Roundworms in Dogs and Cats: What Every Pet Owner Should Know

Roundworms are one of the most common intestinal parasites found in dogs and cats. At Community Animal Hospitals in St. Petersburg, our veterinary team regularly diagnoses and treats roundworm infections — and we want pet owners to understand this parasite so they can protect their furry family members.

What Are Roundworms?

Roundworms, scientifically known as Toxocara canis (in dogs) and Toxocara cati (in cats), are long, spaghetti-like worms that live in your pet’s intestines. Adult roundworms can grow up to several inches long and survive by feeding on partially digested food in the intestinal tract.

These parasites are incredibly common — studies suggest that a significant percentage of puppies and kittens are born with or acquire roundworms within their first weeks of life.

How Dogs and Cats Get Roundworms

There are several ways pets become infected with roundworms:

Ingesting Eggs from Contaminated Soil

Roundworm eggs are shed in the feces of infected animals and can survive in soil for years. When your dog or cat sniffs, licks, or eats contaminated soil or grass, they can ingest these microscopic eggs, which then hatch and develop in the intestines.

Mother-to-Offspring Transmission

This is the most common route of infection in puppies. Roundworm larvae can remain dormant in a mother dog’s tissues and reactivate during pregnancy, crossing the placenta to infect puppies before they’re even born. Larvae can also pass through the mother’s milk to nursing puppies and kittens.

Eating Infected Prey

Cats and dogs that hunt can become infected by eating rodents, birds, or other small animals carrying roundworm larvae in their tissues. This is especially common in outdoor cats.

Symptoms of Roundworm Infection

Roundworm infections don’t always cause obvious symptoms, especially in adult pets with mild infections. However, watch for these signs:

• Potbellied appearance — particularly noticeable in puppies and kittens
• Vomiting — sometimes worms are visible in vomit
• Diarrhea — may be mild or severe
• Dull coat and poor body condition
• Visible worms in stool — they look like white or tan spaghetti
• Coughing — as larvae migrate through the lungs
• Slow growth in young animals

In severe cases, particularly in young puppies and kittens, heavy roundworm burdens can cause intestinal blockages, which can be life-threatening.

Diagnosis

Our veterinarians diagnose roundworms through a fecal examination. A small stool sample is mixed with a special solution that causes roundworm eggs to float to the surface, where they can be identified under a microscope. This simple test is one of the reasons we recommend regular wellness exams and fecal screenings for all pets.

Treatment

The good news is that roundworms are very treatable. Our veterinary team uses safe, effective deworming medications that kill adult roundworms in the intestines. Because these medications don’t always kill migrating larvae, treatment is typically repeated two to three weeks later to catch worms that were immature during the first dose.

Puppies and kittens usually begin deworming protocols as early as two weeks of age, with treatments repeated at regular intervals during their first few months of life.

Prevention

Preventing roundworm infections is far easier than treating them. Here’s what we recommend:

• Year-round parasite prevention — Many monthly heartworm preventives also protect against roundworms. Ask our team which product is right for your pet.
• Regular fecal testing — We recommend at least one to two fecal exams per year as part of your pet’s wellness plan.
• Prompt waste cleanup — Pick up your pet’s stool quickly to reduce environmental contamination.
• Deworm puppies and kittens early — Follow your veterinarian’s recommended deworming schedule starting at two weeks of age.
• Limit hunting — Keep cats indoors when possible and discourage dogs from eating wildlife.

A Note About Human Health

Roundworms are zoonotic, meaning they can potentially infect humans — particularly young children who play in contaminated soil and may put their hands in their mouths. While human infections are uncommon, they can cause a condition called visceral larva migrans, where larvae migrate through body tissues. This is yet another important reason to keep your pets on a regular deworming and prevention program.

Schedule a Parasite Screening Today

As part of our ongoing parasite awareness series, Community Animal Hospitals is encouraging all pet owners in the St. Petersburg and South Pinellas area to schedule a wellness exam and fecal screening. Whether you have a new puppy, a senior cat, or anything in between, Dr. Leslie Block, Dr. Craig Mullenax, and Dr. Mark Williamson are here to help keep your pet parasite-free.

Call us today at (727) 592-1816 to book your appointment, or visit us at communityanimalhospitals.com.