Get Roundworms From Dogs? Zoonotic Risk, Symptoms
Can you get roundworms from dogs? Learn about zoonotic transmission, human and canine symptoms, diagnosis costs, treatment options.
Can You Get Roundworms From Dogs? The Short Answer
Yes — you can get roundworms from dogs. The parasite responsible is Toxocara canis, one of the most common intestinal nematodes in dogs worldwide. According to the Centers for Disease Control and Prevention (CDC), approximately 13.9% of the U.S. population has antibodies to Toxocara, indicating past exposure. In dogs, roundworm infection is even more prevalent: the Merck Veterinary Manual estimates that nearly all puppies are born with or acquire T. canis infection within the first weeks of life.
Roundworms are zoonotic — meaning the disease is transmissible from animals to humans. Transmission occurs when a person accidentally ingests embryonated (infective) Toxocara eggs from contaminated soil, sand, or surfaces where infected dogs have defecated. The condition in humans is called toxocariasis, and it ranges from asymptomatic to severe depending on which organs the migrating larvae affect.
This guide covers everything dog owners need to know: how roundworms spread between dogs and humans, what symptoms to watch for in both species, how veterinarians diagnose and treat canine roundworm infection, realistic costs, and the prevention protocols that actually work.
What Are Roundworms in Dogs?
Roundworms (Toxocara canis and, less commonly, Toxascaris leonina) are parasitic nematodes that inhabit the small intestine of dogs. Adult worms are spaghetti-like, measuring 3 to 7 inches (7–18 cm) long, and are sometimes visible in vomit or feces.
The life cycle is what makes T. canis so successful and so dangerous:
- Adult worms in an infected dog's intestine produce eggs that pass into the environment through feces.
- Eggs embryonate (become infective) in soil over 2–4 weeks under warm, moist conditions.
- Ingestion of embryonated eggs — through grooming, eating contaminated soil, or consuming infected paratenic hosts (rodents, earthworms) — introduces larvae into a new host.
- Larval migration follows one of several pathways depending on the host's age and immune status: tracheal migration (puppies under 6 months), somatic migration (older dogs, where larvae encyst in tissues), or transplacental/transmammary transmission (pregnant dogs to puppies).
The transplacental route is why virtually all puppies carry roundworms. Reactivation of dormant somatic larvae during pregnancy means even well-dewormed dams can infect their litters before birth.
How Roundworms Transfer From Dogs to Humans
Understanding the transmission pathway is critical for prevention. Humans do not catch roundworms directly from touching a dog. The infection route is always fecal-oral, involving embryonated eggs in the environment:
- Fresh dog feces are NOT immediately infectious — eggs require 2–4 weeks in the environment to embryonate.
- Embryonated eggs can survive in soil for years, resisting temperature extremes and common disinfectants.
- Children aged 2–7 are at highest risk due to hand-to-mouth behavior and play in contaminated areas.
- Pica (eating dirt) dramatically increases exposure risk in both children and adults.
- Direct contact with a dog's fur is low-risk unless the coat is contaminated with embryonated eggs from the environment.
Once ingested by a human, T. canis larvae hatch in the intestine but cannot complete their life cycle. Instead, they migrate through tissues — liver, lungs, eyes, brain, muscles — causing inflammatory damage. This aberrant migration is what produces clinical toxocariasis.
Symptoms of Roundworms: Dogs and Humans
Recognizing infection early in your dog reduces environmental contamination and your family's exposure risk. Below is a severity-organized checklist for both species.
Canine Roundworm Symptom Checklist
| Severity | Symptoms |
|---|---|
| Early / Mild | Dull coat, mild potbelly appearance, occasional soft stool, slightly reduced appetite, visible worms in stool (spaghetti-like, white/tan) |
| Moderate | Persistent diarrhea, vomiting (sometimes with visible worms), weight loss despite normal food intake, lethargy, poor growth in puppies, scooting |
| Severe / Advanced | Intestinal blockage (acute vomiting, abdominal pain, no stool passage), severe anemia (pale gums, weakness), pneumonia from larval migration through lungs (cough, nasal discharge), failure to thrive in puppies, death in extreme cases |
Human Toxocariasis Symptom Checklist
| Form | Symptoms |
|---|---|
| Covert (most common) | Often asymptomatic; mild fatigue, abdominal discomfort, headache, cough; elevated eosinophil count on blood work |
| Visceral Larva Migrans (VLM) | Fever, hepatomegaly (enlarged liver), cough/wheezing, abdominal pain, nausea, eosinophilia, hypergammaglobulinemia; primarily affects children 2–7 |
| Ocular Larva Migrans (OLM) | Unilateral vision loss, eye pain, leukocoria (white pupil reflex), strabismus, retinal granuloma; can mimic retinoblastoma; typically in older children/young adults |
| Neurotoxocariasis (rare) | Seizures, headaches, behavioral changes, eosinophilic meningitis; requires MRI and CSF analysis for diagnosis |
Risk Factors: Who Is Most Vulnerable?
Canine Risk Factors
- Age: Puppies under 6 months carry the heaviest worm burdens due to transplacental and transmammary infection.
- Environment: Dogs with outdoor access to yards, parks, or kennels with earthen floors have higher exposure.
- Deworming history: Dogs without regular anthelmintic treatment or those on heartworm preventives without roundworm coverage.
- Hunting behavior: Dogs that chase and consume rodents ingest larvae from paratenic hosts.
- Multi-dog households: Environmental contamination from one infected dog exposes all cohabiting dogs.
- Breed: No breed is genetically predisposed, but puppies from large litters in crowded conditions face heavier exposures.
Human Risk Factors
- Age: Children 2–7 years (geophagia, sandbox play, developing hygiene habits).
- Occupation: Veterinarians, veterinary technicians, landscapers, farmers, and kennel workers.
- Geography: Higher prevalence in the southeastern U.S. due to warm, humid conditions favoring egg embryonation.
- Behavior: Gardening without gloves, not washing hands after handling soil or dog feces, owning multiple untreated dogs.
- Immunocompromise: While toxocariasis affects immunocompetent individuals, severe visceral disease may be more pronounced in immunocompromised patients.
How Veterinarians Diagnose Roundworms in Dogs
If you suspect your dog has roundworms, your veterinarian will typically use one or more of the following diagnostic methods:
| Test | What It Detects | Estimated Cost | Turnaround |
|---|---|---|---|
| Fecal flotation (zinc sulfate or sodium nitrate) | Roundworm eggs in stool; gold standard for patent infections | $25–$55 | Same day (in-clinic) to 24–48 hours (reference lab) |
| Fecal direct smear | Adult worms or larvae in fresh stool; less sensitive than flotation | $20–$40 | Immediate |
| Centrifugal fecal flotation | Higher sensitivity for low egg counts; recommended by CAPC | $35–$65 | Same day to 48 hours |
| Antigen testing (e.g., IDEXX Fecal Dx) | Detects roundworm-specific proteins; can identify pre-patent infections before eggs appear | $40–$75 | Same day to 24 hours |
| CBC and chemistry panel (if symptomatic) | Eosinophilia, anemia, hypoalbuminemia; assesses systemic impact | $80–$200 | Same day to 24 hours |
| Abdominal radiographs (if obstruction suspected) | Intestinal blockage from heavy worm burden; gas patterns | $150–$400 | Immediate |
Diagnostic note: Puppies with pre-patent infections (larvae migrating but not yet producing eggs) may test negative on fecal flotation. The Companion Animal Parasite Council (CAPC) recommends empiric deworming of all puppies starting at 2 weeks of age regardless of test results, because the prevalence is so high and the zoonotic risk so significant.
Treatment Options for Roundworms in Dogs
Roundworms in dogs are highly treatable. Several anthelmintic medications are effective, and most clear the infection within one to two treatment rounds. Your veterinarian will determine the appropriate drug and dosage based on your dog's age, weight, and health status.
| Medication | Active Ingredient | Typical Protocol | Efficacy | Cost Range |
|---|---|---|---|---|
| Pyrantel pamoate (Nemex, Strongid) | Pyrantel (5–10 mg/kg) | Single oral dose, repeated in 2–3 weeks | 90–95% against adult T. canis; less effective against migrating larvae | $10–$25 per dose (liquid); $15–$35 (suspension at vet) |
| Fenbendazole (Panacur) | Fenbendazole (50 mg/kg daily × 3 days) | 3 consecutive daily oral doses; repeat in 2–3 weeks | >95% against adults and some larval stages | $15–$40 per course |
| Milbemycin oxime (Interceptor Plus, Sentinel) | Milbemycin oxime (0.5 mg/kg monthly) | Monthly chewable; treats and controls roundworms as part of heartworm prevention | >98% with consistent monthly use | $8–$22 per month (weight-based) |
| Moxidectin + Imidacloprid (Advantage Multi) | Moxidectin (2.5 mg/kg topical) | Monthly topical application; treats existing infection and prevents reinfection | >99% with consistent use | $15–$25 per month |
| Praziquantel/Pyrantel/Febantel (Drontal Plus) | Combination broad-spectrum | Single dose; covers roundworms, hookworms, whipworms, tapeworms | 95–100% against T. canis | $15–$45 per tablet (weight-based) |
Supportive Care for Severe Cases
Dogs with heavy worm burdens — particularly puppies — may need more than deworming medication alone:
- IV fluids: For dehydrated puppies with diarrhea or vomiting ($60–$150/day).
- Nutritional support: Easily digestible prescription diets (e.g., Hill's i/d, Royal Canin GI) during recovery.
- Anti-emetics: Maropitant (Cerenia) at 1 mg/kg SC or PO if vomiting is severe ($15–$30 per dose).
- Surgical intervention: Rarely, a massive roundworm burden causes intestinal obstruction requiring enterotomy. This is an emergency procedure costing $2,000–$6,000 depending on the facility.
Prognosis by Severity
| Severity | Expected Outcome | Recovery Timeline |
|---|---|---|
| Mild (asymptomatic or potbelly only) | Excellent — full clearance with 1–2 deworming rounds | 1–3 weeks |
| Moderate (GI signs, weight loss) | Very good — full recovery with treatment and supportive care | 2–4 weeks |
| Severe (obstruction, severe anemia, pneumonia) | Guarded to good with aggressive treatment; mortality risk in untreated puppies | 4–8 weeks; surgery recovery adds 2–3 weeks |
Roundworm infection does not reduce a dog's life expectancy when treated promptly. The vast majority of dogs make a complete recovery. Untreated severe infections in young puppies, however, can be fatal due to intestinal blockage or severe malnutrition.
When to See the Vet: Red Flag Symptoms
- Repeated vomiting, especially with visible worms
- Distended, painful abdomen (especially in puppies)
- No stool passage for 24+ hours combined with vomiting
- Pale or white gums (indicates severe anemia)
- Difficulty breathing or persistent cough
- Collapse, extreme lethargy, or inability to stand
- Bloody diarrhea
These symptoms may indicate intestinal obstruction or severe systemic illness requiring emergency intervention. After-hours emergency vet visits typically cost $100–$300 for the exam alone, with total emergency treatment ranging from $500 to $5,000+.
For non-emergency situations — a potbellied puppy with normal energy and appetite, or occasional worms visible in stool — schedule a regular veterinary appointment within 24–48 hours.
Total Cost of Roundworm Diagnosis and Treatment
Here's what dog owners can realistically budget for roundworm management:
| Scenario | Cost Range | What's Included |
|---|---|---|
| Routine screening + deworming | $50–$120 | Fecal flotation + 1–2 doses of pyrantel or fenbendazole |
| Moderate infection with follow-up | $120–$300 | Office visit, fecal test, deworming, recheck fecal, possible second-round treatment |
| Severe infection with supportive care | $400–$1,200 | Emergency visit, CBC/chemistry, IV fluids, anti-emetics, deworming, possible overnight hospitalization |
| Intestinal obstruction (surgical) | $2,000–$6,000 | Radiographs, surgery, anesthesia, hospitalization, post-op care |
| Ongoing prevention (annual) | $96–$264/year | Monthly heartworm/intestinal parasite preventive (Interceptor Plus, Sentinel, Heartgard Plus, etc.) |
Cost-saving tip: Many monthly heartworm preventives — Interceptor Plus, Sentinel, Heartgard Plus, Simparica Trio — include roundworm coverage at no additional cost. If your dog is already on a monthly preventive, check whether it covers T. canis. This single step eliminates most roundworm treatment expenses.
Preventing Roundworm Transmission: Dogs and Humans
Prevention requires a two-pronged approach: keeping your dog parasite-free and reducing human exposure to contaminated environments.
For Your Dog
- Puppy deworming schedule (per CAPC guidelines): Treat at 2, 4, 6, and 8 weeks of age with pyrantel pamoate, then monthly until 6 months old.
- Adult dogs: Monthly broad-spectrum preventive that covers roundworms (most heartworm preventives do). Alternatively, fecal testing 1–2 times per year with targeted treatment.
- Pregnant dogs: Fenbendazole at 50 mg/kg daily from day 40 of gestation through day 14 post-whelping significantly reduces transplacental and transmammary transmission to puppies. Consult your veterinarian for this protocol.
- Environmental control: Remove feces from yards daily. T. canis eggs are not infective for the first 2–4 weeks — prompt removal breaks the cycle.
- Rodent control: Prevent hunting behavior or use pet-safe rodent control to eliminate paratenic host exposure.
For Your Family
- Hand hygiene: Wash hands with soap and water after handling dogs, cleaning up feces, gardening, or playing in soil. Hand sanitizer alone does NOT kill Toxocara eggs — mechanical washing is required.
- Sandbox management: Cover sandboxes when not in use. Replace sand annually if contamination is suspected.
- Produce washing: Thoroughly wash garden vegetables, especially root crops that contact soil.
- Children's play areas: Prevent children from playing barefoot in areas where dogs defecate. Teach children not to put dirt in their mouths.
- Yard maintenance: Designate a specific area for dog elimination away from children's play zones. Pick up feces daily.
- Occupational protection: Wear gloves when gardening, landscaping, or handling animal feces professionally.
Frequently Asked Questions
Can I get roundworms from my dog licking me?
The risk is extremely low. Roundworms are transmitted through ingestion of embryonated eggs from contaminated soil or feces — not through saliva. However, if your dog has fecal residue on its mouth (from grooming) and licks your face or an open wound, there is a theoretical risk. Practicing basic hygiene — not letting dogs lick your mouth, washing your face after close contact — eliminates this minimal risk.
How long does it take for roundworms to go away after treatment?
Most deworming medications begin paralyzing and killing adult worms within 24–48 hours. You may see dead worms in your dog's stool for 2–3 days after treatment. A second dose at 2–3 weeks targets any larvae that matured after the first treatment. A follow-up fecal test at 3–4 weeks confirms clearance.
Can roundworms be fatal to dogs?
In adult dogs, roundworms are rarely fatal. In puppies under 8 weeks with very heavy worm burdens, intestinal obstruction, severe malnutrition, or pneumonia from larval migration can be life-threatening without treatment. Prompt veterinary care dramatically reduces mortality risk.
Do I need to treat myself if my dog has roundworms?
Not automatically. Human toxocariasis is diagnosed via ELISA blood test detecting Toxocara-specific antibodies. If you or a family member has symptoms (persistent abdominal pain, vision changes, unexplained eosinophilia), consult your physician and mention your dog's diagnosis. The CDC does not recommend prophylactic treatment for asymptomatic household members.
Are roundworms the same as heartworms?
No. Roundworms (Toxocara canis) live in the intestine and are transmitted through egg ingestion. Heartworms (Dirofilaria immitis) live in the heart and pulmonary arteries and are transmitted exclusively by mosquitoes. They are different parasites with different life cycles, treatments, and prevention protocols. However, many monthly heartworm preventives also cover roundworms.
How often should I test my dog for roundworms?
The CAPC recommends fecal testing 2–4 times during a puppy's first year and 1–2 times annually for adult dogs. Dogs on monthly broad-spectrum preventives may be tested annually. Dogs in high-risk environments (kennels, shelters, multi-dog households) benefit from more frequent screening.
Disclaimer: This article provides educational information and does not replace professional veterinary advice. Always consult your veterinarian for diagnosis and treatment of parasitic infections in your dog. If you suspect human toxocariasis, consult your physician. For animal poison emergencies, contact the ASPCA Animal Poison Control Center at (888) 426-4435 (24/7, consultation fee applies).
Anouk Beaumont
All our authors care for dogs every day — read more of their work on the authors page.
