Hookworms are very thin parasites, each usually measuring less than .5 inches long, that live in the small intestines of host animals such as your dog. Once the hookworms make a home in your dog's small intestines, they multiply and derive nutrition by sucking blood from your dog. Although they are small, hookworms can extract a significant amount of blood. In addition, as mature hookworms lay thousands of eggs each day, these parasites proliferate rapidly. Left untreated, hookworms can lead to intestinal distress and anemia.

The two species of hookworm that usually infect dogs are called Ancylostoma caninum and Ancylostoma braziliense.

Symptoms of hookworm include itching, diarrhea, bloody stool, vomiting, loss of appetite, weight loss, pale gums and anemia. Your dog may also experience abdominal pain.

Your puppy may contract hookworm larvae, the juvenile form of the worm, from the mother dog before birth or after birth generally through the mother’s milk. Your dog can also contract hookworm orally via toys, grass, water or food bowls contaminated by hookworm larvae or eggs. Finally, hookworm larvae may also be absorbed through the skin of your dog’s paws if your dog walks in an area where infected animals have defecated. Once hookworm larvae are inside your dog’s body, they migrate to the intestines where they mature and feed off of your dog.

Your vet will use a microscope to exam a sample of your dog’s stool. In infected dogs, hookworm eggs will be visible under the microscope.

Your dog should be treated as soon as possible. There are several injectable and oral de-wormers available. These treatments, however, are only effective in killing the mature form of the worm. Therefore, the de-worming must be repeated a few weeks after the first treatment to kill off any worms that were in the larval stage during the first treatment. If your dog is suffering from severe anemia as a result of a hookworm infection, a blood transfusion may be required to replace lost blood.

You can help prevent your dog from contracting hookworm by being mindful of where your dog walks and what objects or places he explores with his mouth. In addition, after checking with your vet, you should put your dog on one of the many heartworm medications that are combined with a hookworm preventative drug to inhibit the maturation of eggs and larvae.

Humans can be infected with hookworms, either by accidental ingestion of infective larvae or, more commonly, in cases where the parasite directly penetrates the skin.