Cats get hookworms primarily by swallowing infectious larvae from contaminated soil or by having larvae burrow directly through their skin, usually through the paws. Less commonly, kittens may pick up the parasite from their mother’s milk, though this route is not as well established in cats as it is in dogs. Once inside the cat, the tiny worms migrate to the small intestine, latch onto the intestinal wall, and feed on blood.
Swallowing Larvae From the Environment
The most common route of infection is ingestion. Hookworm eggs pass out of an infected animal’s body in feces. In warm, moist, shaded soil, those eggs hatch within one to two days. The newly hatched larvae then develop through two molts over roughly five to ten days until they reach an infective stage. At that point, they can survive in the environment for three to four weeks, waiting for a host.
Cats swallow these larvae while grooming dirt off their paws, licking contaminated fur, or eating something off the ground. Outdoor cats and cats that share yards with other animals face the highest risk. Indoor cats with access to a garden, patio, or even contaminated potting soil can also be exposed. Once swallowed, the larvae travel to the small intestine, attach to the lining, and mature into blood-feeding adults. Eggs typically appear in the cat’s feces two to three weeks after infection.
Skin Penetration
Hookworm larvae don’t need to be swallowed to cause infection. They can burrow directly through a cat’s skin, particularly the soft skin between the toes or on the belly. This happens when a cat walks across, lies on, or digs in contaminated soil or sand. Once through the skin, larvae enter the bloodstream and travel to the lungs. From the lungs they move up the airways, get swallowed, and eventually reach the small intestine where they mature into adults.
This skin-penetration route is especially relevant for cats that spend time in warm, humid climates where larvae thrive in soil. Sandy, shaded areas near where animals defecate are hotspots.
Eating Prey Animals
Cats that hunt may be exposed to hookworms through prey. Rodents, insects, and other small animals can carry hookworm larvae in their tissues, acting as transport hosts. When a cat eats an infected mouse or cockroach, those larvae are released during digestion and can establish an infection in the cat’s intestine. According to the Cornell Feline Health Center, it remains somewhat uncertain how significant this route is compared to direct environmental exposure, but it is a recognized possibility for cats that actively hunt.
Mother-to-Kitten Transmission
In dogs, hookworm larvae commonly pass from mother to puppies through milk. In cats, this route is less clearly documented. The main canine hookworm species is known to transmit through nursing, but the hookworm species that typically infect cats, such as Ancylostoma tubaeforme, have not been shown to reliably do the same. Still, kittens are considered highly vulnerable to hookworm infection. Current parasite control guidelines recommend deworming kittens starting at just two weeks of age, repeating every two weeks until regular parasite prevention begins.
What Hookworms Do Inside a Cat
Hookworms are small, only about one to two centimeters long, but they have sharp, hook-like mouthparts that latch onto the lining of the small intestine. They feed on blood, and even a moderate number of worms can cause significant blood loss over time. Signs of infection include:
- Dark, tarry stools or visible blood in feces
- Anemia, which may show as pale gums and lethargy
- Weight loss and poor coat condition
- Diarrhea
Kittens are at the greatest risk because their small bodies can’t tolerate much blood loss. A heavy hookworm burden in a young kitten can become life-threatening quickly. Adult cats with light infections sometimes show no obvious symptoms at all, which is why routine fecal testing matters even when a cat looks healthy.
How Hookworms Are Detected
Veterinarians diagnose hookworms by examining a stool sample under a microscope, looking for the characteristic eggs. The method matters quite a bit. A simple direct smear catches hookworm eggs only about 25% of the time. Standard passive flotation (where the sample sits in a solution and eggs float to the top) improves detection to around 70%. The gold standard is centrifugal flotation, which spins the sample to separate eggs more effectively and detects hookworms essentially 100% of the time when performed properly. Fecal antigen tests and PCR testing are also available and can identify infections that microscopy might miss.
The Companion Animal Parasite Council recommends fecal exams at least four times during a cat’s first year of life, and at least twice a year for healthy adults, with more frequent testing for cats that go outdoors or travel.
Keeping Your Cat Protected
Year-round broad-spectrum parasite prevention is the most reliable way to keep hookworms from becoming a problem. These products protect against hookworms along with other intestinal parasites, fleas, and sometimes heartworm. For cats not on continuous prevention, the recommended schedule is quarterly deworming for adults, with more frequent treatment for kittens: every two weeks starting at two weeks old until two months, then monthly until six months.
Reducing environmental exposure helps too. Picking up feces from litter boxes daily and from outdoor areas regularly limits the number of eggs that develop into infectious larvae. Keeping cats indoors eliminates most contact with contaminated soil and removes the chance of picking up larvae from prey animals. In yards shared with other pets, shaded, moist patches of soil are the highest-risk areas since hookworm larvae need warmth, moisture, and shade to develop and survive.
Hookworms Can Spread to People
Cat hookworms are zoonotic, meaning they can infect humans. People pick them up the same way cats do through skin penetration. Walking barefoot or sitting on contaminated sand or soil gives larvae the opportunity to burrow into exposed skin. In humans, the larvae typically can’t complete their full lifecycle, but they cause a condition called cutaneous larva migrans, sometimes called “creeping eruption.” It shows up as intensely itchy, raised red lines that track across the skin as the larvae migrate. The condition resolves on its own within several weeks as the larvae die, though treatment can speed recovery and relieve itching.
Children and anyone who spends time barefoot in areas where cats or dogs defecate are most at risk. Sandboxes, beaches, and garden beds are common exposure sites.