Canine Roundworms (Toxocara canis) live in a dog’s intestines and feed off ingested food. This causes dogs to not get the full nutritional benefit from their meals which can lead to malnourishment. This is especially dangerous for smaller breeds and puppies.


Roundworms are quite common, with many dogs becoming infected with them at some time in their lives. This is due to the ease in which dogs can ingest worms and worm lava (baby eggs) from their everyday surroundings, including:

  • Drinking contaminated water
  • Eating contaminated soil, stools or other animals such as rodents
  • Mothers can also pass worms on while the puppy is still in the womb

  • Symptoms

    a long canine roundworm

    Roundworm can be particularly dangerous as many dogs don’t show early symptoms. The longer a dog goes untreated the larger worms can grow, causing even more strain on the dog’s health.

    Signs to watch out for:

  • Weakness and a lack of energy
  • Weight loss
  • Stunted growth
  • Swollen belly
  • Vomiting
  • Diarrhoea

  • If you suspect that your dog does have roundworm, you can check their stool to see if any are visible. Larger roundworms can be around 1.5 cm in length (roughly half an inch) and will be whitish or tan coloured. Dried worms can look like small grains of rice or sesame seeds.

    Even if you can’t see any clear signs in the stool but suspect your dog does have worms then you should make an appointment with your vet as soon as possible.

    Treatment Frequency

    The best way to ensure your dog doesn’t contract roundworm is to take regular prevention methods with de-worming medicine.

    How often you de-worm depends on the individual treat level to your pet, such as where they live, where they go for walks and how many dogs they are exposed to. The common veterinary recommendation is:

  • Every 2 weeks for puppies under 12 weeks
  • Once a month until their 6 months old
  • Then every 3 months for life

  • Types of Treatment

    There are many types of de-wormer available on the market but the most common in the UK are tablets, liquids and spot-on treatments. It is advised that you read the instructions before administering any treatment, even if you are familiar with one particular type, as they often require specific steps, such as not administering to a dog on an empty stomach.

    Tablets: These are good to hide in food or treats. One popular trick is to coat them in peanut butter. Some tablets are also flavoured, making it easier to persuade your dog to eat them directly.

    Liquids: These can be dripped straight into the mouth if your dog is well trained.

    Spot On treatments: These can be directly applied to the skin and are slowly absorbed into the bloodstream. These should be applied to areas that won’t be easily licked off, such as the back of the neck.

    De-wormers come in different classes based on the weight, age and breed of your dog. It is recommended that you check with your vet about which type is suitable for your dog. They will also be able to recommend a certain brand which can save a lot of confusion with so many on the market.

    Dogs Passing Worms to Humans

    Infection in humans is possible by the accidental ingestion of roundworm eggs. This can happen by not properly washing hands after cleaning up feces, brining in soil containing eggs into the home or even stroking an infected dog.

    Unlike fleas, roundworm doesn’t live in fur, but if a dog rolls in contaminated soil, or spreads eggs onto their fur in any way, then this can be easily passed on to humans.

    It is rare for humans to get seriously ill from roundworm, but if you are worried that you may have been infected by a dog then you should see a doctor. They will likely prescribe a combination of anti-parasitic and anti-inflammatory drugs.