Hookworms are intestinal parasites of the cat (and dog). Their name is derived from the hook-like mouthparts they use to anchor to the lining of the intestinal wall. They are only about 1/8" (2-3 mm) long and so small in diameter that they are barely visible to the naked eye.

The scientific names for the most common feline hookworms are Ancylostoma tubaeforme and Ancylostoma braziliense. Occasionally, cats will also become infected with the dog hookworm, Ancylostoma caninum.

In general, cats tend to harbor relatively few hookworms when compared to the large numbers found in dogs. Also, the feline hookworms tend to be less aggressive bloodsuckers than the canine species.

What cats are likely to get hookworms?

Hookworms are more common in warm, moist environments. Conditions of overcrowding and poor sanitation contribute to re-infection.

What are the clinical signs?

Feline hookworms tend to “graze” along the lining of the small intestine and are considered “tissue feeders.” When they do suck blood, an anti-coagulant substance is injected at the feeding site. Therefore, the cat can suffer blood loss from ingestion by the hookworm, as well as continued bleeding into the bowel. The blood-loss anemia attributed to hookworms is a more significant problem in kittens than adult cats.

Evidence of hookworm infection includes anemia, the presence of digested blood in the stool, a poor hair coat, and weight loss.

How do cats get hookworms?

Adult hookworms pass hundreds of microscopic eggs in the cat's stool. The eggs are not visible to the naked eye. Larvae (immature worms) will hatch from the eggs and persist in the soil for weeks or months. When larvae are swallowed by the cat, hookworm infection is established. The larvae may also burrow through the cat's skin and migrate to the intestine, where they may mature and complete their life cycle.

In dogs, prenatal infection (infection prior to birth) may be a significant problem. Puppies may become infected by the placental blood flow and then later through the mother’s milk. Prenatal infection has not been demonstrated to occur in kittens.

How is the diagnosis made?

To diagnose hookworm infection, a small amount of the cat’s stool is mixed into a special solution, causing the eggs to float to the top. With a microscopic exam, the eggs are easily identified because of their unique appearance. Since the eggs are produced on a daily basis, hookworm infection is usually fairly easy to diagnose. The number of eggs does not necessarily correlate with the number of worms present. In fact, the number of eggs passed can be greater with light infections (smaller numbers of worms).

How are hookworms treated?

Fortunately, treatment is safe, simple, and relatively inexpensive. After administration of the deworming medication (called an anthelmintic), the adult worms are killed. At least two treatments are needed; they are typically performed at 2-3 week intervals. Ideally, kittens are treated for worms during their kitten vaccination series.

Since the cat's environment can be laden with hookworm eggs and larvae, it may be necessary to treat it with a chemical to kill them. There are several available formulations which are safe to use on grass.

In rare cases, kittens or debilitated cats might require a blood transfusion because of severe anemia.

Will my cat recover?

With appropriate diagnosis and treatment, the prognosis is good for full recovery from hookworm infection.

Can hookworms be prevented?

Prevention of hookworm infection should include the following measures:

  1. All new kittens should be treated by 2-3 weeks of age. To effectively break the life cycle of the most common intestinal parasites, kittens should be dewormed on the schedule recommended by the veterinarian.
  2. Prompt treatment for worms should be given when any parasites are detected; periodic deworming may be appropriate for cats at high risk for reinfection.
  3. Appropriate disposal of cat (and dog) feces, especially from yards and playgrounds, is important.
  4. Strict hygiene is especially important for children. Do not allow children to play in potentially contaminated environments. Be mindful of the risk posed by public parks and non-covered sandboxes. Sandboxes which have fitted covers are popular and are well-advised to prevent infection of children with intestinal parasites.
  5. Control of rodents is important since they may play a role in the transmission of hookworms to cats.
  6. Stool should be removed from litterboxes daily, if possible. Always wash hands after handling litterbox material.

Can hookworms be transmitted to humans?

Feline hookworms do not infect humans internally. However, the tiny larvae can burrow into human skin, causing a disease called cutaneous larval migrans. Also known as “ground itch,” this skin infection does not lead to the maturation of the larvae. Because contact of human skin with moist, larvae-infected soil is required, infection rarely occurs when good hygiene is practiced.

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