Cats are known for their crazy antics and acrobatics, but take a look at an older cat and you quickly realize the difficulty these geriatric pets have in performing even the simple tasks they used to do every day-jumping onto a favorite couch or pouncing at a toy mouse. Many of these feline friends suffer more than just the aches and pains of old age. They have a condition called osteoarthritis, a degenerative joint disease that progresses with age and affects about 75 percent of senior cats.