Roundworms in Cats: Signs, Treatment, and Prevention

Roundworms are intestinal parasites that feed on nutrients from food your cat eats, which can lead to digestive upset, poor growth, and other health concerns.  

The most common feline roundworm is Toxocara cati. Adult worms living in the intestines produce eggs that are shed in the cat’s stool to infect other animals. 

Adult roundworms are often described as looking like strands of spaghetti and may occasionally be seen in a cat’s poop or vomit. However, not seeing worms doesn’t rule out infection, and roundworm eggs are microscopic, so you can’t see them. 

Cats can get roundworms by swallowing parasite eggs or larvae from contaminated environments, feces, or infected animals. 

• Kittens: Kittens commonly get roundworms from their mother while nursing. 
• Adult cats: Hunting rodents and exposure to contaminated soil, feces, or litter boxes are common causes of roundworm infection. 
• Multi-cat homes and shelters: Shared living spaces and litter boxes can increase exposure to roundworm eggs. 

Living indoors doesn’t protect cats from risk because indoor cats can be exposed through tracked-in soil, other pets, or a newly adopted kitten. 

Many cats with roundworms show no symptoms, especially early in an infection. When signs do occur, they often affect the digestive system and may be more noticeable in kittens. 

Common signs include: 

• Potbellied or “bloated” appearance (especially in kittens) 
• Vomiting 
• Diarrhea 
• Poor weight gain or slow growth 
• Dull hair coat 

Less common signs include: 

• Coughing (due to larval migration) 
• Reduced appetite 

Although roundworm infection isn’t typically an emergency, urgent signs include: 

• Severe lethargy 
• Dehydration 
• Repeated vomiting 
• Straining to defecate 
• Painful or swollen abdomen 

Contact your veterinarian if: 

• Your cat is vomiting repeatedly or unable to keep food down. 
• Your kitten has a swollen belly, poor growth, or ongoing diarrhea. 
• Your cat seems lethargic or dehydrated or is showing signs of a possible intestinal blockage (repeated vomiting, lack of feces). 

Veterinarians typically diagnose roundworms by using a microscope to look for parasite eggs in a stool sample. Some clinics may send the fecal sample to a veterinary lab for antigen testing instead. Bringing a fresh stool sample to your cat’s appointment can help your veterinarian make an accurate diagnosis. Routine fecal testing during your cat’s annual wellness appointment can help catch infections early. 

However, active roundworm infections don’t always show up on the first test. Because infected cats may shed eggs intermittently, false negatives can occur. If your veterinarian still suspects roundworms based on your cat’s age, symptoms, or risk factors, they may recommend repeat testing or treatment. 

Roundworms are treated with veterinarian-recommended dewormers. Kittens often need repeat doses because immature worms may survive the first treatment. 

Some cats may be infected with more than one intestinal parasite at the same time. For example, cats with roundworms can also have tapeworms, Giardia, or other parasites that require combination treatments. 

Your veterinarian will determine the most effective course of treatment and recommend year-round prevention to reduce the risk of reinfection. 

Products your vet may recommend include Drontal, Profender, Revolution Plus, or Bravecto Plus. 

It’s not unusual to see worms in your cat’s stool after treatment, especially with heavier infections.  

Some cats may also experience mild digestive upset, but severe vomiting, diarrhea, lethargy, or other concerning symptoms should be reported to your veterinarian. 

As with all illnesses, it’s best to prevent infection when possible. Here are some of the best ways to prevent roundworm infection in cats: 

• Use year-round parasite prevention. Ask your veterinarian which parasite prevention product is right for your cat. 
• Scoop litter boxes daily. Remove feces promptly and wash your hands afterward. 

• Keep cats indoors when possible. Preventing hunting can reduce exposure to infected rodents and other prey animals. 

Keeping litter boxes clean and promptly cleaning accidents can also help maintain a healthier environment. Enzyme cleaners, like Nature’s Miracle Urine Destroyer Plus, and other litter box hygiene products may be helpful additions to your cleaning routine. 

Yes, some roundworms that infect cats can spread to people if parasite eggs are accidentally ingested from contaminated soil, feces, or litter. While this sounds concerning, good hygiene practices greatly reduce the risk. 

To help protect your family: 

• Scoop litter boxes daily. 
• Wash your hands after handling litter, soil, or pet waste. 
• Cover children’s sandboxes when not in use. 
• Encourage children to avoid putting soil, sand, or dirty hands into their mouths. 

Routine parasite prevention and regular veterinary care can also help reduce the risk of roundworm infections in both cats and people. 

Yes. Most roundworm infections can be successfully treated with a veterinarian-recommended dewormer. Reinfection can be avoided by using a year-round preventive. 

Roundworms are typically long, white, spaghettilike worms. 

Yes. Indoor cats can get roundworms from tracked-in soil, a newly adopted kitten, or other household pets who go outdoors. 

Kittens are typically dewormed multiple times during their first few months of life, though the exact schedule depends on their age and risk factors. Your veterinarian can recommend the most appropriate deworming plan, which often aligns with their vaccine schedule. 

Yes. Promptly remove feces, scoop the litter box daily, and wash bedding or other contaminated items to help reduce the risk of reinfection. 

Most roundworm infections can be cleared within a few weeks, though some cats require multiple treatments to eliminate newly maturing worms and prevent reinfection.