Worms in dogs

isolated dog


  • Worms are a very common problem and most pet dogs will catch them at some point in their life.
  • This article focuses on intestinal worms (worms that live in the guts). If you own a pet dog in the UK, you should also be aware of lungworm.
  • Intestinal worms live in the guts, eat your pet’s food and cause damage to the gut lining.
  • Worms aren’t easy to spot and aren’t often seen until they have been treated and killed with a worming product.
  • Treating and preventing worms is easy with regular worming tablets (or spot-on treatments).
  • Certain dog worms can cause problems in humans.

Types of worms in dogs

Intestinal worms

Intestinal worms live inside the intestines (guts). The two most important intestinal worms that affect dogs in the UK are roundworm and tapeworm.

  1. Roundworm look like spaghetti and grow up to 15cm long.
  2. Tapeworm are flat, made up of lots of little segments joined together, and grow up to 60cm long. If your dog has tapeworm, you might see the ‘grain of rice’ size segments ‘crawling’ around your dog’s bottom.
  3. Other - ‘threadworm’ and ‘whipworm’ are intestinal worms that can also affect pet dogs, but they are both rare in the UK.


If you have a pet dog and live in the UK, it’s very important to be aware of lungworm. Lungworm can be deadly and is a risk to dogs across the UK. This article focuses on intestinal worms only.

How do dogs get worms?

Most dogs catch worms by:

  • Eating infected soil or poo, often by accident if it gets onto their nose or fur
  • Eating worm infected fleas when grooming (fleas carry tapeworm)
  • Eating worm infected rats or mice when hunting.

Effects of worms

Intestinal worms live in the guts, eat your pet’s food and damage the gut lining. They cause weight loss, excessive hunger and often, diarrhoea. Left untreated, worms can cause poor general health, gut bleeding and in severe cases: anaemia, gut blockages, intussusception, and occasionally death. Worms are most likely to cause serious illness in puppies, old dogs and poorly dogs.

Symptoms of worms in dogs

Worms often cause symptoms such as:

  • Scooting / an itchy anus (bottom)
  • Weight loss
  • Excessive hunger
  • Diarrhoea
  • Blood in the poo
  • Vomiting / vomiting a worm (can be an indication of a gut blockage)
  • Pot-belly and bloating (in puppies with large numbers of worms)
  • Small tapeworm segments can sometimes be seen around the bottom.

Treating worms

Treating worms in dogs is simple, a worming tablet (or spot on), is all that’s needed. It’s likely you’ll be able to buy a worming tablet without an appointment if your dog has been examined in the past few months (and you know their weight). If your dog hasn’t been seen in over six months, is unwell or has lost/gained a lot of weight, they will need to be seen by your vet before having a worming tablet prescribed.

Preventing worms

It’s easy to prevent worms, just make sure you de-worm your dog as regularly as your vet suggests, this is usually every three months but can vary depending on which product you use and your dog’s lifestyle. If your dog has caught worms despite regular worming, you will need to talk to your vet about changing your worming regime.

Which dog worming tablet?

There are many different worming products available for dogs (including tablets and spot-on treatments). Many of them have combined action against many different types of worms. Your vet will help you decide which is best for you and your dog, based on your dog’s lifestyle. Don’t forget to include lungworm protection in your dog’s worming routine.

WARNING: Always protect your dog with a veterinary licenced product. Products you can buy without a prescription (from a supermarket, human pharmacy, pet shop or online) are not veterinary licenced and often contain less effective ingredients.

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

Home remedies for worms in dogs

To treat worms, you need to use a product with effective ingredients. Home remedies and over the counter products are unlikely to work.

When to contact your vet

Book an appointment 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 but hasn’t had a worming tablet for a while, contact your veterinary practice for advice.

How to collect a poo sample:


Once your dog has had a worming treatment, their outlook is excellent. Thanks to modern medicine, worm infections are simple to treat if they’ve not 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 young children that have been playing in areas that dogs have pooed. 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.

Worms in puppies

It’s very important to keep puppies free from worms, because left untreated, they can cause very serious illness. In large numbers, worms can cause gut blockages, intussusception (telescoped bowel), anaemia and even death.

How do puppies get worms?

Puppies can catch worms from their mother while they are in the womb, or after they have been born, through their mother’s milk. You can prevent your pregnant dog’s unborn puppies getting worms by worming her during pregnancy. Ask your vet for advice on this. Once a puppy starts going outside, they can catch worms in the same way that an adult dog can (from soil, poo, fleas and rodents).

Worming puppies

Puppies need to be wormed from approximately 2 weeks old, every 2 weeks, until they are 16 weeks old. After that, they need worming as regularly as your vet suggests (likely to be every 3 months).

Symptoms of worms in puppies

Symptoms of worms in puppies include:

Published: November 2019

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