Glossary

Hookworm

A small intestinal worm that attaches to the gut wall and feeds on blood, causing anemia in puppies, and can burrow into human skin.

Also called: Ancylostoma, hookworms, intestinal hookworm

Hookworms are tiny worms, about a centimeter long, that hook onto the lining of the small intestine and feed on blood. Puppies can be infected through the mother's milk, and dogs of any age pick up larvae from contaminated soil or by larvae burrowing through skin.

Blood loss is the main danger. Heavily infected puppies can become weak and pale, with dark, tarry stool, diarrhea and poor growth, and some can die. Adult dogs may carry hookworms with few signs.

Eggs appear in a stool sample, so a vet uses a fecal test to find them. Hookworm larvae can enter human skin, especially from barefoot contact with soil, causing an itchy rash, so prompt stool cleanup helps. Deworming and monthly preventives work against some hookworms, but a veterinarian should choose the product.

Last reviewed November 8, 2026

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Related terms

Roundworm A common intestinal worm that often infects puppies, frequently from the mother, and can pass to people, especially children. Whipworm A parasite of the large intestine whose eggs stay in soil for years and which can cause chronic, mucus-covered diarrhea in dogs. Fecal test A laboratory check of a dog's stool for parasite eggs and organisms such as roundworm, hookworm, whipworm and Giardia.