This article is educational and is not a substitute for veterinary diagnosis or treatment.

Roundworms in Dog Poop: What Owners See and What Testing Confirms

Direct Answer and Owner Triage

If you see what looks like spaghetti or vermicelli in your dog's stool or vomit, you are likely seeing adult roundworms. These are large, pale, coiled parasites that can be several inches long. Your dog needs veterinary attention. Do not wait. Roundworms are not only a health problem for your dog but also a zoonotic risk, meaning they can infect people, especially children. The Companion Animal Parasite Council (CAPC) recommends year-round broad-spectrum parasite control with regular fecal testing [1].

Urgent triage summary: If you see visible worms, contact your veterinarian within 24 hours for a fecal examination and deworming medication. If your dog is a puppy, is vomiting repeatedly, has a bloated belly, or is not eating, seek same-day veterinary care. If you see worms and your dog is lethargic, collapsed, or has bloody diarrhoea, go to an emergency veterinary hospital immediately.

At a Glance: What Owners See vs. What Testing Confirms

Understanding Roundworms: Anatomy and Life Cycle

Roundworms (nematodes) in dogs are most commonly Toxocara canis and less commonly Toxascaris leonina. They are intestinal parasites that live in the lumen of the small intestine, where they feed on partially digested nutrients. Adult female T. canis can reach up to 18 cm in length and produce up to 200,000 eggs per day. These eggs are passed in the feces and become infective after 2 to 4 weeks in the environment, depending on temperature and humidity. The eggs are extremely hardy and can survive in soil for years.

The life cycle of T. canis is complex and includes several routes of infection:

1. Direct ingestion of eggs: A dog sniffs or eats contaminated soil, grass, or feces. The eggs hatch in the intestine, and larvae penetrate the intestinal wall. In puppies, the larvae migrate through the liver and lungs (tracheal migration), are coughed up and swallowed, and develop into adults in the small intestine. In adult dogs, the larvae often undergo somatic migration, encysting in tissues like muscle and liver, where they can remain dormant for years.

2. Transplacental transmission (prenatal): This is the most important route in puppies. Dormant larvae in a pregnant bitch's tissues become reactivated during late pregnancy and cross the placenta. Puppies are born with larvae already in their tissues. This is why puppies must be dewormed starting at 2 weeks of age, as recommended by the CAPC [1].

3. Transmammary transmission (milk): Larvae can also be passed to puppies through the mother's milk during the first few weeks of life.

4. Ingestion of paratenic hosts: Dogs can become infected by eating rodents, birds, or other animals that have ingested roundworm eggs and carry dormant larvae in their tissues.

Toxascaris leonina has a simpler life cycle. It does not undergo tracheal migration, and prenatal or transmammary transmission is rare. Infection occurs through ingestion of eggs or paratenic hosts.

What Owners See: Visual Identification

The most common reason owners seek veterinary care for roundworms is seeing the adult worms in their dog's stool or vomit. These worms are unmistakable. They are long, round, and pale (white, cream, or tan), resembling spaghetti or angel hair pasta. They are often moving or coiled together in a mass. In stool, they may be passed whole or in segments. In vomit, they can appear as a tangled clump.

Other signs owners may notice include:

• Pot-bellied appearance: Especially in puppies, a distended abdomen is a classic sign of a heavy roundworm burden.
• Dull, dry coat: Poor nutrient absorption can affect coat quality.
• Diarrhoea or soft stool: Sometimes with mucus.
• Vomiting: Can be due to intestinal blockage or irritation from a large number of worms.
• Coughing: If larvae are migrating through the lungs, a mild cough may occur.
• Poor growth or weight loss: Puppies may fail to gain weight or may lose condition.
• Lethargy: General malaise is common.
• Scooting or licking the anus: Irritation from worms passing.

It is important to note that many dogs, especially adults, show no visible signs at all. They may be shedding eggs in their feces without the owner ever seeing a worm. This is why routine fecal testing is critical.

Diagnostic Uncertainty: What Testing Confirms

Seeing a worm in the stool is a definitive diagnosis of roundworm infection. However, the absence of visible worms does not rule out infection. Microscopic fecal examination is the gold standard for diagnosis. The most common method is fecal flotation. A small sample of feces is mixed with a flotation solution (e.g., zinc sulfate or sodium nitrate) that causes the eggs to float to the surface. A coverslip is placed on top, and the material is examined under a microscope. Roundworm eggs are oval, have a thick, smooth shell, and contain a single-celled or morulated embryo. T. canis eggs have a characteristic pitted (pitted) surface, while T. leonina eggs are smooth.

What testing confirms:

• Presence of eggs: Confirms active infection and that the dog is shedding eggs into the environment.
• Egg count (quantitative flotation): Can estimate the worm burden. High egg counts indicate a heavy infection.
• Species identification: Differentiating T. canis from T. leonina is important for understanding the life cycle and risk of transmission, but treatment is similar.
• Negative test: Does not guarantee the dog is worm-free. Eggs are shed intermittently, and a single negative test can miss an infection. The CAPC recommends at least 2 to 4 fecal tests in the first year of a puppy's life and 1 to 2 tests per year in adult dogs [1].

Other diagnostic methods:

• Baermann technique: Used to detect lungworm larvae (e.g., Angiostrongylus vasorum) if respiratory signs are present. This is not a routine test for roundworms.
• PCR (polymerase chain reaction): Can detect roundworm DNA in feces. This is more sensitive than flotation but is not widely used in general practice.
• Blood tests: Not typically used for roundworm diagnosis. Serology (antibody testing) is available for research but not for routine clinical use.

Differential diagnoses: Other parasites that can cause similar signs or be mistaken for roundworms include:

• Hookworms: Much smaller, thread-like worms that attach to the intestinal wall and cause bloody diarrhoea. Their eggs are different on microscopy.
• Whipworms: Smaller, thread-like worms that live in the cecum. Their eggs are football-shaped with bipolar plugs.
• Tapeworms: Segmented, flat worms that look like grains of rice or cucumber seeds. They are passed in segments, not as long spaghetti-like strands.
• Lungworms: Can cause coughing and respiratory signs. Diagnosed via Baermann technique or bronchoscopy.
• Other causes of diarrhoea or vomiting: Dietary indiscretion, infections (viral, bacterial), inflammatory bowel disease, pancreatitis, etc.

Risk Factors and Epidemiology

Roundworms are one of the most common intestinal parasites in dogs worldwide. Prevalence varies by region, age, and lifestyle.

• Puppies: The highest prevalence is in puppies under 6 months of age. The CAPC reports that nearly all puppies are born with T. canis larvae or acquire them through milk [1]. In some studies, prevalence in puppies exceeds 50%.
• Adult dogs: Prevalence is lower but still significant, especially in dogs with outdoor access, those that hunt, or those in multi-dog households or kennels.
• Geographic variation: Roundworms are found globally. In the United States, prevalence is higher in the South and Southeast, where the climate is warmer and more humid. In Canada, prevalence is lower but still present. In Europe, T. canis is the most common roundworm. In Australia, both T. canis and T. leonina are found.
• Shelter dogs: High prevalence due to overcrowding, stress, and lack of routine deworming.
• Dogs that eat raw meat or offal: Risk of infection from paratenic hosts.

Veterinary Examination and Diagnostics

When you bring your dog to the veterinarian for suspected roundworms, the following will occur:

1. History and physical examination: The veterinarian will ask about your dog's age, vaccination status, diet, travel history, exposure to other animals, and any symptoms. A thorough physical exam will assess body condition, coat quality, abdominal distension, and overall health.

2. Fecal examination: A fresh fecal sample (less than 24 hours old) is ideal. The sample can be collected at home or in the clinic. The veterinarian will perform a fecal flotation test. Results are typically available within 30 minutes.

3. Additional tests: If your dog has respiratory signs, a Baermann test or bronchoscopy may be recommended. If your dog is very ill, blood work (complete blood count, biochemistry) may be done to assess for anemia, electrolyte imbalances, or organ damage.

4. Treatment plan: If roundworms are confirmed, the veterinarian will prescribe a dewormer. Common options include:

   • Pyrantel pamoate: Safe for puppies and pregnant bitches. Effective against adult roundworms.
   • Fenbendazole: Broad-spectrum, effective against roundworms, hookworms, whipworms, and some tapeworms. Often given for 3 to 5 days.
   • Milbemycin oxime: Found in many monthly heartworm preventives (e.g., Interceptor, Sentinel).
   • Selamectin: Topical heartworm and parasite preventive.
   • Moxidectin: Found in some monthly products (e.g., Advantage Multi).

   The veterinarian will determine the correct dose based on your dog's weight. A single dose may not kill all worms, especially migrating larvae. A repeat dose is often given 2 to 4 weeks later. For puppies, the CAPC recommends deworming at 2, 4, 6, and 8 weeks of age, then monthly until 6 months old [1].

Evidence-Based Management and Treatment

Treatment for roundworms is highly effective when done correctly. The goal is to eliminate adult worms and reduce the environmental egg burden.

Step-by-step management:

1. Veterinary prescription: Do not use over-the-counter dewormers. They are often less effective and may not target all life stages. Your veterinarian will prescribe a product that is safe and effective for your dog's age, weight, and health status.

2. Follow the dosing schedule: Most dewormers require a second dose 2 to 4 weeks after the first to kill any newly hatched larvae. For heavy infections, a third dose may be needed.

3. Treat all dogs in the household: If one dog has roundworms, others are likely infected. The veterinarian may recommend treating all dogs simultaneously.

4. Environmental decontamination: This is critical to prevent reinfection and reduce zoonotic risk. Roundworm eggs are extremely resistant to disinfectants and can survive in soil for years. The following steps are recommended:

   • Pick up feces daily: Use gloves or a pooper scooper. Dispose of feces in a sealed bag in the trash.
   • Clean hard surfaces: Use a 1:10 bleach solution or a commercial disinfectant labeled for parasite eggs. Let it sit for 10 minutes before rinsing.
   • Remove contaminated soil: In areas where dogs defecate, remove the top layer of soil and replace it with fresh soil or gravel.
   • Prevent access: Keep dogs away from areas where other animals defecate, such as dog parks, unless they are on a preventive program.
   • Hand washing: Everyone in the household, especially children, should wash hands thoroughly after handling the dog, playing outside, or gardening.

5. Zoonotic risk education: The veterinarian will explain the risk of human infection. Children are at highest risk because they are more likely to put contaminated hands or objects in their mouths. Ocular larva migrans (a roundworm larva migrating to the eye) can cause blindness. Visceral larva migrans can cause fever, cough, and liver enlargement.

6. Follow-up fecal testing: A follow-up fecal test 2 to 4 weeks after treatment is recommended to confirm the infection is cleared. The CAPC recommends at least 2 negative fecal tests before declaring a dog parasite-free [1].

Unsafe Home Remedies and Myths

Do not attempt to treat roundworms with home remedies. The following are unsafe or ineffective:

• Garlic: Can cause hemolytic anemia in dogs, especially in large amounts. It is not an effective dewormer.
• Pumpkin seeds: Contain cucurbitacin, which may have a mild anti-parasitic effect, but it is not sufficient to eliminate a roundworm infection.
• Diatomaceous earth: Can cause respiratory irritation if inhaled and is not reliably effective against internal parasites.
• Apple cider vinegar: No scientific evidence supports its use as a dewormer.
• Fasting or feeding a special diet: Does not kill roundworms.

The only safe and effective treatment is a veterinary-prescribed dewormer.

Prevention

Prevention is the cornerstone of roundworm control. The CAPC recommends the following [1]:

• Year-round broad-spectrum parasite control: Use a monthly heartworm preventive that also controls roundworms (e.g., milbemycin oxime, selamectin, moxidectin). This is the single most effective prevention strategy.
• Regular fecal testing: At least 1 to 2 times per year for adult dogs, and more frequently for puppies.
• Puppy deworming protocol: Deworm puppies at 2, 4, 6, and 8 weeks of age, then monthly until 6 months old.
• Pregnant bitch deworming: Deworm pregnant bitches during the last trimester to reduce prenatal transmission.
• Environmental hygiene: Pick up feces immediately and dispose of it properly. Do not compost dog feces.
• Hand washing: Teach children to wash hands after playing with dogs or outdoors.
• Control paratenic hosts: Prevent your dog from hunting or eating rodents.

Prognosis

The prognosis for roundworm infection is excellent with proper treatment. Most dogs recover fully within a few weeks. Puppies with heavy infections may take longer to regain condition. In rare cases, a massive worm burden can cause intestinal obstruction, which requires surgical intervention. However, this is uncommon with modern deworming protocols.

The main concern is zoonotic transmission. With proper treatment and environmental hygiene, the risk to humans can be effectively managed.

Emergency Red Flags

Seek emergency veterinary care immediately if your dog shows any of the following:

• Inability to defecate or pass gas: May indicate an intestinal blockage.
• Repeated vomiting, especially if the dog cannot keep water down: Risk of dehydration.
• Lethargy, collapse, or weakness: May indicate anemia or severe dehydration.
• Bloody diarrhoea: Can be a sign of hookworm co-infection or other serious conditions.
• Distended, painful abdomen: May indicate obstruction or bloat.
• Seizures: Rarely, migrating larvae can cause neurological signs.
• Sudden blindness or eye inflammation: In humans, this is an emergency. In dogs, ocular larva migrans is rare.

Clinical Reasoning Behind Diagnostic Workflow

The diagnostic approach to suspected roundworm infection follows a deliberate clinical reasoning pathway that balances sensitivity, practicality, and cost. When an owner reports seeing spaghetti-like worms in stool or vomit, the veterinarian already has a presumptive diagnosis, yet fecal testing remains essential for several clinically important reasons. First, visible adult worms confirm patent infection but do not reveal the full parasite burden or the presence of other coinfecting parasites. Studies cited by the Companion Animal Parasite Council indicate that coinfections with hookworms, whipworms, or coccidia occur in a substantial proportion of dogs presenting with visible roundworms [1]. Second, fecal flotation provides quantitative data through egg per gram counts, which helps the clinician gauge infection intensity and tailor follow-up intervals. Third, a baseline negative test after treatment serves as the only objective measure of cure, since clinical signs may resolve before all worms are eliminated.

The timing of fecal sample collection introduces another layer of clinical reasoning. Roundworm egg shedding follows a circadian pattern, with peak egg output occurring in the early morning hours in many dogs. Samples collected later in the day may yield falsely low egg counts. Additionally, female worms do not shed eggs continuously; they release eggs in intermittent bursts. A single negative fecal flotation therefore carries a false negative rate that varies with worm burden and sample handling. The CAPC guidelines address this uncertainty by recommending that a single negative test never be used to declare a dog parasite-free, particularly in puppies or dogs with compatible clinical signs [1]. For this reason, many veterinary practices now employ combined testing protocols that include both flotation and antigen testing when available, though antigen tests for roundworms are less commonly used than for hookworms.

Centrifugal flotation offers superior sensitivity compared to passive flotation methods. In passive flotation, the sample sits undisturbed for 10 to 15 minutes, allowing eggs to rise by gravity alone. Centrifugal flotation spins the sample at low speed, forcing eggs to the surface more efficiently and recovering a higher proportion of eggs, especially when burdens are low. Veterinary practices that use passive methods may miss up to 30 percent of low-burden infections. Owners should understand that not all fecal tests are equivalent, and a negative result from a passive flotation does not carry the same diagnostic weight as a negative result from a centrifugal method. When clinical suspicion remains high despite a negative passive flotation, the veterinarian may request a second sample for centrifugal analysis or recommend empiric deworming based on risk assessment.

Owner Observation and Preparation for a Veterinary Visit

Owners who suspect roundworms can contribute meaningfully to the diagnostic process by collecting and presenting high-quality information and samples. The single most useful action an owner can take is to collect a fresh fecal sample within 12 hours of the veterinary appointment. Samples older than 24 hours may have eggs that have already hatched or degraded, reducing diagnostic sensitivity. The sample should be collected directly from the ground immediately after defecation, avoiding contact with soil or grass that could introduce environmental contaminants. A clean plastic bag, a dedicated fecal collection container from the veterinary clinic, or a clean glass jar with a tight lid all work well. The sample should be refrigerated if it cannot be brought to the clinic within two hours, but freezing destroys egg morphology and renders the sample useless.

Photographic documentation of visible worms provides valuable clinical information. Owners should photograph any worms seen in stool or vomit, placing them next to a coin or ruler for scale. These images help the veterinarian confirm species identification and distinguish roundworms from tapeworm segments, which are flat and rice-like rather than cylindrical and spaghetti-like. Owners should also note the date, time, and circumstances of each observation, including whether the worms were moving, whether they appeared in a single stool or over multiple days, and whether the dog had recently received any deworming medication.

A thorough history should include the dog's age, breed, weight, and lifestyle factors such as outdoor access, hunting behavior, contact with other dogs, and travel history. Owners should report any recent changes in appetite, thirst, energy level, stool consistency, or coughing. The veterinarian will also need to know about any medications the dog has received in the past three months, including heartworm preventives, over-the-counter dewormers, and supplements. Many monthly heartworm preventives contain ingredients that suppress roundworm egg shedding without eliminating adult worms, creating a situation where fecal tests may be negative despite ongoing infection. This phenomenon, known as egg suppression, complicates diagnosis and underscores the importance of using products with proven efficacy against all life stages.

Owners should also prepare to discuss household hygiene practices and the presence of children or immunocompromised individuals in the home. This information directly informs the veterinarian's risk assessment and recommendations for environmental decontamination. The zoonotic potential of Toxocara canis demands that households with young children receive more aggressive environmental management guidance, including potential soil removal in high-traffic play areas.

Evidence Limitations in Roundworm Diagnosis and Treatment

The evidence base for roundworm management contains several important limitations that clinicians and owners should understand. First, the diagnostic sensitivity of fecal flotation varies widely across studies, with reported sensitivities ranging from 60 to 95 percent depending on the method used, the technician's experience, and the parasite burden. This variability means that a negative test cannot definitively rule out infection, particularly in adult dogs with low-level shedding. The CAPC acknowledges this limitation by recommending that clinical decision-making incorporate risk factors and history alongside test results [1].

Second, the efficacy of individual deworming agents is typically reported from controlled laboratory studies using experimental infections, which may not reflect real-world conditions. Field studies consistently show lower efficacy rates, likely due to factors such as reinfection from the environment, concurrent infections with other parasites, and variable drug absorption in dogs with gastrointestinal disease. For example, pyrantel pamoate, a common first-line dewormer, shows efficacy rates above 95 percent against adult Toxocara canis in controlled studies, but field studies report rates closer to 85 to 90 percent. This discrepancy supports the CAPC recommendation for repeat dosing at two to four week intervals to catch any surviving worms [1].

Third, the optimal interval for routine fecal testing in adult dogs remains debated. The CAPC recommends one to two tests per year, but this recommendation is based on expert consensus rather than high-quality prospective studies. Some veterinary parasitologists argue that annual testing is sufficient for dogs on year-round broad-spectrum preventives, while others advocate for biannual testing given the potential for breakthrough infections. Owners should discuss their dog's specific risk profile with their veterinarian to determine an appropriate testing schedule.

Fourth, the effectiveness of environmental decontamination measures is poorly studied. While it is known that roundworm eggs are highly resistant to disinfectants and can survive for years in soil, there are no controlled trials comparing different decontamination strategies. Recommendations to remove topsoil, apply heat, or use bleach solutions are based on laboratory data and expert opinion rather than field validation. Owners should understand that complete environmental decontamination is rarely achievable and that prevention through regular deworming and prompt feces removal is more practical and effective.

Prevention Strategies Across Life Stages

Prevention of roundworm infection requires a life-stage-specific approach that accounts for the unique transmission routes and risk factors at each age. In puppies, the primary prevention goal is to interrupt transplacental and transmammary transmission. The CAPC-recommended deworming protocol starting at two weeks of age targets larvae that have already migrated into the puppy's tissues before birth [1]. This early intervention is critical because puppies can begin shedding eggs as early as three weeks of age, contaminating the environment before most owners realize an infection exists. Breeders and new puppy owners should be particularly vigilant about following this schedule, as missed doses can lead to heavy environmental contamination that persists for years.

In juvenile dogs between six months and two years of age, the prevention focus shifts to maintaining monthly broad-spectrum parasite control and conducting fecal testing at least twice during this period. This age group remains at elevated risk because they have not yet developed the partial immunity that limits worm burdens in older dogs. Juvenile dogs that attend training classes, dog parks, or boarding facilities face additional exposure risks and may benefit from more frequent testing.

Adult dogs on year-round heartworm prevention that includes roundworm control have the lowest risk of patent infection, but breakthrough infections can still occur. The most common cause of breakthrough is inconsistent administration of preventive medication. Owners who miss doses or delay treatment create windows of vulnerability during which ingested larvae can develop into egg-shedding adults. Another cause is the use of products that suppress egg shedding without killing adult worms, as mentioned earlier. Owners should verify that their chosen preventive contains an ingredient with proven adulticidal activity against roundworms, such as milbemycin oxime or moxidectin.

Senior dogs present a unique prevention challenge because age-related immune senescence may increase susceptibility to new infections or reactivation of dormant larvae. Additionally, senior dogs are more likely to have concurrent medical conditions that complicate deworming decisions. For example, dogs with kidney or liver disease may require dose adjustments for certain deworming agents. The CAPC recommends that senior dogs continue year-round prevention and undergo fecal testing at least annually, with more frequent testing if they have outdoor access or other risk factors [1].

Prognosis and Long-Term Monitoring

The prognosis for dogs with roundworm infection is excellent when treatment is administered correctly and followed by appropriate monitoring. Most dogs become egg-negative within two to four weeks of the initial deworming dose, and clinical signs such as diarrhea, poor coat quality, and pot-bellied appearance resolve within the same timeframe. Puppies with heavy burdens may take longer to regain normal body condition, particularly if they were already growth-restricted at the time of diagnosis. In these cases, nutritional support and monitoring for secondary complications such as intestinal obstruction are warranted.

Long-term monitoring should include a follow-up fecal test two to four weeks after the final deworming dose to confirm egg negativity. The CAPC recommends at least two negative fecal tests before declaring a dog parasite-free, particularly in puppies and dogs with heavy initial burdens [1]. After successful treatment, dogs should remain on year-round broad-spectrum parasite control and undergo routine fecal testing according to their life stage and risk profile.

Reinfection is common in dogs with ongoing environmental exposure. Owners should understand that a single successful treatment does not confer immunity, and dogs can be reinfected immediately if they ingest eggs from contaminated soil. This reality underscores the importance of combining treatment with environmental management and ongoing prevention. Dogs that experience recurrent infections should be evaluated for underlying factors such as pica (eating non-food items), coprophagy (eating feces), or inadequate environmental hygiene.

Special Population Considerations

Pregnant and lactating bitches require special consideration in roundworm management. The reactivation of dormant larvae during pregnancy is the primary source of infection in neonatal puppies, making prenatal deworming a critical intervention. The CAPC recommends deworming pregnant bitches during the last trimester with a product safe for use in pregnancy, such as fenbendazole given daily for three to five days [1]. This treatment reduces the number of larvae that can cross the placenta or enter the milk, though it does not eliminate the risk entirely. Puppies from treated bitches still require the standard deworming protocol starting at two weeks of age.

Lactating bitches can also shed eggs in their feces, contaminating the whelping area and exposing puppies to environmental infection. The bitch should be dewormed concurrently with her puppies and maintained on monthly prevention throughout the nursing period. The whelping area should be cleaned daily with a bleach solution or steam cleaner to reduce environmental egg contamination.

Immunocompromised dogs, including those receiving chemotherapy, long-term corticosteroids, or other immunosuppressive medications, may be at increased risk for heavy roundworm burdens and more severe clinical disease. These dogs may also have impaired responses to deworming medications. The veterinarian may recommend more frequent fecal testing and empiric deworming in this population, particularly if they have outdoor access or other risk factors. Owners of immunocompromised dogs should be especially diligent about environmental hygiene and zoonotic risk reduction.

Working dogs, including hunting dogs, search and rescue dogs, and farm dogs, face elevated exposure risks due to their frequent contact with soil, wildlife, and other animals. These dogs should be on year-round broad-spectrum parasite control and undergo fecal testing at least twice per year. Hunting dogs that consume raw game or offal are at particular risk for infection from paratenic hosts and may benefit from more frequent deworming. The veterinarian may recommend quarterly fecal testing for high-risk working dogs.

Multi-dog households and kennels present unique challenges for roundworm control. Once one dog in a household tests positive, all dogs should be treated simultaneously to prevent reinfection cycles. The environment in multi-dog settings becomes contaminated more quickly and heavily, requiring more aggressive deworming schedules and environmental management. Kennels should implement biosecurity protocols that include regular fecal testing of all dogs, prompt isolation and treatment of positive dogs, and daily removal of feces from runs and exercise areas. The CAPC provides specific guidelines for parasite control in kennels and shelters that owners of multi-dog households may find useful [1].

Frequently Asked Questions

1. Can I get roundworms from my dog? Yes, roundworms are zoonotic. Humans can become infected by ingesting eggs from contaminated soil, surfaces, or dog feces. Children are at highest risk. The infection is called visceral larva migrans (fever, cough, liver enlargement) or ocular larva migrans (eye inflammation, vision loss). Always wash hands after handling your dog or cleaning up feces.

2. How long do roundworm eggs live in the environment? Roundworm eggs are extremely hardy and can survive in soil for years, even in cold climates. They are resistant to most disinfectants. The only reliable way to kill them is with heat (e.g., boiling water, steam cleaning) or by removing contaminated soil.

3. My dog was just dewormed. Why do I still see worms in the poop? It is normal to see dead or dying worms in the stool for 1 to 3 days after deworming. The worms are being expelled from the body. If you see worms after 5 days, the treatment may not have been effective, or your dog may have been reinfected. Contact your veterinarian.

4. How often should I deworm my dog? Puppies should be dewormed every 2 weeks from 2 to 8 weeks of age, then monthly until 6 months old. Adult dogs should be on a monthly heartworm preventive that also controls roundworms. The CAPC recommends year-round prevention [1].

5. Can I use an over-the-counter dewormer? It is not recommended. Over-the-counter dewormers may not be effective against all life stages of roundworms, and they may not be safe for all dogs (e.g., puppies, pregnant bitches, dogs with certain health conditions). Always use a veterinary-prescribed product.

6. Do I need to treat my other pets if one has roundworms? Yes, it is highly recommended to treat all dogs in the household. Cats can also get roundworms, but the species (Toxocara cati) is different. Your veterinarian can advise on the best approach for multi-pet households.

7. Can roundworms cause my dog to cough? Yes, during the larval migration phase, roundworm larvae pass through the lungs, which can cause a mild cough. This is most common in puppies. If your dog has a persistent cough, your veterinarian may recommend a Baermann test to rule out lungworms.

8. How do I clean my yard after my dog has roundworms? Pick up all feces immediately. Remove the top layer of soil in areas where your dog defecates and replace it with fresh soil or gravel. You can also use a 1:10 bleach solution on hard surfaces, but it will not kill eggs in soil. The most effective approach is to prevent your dog from defecating in the same area for several months to allow eggs to die naturally.

References

[1] Companion Animal Parasite Council. Ascarid Guidelines for Dogs. https://capcvet.org/guidelines/ascarid/

[2] Merck Veterinary Manual. Roundworms in Small Animals. https://www.merckvetmanual.com/digestive-system/gastrointestinal-parasites-of-small-animals/roundworms-in-small-animals

[3] Centers for Disease Control and Prevention. How Toxocariasis Spreads. https://www.cdc.gov/toxocariasis/spreads/index.html

[4] Centers for Disease Control and Prevention. Guidelines for Veterinarians: Prevention of Zoonotic Transmission of Ascarids and Hookworms of Dogs and Cats. https://stacks.cdc.gov/view/cdc/5908/cdc_5908_DS1.pdf

[5] European Scientific Counsel Companion Animal Parasites. Worm Control in Dogs and Cats. https://www.esccap.org/guidelines/gl1/

[6] Rostami A, Riahi SM, Hofmann A et al. Global prevalence of Toxocara infection in dogs. Adv Parasitol. 2020. https://pubmed.ncbi.nlm.nih.gov/32381218/

[7] Companion Animal Parasite Council. General Guidelines for Dogs and Cats. https://capcvet.org/guidelines/general-guidelines/

[8] Centers for Disease Control and Prevention. Toxocariasis Fact Sheet. https://stacks.cdc.gov/view/cdc/29436/cdc_29436_DS1.pdf

[9] Merck Veterinary Manual. Gastrointestinal Parasites of Dogs and Cats That Also Infect People. https://www.merckvetmanual.com/multimedia/table/gastrointestinal-parasites-of-dogs-and-cats-that-also-infect-people

[10] Abdel Aziz AR, El-Meghanawy RA, Abou El-Dahab MM et al. Prevalence and risk factors associated with Toxocara canis in dogs and humans. J Parasit Dis. 2023. https://pubmed.ncbi.nlm.nih.gov/37772411/

Related Veterinary Guides

• Hookworms in Dogs: Symptoms, Diagnosis, and Treatment
• Intestinal Parasites in Puppies: A Complete Guide
• Heartworm Disease in Dogs: Prevention and Treatment
• Zoonotic Diseases from Dogs: What Every Owner Should Know
• Fecal Testing for Dogs: Why It Matters and What It Detects