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What are Toxocara Canis?

Mature roundworms feed on the partially digested food located in a dog’s intestines.  The parasite takes nutrients and nourishment away from the dog. Puppies are more susceptible to roundworms because their immune systems are not fully developed. Toxocara canis is more common in warm, wet and tropical areas.

If your dog is showing symptoms of having roundworms or if you visually see “spaghetti type” worms in his vomit or stool, he should be seen by a veterinarian as soon as possible. Untreated roundworms can cause malnutrition and may be lead to intestinal obstruction or rupture.

Toxocara canis is a species of roundworm. Toxocara canis is the most common parasitic worm found in dogs.  This species of roundworm can be transmitted to people by contact with contaminated feces or soil.


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Symptoms of Toxocara Canis in Dogs

Symptoms may include:

  • Mild to severe diarrhea
  • Vomiting
  • Gagging
  • Weight loss
  • Weakness
  • Dull hair coat
  • Poor skin condition
  • Loss of appetite
  • Abdominal pain - Whimpers or cries out
  • Distended abdomen - Pot belly appearance due to a large infestation of roundworms in the intestines
  • If roundworms have traveled into the lungs, coughing and/or pneumonia may occur
  • Stunted growth in puppies
  • Visible worms in the dog’s vomit or stool
  • Anemia
  • Abdominal obstruction or rupture

Causes of Toxocara Canis in Dogs

Toxocara canis can be transmitted by:

  • The roundworm larvae can be transmitted before birth or through the mother’s milk to the puppies
  • If the dam ever had roundworms and was treated; she may still carry dormant (encysted) larvae in her tissues
  • These dormant roundworm larvae can revive and pass on to her puppies 
  • Dogs can become infected with Toxocara canis by ingesting feces or soil which is contaminated with larvae
  • If the dog eats an infected animal (rat, mice, birds) he may contract the roundworm
  • Cockroaches and earthworms may also carry roundworm larvae, which can be transmitted to the dog if they are ingested

Diagnosis of Toxocara Canis in Dogs

The veterinarian will want to know the symptoms you have observed and when they started.  He may want to go over your dog’s medical history, vaccination and deworming records. The veterinarian will then perform a physical examination on your dog which could include taking the temperature, weight, and blood pressure, listening to the lungs and palpating the abdomen area.  

The vet may recommend a complete blood count and the analysis of a fecal smear. The fecal sample is then examined under a microscope and checked for roundworm eggs. The veterinarian may also choose to run a fecal flotation test.  This test mixes fecal matter with a chemical solution which is placed in a test tube and spun down in a centrifuge.  Roundworm eggs and cysts will float to the top of the test tube.

Treatment of Toxocara Canis in Dogs

Puppies and dogs diagnosed with toxocara canis will need to be de-wormed.  Typically, the de-wormer is given over a few weeks.  The treatment goal is to kill the mature roundworms and their larvae. 

Elderly dogs and puppies with a severe infestation of Toxocara canis may need to be hospitalized.  Once hospitalized, the patient can receive 24/7 supportive care. Anemic (low red cell count) dogs may require a blood transfusion, supplements and B-12 injections.

If there are other pets in the household; they should also be treated for roundworms.

Your pet’s home and yard must also be treated for roundworms. Your dog’s kennel, bedding, blankets and toys should be cleaned with hot water and a diluted bleach solution.  The infected dog’s feces should be removed from the yard. Carpets and tile flooring should be thoroughly cleaned. If you have small children who play in the yard, the area should be professionally treated for roundworms. 

Recovery of Toxocara Canis in Dogs

Once treated, most dogs make a full recovery from Toxocara canis.  Follow-up visits will be required to monitor the dog’s progress and to re-check a fecal sample.  Anemic and/or malnourished dogs will need a retake of a complete blood count which will help determine if the red blood cell count is back to a normal range.  

The veterinarian may recommend that the patient be placed on a monthly heartworm medication which can also help prevent and control roundworms. Dogs should be seen once a year for a wellness exam.  Puppies and elderly dogs need to be seen more often. The veterinarian can provide you with a wellness plan which is right for your dog.

It is a good precaution to pick up dog feces from the yard daily. In addition, children should wash their hands after playing in the yard. Roundworm symptoms in people include parasites in a bowel movement or coming out of the mouth or nose, stomach ache and vomiting. Please see your physician if you or your child are having these symptoms.

Toxocara Canis Questions and Advice from Veterinary Professionals

Dogo Argentino
6 Years
Mild condition
0 found helpful
Mild condition

Has Symptoms

Standing under a bush, drooling

My 6year old Dogo Argentino started with stomach pains, elevated body temperature and poor appetite.
No vomiting, no diarrhoea.
While placed on a drip of RL with AB iv, he started with massive hemorrhagy from the anus. The Vet present at this near fatale moment saved Bravo with blood clotting medication.
The stool test showed Toxocara spp.
Since that episode in May 2018, I have done a stool test every 2 months, with 4 occurrences of Toxocara spp - despite deworming with different products like Drontal Plus 5tbl, Nemocid (Human med), Plozin 5tbl.
We have 5 other dogs in our home + garden, they are dewormed always along with Bravo.

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Serbian Husky
2 Months
Mild condition
0 found helpful
Mild condition

Has Symptoms

Doesn't want to eat
stomach noises,
one warm in her poop

Medication Used

Maxi animo's vermifuge

My two months Serbian husky Luccy had some stomach noises this morning and after eating a little bit she pooped a warm (like the one described in the article) she is usually playful and eats a lot but today she was escaping her food and seems tired. I want to note that she drinks a lot of water and two days ago the vet said that she's fine. Last week we saw a warm in her vomit and gave her a 3 days treatment with Maxi Animo's Vermifuge (half a pill per day) and we thought she recovered so we stopped it.

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Rotweiller mix
6 Months
Fair condition
0 found helpful
Fair condition

Has Symptoms


Hi, I wanted to bring my almost 6 months old puppy to day care and did fecal test as it was required. The result came back as TOXOCARA SP OVA PRESENT FEW (3-10). What medication should I buy?

Dr. Michele King, DVM
Dr. Michele King, DVM
1611 Recommendations
Thank you for your email. Roundworms are quite common in puppies and can be treated by a number of deworming medications - your veterinarian will be able to prescribe an appropriate medication for Blue to treat the Roundworms.

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German Shepherd Dog
3 Months
Fair condition
1 found helpful
Fair condition

Has Symptoms

loose poop in middle of the day. o

My 3 month puppy tested Toxocara SP OVA positive. A day before, he just had his second dose of pyrantel Pamoate 50mg/mL. Dose he need extra medicine. He has no symptoms.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
3320 Recommendations
Whilst Nemo has already received a second dose, a third dose shouldn’t be necessary but may be given after two or three weeks; it is always best practice to have another faecal test to check for the presence of parasites after treatment has ended. Regards Dr Callum Turner DVM

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