If your dog or cat is of an extra-fluffy variety, you’ve probably wondered if she wouldn’t be happier sometimes without that thick fur coat on. Hold the clippers, warns the ASPCA, the American Society for the Prevention of Cruelty to Animals. Fur acts as a layer of insulation, one animal hospital doc tells the ASPCA blog. That coat keeps your pet warm when it’s cold, but also, counterintuitively perhaps, helps to prevent overheating when it’s hot out. On a dog, it’s fine to trim long hairs, but be sure to leave the mat of her coat alone. For cats, don’t trim at all, the ASPCA vet advises; just brush.