Does my indoor cat need flea prevention? Indoor cats need flea and heartworm prevention – fleas and other insects can catch a ride on your own shoes, pant legs, or with the family dog. Heartworms are spread by mosquitoes. Heartworm disease is rare in cats compared to dogs, but it still happens and there is no cure for cats. Fleas and ticks aren’t just annoying; they also carry disease. Use a high quality prevention each month – and make sure it is for cats. Cats are much more sensitive to toxins than dogs and can’t use a product for dogs, even if the weight range is right. Discuss with your veterinarian. Download our free book about cats!