Our 19 year old cat has a terrible clump of feces maated to her skin and fur on her rectum and area. She's too old to be given anesthesia to get it removed-we would be very grateful for suggestions to help us get this taken care of. It breaks our hearts and she won't use her litter box now because of this clump.
Thank you for your time

Will she let you cut on her? You will need to get very small clip scissors and clip hair by hair... it will be pretty gross, but you need to get it. If she is not using the litter box, then she is more than likely in pain from the matt.

If she resist you. Take a towel and spread it... fold it so that there is enough room for her rear to stick out. Wrap the towel around her so that you secure her front claws and head in the towel... covering their face helps to calm them and it is less likely that you will get bitten or scratched this way. Also you need the help of another person. Make sure that you hold her body firm to the table, floor or your body so the she does not get loose. According to how tough she is the one holding her could wear some leather work gloves.
You may only be able to work on it a little at the time but in a few days you should be able to take care of this.

Also you could call around explain the situation to a good experienced groomer or vet they should be able to help.
When I was in high school I worked in a vets office as an assistant to the vet techs. We had a old poodle named Charlie that would come in to get a bath and clipped... lol,it took 3 of us to manage him with out medication. But he left that vets office as pretty as could be.

Follow Bushg's instructions, and get as close to the skin as possible. Once you get to the point where you are going to pull skin off to get the rest off, try using vaseline or some type of cooking oil, (veg. olive, etc) to soften up the remainder that is adhered to the skin.
It may take a day or two to soften up enough to get off her skin. If the skin area looks bad, take her to the vet for an evaluation to make sure there is not an infection. You might need a topical antibiotic. If it looks okay, keep an eye on the area for the next week to make sure she is healing and the area is not getting worse.

After you get it off, keep her hair trimmed at her hind quarters to prevent future problems.