Felix has been having major problems with his fur lately. He had a really sore anus because a lot of his fur didn't come back up in a hair ball. It was swollen, red, and bleeding. Thankfully, that passed and he healed. But he's been having hairballs almost everyday. Smokey rarely does because she enjoys being groomed so I do it often with her. She barely sheds because of this. Felix on the other hand, becomes very aggressive when I pull out the brush or the nail clippers. He has a brush of his own but I can only brush him for about 10 seconds before he latches onto my hand and draws blood. I just bought a deFurminator at Pet Smart because they were on sale and I had a coupon so that's extra money off. I figured it would work faster than a brush and it does. I definitely got more fur out with one go vs using a regular old cat brush. But he's still so aggressive. He started growling and hissing. He grabbed my hand and bit me really hard. Why is this? He's been getting groomed since he was a little kitten. It's nothing new. He's in good health otherwise but I haven't groomed him as often as I should.