Roundworms are one of the most common intestinal parasites affecting dogs, especially puppies. Most infections can be successfully treated with veterinarian-prescribed deworming medications, but early diagnosis is important because untreated roundworms can lead to poor growth, digestive upset, intestinal blockage, and ongoing contamination of your dog's environment.
Alongside conventional treatment, good hygiene, nutrition, and supportive care can help your dog recover while reducing the risk of reinfection.
Key Takeaways
- Roundworms are common intestinal parasites that live in a dog's small intestine.
- Puppies are especially vulnerable because they can become infected before birth or through their mother's milk.
- Adult dogs usually become infected by swallowing eggs from contaminated soil, feces, or infected prey.
- Common symptoms include a pot-bellied appearance, vomiting, diarrhea, poor growth, weight loss, and visible worms in stool or vomit.
- Deworming medications effectively eliminate adult worms but may require repeated treatments.
- Good sanitation and regular fecal examinations help prevent reinfection.
- Holistic dewormer therapies may support digestive and immune health but should never replace proven deworming medications.
What Are Roundworms in Dogs?
Roundworms are long, spaghetti-like intestinal parasites that live inside your dog's small intestine, where they feed on partially digested food. The two species most commonly diagnosed in dogs are Toxocara canis and Toxascaris leonina, with Toxocara canis responsible for most infections in puppies.
Adult roundworms produce thousands of microscopic eggs every day. These eggs are passed in your dog's feces and contaminate soil, grass, yards, parks, and other environments where dogs spend time. Once the eggs mature, they can infect other animals that accidentally swallow them.
Roundworms are among the most common parasites diagnosed in veterinary medicine because their life cycle makes them highly effective at spreading between dogs.
How Do Roundworms Affect Your Dog?
Roundworms damage your dog's health by competing for nutrients inside the digestive tract while triggering inflammation within the intestines.
After infective eggs are swallowed, larvae hatch inside the intestine and migrate through various tissues before eventually returning to the small intestine to mature into adult worms. During this migration, the immune system responds to the parasites, causing inflammation that contributes to digestive upset and poor nutrient absorption.
Heavy infections are especially dangerous for puppies because their developing bodies require significant nutrition for normal growth. Large numbers of worms may consume nutrients that would otherwise support healthy development.
In severe cases, large masses of worms can even obstruct the intestines, creating a medical emergency.
What Causes Roundworms in Dogs?
Dogs become infected through several different routes depending on their age and lifestyle.
Infection Before Birth
Toxocara canis has a unique life cycle that allows dormant larvae inside an infected mother to reactivate during pregnancy.
These larvae migrate across the placenta and infect puppies before they are even born. This is why many puppies develop roundworm infections despite never leaving their mother's care.
Nursing From an Infected Mother
Larvae may also pass into the mother's milk after birth.
As puppies nurse, they ingest the microscopic larvae, which then mature inside the intestines.
Because of these transmission routes, routine puppy deworming is recommended even when no worms are visible.
Swallowing Infective Eggs
Adult dogs most commonly become infected after swallowing microscopic eggs found in contaminated:
- Soil
- Grass
- Water
- Food bowls
- Feces
- Kennels
- Dog parks
The eggs are remarkably durable and may survive in the environment for months or even years under favorable conditions.
Eating Infected Animals
Rodents, birds, earthworms, and other small animals can carry immature roundworm larvae.
Dogs that hunt or scavenge may become infected after eating these intermediate hosts.
Symptoms of Roundworms in Dogs
Many adult dogs with mild infections show few obvious signs. Puppies, however, often develop more noticeable symptoms because of their smaller body size and immature immune systems.
Pot-Bellied Appearance
A swollen, rounded abdomen is one of the classic signs of heavy roundworm infections in puppies.
The enlarged appearance results from intestinal inflammation, gas accumulation, and the physical presence of numerous worms inside the digestive tract.
Vomiting
Dogs with significant roundworm burdens may vomit, particularly after eating.
Occasionally, adult worms are expelled in the vomit and appear as long, white, spaghetti-like strands.
Diarrhea
Inflammation caused by intestinal parasites can interfere with normal digestion and water absorption, leading to soft stools or diarrhea.
Persistent diarrhea increases the risk of dehydration, particularly in young puppies.
Poor Growth
Because roundworms compete for nutrients, infected puppies may fail to gain weight normally despite eating well.
Delayed growth is often one of the earliest clues that intestinal parasites are present.
Weight Loss
Adult dogs with heavier infections may gradually lose weight as nutrients are diverted toward the parasites rather than supporting normal body function.
Dull Hair Coat
Poor nutrient absorption frequently affects skin and coat quality.
Dogs with chronic parasite burdens may develop dry, brittle fur that lacks its normal shine.
Coughing
During larval migration through the lungs, some puppies develop mild coughing before the parasites return to the intestines.
Although temporary, this respiratory phase forms part of the parasite's normal life cycle.
Visible Worms
Seeing spaghetti-like worms in your dog's stool or vomit is one of the clearest indicators of roundworm infection.
Even if worms are visible, veterinary examination remains important because additional parasites may also be present.
Can Humans Catch Roundworms From Dogs?
Yes. Certain canine roundworms can infect people, making them a zoonotic parasite.
Humans become infected by accidentally swallowing microscopic eggs from contaminated soil or surfaces—not through direct contact with the worms themselves.
Young children have the greatest risk because they frequently place contaminated hands or objects in their mouths after playing outdoors.
Once inside people, the larvae do not mature into adult worms but may migrate through various tissues, causing conditions known as visceral larva migrans or ocular larva migrans.
Good handwashing, prompt feces removal, and regular deworming significantly reduce this risk.
When Should You See Your Veterinarian?
Dogs should be examined whenever roundworm infection is suspected.
Seek prompt veterinary care if your dog:
- Vomits repeatedly
- Stops eating
- Has severe diarrhea
- Appears weak or dehydrated
- Has a swollen abdomen
- Passes large numbers of worms
- Shows signs of abdominal pain
Puppies should always be evaluated because heavy parasite burdens can become serious quickly.
How Veterinarians Diagnose Roundworms
Most veterinarians diagnose roundworms using a fecal flotation test, which detects microscopic eggs in a stool sample.
Because eggs are not shed continuously, repeated fecal testing may occasionally be recommended if symptoms strongly suggest parasites despite an initial negative result.
If adult worms are passed in stool or vomit, your veterinarian may identify the species based on their appearance.
Routine fecal examinations remain one of the most effective ways to detect intestinal parasites before obvious illness develops.
Treatment for Roundworms in Dogs
Roundworms are highly treatable, and most dogs recover completely with appropriate veterinary care.
Several safe and effective prescription and over-the-counter deworming medications eliminate adult worms living in the intestines.
Common active ingredients include:
- Fenbendazole
- Pyrantel pamoate
- Milbemycin oxime
- Moxidectin
Because medications generally kill adult worms rather than migrating larvae, repeat treatments are often necessary several weeks later to eliminate newly matured parasites.
Your veterinarian may also recommend monthly heartworm preventives that provide ongoing protection against common intestinal parasites.
Can Roundworms Be Treated at Home?
There is no scientifically proven home remedy capable of reliably eliminating roundworms in dogs.
Although pumpkin seeds, garlic, diatomaceous earth, and various herbal remedies are commonly promoted online, veterinary research has not demonstrated that these approaches consistently eliminate established infections.
Delaying effective treatment allows parasites to continue reproducing and contaminating your dog's environment.
The safest and most effective treatment remains veterinarian-recommended deworming medication.
Can CBD Help Dogs With Roundworms?
CBD does not kill intestinal parasites and should never be considered a treatment for roundworm infections.
However, researchers continue investigating CBD's effects on inflammation, stress, appetite, and overall wellness through the endocannabinoid system.
For some dogs recovering after deworming treatment, CBD may help support comfort like Prana Pets CBD Oil for Dogs, encourage relaxation, and promote overall well-being. Current evidence specifically evaluating CBD for intestinal parasites is lacking, so it should only be considered a complementary wellness supplement rather than an antiparasitic therapy.
Supporting Recovery After Deworming
Most dogs begin feeling better within a few days after treatment, although complete recovery depends on the severity of the infection.
Supporting your dog's recovery includes:
- Providing plenty of fresh water
- Feeding a complete, balanced diet
- Keeping living areas clean
- Picking up feces promptly
- Washing bedding regularly
- Following all repeat deworming instructions
- Scheduling recommended fecal rechecks
These simple measures reduce reinfection while supporting digestive healing.
Preventing Roundworms
Prevention is easier than treating repeated infections.
Reduce your dog's risk by:
- Following routine puppy deworming schedules
- Using monthly parasite prevention
- Cleaning up feces daily
- Preventing hunting and scavenging
- Washing hands after handling pets
- Scheduling annual fecal examinations
- Keeping kennels and yards clean
Because roundworm eggs survive for long periods in soil, environmental hygiene plays a major role in prevention.
Frequently Asked Questions
Can roundworms go away without treatment?
No. Most roundworm infections require deworming medication. Left untreated, adult worms continue reproducing and shedding eggs into the environment, increasing the risk of reinfection and transmission to other animals.
How long does it take to get rid of roundworms?
Most deworming medications begin killing adult worms within 24 to 48 hours, but repeat treatments are often necessary two to four weeks later because immature larvae continue developing after the initial treatment.
Can I see roundworms in my dog's poop?
Yes. Adult roundworms often resemble long, white, spaghetti-like strands in stool. However, many infected dogs shed only microscopic eggs, so the absence of visible worms does not rule out infection.
Can indoor dogs get roundworms?
Yes. Indoor dogs can become infected through contaminated shoes, soil, infected prey animals, or transmission from their mother before birth.
Are roundworms painful?
Many dogs show no discomfort with mild infections. Heavy parasite burdens, however, may cause abdominal pain, intestinal inflammation, vomiting, diarrhea, and in severe cases intestinal obstruction.
Can my dog get roundworms again?
Yes. Successful treatment does not provide lasting immunity. Dogs may become reinfected whenever they ingest infective eggs or prey animals carrying larvae.
Should I disinfect my yard?
Prompt feces removal helps reduce contamination, but completely eliminating roundworm eggs from soil is difficult because they are highly resistant to environmental conditions. Routine parasite prevention remains the most effective long-term strategy.
References
Bowman DD. Georgis' Parasitology for Veterinarians. 11th ed. Elsevier; 2020.
Companion Animal Parasite Council (CAPC). Roundworms (Toxocara canis, Toxascaris leonina) Guidelines. https://capcvet.org
Centers for Disease Control and Prevention. Parasites – Toxocariasis. https://www.cdc.gov/parasites/toxocariasis/
Merck Veterinary Manual. Gastrointestinal Parasites of Small Animals. https://www.merckvetmanual.com
American Animal Hospital Association (AAHA). Canine Life Stage Guidelines. https://www.aaha.org
European Scientific Counsel Companion Animal Parasites (ESCCAP). Control of Roundworms in Dogs and Cats. https://www.esccap.org
World Small Animal Veterinary Association (WSAVA). Global Guidelines. https://wsava.org
