How to treat dogs and cats for worms

July 6, 2022 - 8 min read

This article was written for the United Kingdom market and the advice provided may not be accurate for those in the United States.

Dog sniffing poo
Dog sniffing poo

The thought of worms in your cats and dogs probably makes your skin crawl. But they’re incredibly common – almost all cats and dogs will have intestinal worms at some point in their lives.

Worms are easy to treat and are normally not life-threatening for your pet, but they can lead to more serious health complications if they’re left and allowed to reproduce.

Follow a recommended worming schedule to keep intestinal worms in check, as well as other types of internal parasites like heartworm and lungworm.

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Why do I need to worm my pet regularly?

It often won’t be obvious that your dog or cat has worms. They probably won’t have any symptoms until they have a very heavy infestation, and by that point, the worms could be doing them real harm.

A regular, preventative worming schedule will keep on top of the number of worms they have and make sure they never have enough buildup to cause them problems.

How often should I worm my dog or cat?

As a general rule, both dogs and cats should be wormed every three months.

But you need to talk to your vet about your own pet’s lifestyle as some are at greater risk than others and they may recommend you worm them more frequently.

Worming more often might be recommended for:

  • Cats that hunt wild rodents and birds often

  • Dogs and cats that are fed a raw food diet

  • Dogs that tend to eat the poo of other animals

  • Animals that are frequently exposed to fleas

Because of these different lifestyle factors, some animals may need worming more often than others. For example, a farm dog may need to be wormed more frequently than household pets.

Cats and dogs that appear healthy can still carry worms, which is why it’s important to worm dogs regularly.

Dog and cat worming schedules

There are different types of deworming medication available which prevent and treat intestinal parasites:

  • Liquid or paste

  • Tablet

  • Spot-on treatments

It’s really important that you know that not all worming medications kill the same worms. Different worms may need different treatments and you should speak to your vet for advice on the best wormer or combination of wormers for your pet.

Most wormers are given every three months. But wormers that treat non-intestinal worms like lungworm and heartworm tend to have a more frequent treatment schedule.

For example, if you live in an area where your dog’s at risk of lungworm, your vet might advise a monthly treatment that kills lungworm and intestinal worms instead of a three-monthly treatment for intestinal worms only.

How to worm puppies and kittens

Did you know that puppies and kittens are often born with worms? They can catch roundworm from their mother while still in the uterus and they can also get them from their mother’s milk shortly after birth.

Because of this, a worming schedule for puppies and kittens should begin at three weeks old. Worming should then be repeated about every two weeks to prevent reinfection, until they’re six months old.

Follow your vet’s advice on what worming product you should give your puppy or kitten and how often. Worms can be particularly damaging in young animals so it’s important you have an effective deworming schedule for them.

Can you worm a pregnant cat or dog?

You can and should worm pregnant pets. It’ll protect both your pregnant cat or dog and her puppies or kittens.

Other ways to prevent worms

Dogs inevitably like to put different things in their mouth. It’s important to keep a dog’s surroundings clean and to prevent them spending time in areas that may be contaminated–this can reduce the risk of worm infections being picked up.

Regularly clean toys and bowls for your pets to avoid cross contamination.

Flea preventative treatment is also important in dogs and cats as fleas are the most common way of contracting tapeworms.

Are there natural alternatives to regular worming treatments?

Some people feel that frequent worming medications can be harsh on your pet’s system and may look to natural alternatives.

As long as you follow the dosing amount and intervals, commercial wormers are safe for your pet. Natural alternatives to wormers aren’t likely to be as effective and could even be harmful.


Garlic is actually toxic to dogs and cats. It’s likely to do your pet more harm than good.

There’s no reliable evidence showing that garlic can reduce either adult worms or eggs in dogs and cats, yet it’s one of the most commonly suggested alternative worm remedies.

Pumpkin seeds

Social media myth has it that pumpkin seeds contain a chemical called cucurbitin which ‘paralyses’ worms so they can then be expelled.

Again, there’s just no evidence for the claims. Adding a fatty, fibrous food to your dog’s diet is quite likely to upset their tummy though and it’s pretty unlikely cats will be inclined to eat them in the first place.

‘Hairy’ treats

The theory here is that furry treats like rabbit or cows ears will act like a ‘brush’, sweeping away intestinal parasites as they pass through your dog’s digestive system.

At least this one is unlikely to do any harm – your dog will probably find the odd furry ear a very welcome treat.

Again, there’s no evidence that this works, but there's no harm trying it in addition to a more conventional worming regime from your vet.

Types of intestinal worms in dogs and cats

There are four common types of intestinal worms in dogs, they are:

  • Roundworms

  • Tapeworms

  • Hookworms

  • Whipworms



Roundworms are the most common parasitic worms for dogs and cats. They are brown and can grow up to around 10cm. You may see them in your pet’s poo, where they look like noodles.

Roundworms live in the gut where they ‘steal’ nutrients from your dog or cat’s food. This can cause diarrhoea, vomiting, stomach pain and weight loss. Pets can become more lethargic and develop a swollen potbelly.

Roundworms are particularly dangerous for puppies because they can stunt their growth by depriving them of the vital nutrients needed for their development into adulthood.



Tapeworms are also very common and live in the intestines. They are white, flat and around 30cm long, although they can grow much bigger.

You’re unlikely to see a full-sized adult tapeworm, but they are normally seen as broken-off pieces that look like grains of rice in a dog’s poo. Like roundworms they can cause weight loss.

Dogs and cats normally become infected with tapeworms from fleas which they often accidentally eat. These infected fleas spread the parasite which leads to worms. Cats can also pick them up by hunting and eating infected rodents or birds.

Dogs can also get tapeworm by eating the poo of infected animals like sheep or cows, or even from raw meat.

Dogs with tapeworm sometimes ‘scoot’ which involves dragging their bottom across the ground. This is because the broken-off pieces cause itching.


Hookworms aren’t frequently found in UK in dogs but they are fairly common in foxes. Cats are unlikely to get hookworm, although it is possible.

Hookworms are small – around 10-20mm long. These blood-sucking parasites live in the digestive system of dogs and cats. They have a hook that attaches to the intestinal lining and feeds on blood, which can cause anaemia. This loss of blood can be particularly dangerous for puppies and kittens.

Unusually, hookworm can get into your pet through their skin. They can also migrate around the body. Intestinal hookworms are usually a result of ingesting the larvae found in the poo of other dogs or foxes.

Hookworm have similar symptoms ot other types of intestinal worms: vomiting, diarrhoea, anaemia, weakness, lethargy and pale gums.


Whipworm are pretty rare in dogs in the UK and they don’t infect cats. They live in the large intestine of dogs and get their name from their shape. They have one end which is tapered and looks like a whip.

This thicker end embeds itself in the intestinal wall as the worm matures. This causes irritation and discomfort for infected dogs and is particularly dangerous for puppies.

Adult whipworms lay their eggs in the large intestine, where they are passed into a dog’s poo to infect the environment. Signs of whipworm include diarrhoea, vomiting and weight loss.

Non-intestinal worms in dogs and cats

There are some other types of worms that your pet can catch. Thankfully they’re fairly rare, but can have some serous symptoms.


Lungworm used to be rare in the UK, but they’ve become much more common and infections are no longer concentrated in certain parts of the UK. Dogs pick them up by eating slugs and snails, or objects they have left their slime on.

Lungworm are only small, but they live in the heart and arteries of the lungs where they can do terrible damage.

Symptoms include a cough and struggling to breathe. Severe infestations are life threatening but fortunately they’re easily dealt with by using the right regular worming treatment.


Heartworm are spread by mosquitos. They aren’t found in the UK, but your dog is at risk if you take them abroad or they’re from overseas.

They travel in the bloodstream and live in the heart. It can take six months or so for them to show symptoms. The most common symptom is a cough.

The worms can eventually block the flow of blood to the heart and sadly this is usually fatal.


Thelaziasis is an eyeworm infection that has had only a few cases in the UK. It has been found in dogs brought back from Europe.

Inflammation of the eye is the main symptom and sometimes worms can be seen on the surface of the eye.

Symptoms of worms in dogs and cats

All four types of intestinal worms tend to have some common symptoms but it can be difficult to spot the signs of worms in the early stages of infection.

Typical symptoms are:

  • Weakness and listlessness

  • Loss of appetite

  • Weight loss despite an increased appetite

  • Diarrhoea or vomiting

  • Swollen belly

  • Dry coat

  • Scooting (when your dog rubs their bottom on the floor)

  • Licking their rear

  • Coughing

  • Signs of infection in a puppy’s poo such as spaghetti-like worms, rice-like grains, mucus or blood

Your vet may diagnose worms by performing a microscopic examination on their stool specimen, or they may just prescribe a treatment based on these symptoms.

How do animals get worms?

The most common ways dogs and cats get worms are:

  • Eating worm eggs found in contaminated soil

  • Transmission from a mother to a puppy or kitten through her milk

  • Transmission during pregnancy from a mother to her unborn offspring

  • Contaminated animal faeces from outside

  • Eating infected fleas

  • Killing or eating dead animals such as rodents, birds and insects (slugs, earthworms, cockroaches) that are carrying worm eggs

Can cats catch worms from dogs?

Cats can catch worms from dogs and vice versa. They can cross from one to the other with fleas infected with tapeworms, or one species may come into contact with the poo of the other.

If you have a multi-pet household with cats and dogs, it’s a good idea to deworm everyone at the same time so they don’t pass them back and forth.

Can people catch worms from dogs and cats?

Humans can catch intestinal worms from dogs, but this is rare and unusual. The most common parasite passed from dogs to humans are hookworms, which are more prevalent in children than in adults.

Raw feeding and worms

Raw meat can be one way dogs and cats get worms, but it’s unlikely to be a risk with frozen commercial raw food.

Raw pet meat usually meet standards that make it fit for human consumption. The food will also usually have been frozen for some time, killing worms and parasites.

If you’re raw feeding from a non-commercial source of meat, be cautious. Freeze meat for a few days before feeding and make sure you worm your pet regularly.

Derri Dunn
Content marketer

Derri is a personal finance and insurance writer and editor. After seven years covering all things motoring and banking at GoCompare, Derri joined ManyPets in 2021 to focus on pet health. She has fostered cats and kittens for Blue Cross and Cats Protection and is owned by tabby cat Diggory and two badly behaved dogs.