My cat is big, eats a lot, and has an itchy butt. Does he have worms?

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to hear about Oscar. So you should decrease the amount of food you are feeding especially since Oscar is neutered and is probably an indoor only cat. Indoor cats do not require as much food as what most people think. Maybe even as little as 1/4 to 1/3 cup of dry food per day but of course it does depend on what you are feeding him. Best thing to do is measure his food, don't feed free choice with a full bowl of food, and then start cutting back at least 25% or a quarter of the food per day, including treats. The anal itching could be tapeworms and that is usually flea related, the pet ingests a flea while grooming and the tapeworm eggs hatch and create problems. It could also be fleas, mites, anal gland problems. Best thing is to have your vet evaluate Oscar, advise nutritional issues, and identify what is causing the itch. Most likely, the cause is determined by physical exam only and then expressing the anal glands if they are enlarged. If Oscar is good they might be able to express them while he is awake. Otherwise sedation is sometimes required. Also skin infections or dermatitis can cause itching. Good luck with Oscar