Worming your dog - Q&A

Estimated Reading Time 5 minutes
Worming your dog - Q&A

How do you know if your dog has worms? And when should you worm your dog? Dogs are at risk of being infected with many different worms, including roundworms, tapeworms and lungworm. They can pick them up in a number of ways: from other infected animals, from their mother if she is infected while pregnant, or from eating worm eggs in infected faeces, urine or grass. So, the answer to this question can be complex. Here we answer your most common questions about worming your dog!

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Roundworms are the most common worms in puppies. It is important to note that they can infect humans. The infection in dogs can cause varying signs, from mild abdominal pain to blindness, and can even cause death in puppies, if they have a large burden. These worms are transferred from the bitch to the puppy during pregnancy and lactation. The puppy can also become infected during the first months of life from contamination of their environment.

Adult round worms are 3-10 cm long, round and are yellowish-white to brownish-red in colour. The worm can also be seen in stools, or if the dog vomits them up. A heavy worm burden in puppies may be seen as a swollen abdomen (pot-bellied appearance), or a cough. A mild to moderate worm burden causes non-specific signs, such as poor growth, a poor appetite, diarrhoea, vomiting, a dull and starry coat, and fatigue.


Tapeworms are not as common as roundworms. Dogs that hunt or are raw fed are at increased risk of a tapeworm infection. If your dog does not hunt, or eat raw meat, then it is possible for them to get infected by ingesting fleas from their coat whilst grooming. If your dog’s flea treatment is up-to-date, and they are not raw fed and do not hunt, then their risk of tapeworm is low.

Tapeworms are long, often 15cm or more in length, and flat in appearance. Unless the dog is extremely active, the parasite does not cause harm. Tapeworm infection usually does not cause any clinical signs, but sometimes loose stools or other digestive disorders occur. Tapeworms can also be detected as small white flat segments that move in the fur around the buttocks of the dog, or in the stool. Sometimes a chain of these white parts is seen in the dog's stool.


Lungworm (canine angiostrongylosis) is a life-threatening disease of dogs caused by Angiostrongylus vasorum. Vets are now reporting significantly more cases of the disease in the last few past years. It is passed on by dogs eating slugs or snails, often not on purpose. Your dog may eat them by accident, for example, when a slug or snail is sitting on the grass or a favourite toy! As yet, it is unclear why there has been an increase in case numbers more recently, but the worm is known to favour warmer temperatures. Foxes can also be infected, spreading worm larvae in their faeces. Therefore, the increase in urban fox populations may be another reason why vets are seeing more cases.

Infestations of this lungworm can result in death if not diagnosed, or if left untreated. Early diagnosis by a vet, followed by appropriate treatment, will usually lead to a full recovery. There are many signs to look out for. Equally, an infected dog may appear totally healthy. Persistent coughing, reluctance to exercise, depression, weight loss, fits, vomiting, diarrhoea, weakness, paralysis, behavioural changes and persistent bleeding from insignificant wounds are all possible signs. The wide range of signs can easily be confused with other diseases, so discussing these with your vet is important, if you have noticed any of the signs above.

When should you worm your dog?

In the past, all adult dogs were regularly wormed. This approach is no longer recommended, for several reasons. Firstly, each dog will have a different level of exposure and risk of worms, therefore it makes sense to tailor their worming protocol to their individual needs. There is also no scientific basis for a fixed worming protocol. A blanket worming approach for all dogs increases the risk of worms developing resistance to the drugs. Over time, this approach causes the drugs to become less effective in treating worm infections.

Based on current scientific evidence, we now recommended that you only worm adult dogs if you have seen worms in their stool, or if they vomit or cough up worms. A Faecal Worm Egg Count Test can also be arranged by your vet. A fresh faecal sample is submitted to a lab for detailed parasite analysis, which will tell you whether or not you need to worm your dog at that particular time point. These can be repeated every 3 months, if necessary. You can also worm your dog if you have a strong suspicion of an infection. We recommend that this is done after discussion with your vet.

Puppies are usually wormed by the breeder and at intervals depending on the drug preparation used. In most cases, puppies are wormed before moving to their new home, at the age of 8 weeks. Ask the breeder for further details about your puppy’s worming treatments. Puppies should then be wormed every two weeks until 12 weeks old because the majority will have roundworms, then every month until 6 months of age.

Many countries require dogs to be wormed for European tapeworm before arriving, and after leaving the country. This must be performed and certified by an Official Veterinarian, documenting the treatment in your dog’s passport. Dogs without the correct documentation are not permitted to travel. Please read our article about traveling abroad with a dog, for further guidance.

What can you do to help your dog?

  • Discuss your the specific risk for your dog with your vet who will be able to recommend the best worming protocol for you

  • Dogs that go outside should be treated every 3 months. Dogs that are raw fed or hunt should be wormed monthly

  • Bitches should be wormed during pregnancy to reduce contamination to the puppies

Still worried?

If you suspect that your dog has a worm infection, or if you would like an initial assessment, or have any queries regarding worming your dog, then please book an appointment with one of our FirstVet Vets, who will advise you about a suitable regime.

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