Hookworms in Cats

Vet examining cat
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Hookworms are intestinal parasites that are relatively common in cats. There are a few species of hookworms that affect cats, and some can also affect humans by migrating within the skin.

Hookworms are small, thin worms that are less than an inch long. The appearance of the mouthparts vary by species, but all hookworms have structures (teeth or plates) to help them attach to the intestinal wall, Unlike roundworms (which just float around and steal nutrients from the cat's meals), hookworms attach to the intestinal wall and feed on blood and/or tissues. They can detach and move to other spots, leaving little ulcers where they have fed previously.

The severity of symptoms varies between the hookworm species and most infections are not life-threatening, but and one type of hookworm (Ancylostoma tubaeforme) can cause fatal blood loss in kittens with heavy infections.

The Hookworm Life Cycle 

Hookworm eggs are passed in the feces, and under warm, moist conditions hatch into larvae after several days. These larvae have several ways they can infect cats:​

  • they can be ingested directly (for example, when cats lick the ground or groom themselves when larvae are present on their fur)
  • they can migrate through the skin (usually through the belly or paws)
  • they can be ingested by another animal such as a rodent or cockroach, and then ingested by a cat that eats that infected animal

Once the hookworm larvae get into a cat, they may develop into adults in the intestines or migrate through the tissues to the lungs, from where they are coughed up and swallowed, and then finally develop into adults in the intestines.​

Signs and Symptoms of Hookworms

Hookworms can produce any of the following symptoms, though symptoms may only appear with heavy infections:

  • failure to gain weight or weight loss
  • diarrhea
  • anemia (pale gums, weakness) sometimes seen
  • bloody or tarry stools may be present
  • sometimes coughing can occur due to the larval migration through the lungs (with very heavy infections)
  • skin irritation, most often on the feet between the toes, due to migrating larvae

The severity of the disease depends on the species of hookworm involved, as well as the number of worms and the age and health of the infected cat.​

Diagnosis of Hookworms

The eggs of hookworms can be detected under the microscope in a routine check of a stool sample (the test process is called fecal flotation). It can take a while for young kittens to start shedding eggs, however, so routine deworming of kittens is recommended.

Treating Hookworms

Treatment is the same, regardless of the species of hookworm involved. There are a number of medications that can be used to treat hookworms, and your vet can help you pick the one right for your cat. Medications will only affect hookworms in the intestines, not migrating larvae.

Treatment should be repeated to deal with larvae as they mature (e.g. at 2-week intervals). The number of treatments necessary will depend on the age of the cat and the situation and will be recommended by your vet.

If you have a pregnant cat, consult your vet for a deworming protocol for both the mom and kittens. Once dewormed, many of the monthly medications designed for parasite control contain medication that will prevent hookworm infections on an ongoing basis -- options that can be discussed with your vet. If your cat is not on one of these preventatives, your vet will recommend a regular deworming protocol to keep hookworms at bay.

Keeping pet wastes picked up, and preventing pets from eating rodents can also help prevent infection with worms.

People and Cat Hookworms

The larvae of hookworms can infect people as well as cats. This happens when eggs are ingested, and The larvae don't develop into adult hookworms in people, but the larvae migrating through the skin can cause irritation and inflammation, though most cases are not serious. Migration of hookworm larvae through human skin is called "cutaneous larva migrans."

Proper treatment and prevention of hookworm infections is important to prevent this human health concern, as is good hygiene. Keeping pet waste picked up, especially in areas where children or other people contact the ground (especially sandboxes) is also helpful in preventing human cases.

Please note: this article has been provided for informational purposes only. If your pet is showing any signs of illness, please consult a veterinarian as quickly as possible.