Worms in Dogs: Types, Symptoms, Treatment and Prevention

Finding worms is one of those moments that makes owners feel they have done something wrong. They have not. Internal parasites are very common in dogs, particularly in the first few months of life, and even well cared for puppies commonly arrive with them. The good news is that worms are straightforward to prevent and, in most cases, easy to treat. Because they can make young puppies genuinely unwell and some can pass to people, they are worth staying ahead of rather than dealing with after the fact.

Key takeaways

• Worms are common in dogs and cause signs including diarrhoea, weight loss and a ravenous appetite.

• Some worms are zoonotic, meaning they can pass to humans, and those at highest risk are young children, the elderly and people who are immune-suppressed.

• The best protection against worms is a regular, vet-approved wormer, with monthly treatment needed for lungworm.

What Are Worms in Dogs?

Several types of worm can live inside a dog. Some are visible to the naked eye, while others are microscopic and only found on testing. They take nutrients from your dog, and some attach to the intestinal wall and cause steady blood loss.

Types of Worms in Dogs

Which worms a dog is likely to pick up depends on where in the world they live. In the UK, a handful come up again and again.

Roundworm

Roundworms are the most common worm we see and look like strands of cooked spaghetti. Your dog may pass them in their stool, or even vomit them up if the burden is heavy. These are usually the worms behind the classic pot-bellied puppy.

Tapeworm

You may spot the segments, which look like grains of rice, stuck to the fur around your dog’s bottom or in their bedding. The tapeworm itself is long, lives inside the intestine and is rarely passed whole.

Hookworm

Hookworms are small but do a disproportionate amount of damage. They attach to the gut wall and feed on blood, which can lead to anaemia. In young puppies with a heavy burden, the blood loss can be severe enough to be fatal.

Whipworm

Whipworms live in the caecum and large intestine, where they cause weight loss and persistent diarrhoea, often with fresh blood. They look like fine cream threads but are rarely seen in the stool, as they stay within the intestine.

Lungworm

Lungworm is different to the others here. The adult worms live in the heart and the major blood vessels of the lungs rather than the gut, and an untreated infection can cause bleeding problems, coughing and sudden collapse. You can check how common lungworm is in your area using the lungworm map.

Heartworm

Heartworm is not endemic in the UK and is rarely seen here. It does turn up in dogs that have travelled or been imported from countries such as the USA, Spain and Romania, because mosquitoes are needed to complete its life cycle. It is worth mentioning any time abroad to your vet.

Symptoms of Worms in Dogs

The signs will vary from one dog to another and depend on the age of the dog, their health status, how heavy the worm burden is, as well as which parasite is involved.

Worms in Dog Poo or Vomit

For many owners, the first sign is seeing worms in the stool or, less often, in vomit. It is a horrible thing to come across, though it is genuinely useful information, so if you can bear to note what they look like it will help your vet. They are usually alive and moving, unless your dog has recently been given a wormer, in which case they may be dead.

Weight Loss, Pot Belly and Dull Coat

As the parasites take nutrients from the dog, weight falls away and the coat becomes dull and lacklustre. Some dogs also go off their food, while others seem permanently hungry. Abdominal swelling may also develop, from a combination of gas build-up and the sheer physical presence of the worms. A pot belly is most obvious in young puppies, whose core muscle tone is still developing.

Diarrhoea, Vomiting and Scooting

One of the core symptoms of worms is diarrhoea, as the worms trigger gastrointestinal inflammation. The stool can contain mucus and blood. This can sometimes be confused with an infection such as Parvovirus.

With heavy burdens, vomiting is also possible. Scooting along the floor is another sign, caused by irritation around the anus and localised itching.

Coughing and Breathing Changes

Lungworm and heartworm are the usual culprits when breathing is affected, as both migrate through the heart and lungs. Roundworm and hookworm larvae also pass through the lungs as part of their life cycle, so they can cause coughing too, particularly in puppies.

Symptoms of Worms in Puppies

Puppies tend to have more symptoms than adult dogs, and we more commonly encounter:

• Diarrhoea

• Vomiting

• Hunger

• A pot belly appearance

• Weakness

• Lethargy

• Bloody stool

• Pale gums

• Poor growth

• Coughing

How Do Dogs Get Worms?

Dogs pick up worms in a handful of predictable ways.

Many puppies are born already carrying roundworm, as larvae cross the mother’s placenta. They can also develop an infestation when they consume the mother’s milk.

One of the more common ways for dogs to get tapeworm is when they are transmitted by fleas. They can also be ingested in raw meat.

Lungworm is contracted by eating slugs or snails or the slime trail that they leave behind them.

Dogs can also get worms from eating contaminated grass or prey, like rodents and birds.

How Vets Diagnose Worms in Dogs

Most of the time, a vet treats for worms based on the history and symptoms, without needing specific tests. Where it would change the plan, a stool sample can be analysed. This identifies which parasite is involved and gives an idea of how heavy the burden is.

To diagnose lungworm, your vet can run a blood test, faecal test and/or perform chest X-rays.

Treatment for Worms in Dogs

Worms are treated with medication, and in most cases a single appropriate dose does the job. The product used as a preventative is also the treatment.

Prescription Wormers vs Pet Shop Products

Over the counter wormers can work against common intestinal worms, but the active ingredients vary and not every product covers every parasite. Dose is also based on weight, so an underdosed dog may be left with a burden you think has been treated. Your vet can advise on the right product for your dog.

Lungworm is the clear exception. Preventing and treating it requires a prescription product in the UK, which only a vet can issue. Examples include milbemycin oxime and moxidectin. No pet shop wormer covers lungworm.

It is also worth knowing that most wormers do nothing for external parasites, so a separate product is usually needed for fleas and ticks.

How Long Does It Take to Get Rid of Worms?

Most wormers begin killing the parasites within hours, and an intestinal infestation usually clears within a few days. You may see dead worms in the stool during that time, which is normal. Lungworm takes longer to resolve, particularly in severe cases where the parasites have already caused internal damage.

How to Prevent Worms in Dogs

The simplest and most effective protection is staying on top of routine worm and flea prevention. Breeding bitches should be wormed before mating and during pregnancy, and puppies should be treated from two weeks of age, which is part of the care they need in their first weeks at home.

It also helps to discourage hunting of rats and birds, and some owners choose to keep raw meat out of the diet. Watch for slug and snail trails in the garden, and avoid leaving your dog’s toys and water bowls outside overnight, where they can pick up slime trails.

Worming Schedule for Puppies and Adult Dogs

Puppies are typically wormed every two to three weeks from two weeks of age until 12 weeks old, then monthly until six months. After that, most adult dogs are treated roughly every three months, adjusted for their lifestyle. Lungworm is the exception and needs monthly prevention all year round.

Can Humans Get Worms From Dogs?

Yes, though this tends to worry owners more than the actual risk warrants. Roundworm is the main concern, and children are most at risk because of hand-to-mouth contact with contaminated soil. With regular prevention and ordinary hygiene, the risk is very low. Wash hands after handling soil or stool, and pick up from the garden promptly rather than leaving it.

When Worms Become an Emergency

Worms are occasionally life threatening. This is most likely in young puppies carrying very heavy burdens, and in dogs whose lungworm has gone untreated, where the risk is bleeding that will not stop.

The red flags are pale gums, marked lethargy, dehydration, a persistent cough, unexplained bruising or any difficulty breathing. Contact an emergency vet right away if your pet is displaying any of these symptoms.

Get Emergency Veterinary Advice for Your Dog

We are here to provide 24/7 vet care for your pet at any hour. Please get in touch if you think your dog may have worms, or if a puppy is unwell and you are not sure how worried to be, and we will talk you through the next step.

Worms in Dogs: FAQs

What do worms look like in dog poo?

It depends on the type. Roundworms look like strands of spaghetti, tapeworm segments like grains of rice, and whipworms like fine threads, though these are rarely seen at all.

How often should I worm my dog?

How often we worm a dog depends on their lifestyle, location, and age. Talk to your vet about the ideal routine for your dog, which may change over their lifetime. Lungworm prevention should be monthly.

Can I get worms from my dog licking me?

The risk is low, but it is sensible to wash licked skin with warm, soapy water, and to keep your dog’s worming up to date if they lick faces or hands.

Are worms in dogs an emergency?

It is uncommon, but worms can become an emergency, particularly in a very young puppy or in a dog with untreated lungworm. If you are worried your pet is not coping, contact your local emergency vet right away.