The most common worms in dogs and cats in the United States are the roundworm, tapeworm, whipworm, and hookworm - which live primarily in the animal’s intestine and the heartworm, which lives within the heart and in the blood vessels leading from the heart to the lungs. 
In many cases, a pet owner will note the signs of worm infection, or it will be detected during a regular checkup when your veterinarian does a microscopic exam of your pet’s stool sample. Heartworm detection requires a blood test. Your veterinarian can easily make a specific diagnosis and begin effective worm treatments that usually cause little discomfort to your pet. Heartworm treatment is an exception. Minor worm infections can be of little significance, but nearly all these parasites will induce serious disease if present in overwhelming numbers. Many pets have various levels of immunity, or at least some resistance to many worm species. It is not unusual for a normal adult animal to have small populations of adult roundworms and hookworms, as well as resting larvae, in body tissues. Common Symptoms of Worm Infection |