Worms in dogs

isolated dog


  • Gut worms are a common problem in dogs and without regular treatment, most will catch them at some point in their life.
  • Worms steal food and cause damage to the gut lining.
  • It’s rare for worms to cause serious illness in adult dogs, but common for them to cause problems in puppies.
  • Dogs can also be affected by lungworm, which can cause very serious illness and even death.
  • Regular deworming will prevent problems from developing.

General information

Worms live in the guts, steal food and cause damage. Although worms rarely cause serious illness in adult dogs, they can cause very serious problems for puppies (such as dehydration, anaemia, gut blockages and even death.)

Most dogs catch worms from:

  • Eating soil or other animals poo
  • Fleas (fleas carry tapeworm)
  • Eating rats and mice when hunting.

Two common intestinal worms that affect dogs in the UK are roundworm and tapeworm.

  • Roundworm look like spaghetti and can grow up to 15cm long
  • Tapeworm are made up of little segments the size of a grain of rice. These segments can sometimes be seen crawling around the bottom.

'Threadworm' and 'Whipworm' can also affect pet dogs, but they are both rare in the UK.


Dogs can also be affected by lungworm, a very serious condition that can cause severe illness and even death. This article is above intestinal worms, read our lungworm for more information.


Symptoms of worms in dogs

Worms often cause symptoms such as:

Treatment and prevention

Puppies. Your puppy will need a special worming treatment suited to your puppy’s age and weight. They should have their first treatment at three weeks old and after that, they should be wormed every two weeks until they are 16 weeks old. After 16 weeks, they will need a treatment every one-three months (or as regularly as your vet suggests).

Adult dogs. A worming treatment every three months is usually enough to prevent problems from developing. It may be necessary to deworm your dog slightly more regularly if they scavenge a lot. Remember to protect your dog against lungworm as well as gut worms.

What to expect after treatment. You may see dead worms in your dog’s poo if they had a heavy infestation, but it’s more than likely that you won’t see anything after giving a treatment. Contact your vet if your dog has diarrhoea or seems unwell.

Watch our video: ‘How to give your dog a tablet’.

Which wormer?

There are many different worming products available for dogs (including tablets, liquids, pastes and spot-on treatments). The best one for your dog will depend on their temperament and lifestyle.

Prescription wormers. It’s best, where possible, to use a prescription worming treatment from your vet. If your dog is healthy and visits the vet regularly, your surgery is likely to be happy to dispense a worming treatment without an appointment. If your dog hasn't been examined for a while it’s best to book an appointment. Your vet surgery will need to know how much your dog weighs so they can provide the right treatment dose.

Non-prescription wormers. There are some worming treatments that are available without a prescription. Some can be picked up directly off the shelf, and others (called ‘NFA-VPS’ products) are non-prescription but can only be sold by a specially qualified person. NFA-VPS products are stored in a locked cupboard and tend to be more effective than products you can pick up from a shelf without speaking to someone. If you buy a NFA-VPS product, it's likely that you will be asked your dog's weight. You can watch a video on weighing your dog here.

Home remedies for worms in dogs

To treat worms, you need to use a product with proven ingredients. Unfortunately, home remedies are very unlikely to work.

When to contact your vet

Get in contact with with your vet if you think your dog has worms. It may help to bring a sample of their poo (or a photograph) to show your vet. If your dog is healthy and needs a worming tablet, call your veterinary practice for advice.

Watch our video on how to collect a poo sample:

If your dog is healthy and needs a worming tablet, call your veterinary practice for advice.


Excellent, thanks to modern medicine, worms are very simple to treat if they haven’t been left too long.

Can humans catch worms?

It’s very rare for humans to catch dog worms, but it does occasionally happen. It’s most common in young children that have been playing around dog poo. Dog worms cause damage to humans by lodging in organs such as the liver, heart, brain and eyes. If you have small children it is extremely important to make sure your dog is regularly wormed with an effective product. If you have concerns for you or someone else, it is best to contact your doctor, or the NHS for advice.

Published: July 2020

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst