Heartworms are internal parasite that infests the heart of infected dogs, and the heart and lungs of an infected cat. These parasites are transmitted to our dogs and cats through mosquitoes that are carrying microfilaria, which are young heartworms. After bitten by the infected mosquito, the dog or cat has the young heartworm in their bloodstream, where they begin to grow. Heartworms can be treated in dogs, but cats that are infected cannot be treated. The best way to prevent heartworms in your dog or cat is to keep them on a monthly preventative, or a 6-month heartworm injection for dogs. Bring your dog or cat in today, and Dr. Mchughes can determine which heartworm preventative is right for your pets.