It’s unpleasant to think about hookworms. The name conjures up an awful vision, but it’s even more unpleasant for your pet to have them. Dogs and cats, both young and old, are at risk for the nasty parasites. And because the eggs can be transmitted through pets’ feces, people can also become infected. Symptoms in pets can include anemia, black diarrhea, coughing, a dull coat, and failure to gain weight. Fortunately, antiparasite drugs can be used to treat an infection, and monthly preventive medicine can protect your pet from hookworms.


Hookworms are internal parasites that generally live in the small intestines of puppies, kittens, dogs, and cats. These worms attach to the intestinal tissue and suck blood and other nutrients from their hosts. Infected mother dogs can transmit hookworm larvae to their puppies during nursing. These larvae migrate through the puppy’s body to the lungs, where they are coughed up and swallowed, finally arriving in the small intestine.

Infected dogs and cats also release hookworm eggs into the environment through their feces. In the environment, hookworm larvae develop into the infective stage and hatch from the eggs so that when pets lie down in contaminated environments they pick up hookworm larvae in their coats and become infected during grooming. Eating stool outright can also lead to infection.

Hookworm larvae in the environment can also penetrate the pet’s skin (dog or cat) and travel through the body, eventually arriving at the small intestine. Dogs and cats can also become infected with hookworms by eating infected animals, such as rodents, or insects, like cockroaches.

Hookworm infections are considered zoonotic, meaning that they can be transmitted from animals to humans. Typically, people are infected when hookworm larvae from the environment penetrate the skin. The larvae then migrate under the skin, resulting in a condition called cutaneous larva migrans. People with this condition may experience itchy skin lesions with a snakelike pattern.

Occasionally, ingested larvae will migrate to the intestine, causing abdominal pain. However, hookworms do not mature to adults in humans, so these infections usually resolve on their own.

Signs and Identification

Hookworm infections are most severe in young puppies and kittens. Given a large enough worm burden, pets can die from hookworms. Signs of a hookworm infection include:

  • Pale gums (from anemia related to blood loss)
  • Dark, tarry diarrhea
  • Thin, dull coat
  • Failure to gain weight
  • Lethargy
  • Coughing
  • Red, itchy skin lesions, especially on the paws
Diagnosing a hookworm infection is usually achieved by identifying hookworm eggs during a fecal examination. Unfortunately, hookworm adults don’t shed eggs all the time, so it can be difficult to identify the infection in some cases. That’s why routine deworming and several fecal examinations are always recommended in puppies, kittens, and pets with signs listed above.

Affected Breeds

Dogs or cats of any breed can become infected with hookworms.


Puppies and kittens are routinely treated every few weeks with an antiparasite medication that eliminates hookworms and other internal parasites for at least two sequential treatments or until they are old enough to be placed on a monthly preventive medication.

Because hookworms can cause anemia (decreased red blood cells), pets with severe infections may require fluids, iron supplements, and even blood transfusions.

Several antiparasite medications can be used to treat hookworm infections in dogs and cats.


All pets should be on a monthly parasite preventive regimen.

To prevent human infection, pet owners should remove and dispose of feces from the yard and sandboxes as soon as possible. Gloves and shoes should be worn at all times while gardening.

This article has been reviewed by a Veterinarian.