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Roundworms In CatsUpdated 8 months ago

Roundworms can cause some pretty big problems for kittens and cats if not addressed; and even infect and harm people.[1] With detection in the stool sample “rounds” are often easy to treat and even prevent so your cat can stay healthy.

My Cat Tested Positive For Roundworms

Finding roundworms or roundworm eggs in your cat’s stool sample likely means your cat is infected with roundworms and should be treated with a deworming medication. A test result is not the same as a veterinarian’s diagnosis, so it’s always best to consult with a veterinarian about your cat’s test results to determine the safest and most effective treatment and prevention plan, and when to do follow-up stool tests.

MySimplePetLab Routine Cat Stool Tests report roundworm positive results using a quantitative estimation scale of 1 (1 egg or parasite was seen), 1+ (2 to 4 eggs or parasites were seen), 2+ (5 to 10 eggs or parasites were seen), 3+ (11 to 50 eggs or parasites were seen), or 4+ (>50 eggs or parasites were seen) per (approximately) one gram of stool. This is based on both a naked-eye visual and then a microscopic exam of the stool after special preparation and centrifugation techniques. This scale provides some perspective on the potential burden of worm infection (more eggs likely means more worms in the intestines).

Most veterinarians will recommend rechecking a cat’s stool sample 2-4 weeks after treatment for roundworms. If you have other cats (or dogs) in the household, they should be tested as well since roundworms in one cat can often mean roundworms in others.

My Cat Tested Negative For Roundworms

If your cat had a stool O&P (fecal ova and parasite) test and roundworms were not seen, that is great news. It may mean that you are doing a good job preventing roundworm infections by regularly deworming your cat or maybe, you and your cat were lucky! Either way, no one wants their cat shedding roundworm eggs into the home or community environment, putting other pets at risk of infection, your cat at risk of re-infection, or you or your human family at risk of infection. Most veterinarians recommend retesting your adult cat for roundworms every 6 to 12 months.

Keep in mind that it is possible for cats to have roundworm infections without their eggs being found in the stool test (called a “false negative” result); especially if the infection is mild (very small number of worms) or is recent (roundworms are still too young to shed eggs). Also depending on their lifestyle, cats can remain at risk of roundworm egg exposure so a negative test result today doesn’t mean it couldn’t be positive later. This explains why regularly testing for roundworms (1-2 times per year in adult cats; 3-4 times for kittens) is most often combined with regular deworming treatments throughout the cat’s life.

Learn More About Roundworms

What Are Roundworms?

Roundworms are parasitic worms that live as adults inside a cat’s intestinal tract. There they feed on partially digested food passing through a cat’s digestive system. The two main species of roundworms that infect cats are Toxocara cati and Toxascaris leonina. Toxocara cati is more common and more likely to cause serious disease in cats. Importantly, it can even infect and cause illness to people, especially children.[1

How Common Are Roundworms?

Roundworms are extremely common parasites of cats across the United States, with as high as 1 in 4 cats testing positive.[6] While infection is likely to be higher in cats going outdoors, or cats that eat rodents, roundworms are commonly found in cats that are indoor-only.[6] Veterinarians throughout the U.S. regularly screen cat stool samples for roundworms.

What Do Roundworms Look Like?

Adult roundworms look like spaghetti and can be seen without magnification. They are usually narrow, up to a few inches in length, and white or brown in color. They have a mouth to suck up food and a digestive tract to process the nutrients. Roundworms are sometimes seen wiggling in a cat’s stool or sometimes even in a pool of vomit.[3

Roundworm eggs are only detectable by examining a stool sample under a microscope (MySimplePetLab Routine Cat Stool Test).  If found, that is a telltale sign that adult roundworms have infected the cat and treatment is needed.

What Symptoms Are Caused By Roundworms?

Cats with roundworms often don’t show signs of infection but can still be contaminating the environment with eggs when passing stool, putting other cats at risk.[2] If adults are seen in the stool, roundworms appear pale-colored and spaghetti-like; and sometimes still wiggling!

Cats and kittens infected with roundworms can suffer from:[6]

  • Gut distress, often in the form of soft stools, diarrhea or vomiting
  • Malnourishment, weight loss, and a pot-bellied appearance because roundworms steal needed nutrients from cats and kittens
  • Breathing issues like coughing or even pneumonia since young (larvae) roundworms migrate through and injure cat’s lungs during their life cycle.

If your cat is acting sick, please contact a veterinarian right away.

How Do Cats Get Roundworms?

Unlike puppies, kittens don’t get roundworms while in the mother’s womb.[2] However kittens (and puppies) can get infected during nursing from infected mothers.[2] Roundworms are also commonly spread by accidentally ingesting their eggs from another animal’s stool, from contaminated plants like grass or soil where stool had been, or from eating other infected animals like insects, rodents or birds. 

Because roundworm eggs are difficult to kill in the environment and can survive for years, it’s best to deworm cats regularly and promptly clean up their stool.[7]

What Is The Roundworm Lifecycle?

Most adult cats get infected with roundworms by eating the infective eggs from contaminated grass/plants or soil (where cat stool with roundworm eggs had decomposed), or from eating an insect, rodent, or bird carrying or infected with roundworms. Most kittens get roundworms when the larvae are passed to them by their mother through her milk.[2]

Once inside a cat’s body, ingested roundworm eggs of Toxocara cati hatch into larvae. The larvae pass through the intestinal walls, then through the cat’s liver and lungs, and into their windpipe. The cat then coughs up and swallows these roundworm larvae, which carries them to the intestines where they stay to grow into adults. Roundworms don’t attach to the lining of the intestine; rather they “swim” in the digestive tract and feed on the food passing through the intestines. These adults soon start laying eggs which pass into the stool and become infective in 1-4 weeks (after all or most of the stool has decomposed). Roundworm eggs are very hardy and can remain infective in an environment for years.

A single adult roundworm can lay up to 85,000 eggs in a single day![3] This is why stool (fecal) tests search for evidence of eggs to determine if the cat is infected.

Can People Or Other Pets Get Roundworms?

Yes, roundworms can infect humans[2] and other pets, including dogs.[2,4] Roundworm eggs may accumulate in large numbers in outdoor environments. Contact with contaminated plants, soil, or cat stool can lead to accidental ingestion and infection by roundworms in humans (especially kids) and other animals.[2]

Roundworms are especially dangerous to children (usually acquired through eating dirt or sand), pregnant women, the elderly, and people with compromised immune systems. Infected individuals may experience symptoms ranging from eye, lung, and heart problems to more concerning neurologic symptoms.[1]It’s best to prevent children from playing in areas contaminated with cat stool.[7]

Stool testing your cat, regular deworming, and picking up cat stool right away are the best ways to avoid spreading roundworm infections to other animals and people. Also, practice good hygiene by thoroughly washing your hands with soap and water (get those thumbs too!) after touching stool, soil, and other materials that could be contaminated with pet stool.[7]

Dogs are also at risk of getting roundworms, becoming infected by swallowing the infective eggs or as puppies, from their mothers. Dogs can sometimes even get roundworm (Toxascaris leonina) infections from cats. It’s important to regularly deworm dogs and promptly remove stool from the yard to avoid spreading the eggs.[7]

How Are Roundworms Prevented And Treated?

Roundworms are an unwanted pest for cats but deworming for them may not be as complicated as you think. Cat owners can choose from a variety of over-the-counter and veterinary-prescribed deworming options.[6]

The best way to control roundworms is through regular deworming, before they become a problem and need treatment. Kittens are typically dewormed multiple times (3-4 times) before a year of age while cats can be dewormed monthly for roundworms using a combination heartworm preventative. This is because many heartworm preventatives also deworm for roundworms.[2,6] A veterinary consultation can help you determine the best options for you and your cat.

Since roundworm eggs are very difficult to clear from contaminated soil, it’s best to prevent them from getting there in the first place. This is done through regular cat deworming as described but also importantly, cleaning up cat stool (feces) quickly so the eggs can’t remain in decomposing stool and become a source of infection for other animals or reinfection of your cat.

Where Are Roundworm Medications Purchased?

While MySimplePetLab does not dispense or prescribe medications, there are numerous deworming medications available over-the-counter (OTC) and through veterinarians for roundworm prevention and treatment. Roundworm medications are even included in many monthly heartworm preventatives. Roundworm medications typically use pyrantel pamoate, milbemycin oxime, moxidectin, selamectin, or fenbendazole to reduce or eliminate roundworms from the cat.[5,6]

It’s always best to consult with a veterinarian prior to administering any medication, even an OTC version, to make sure it will be safe and effective for your pet. Always read the medication administration directions carefully and be on the lookout for potential side effects (like vomiting) when any deworming medication is administered.

When/How Is Cat Stool Tested For Roundworms?

Veterinarians recommend stool (fecal) testing kittens 2 to 4 times during their first year of life, and 1 to 2 times each year in adult cats (every 6 to 12 months).[2] This stool test is called a “Fecal O&P”, with the O&P meaning “ova (eggs) and parasites”. It includes special preparations of the stool sample and analysis using a microscope to look for certain types of parasites like roundworms. This same test is also used to recheck stool samples after treatment. Typically, a recheck stool test is done 2-4 weeks after deworming a cat that was treated for roundworms to help confirm that the treatment was effective.

Cats should also be tested when symptoms of possible roundworm infection are present such as soft stools or diarrhea, vomiting, weight loss, pot-bellied appearance, or coughing. Please contact a veterinarian right away if your cat is acting sick.

Some veterinarians still do the Fecal O&P at their practice with trained veterinary technicians. Most however, “refer” or ship their patient’s stool samples to a reference laboratory for preparation (including centrifugation), analysis, and reporting, where the laboratory technicians and testing processes are more specialized. Routine stool testing can identify the presence roundworms but doesn’t typically distinguish between species of roundworms (T.cati; T. leonina).

With the simple and convenient MySimplePetLab testing solution from home (MySimplePetLab Routine Cat Stool Test), you can directly access this same professional reference lab testing for roundworms that veterinary professionals use every day. MySimplePetLab uses reference quality stool preparation techniques and centrifugation, along with a highly trained laboratory team to maximize the likelihood of finding roundworms and their eggs if present in the sample.


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  1. American Kennel Club, Roundworms in Dogs: Symptoms, Treatment, and Prevention
  2. Pets & Parasites, Cat Owners – Roundworms
  3. WebMD, Roundworms in Dogs
  4. PetMD, Roundworms in Cats
  5. PetMD, Pyrantel Pamoate for Dogs and Cats
  6. Companion Animal Parasite Council, Cat – Ascarid
  7. Centers for Disease Control and Prevention, Parasites – Toxocariasis (also known as Roundworm Infection)
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