Gastrointestinal parasitism in cats is a significant concern, with prevalence rates as high as 45%. Cats can be affected by various types of parasites, ranging from wormlike organisms (such as roundworms, hookworms, and tapeworms) to one-celled protozoa (such as Isospora, Giardia, and Toxoplasma). These parasites can cause a variety of nonspecific symptoms, such as a dull coat, vomiting, diarrhea, anemia, and dehydration, weakening the cat and making it susceptible to other infections and diseases.
Wormlike Parasites
- Roundworms (Toxascaris leonina and Toxocara cati):
Roundworms are the most common intestinal parasite in cats, particularly in kittens. Cats become infected by ingesting eggs from contaminated feces or by eating infected rodents. Kittens can also become infected through their mother’s milk. Symptoms include a pot-bellied appearance and, in severe cases, intestinal blockages. Diagnosis is confirmed through stool analysis, and effective treatments are available. - Hookworms (Ancylostoma and Uncinaria):
Hookworms attach to the intestines and feed on blood, potentially causing anemia in severe cases. Cats can become infected by ingesting larvae or through skin penetration. Symptoms include black, tarry stools due to blood loss. Like roundworms, hookworm infections are treatable, and maintaining cleanliness in litter boxes is crucial for prevention. - Tapeworms (cestodes):
Tapeworms are long, segmented worms that live in the small intestine. Cats become infected by ingesting fleas or rodents carrying the parasite. While tapeworm infections rarely cause serious disease, reinfection is common without proper flea and rodent control. Segments of tapeworms can sometimes be seen near the cat’s tail or in feces. - Whipworms:
Whipworms are uncommon in cats in the U.S. and typically reside in the large intestine without causing significant disease. - Stomach Worms (Ollanulus tricuspis and Physaloptera):
These worms are rare and may cause chronic vomiting and appetite loss in infected cats. Diagnosis is difficult, and prevention relies on limiting exposure to vomitus or intermediate hosts, such as insects.
Protozoan Parasites
- Isospora (coccidia):
Coccidiosis, caused by Isospora, is commonly seen in kittens. It can damage the lining of the intestine, causing diarrhea. The infection spreads through contact with feces, and good sanitation is essential for prevention. - Giardia:
Giardia infects the small intestine and is more common in crowded environments. Infected cats may show signs of chronic diarrhea, though many cats are asymptomatic. Diagnosis requires multiple fecal tests, and proper hygiene is essential to control the infection. - Toxoplasma:
Cats are the definitive host for Toxoplasma, and they become infected by eating tissue cysts from prey or raw meat. While the infection is common, it rarely causes disease in cats. However, it can pose a risk to humans, particularly pregnant women, so avoiding contact with contaminated feces is important.
Treatment and Prevention
Effective treatment typically involves administering medications prescribed by a veterinarian. However, reinfections are common without preventive measures, such as maintaining clean litter boxes, controlling intermediate hosts like fleas and rodents, and avoiding raw meat diets. Regular veterinary care, including stool examinations, is essential to ensure a cat’s good health and to protect humans from potential zoonotic infections.
