Hookworms in Cats

Vet examining cat
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Intestinal parasites are relatively common in cats. Hookworms are a common parasite that may affect your cat, but thankfully, your veterinarian can usually treat this condition with medication. There are a few species of hookworms that affect cats, and some hookworm larvae can also affect humans by migrating within the skin.

What Are Hookworms?

Hookworms in Cats

Hookworms are small, thin worms less than an inch long that can infect the intestines of humans and animals like cats. These worms attach themselves to the intestinal lining with hook-shaped anchors on their mouths, which allows them to feed on nutrients from the host.

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 "hook" themselves onto 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 the most common type of hookworm in the United States (Ancylostoma tubaeforme) can cause fatal blood loss in kittens with heavy infections.

Signs and Symptoms of Hookworms in Cats

Hookworms can produce any of the following symptoms in a cat, 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 seen on the feet between the toes, due to the penetration and migration of 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.​

Causes of Hookworms

Hookworm eggs are passed in the feces. Under warm, moist conditions, the eggs hatch into larvae capable of infecting a new host 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 typically migrate through the tissues to the lungs. Then the larvae are coughed up and swallowed, which is how they enter the intestines. Once in the intestines, they finally develop into adults.

Diagnosis of Feline Hookworms

If you suspect hookworms in your cat, it's best to schedule a vet appointment as soon as possible. The vet will examine the cat and will likely need a stool sample. 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 hookworm eggs so routine deworming of kittens is recommended.

Treatment and Prevention

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 recommend the one right for your cat. Over-the-counter dewormers for feline hookworms are also available but be sure to exactly follow the directions printed on the label.

Medications will only affect hookworms in the intestines, not migrating larvae so treatment should be repeated to deal with larvae as they mature (e.g. at two-week intervals). The number of treatments necessary will depend on the age and health of the cat. Your vet will share the right frequency interval for your cat's treatment.

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. These are 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 Feline Hookworms

The larvae of hookworms can infect people as well as cats. This happens when larvae from the environment migrated into and through the skin. The larvae don't develop into adult hookworms in people, but migrating larvae cause skin irritation, itchiness, and inflammation. Although most cases are not serious, it's best to speak with a doctor right away if your cat has been diagnosed with hookworms and you suspect the parasite may have infected a person in your home. Migration of hookworm larvae through human skin is called "cutaneous larva migrans."

Proper treatment and prevention of hookworm infections and good hygiene are important to prevent this human health concern. Keep pet waste picked up and your dogs and cats current on their deworming to help prevent human cases.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.
Article Sources
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  1. Zoonotic Hookworm. Centers for Disease Control and Prevention.

  2. Gastrointestinal Parasites of CatsCornell University College Of Veterinary Medicine.

  3. Gastrointestinal Parasites Of CatsMerck Veterinary Manual.