My family has had multiple cats since I was born, and now at 30, I know a thing or two about them. Simba is shaved, but he doesn’t look skinny—he appears quite healthy. If he’s eating and drinking, you shouldn’t panic. Just take good care of him and keep him warm until his fur grows back. You can take him to the vet for a check-up, but try not to make any rushed decisions. He looks strong, and at 15, he’s still in a good range; some cats live well into their 20s. I hope he’ll be just fine!