Hookworms are small parasitic worms that attach to the lining of a cat’s intestine and feed on blood. They’re among the most common intestinal parasites in cats, particularly dangerous for kittens, and capable of spreading to humans. Adult hookworms are tiny, roughly 10 to 15 mm long (about half an inch), with hook-like mouthparts that let them latch onto intestinal tissue and draw blood continuously.
Species That Infect Cats
Several hookworm species target cats. The most common is Ancylostoma tubaeforme, which is considered the primary feline hookworm. Cats can also be infected by Ancylostoma braziliense and Uncinaria stenocephala, both of which infect dogs as well. Ancylostoma caninum, traditionally thought of as a dog hookworm, has a broad enough host range to infect cats too.
These species differ slightly in their mouthparts. Some have pairs of teeth they use to grip the intestinal wall, while others have flat cutting plates. The practical difference for your cat is minimal: all of them feed on blood, and all of them cause the same general set of problems.
How Cats Get Hookworms
Hookworm eggs pass out of an infected cat’s body in feces. Once in the environment, the eggs hatch into larvae that go through several stages before becoming infective. These third-stage larvae, each about half a millimeter long, are the form that actually causes new infections. Cats pick them up in three main ways.
- Skin penetration. Larvae in contaminated soil or bedding can burrow directly through the skin, typically through the paw pads. From there, they travel through the bloodstream to the lungs, get coughed up and swallowed, and eventually reach the intestine where they mature into adults.
- Oral ingestion. Cats can swallow larvae while grooming dirty paws, eating contaminated prey, or licking contaminated surfaces. Some species cause intestinal infection specifically through this oral route rather than skin entry.
- Transmammary transmission. A nursing queen can pass larvae to her kittens through her milk. This is one reason hookworm infections are so common and dangerous in very young kittens: they can be infected before they ever set foot outside.
Warm, moist, shaded soil is ideal for larval survival. Sandy or loamy ground near areas where cats defecate, such as garden beds or under porches, can harbor infective larvae for weeks. Direct sunlight, freezing temperatures, and dry conditions kill larvae more quickly.
Signs of Hookworm Infection
The severity of symptoms depends on the number of worms, the cat’s age, and overall health. A healthy adult cat with a light infection may show no obvious signs at all. Heavier infections and infections in kittens are a different story.
Because hookworms feed on blood, the hallmark sign is anemia. You might notice pale gums, lethargy, and weakness. In kittens, blood loss can become life-threatening quickly because their small bodies have so little blood volume to spare. Dark, tarry stools (a sign of digested blood) or visible blood in the stool are common with significant infections. Chronic hookworm disease leads to weight loss, poor coat quality, and failure to thrive, especially in young or malnourished cats.
Some cats develop skin irritation at the site where larvae penetrated, typically between the toes or on the belly. This can look like redness or small sores and may cause excessive licking or chewing at the affected area. Respiratory signs like coughing can occasionally occur as larvae migrate through the lungs, though this is more noticeable in heavy infections.
How Hookworms Are Diagnosed
The standard method is a fecal flotation test. Your vet mixes a small stool sample with a special solution that causes hookworm eggs to float to the surface, where they can be identified under a microscope. It’s a quick, inexpensive test and catches most infections.
Fecal flotation does have limits. It only detects eggs, so it can miss infections where all the worms are the same sex (and therefore not producing eggs) or where the worm burden is very light. Newer fecal antigen tests, which detect proteins shed by the worms themselves rather than eggs, are more sensitive. In one study comparing the two methods in feral cats, antigen testing identified 38% of cats as positive compared to 26% by standard flotation. These antigen-based tests are becoming more widely available through commercial veterinary labs.
Because hookworm eggs take a couple of weeks to appear in stool after initial infection, a single negative test doesn’t always rule out hookworms, especially in a kitten with suspicious symptoms. Retesting after two to three weeks may be necessary.
Treatment and Deworming Schedules
Hookworms are treatable with common deworming medications. Pyrantel pamoate is one of the most widely used options for cats. It’s effective against both hookworms and roundworms, safe for young kittens, and safe for pregnant queens. Fenbendazole, the active ingredient in several veterinary dewormers, also targets hookworms along with a broad range of other intestinal parasites including roundworms, whipworms, and tapeworms.
A single dose of dewormer kills the adult worms in the intestine but doesn’t affect larvae that are still migrating through the body. Those larvae will eventually reach the gut and mature, which is why repeat treatments are necessary. The standard approach is to deworm again two to three weeks after the first dose to catch newly arrived adults before they start producing eggs.
Kitten Deworming Protocol
Kittens are at highest risk and need the most aggressive schedule. The University of Wisconsin Shelter Medicine program recommends starting pyrantel as early as two weeks of age, then repeating every two weeks until the kitten reaches 16 weeks old. This frequent dosing accounts for transmammary transmission and the ongoing migration of larvae through the kitten’s body during those critical early weeks. Kittens with severe anemia from hookworms may also need supportive care, including nutritional support and, in extreme cases, blood transfusions.
After the initial kitten series, most cats transition to a routine deworming or broad-spectrum parasite prevention program. Monthly preventives that cover hookworms, along with heartworm and fleas, are available and simplify long-term protection, particularly for cats that go outdoors.
Hookworms Can Spread to People
Cat hookworms are zoonotic, meaning they can infect humans. The most common result is a condition called cutaneous larva migrans. Larvae in contaminated soil penetrate exposed skin, usually bare feet, and begin burrowing through the upper layers. They can’t complete their life cycle in a human host, so instead of reaching the intestine they wander beneath the skin, creating raised, red, intensely itchy tracks that snake across the affected area.
Cutaneous larva migrans is uncomfortable but self-limiting in most cases, and it responds well to treatment. In rare situations, hookworm larvae can migrate to deeper tissues, potentially affecting the intestine, lungs, or even the eye.
The practical takeaway: if your cat has hookworms, the contaminated environment is the risk, not the cat itself. You won’t catch hookworms by petting your cat. The danger comes from skin contact with soil or sand where infected cats have defecated. Wearing shoes outdoors, keeping children’s sandboxes covered, and promptly cleaning up cat feces all reduce the risk substantially. Treating your cat eliminates the source of environmental contamination over time.
Preventing Reinfection
Deworming your cat solves the immediate problem, but the environment can remain a source of reinfection. Hookworm larvae survive best in warm, moist, shaded soil. If your cat has outdoor access, keeping the yard clean of feces reduces larval contamination significantly. Concentrate on areas your cat frequents, and remove stool daily if possible.
For indoor cats, keeping litter boxes clean and changing litter regularly limits any environmental buildup. Cats that hunt are at ongoing risk from ingesting infected prey, so a monthly parasite preventive is the most reliable long-term strategy for cats that spend any time outdoors. Regular fecal testing, typically once or twice a year as part of routine vet visits, catches reinfections before they become a problem.