Worms in Dogs - Causes, Symptoms & Treatment

Dr. Jason Gagné, DVM, DACVIM
By Dr. Jason Gagné, DVM, DACVIM
Updated: 5/20/20242-4 minutes
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Nobody likes to think of their dog as having worms, but there’s nothing unusual about it – in fact, your puppy or dog has probably had them at some point in their lives!

Most puppies are actually born with worms, which are contracted from their mother’s milk, while other dog worms are obtained from fleas or the environment. If your puppy or dog has worms, there’s no need to worry – your vet can help you with treatment. If done speedily, there’s no need for your dog’s health to be compromised at all.

Types of Worms in Dogs

There are many kinds of worms that your dog could have, but some are more common than others. They tend to have different symptoms, so just look out for anything particularly unusual – worms in dog poop, vomiting or weight loss are all possible signs that these little creatures are involved.


  • Puppies are infected with roundworms (Toxocara spp and Toxascaris spp) from their mother’s milk. 

  • This is why it is important to worm expectant and nursing mothers with a safe, veterinary licensed product. 

  • Dogs can also be infected by eating contaminated rodents or soil. 

  • These worms can also be found in dog poop. Roundworms in dogs can be identified as spaghetti-like shapes in the feces or, in severe cases, in vomit.


  • Dogs can be infected with tapeworms (Taenia spp., Echinococcus spp., Dipylidium spp.) by fleas or infected carcasses (such as rodents, sheep, or rabbits). 

  • Segments of tapeworm in dogs may be seen in feces or on your dog’s bottom, and they look like grains of rice.

Hookworms and Whipworms

  • These worms are two of the most common parasites in dogs and are found in the intestine. 

  • They can be transmitted through the mother’s milk or just the environment.


  • This worm (Angiostrongylus vasorum) is a little different; it lives in the dog’s blood vessels and affects their lungs. 

  • Dogs can pick up lungworms worm by eating slugs and snails.


  • This worm can be found in dogs’ hearts, lungs and blood vessels.  

  • Dogs are infected via mosquitoes.

We’ve put together a list of some of the common types of dog worms, how they can be contracted and how they can appear.

Symptoms of Worms in Dogs

It’s not always easy to spot dog worms, so don’t worry if you get it wrong – if you’re unsure about worms in your dog, or you don’t know what kind they are, your vet will happily check your dog over to see if there’s a problem. Regular vet checkups will give your vet the chance to spot any potential dog health problems and help resolve them before they become serious. In any case, your vet should be consulted before you try to formulate any treatment yourself, just in case there’s a different problem at hand.

So you know what to look out for, signs of dog worms include: 

  • Worms in dog poop, vomit or on their bottom 

  • Weakness and depression 

  • Diarrhea or vomiting 

  • Weight loss despite a good appetite 

  • An abnormally swollen stomach 

  • Severe vomiting, loss of appetite and depression might be a result of a large burden causing a blockage of the intestine (which is usually seen in puppies) 

  • Coughing and bleeding problems, among various other signs, may suggest Lungworm

Treatment and Prevention of Worms in Dogs

Your puppy should already be worm-free if they’ve come from a reputable breeder or rescue, as they will have been wormed before coming home with you. Keep the paperwork detailing the worming treatment safe, and ask your vet how to continue the program. If you keep track of your pet’s worming treatment and keep checking for symptoms, their chances of health complications from worms is greatly reduced.

It’s not just puppies that you need to keep an eye on: adult dogs need worming too, as they might pick something up on their adventures! Ask your vet to supply a wormer and provide more information on symptoms of worms in dogs. They can also tell you how frequently your dog would benefit from worming, so you can get a routine in place.

Sometimes, if your dog might have worms, your vet will ask for a stool sample. The worms in dog poop are not always visible to the naked eye, so this allows the vet to look at it under a microscope for signs of worm eggs.

If your dog is joining you abroad, certain worming protocols are required, so check before you go! Ask your vet about these protocols well in advance of any travel plans, so you know you’re prepared for the trip. Find out more about how to travel safely with your dog on the plane, with our easy-to-follow guide, next.

Dog Worms and Humans

Sometimes, dog worms can be transmitted to humans, or spread dog-to-dog via feces. Because of this, it is always a good idea to dispose of stools when your dog goes to the toilet outside. This will help to prevent reinfestation, and will protect his playmates as well.

Although it’s tempting for them, try not to let your dog eat slugs and snails. Human infection is uncommon, but always use proper hygiene measures, such as making sure children wash their hands after playing with your pet, just to be safe. 

All in all, worms in dogs are generally nothing to worry about – as long as you catch them and treat them in good time, your dog will be as happy as ever! 

There are a number of other parasites to keep an eye out for, including mites and ticks. For more tips from Purina experts on how to prevent or treat dog parasites, explore our other dog parasite articles.

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