Feline Hookworms

Hookworms are small parasitic worms that live in the small intestine, affecting cats, dogs, and even humans. The two most common species infecting cats are Ancylostoma tubaeforme and Ancylostoma braziliense, with A. tubaeforme being the primary culprit worldwide and A. braziliense more common in tropical and subtropical regions. A third species, Ancylostoma ceylanicum, can also cause infection, though it closely resembles A. braziliense and is difficult to distinguish as a separate diagnosis.

Hookworms feed on blood from the intestinal wall, and in large enough numbers, this can lead to iron deficiency anemia, a condition called ancylostomiasis. The bite sites can continue oozing blood even after a worm has fed, adding to ongoing blood loss. These infections can be fatal, especially in kittens.

Hookworm eggs need warm, sandy soil to survive, and generally only last a few weeks under natural conditions, though under the right conditions, they can hatch into infective larvae in as little as 5 to 7 days. Direct sunlight or drying out kills the eggs quickly.

It's the larvae, not the eggs, that cause infection, typically by penetrating the skin, though ingestion is also possible. Once inside a cat, the larvae travel through the bloodstream to the lungs, then migrate up the trachea into the throat. This often triggers coughing, and the swallowed larvae then pass down the esophagus into the digestive system, eventually settling in the small intestine, where they hook into the lining and begin feeding on blood. Once mature, adult worms mate, and females can lay tens of thousands of eggs per day, which pass out in the cat's feces to continue the cycle. A cat becomes capable of spreading the infection to other cats roughly 2 to 4 weeks after their own initial infection.

Hookworm infection happens either through skin penetration by larvae or through ingestion. Eggs are typically found in contaminated soil, grass, or standing water. After hatching, larvae most often enter a cat through the feet when walking across contaminated ground.

Unlike hookworm infection in dogs with Ancylostoma caninum, transmammary transmission is not known to occur with A. tubaeforme in cats. Kittens instead become infected primarily through ingestion of larvae in the environment or from infected prey (such as rodents), or through skin penetration.

Hookworm larvae entering through the skin often leave small lesions on the paw pads and between the toes, an early sign worth watching for, alongside repeated coughing.

Because hookworms cause anemia, later-stage symptoms can include dark, tarry stool and diarrhea, along with pale gums, lips, and nostril linings. Affected cats often look generally unwell and eat less than usual. Complications can progress quickly and become fatal without prompt treatment. Interestingly, older cats can sometimes carry a light hookworm burden with few or no visible symptoms, while young kittens can become severely ill from a comparable number of worms - their smaller size and less mature immune systems leave far less room for error.

Hookworms are too small to see with the naked eye, so diagnosis requires a microscopic exam of a fecal sample to check for eggs. If multiple kittens in a litter have died unexpectedly, hookworm infection is worth investigating as a possible cause.

Keeping your cat's environment clean matters a great deal, particularly sleeping and litter areas, and any spots where water tends to collect, like containers, damp low-lying areas, or ponds.

There's no vaccine available for hookworm infection, so prevention relies on staying observant and seeking veterinary care promptly if symptoms appear.

Hookworms can be transmitted to humans, most often causing a localized skin reaction called cutaneous larva migrans when larvae penetrate the skin. Reasonable care like using gloves when cleaning litter boxes or handling an infected cat helps reduce this risk.