rubbing coconut oil into her fur. I've found that this makes mats a lot easier to comb out.

General rule, do a little bit a time until you get all the mats done. In future, check for mats regularly and tackle them as they arise. Please don't just ignore them until the problem is so severe you need professional help, unless you like paying out lots of $$ for these services.