Introduction
Parasites are organisms that live in or on another organism, known as the host, and benefit by receiving food, shelter, and the ability to reproduce while potentially harming the host. Parasites that live in the gastrointestinal tract of cats are a common concern for cat owners. Intestinal parasites, or parasitic worms, inhabit the gastrointestinal tract and can cause a variety of symptoms and health problems in cats.
There are several common parasites that cats may harbor, including roundworms, hookworms, tapeworms, and protozoa. These parasites feed off the cat and absorb nutrients at the expense of the cat’s health. Parasites not only rob cats of nutrients, but they can cause gastrointestinal upset, diarrhea, vomiting, weight loss, lethargy, a scruffy haircoat, and even transmit zoonotic diseases to humans in some cases. That’s why it’s important for cat owners to understand intestinal parasites, how cats become infected, the risks for indoor versus outdoor cats, how to diagnose a parasitic infection, and options for safe and effective treatment.
Common Parasites in Cats
The most prevalent parasites in cats are roundworms, tapeworms, hookworms, and giardia. According to Cornell Feline Health Center, roundworms are the most common intestinal parasite, affecting 25% to 75% of cats, with higher rates in kittens (source). The two main species are Toxocara cati and Toxascaris leonina. Tapeworms are also very common in cats. The most common species is Dipylidium caninum, which cats get from ingesting fleas. Hookworms such as Ancylostoma tubaeforme infect about 15% of cats. Finally, giardia is a protozoan parasite that can cause chronic diarrhea in cats.
How Cats Get Parasites
Cats can get intestinal parasites like worms and protozoa by ingesting contaminated substances or through vectors like fleas.
One of the most common ways cats get infected is by ingesting feces that is contaminated with parasite eggs or oocysts. This can happen when cats use a shared litter box with an infected cat, or come into contact with infected feces outside from other cats, dogs, or wildlife.
Fleas are another major vector for parasites like tapeworms. When a cat swallows an infected flea while grooming, the tapeworm larvae can be released and mature in the cat’s intestine. Tapeworms like Dipylidium caninum use fleas as intermediate hosts.
Cats that hunt and eat infected prey like mice or birds can also pick up parasites like Toxoplasma gondii. The parasite transfers to the cat once the infected prey is consumed.
Some key references on parasite transmission in cats:
[1] https://vcahospitals.com/know-your-pet/internal-parasites-in-cats
Risk Factors for Indoor Cats
Even cats that are kept strictly indoors can be exposed to parasites. Here are some of the main risk factors for indoor cats:
Goes Outside: Indoor cats that are able to go outside, even occasionally or under supervision, have a higher risk of picking up parasites. Parasites can be contracted from contaminated soil, feces, or prey (Internal Parasites in Cats – VCA Animal Hospitals).
Eats Raw Prey: Feeding raw, undercooked meat or prey items to cats can expose them to parasitic contamination. Parasite eggs may be present in the raw meat or organs (Parasite Concerns for Indoor Cats).
Contaminated Litter: Parasite eggs can spread through contaminated fecal matter. Litter boxes can be a source of exposure, especially in multi-cat households if one cat has an untreated parasite infection (Can My Indoor Cat Get Worms?).
Prevalence Rates in Indoor Cats
Studies have found varying rates of intestinal parasite infections in indoor cats. According to a 2023 study published in PLOS One, the overall prevalence rate of intestinal parasites in household cats was 94.4% (Adhikari et al.). Another 2019 meta-analysis published in Veterinary Parasitology found that 25.4% of strictly indoor cats were infected with at least one parasite (Chalkowski et al.).
The most comprehensive data comes from a 2010 study published in the Journal of Feline Medicine and Surgery, which tested over 11,000 cats from the U.S. and Canada. They found parasites in 19.6% of exclusively indoor cats. The most common parasites found were Toxocara cati (13.2%), Cystoisospora species (4.1%), Ancylostoma tubaeforme (4.1%), Toxascaris leonina (3.7%), and Dipylidium caninum (0.4%) (Bowman et al.)
Overall, while rates vary, studies consistently show that intestinal parasites are common in indoor cats. However, indoor cats have lower rates than outdoor cats, likely due to reduced exposure. Careful prevention and testing can help minimize infection risk.
Preventing Parasites in Cats
There are several key steps cat owners can take to help prevent parasites in indoor cats:
Veterinary Care: Bringing your cat to the veterinarian for annual exams and preventative care is important for monitoring your cat’s health and detecting any parasite issues early (https://catfriendly.com/keep-your-cat-healthy/parasite-prevention/). Your vet can recommend the right parasite prevention based on your cat’s risk factors and lifestyle.
Deworming: Many vets advise deworming kittens frequently and then maintaining a regular deworming schedule for adult cats. Deworming medications kill intestinal parasites like roundworms and hookworms. Following your vet’s deworming protocol helps remove any parasites and prevent reinfection (https://www.bocamidtownevet.com/feline-parasite-prevention-how-to-protect-your-cat-from-internal-and-external-parasites/).
Flea Control: Using monthly topical or oral flea preventatives is important even for indoor cats, as fleas can still be brought inside on people and pets. Flea medications kill fleas and also prevent flea infestations. Fleas are common carriers of tapeworms, so controlling fleas also reduces tapeworm infection (https://www.petsandparasites.org/cat-owners/overview/).
Clean Litter: Scooping your cat’s litter box daily and completely replacing the litter regularly can remove parasite eggs and cysts shed in feces before they can mature and reinfect your cat. Keeping your cat’s litter box and living space clean limits contamination (https://www.petsandparasites.org/cat-owners/overview/).
Signs of Parasites in Cats
There are several common signs that may indicate your cat has a parasitic infection. These include:
Diarrhea – Loose, watery, or bloody stool can be caused by parasites irritating the intestinal tract. Certain parasites like Giardia can lead to explosive, foul-smelling diarrhea. Tapeworms may cause diarrhea along with shed tapeworm segments in the stool.
Vomiting – Some parasites like roundworms can cause vomiting if there is a heavy worm burden blocking the intestinal tract. Vomiting may also occur from intestinal inflammation and irritation.
Lethargy – Parasites can cause fatigue, malaise, and depression as they sap nutrients from the body. Kittens with heavy parasite loads may be stunted in their growth.
Weight loss – Parasites can impair nutrient absorption and cause weight loss. This is especially common with hookworm infections as they feed on blood, causing anemia.
Other possible signs include a dull coat, mucousy or bloody stool, coughing, loss of appetite, and a pot-bellied appearance. Kittens tend to show more signs than adult cats. If you notice any of these symptoms, have your vet test your cat’s stool for parasites.
Sources:
Diagnosing Parasites
There are several ways veterinarians test for parasites in cats:
Fecal Tests: One of the most common ways to check for intestinal parasites is by doing a fecal flotation or direct smear test. This involves collecting a stool sample from the cat and mixing it with a solution that causes parasite eggs, larvae, or cysts to float to the top where they can be examined under a microscope. Fecal tests allow detection of parasites like roundworms, hookworms, whipworms, tapeworms, giardia, and coccidia (https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/gastrointestinal-parasites-cats-brochure).
Imaging: X-rays or ultrasound can sometimes reveal larger parasites like roundworms in the intestines or lungs. Tapeworm segments may also occasionally be visible on imaging.
Biopsy: Taking a tissue sample for examination under a microscope can help diagnose certain parasites like Toxoplasma that infect organs and muscles.
Treating Parasites in Cats
There are several medications available for treating intestinal parasites in cats. The most common treatments are dewormers that target specific types of worms.
Here are some of the most commonly used deworming medications for cats:
- Fenbendazole – treats roundworms, hookworms, whipworms, and tapeworms (Cornell Feline Health Center)
- Praziquantel – treats tapeworms
- Pyrantel pamoate – treats roundworms and hookworms
- Ivermectin – treats roundworms and ear mites (VCA Animal Hospitals)
In addition to deworming medications, controlling external parasites like fleas is also important, as they can transmit tapeworms. Regular monthly use of flea control products is recommended.
For protozoal parasites like giardia and coccidia, veterinarians may prescribe medications such as metronidazole, tinidazole, and sulfadimethoxine.
It’s important to complete the full course of any prescribed parasite medication, even if symptoms resolve, in order to fully eliminate the infection.
Conclusion
Parasites are quite prevalent in indoor cats, with some estimates finding that up to 50% of cats may have parasites at any given time. While outdoor cats have a higher risk, indoor cats are still susceptible through various means. By being aware of the common parasites, how cats become infected, and what symptoms to look out for, cat owners can better protect the health of their feline companions.
Prevention is key when it comes to protecting cats from parasites. Strategies like consistent flea/tick control, avoiding exposure to feces, proper sanitation, and routine vet checks are all important in keeping indoor cats parasite-free. With vigilance and care, indoor cat owners can greatly minimize the chances of their cats acquiring dangerous parasitic infections.