MSD Manual

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Gastrointestinal Parasites of Cats

Gastrointestinal Parasites of Cats

Common Name (Scientific Name)

How Contracted


Control and Prevention*

Hookworms (Ancylostoma tubaeforme, A. braziliense, A. ceylanicum, Uncinaria stenocephala)

Ingestion of larvae in environment or by eating infected rodents; penetration of skin by larvae

Often no signs; weight loss and anemia can occur.

Several drugs are available for treating hookworm infection. Some heartworm preventives also control hookworms.

Roundworms (Toxascaris leonina, Toxocara cati)

T. cati—sometimes passed from mother to kittens during nursing

Both species—ingestion of eggs or eating infected rodents

Often no signs; diarrhea, poor growth, dull coat, or a distended, swollen abdomen; worms may be vomited or passed in feces

Kittens should be dewormed on multiple occasions in the first 3 months of life; some monthly heartworm preventives will also prevent roundworm infection.

Stomach worms (Physaloptera species)

Cats eat hosts (beetles, cockroaches, crickets, mice, frogs)

Often no signs. Stomach inflammation which can result in vomiting, loss of appetite, and dark feces. In heavy infections, anemia and weight loss.

Several drugs from your veterinarian can be used to treat infection.

Ollulanus tricuspis

Cats pick up infection through contaminated vomit

Gastritis (stomach inflammation); causes vomiting minutes to a few hours after a meal

Drugs are available from your veterinarian to treat infection.

Tapeworms (cestodes), (Dipylidium caninum, Taenia taeniaeformis)

Eating infected fleas or prey animals

Most infections have few signs. Poor absorption of food or diarrhea may occur; unthriftiness.

Control requires medication to treat the tapeworms and preventing access to prey animals so the cat isn’t reinfected. Flea control is also important for D. caninum.

Threadworms (Strongyloides species)

Occurs more frequently in conditions of crowded, wet, unsanitary housing. Infective stage in environment penetrates skin; also swallowed

Bloody, watery diarrhea, emaciation, and reduced growth rate. Disease can be life-threatening in cats with a weakened immune system.

Drugs are available from your veterinarian to treat infection. Isolation of sick animals; thorough washing of pet living areas. . Use caution when handling infected pets because the worms can cause serious disease in people.

*A number of antiparasitic drugs (anthelmintics) are available to treat parasites in cats.