Pet Talk: Common Feline Parasites

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Depositphotos_11105735_originalWhether your cat stays indoors or outdoors, all cats are at risk of getting parasites. Recognizing the signs of parasites and knowing their life cycles could help maintain your cat’s health. Dr. Sina Marsilio, internist and researcher at the Texas A&M University College of Veterinary Medicine’s Gastrointestinal Laboratory, explained the most common parasites found in cats include fleas, ticks, roundworms, hookworms, tapeworms, and heartworms.

“The parasites most common in cats depend on where the cat lives and if it is an indoor or outdoor cat. Generally, indoor cats have fewer parasites than outdoor cats,” she said. “The most common external parasites affecting the skin are fleas and ticks. While there many different internal parasites, most of them affect the gastrointestinal tract. However, especially in Texas, we need to be aware of heartworms in cats, which mostly affect the heart and lung vessels.”

All cat owners should treat their pet for fleas and ticks. If left untreated, these pesky parasites can infest not only pets, but homes and yards as well. Cats can acquire fleas from other animals, including wildlife in the backyard or another pet in the household.

“Fleas live in the cat’s fur where it is warm and moist,” Marsilio said. “They stick to the cat’s skin and suck blood. These bites can cause itching and cats respond by licking and scratching. The skin around the back of the neck and the top of the tail head is most commonly affected.”

Severe flea infestation may lead to anemia because the fleas can potentially suck more blood than the cat can produce. Kittens are especially at risk. In addition, your cat may be allergic to the fleas’ saliva, which can lead to a condition called flea allergy dermatitis. Cats with a flea allergy may obsessively scratch, leaving the skin hairless, red, and crusty. Fleas also carry tapeworm eggs and bacteria, which can lead to other health issues.

Internal parasites, such as roundworms, hookworms, and tapeworms can be wormlike or single-celled microscopic organisms called protozoans. They can seriously affect the gastrointestinal tract.

“Gastrointestinal parasites primarily cause signs of gastrointestinal disease, including loss of appetite, weight loss, vomiting, diarrhea, mucoid or bloody feces, and pot-bellied appearance,” Marsilio said. “Any blood loss caused by the parasite can lead to anemia. Vomiting and diarrhea can cause dehydration, which makes your cat susceptible to various other bacterial and viral infections. Some gastrointestinal parasites may even be zoonotic, meaning they can be transferred from animals to humans.”

Roundworms resemble spaghetti and are about three to four inches long. They commonly infect outdoor cats from hunting and eating infected mice. Hookworms primarily reside in the small intestine and feed on the cat’s blood. An infestation can lead to life-threatening anemia, especially in kittens. Tapeworms are long and flat, four to 28 inches in length. They can be transmitted to cats when they eat or get bitten by other animals, such as fleas or rodents. Heartworms are transmitted via mosquitoes as larvae. Treatment for heartworms can be long and expensive, so prevention is very important.

“Even though dogs are at greater risk for a heartworm infection, they do occur in cats. Heartworm disease might be without any clinical symptoms, but when clinical signs occur, they are usually severe to even life threatening,” Marsilio said. “Cats with heartworm disease may show coughing, wheezing, difficulty breathing, vomiting, or neurological signs such as falling over, collapsing or having seizures.”

If one’s cat has a parasite, including fleas and ticks, be sure to visit a veterinarian for treatment.

“In general, your veterinarian is always the best source of information,” Marsilio said. “They know about you and your cat’s history and lifestyle, and they can determine the specific risks for your pet.”

This Pet Talk is from the Texas A&M College of Veterinary Medicines & Biomedical Sciences. To read more Pet Talks, or to learn more about pet care, visit