The Ultimate Guide to Worms in Pets

Knowing which parasites can affect your pet is essential to ensuring they are happy and healthy.

Pets can pick up both external parasites (such as fleas, ticks, and mites) and internal parasites (such as intestinal worms). These worms can have a profound effect on your pet’s digestive and overall health, so it’s important for you to know the types of worms that can affect your pet, as well as the symptoms of worms and how to treat them.

That’s why we’ve put together this guide, complete with all the information you need to keep your pet worm-free!

Contents:

1. Tapeworms in Cats and Dogs
2. Roundworms in Cats and Dogs
3. Hookworms in Cats and Dogs
4. Whipworms in Cats and Dogs
5. Heartworms in Cats and Dogs
6. Lungworms in Cats and Dogs
7. Worming Puppies
8. Worming Kittens
9. Preventing Worms in Dogs and Cats

Tapeworms in Dogs and Cats

One of the most common worms found in pets is the tapeworm (Dipylidium caninum), which attaches itself to the wall of your pet’s small intestine with hook-like mouthparts so it can feed off what the host eats.

Despite their scientific name, tapeworms can affect cats and dogs, and can even spread to humans in certain circumstances.

An adult tapeworm is a long, flat, white worm that can reach up to 50cm in length. They’re composed of dozens of 3mm segments, which continue to spread down the small intestine before the tail-end segments break off in your dog’s faeces. These can often be seen crawling around in fresh droppings and can even be found around your pet’s rear end or tail.

These segments also contain tapeworm eggs, which will lurk in the environment, waiting for the life cycle to begin again.

How Do Pets Get Tapeworms?

Pets can pick up a tapeworm in a couple of ways, but the most common is through fleas.

Flea larvae will ingest the tapeworm egg, which they will carry onto the pet once they’ve grown. The pet will then ingest the infected flea (likely while grooming), and the immature worm will hatch, settle in the small intestine, and grow into an adult tapeworm. This is why ensuring your pet is properly treated for fleas and worms is so essential.

If you’re worried your dog may have fleas, check out our complete guide to getting rid of them. Also, to protect them against tapeworms, you should protect them against fleas, with a suitable flea treatment for dogs or cat flea treatment.

Another way pets can pick up tapeworms is by scavenging or eating something infected with tapeworm eggs or larvae. This can be from eating raw meat from livestock or rodents, or from eating another dog’s infected faeces. It’s gross, but it does happen

Symptoms of Tapeworms in Dogs & Cats

There aren’t many noticeable symptoms when it comes to a minor tapeworm infection besides being mindful of your dog’s poop.

Here, you may be able to see the broken-off segments of a tapeworm crawling around, or even in their bedding. These parts tend to look like mobile grains of rice. If these segments have dried, they can appear like tiny yellow specks that stick to your dog’s fur or bedding.

For more severe infections, there are some symptoms you can look out for, including:

• Your pet scooting on their bum and trying to lick or bite the area.
• Vomiting (however, this could be a sign of various things)
• Weight loss despite eating normally (caused by the tapeworm feeding on the nutrients in your pet’s food)

Symptoms of tapeworm infestations can also overlap with symptoms of other conditions. If you notice any of the above symptoms in your pet, book a consultation with your vet for a complete diagnosis.

While it can be difficult to diagnose a tapeworm infestation, as the tapeworm will not shed segments every time your pet poops, your vet may be able to diagnose tapeworms by examining a stool sample under a microscope.

Roundworms in Dogs and Cats

Another common worm that pets pick up is a roundworm, named for its tubular or round shape.

Also referred to as nematodes or ascarids, roundworms are another kind of internal parasite that live within your pet’s intestine and feed off the partially digested food contents. They can grow inside the intestines to be 13 inches long and as thick as a pencil. Plus, they can live for years inside a host, where an adult female roundworm can lay more than 200,000 eggs a day, which are passed through faeces and spread the infection further.

Roundworms are the most common intestinal worms in the UK, and most pets have been infected with them at some point in their lives.

An infected mother can even pass roundworms to their young with the infection passing to puppies or kittens via the placenta while still in the womb or through the mother's milk.

There are two kinds of roundworms that your pet can pick up:

• Toxocara canis
• Toxascaris leonina

Of the two, Toxocara canis is the more dangerous of the pair and can spread other diseases to your pet, as well as be transmitted to humans.

Roundworms pose a particular risk to children, puppies and kittens because their intestines are smaller, leaving less room for the worms to grow, which can result in:

• Stomach pain and bloating
• Vomiting
• Worms coming out of the animal’s nose or mouth
• Fever
• Wheezing and coughing
• Weight loss or failure to grow
• Blocked intestines

In some severe cases, children may even need to undergo surgery to remove the roundworm blockage from their intestines. This is why treating all your pets for worms is essential, especially if you have children in the home.

How Do Pets Get Roundworms?

Roundworm infestations start when an animal consumes the roundworm eggs. The eggs pass through the animal's digestive system and settle in the stomach, where they hatch and grow before starting the life cycle again.

Pets can pick up roundworms in a variety of ways, including:

• Eating or licking infected faeces
• Eating infected soil or drinking infected water
• Eating raw meat from an infected animal, particularly cats who like to hunt rodents that act as a paratenic host accidental transport host).

As mentioned above, puppies and kittens can also catch roundworms from their mother while in the womb or by consuming milk.

Like children, kittens, and puppies don’t have enough space for the roundworms to grow properly, which can result in bloating and intestinal blockages. Worming puppies and kittens is just as important as treating adults, as roundworms can cause stunted growth and other problems in young animals.

Symptoms of Roundworms in Dogs & Cats

Most pets (particularly adult pets) won't show any symptoms of a roundworm infection unless it has become severe. This can happen much quicker in puppies and kittens, and you may notice the following symptoms:

• Diarrhoea
• Vomiting
• Weight Loss
• Dull hair
• Potbellied appearance

Growing animals may also exhibit signs of stunted growth from the lack of nutrients.

In severe cases, dogs can throw up roundworms or cough them up if they have entered the lungs. If you think your pet may have roundworms, you may be able to spot them in their faeces or vomit.

Sometimes, a vet can properly diagnose roundworms in your pet by mixing a stool sample with a liquid solution that causes the roundworm eggs to rise up. They can then be viewed beneath a microscope and identified.

Hookworms in Dogs and Cats

Hookworms (specifically Ancylostoma caninum, Ancylostoma brasiliense, and Unicinaria stenocephala) are another parasite that can live inside your pet’s large intestine. There, they will attach themselves to your pet’s intestinal wall lining, where the hookworm will feed off your pet’s blood instead of consuming nutrients from your pet's food.

Hookworm eggs are then released into your pet’s digestive tract and passed back into the environment through faeces to start their life cycle again.

Hookworms receive their name from their visibly bent head and mouth parts, which resemble a hook, allowing them to anchor themselves onto your pet’s intestinal lining. These worms are thin and white, growing to 8-15 mm in length, depending on age and sex.

As with tapeworms and roundworms, hookworms can also be spread to humans, or humans can pick them up from the environment.

How Do Pets Get Hookworms

Like other parasites, hookworms can be picked up by your pet from its environment, particularly through eating infected soil, faeces, or drinking infected water.

However, unlike the previous worms we’ve mentioned, hookworms can also be picked up through your pet’s skin as larva before making their way through the bloodstream to the lungs before being coughed up and swallowed to find themselves in the intestines. Here, they will grow and continue the life cycle.

Like roundworms, hookworms can also infect litters of puppies and kittens by being ingested through their mother’s milk and passing through the placenta while they’re still in the womb.

Symptoms of Hookworms in Dogs and Cats

As pets often pick hookworms through the skin, you may be able to see the site of infection where the hookworm larvae burrowed through.

Hookworms feed on blood, which can also cause your pet to suffer from anaemia, the symptoms of which include:

• Pale gums, ears or eyes
• Weakness or lethargy
• Weight loss
• Bloody diarrhoea or black stools
• Poor growth

If you notice any of these symptoms in your dog, consult your vet immediately as they can not only be a sign of a hookworm infestation but also other illnesses. If left untreated, a hookworm infestation can be fatal.

Whipworms in Dogs and Cats

Whipworms (also called Trichuris vulpis) are another common worm your pet can become infested with.

Whipworms get their name from their peculiar shape: a thick anterior end with a long, thin posterior end which resembles a whip. Whipworms can grow up to 6mm long and live in the cecum (a pouch that forms in the first part of the large intestine) and your pet's large intestine, where they attach themselves to the mucosal lining.

Despite their small size, whipworms can cause a lot of discomfort to your pet as they irritate their internal organs and are more likely to spread disease than the other worms mentioned in this guide. While whipworms are found in the UK, they are more commonly found in Europe and are far more likely to infect your dog than a cat.

Whipworm eggs are passed from your pet into the environment through their faeces, where the eggs can survive for up to five years, giving plenty of time for them to reinfect another host and start their lifecycle over.

Once a female whipworm has hatched inside your pet, it takes approximately 11-12 weeks for them to lay their eggs, which they do at an inconsistent rate. This makes it difficult to diagnose a whipworm infestation early on and can result in many false negative tests.

How Do Pets Get Whipworms?

Pets become infected with whipworms by ingesting infected matter from their environment, such as through soil, faeces, water, or from grooming themselves after stepping or rolling in something.

Whipworms may not lay many eggs, but due to their robust nature and resistance to drying out, the eggs can be spread across a wide area and tend to be most common in places with a lot of dog traffic, such as dog walking spots and kennels.

Remember, just because an area has been deemed a low whipworm risk, doesn’t mean your pet can’t still be infected.

Symptoms of Whipworms in Dogs & Cats

Whipworms can cause a lot of damage and discomfort to your pet, so knowing the signs of an infection is essential and should be taken seriously.

The most common signs of whipworms in your pet include:

• Watery, bloody diarrhoea
• Weight loss
• Dehydration
• Anaemia
• Overall health decline

Unlike the other worms mentioned, whipworms are not zoonotic and so cannot be passed from your pet to you.

Heartworm in Dogs and Cats

Heartworms are stringy, spaghetti-looking worms that, after entering your pet, live in the right side of their heart and the main artery to the lungs. The males can reach between 4 and 6 inches, while females are much longer, at an average of 10-12 inches.

Thankfully, heartworms are not native to the UK, but that doesn't mean you shouldn't worry about them. They are, however, a serious risk to dogs brought over from warmer countries and those that travel outside of the UK.

If left untreated, heartworms can be fatal to your dog, so take all the necessary precautions before taking your dog on holiday or when adopting a dog from abroad.

How Do Pets Get Heartworm?

Similar to tapeworms, heartworms use other parasites to enter your pet as they're transmitted through the bite of an infected mosquito. The tiny offspring of these worms (known as microfilariae) travel through the infected animal's blood and are ingested by mosquitoes when they bite to feed.

The infected mosquito then transmits immature heartworms to the new host when it bites another dog, allowing the heartworm infestation to take root.

Once inside your dog's body, the offspring of these worms travel through the bloodstream to the heart, a process that can take up to 6 months.

There, they mature into worms that can cause significant damage to your dog's heart, lungs and other organs, and these effects can linger even after the parasite is gone. Some of the conditions heartworms can cause in dogs include:

• Inflammation of the blood vessels
• Blocked blood flow from the heart and lungs
• Pulmonary Thrombosis (clots in the heart)
• Heart and kidney failure

While cats are not ideal hosts for heartworms, they can still contract them, though most worms do not reach maturity inside a cat. This makes heartworm hard to diagnose in cats, but even the larvae in their bloodstream can do damage to your cat, so it's always important to be cautious when adopting a cat from abroad in case they're infected.

Symptoms of Heartworm in Dogs and Cats

At the start of a heartworm infestation, your pet is unlikely to show many symptoms. This is a problem because it takes these worms so long to mature that by the time you notice symptoms, considerable damage may already be done to your dog's vital organs.

As the infestation progresses, your dog will begin to show significant symptoms, which include:

• Mild but persistent cough
• Reluctance to walk or play
• Fatigue after slight activity
• Decreased appetite leading to weight loss

The latest stages of a heartworm infection cause a condition called caval syndrome, by which point the number of worms in the heart can lead to sudden blockages in blood flow, potentially leading to cardiovascular collapse.

The key symptoms of a heartworm infestation of this magnitude include:

• Laboured breathing
• Pale gums
• dark, coffee-coloured urine

Dogs that are suffering from caval syndrome will require surgery to remove the worms from their bodies. Dogs that do not receive veterinary intervention rarely survive.

Lungworms in Dogs and Cats

Lungworm is now recognised as an endemic condition across the UK as the number of cases reported by veterinary clinics rises.

These white, thread-like worms can affect both cats and dogs, as well as foxes, which is part of the reason why it's become such a widespread problem. What's worse, only half of pet owners across the UK know what lungworms are, and only 33% take action to treat their pets for them.

While lungworm is less common than other intestinal worms, if left untreated, it can cause damage to numerous organs, including the heart and lungs, and can be fatal in dogs.

How Do Pets Get Lungworms?

Much like other types of worms, lungworm is spread through the faeces of an infected animal. However, the key difference between lungworm and other such worms is that they can also infect slugs, snails and frogs.

Your dog or cat can pick up lungworms while sniffing or digging in the undergrowth, eating grass, or hunting.

The larvae of these worms can even be released into the slime trails left by slugs and snails, meaning any toys left outside that slugs might crawl over can also be infected.

Symptoms of Lungworms in Dogs and Cats

Unfortunately, the signs of lungworm in pets can easily be confused with other illnesses, so it's essential to recognise the possible symptoms so you can contact your vet as soon as possible for a professional diagnosis.

The symptoms of lungworm to look out for include:

• Behavioural changes (such as lethargy, depression or seizures)
• Coughing
• Tiring quickly, even after slight exercise
• Loss of appetite leading to weight loss
• Vomiting and/or diarrhoea
• Blood clotting problems (such as excessive bleeding from minor wounds, nose bleeds, bleeding from eyes, pale gums)

Many worming treatments for dogs and cats tend to target intestinal worms, so they may not protect your dog from lungworms. When choosing a worming treatment for your pet, always read the packaging to ensure the treatment targets all the worms you need.

Treating Cats and Dogs for Worms

No matter how well-trained or behaved your pet is, they still have a mind of their own. The odds are your pet will pick up at least one of these parasites during their lifetime, so knowing how to treat and prevent infections is crucial.

There is a wide variety of pet wormers available, from powders and chewable tablets to spot-on treatments and even oral suspensions. The best worming treatment for your pet depends on their species, lifestyle, and temperament.

Some treatments are known as broad-spectrum wormers, meaning they treat more than just one type of worm and are typically effective against all those listed here, as well as other worms such as heartworms and lungworms.

Active Ingredients in Pet Wormers

Different wormers will have different active ingredients that may or may not be effective for your situation, but the most common are:

• Piperazine - Effective against two types of roundworms in cats and dogs.
• Fenbendazole - A broad-spectrum wormer for use in small and large animals. In dogs, this ingredient is effective against roundworms, hookworms and whipworms.
• Praziquantel - A popular drug for treating adult tapeworm infections in dogs, but doesn’t kill eggs or larvae, so it can result in reinfection.
• Ivermectin - The most commonly used as a preventive for heartworms in cats and dogs, but at higher doses, it can also be effective against external parasites.

How often you worm your pet will depend on a few factors, such as the extent of the infestation or whether you're using the treatment preventatively. Treating infestations typically requires multiple treatments over a few days or weeks, but your vet should determine the schedule.

Otherwise, adult cats and dogs should be treated for worms either monthly or every three months (depending on their risk) as part of their routine healthcare.

Even indoor pets should be routinely treated for worms, since worm eggs from outside can be inadvertently brought into your home on clothes or by other pets. It’s best to be proactive and protect your pet.

Check out our guide if you're unsure how often you should be worming your pet.

Do Puppies Need Worming?

Yes, puppies do need to be treated for worms, and more frequently than adult dogs do .

Puppies can get worms even before they're born via their mother, either through the placenta or their milk.

Worms can also cause serious health issues for puppies, as their intestines are much smaller and don’t provide space for worms to grow, leading to intestinal blockages and bloat.

A general puppy worming routine should look like:

• 2 weeks old - First worming treatment

• Every 2 weeks - repeat treatment
• 12 weeks old - Switch to regular dog worming routine

After these first few weeks, puppies should be moved onto an appropriate puppy wormer and treated every three months, depending on their risk factor, which your vet should evaluate.

To help protect puppies from worms, the mother must be kept up to date with her worming treatments before pregnancy, as well as during and after. In this instance, always make sure you choose a product that is suitable for use in pregnant and lactating bitches.

Do Kittens Need Worming?

Yes, as with puppies, kittens need to be treated for worms. Kittens can also contract worms through their mother's milk.

Worms (particularly roundworms) in kittens can be detrimental to their growth, development, and overall health.

A general kitten worming routine should look like:

• 2-3 weeks old - First worming treatment
• Every 3 weeks - Continue treatment
• 8 - 9 weeks old - Worm monthly
• 6 months old - switch to regular cat worming routine

Even if you plan to keep your new kitten indoors, they will still need appropriate worming, depending on their risk.

Both kitten and puppy worming treatments are determined by body weight. Even if a puppy or kitten is old enough for worming, you should not worm them until they reach the suggested body weight or consult your vet for recommendations.

How to Prevent Worms in Dogs & Cats

Prevention is always the best course of action when it comes to parasites in pets.

This way, you can counter any infestation before the worms have time to do serious damage or spread additional disease to your pet.

Some of the most effective ways to prevent worm infestations in your pet include:

• Treating them regularly with a suitable broad-spectrum worming treatment.
• Regularly disinfect your pet’s food and water bowls.
• Avoid feeding your pet raw meat or letting them eat things that may potentially be contaminated (soil, animal faeces, etc.)
• Always clean up after your pet.
• Build up a strong recall and "leave it" command in dogs to stop them eating things they shouldn't.

By being proactive with your pet's parasite prevention, you can ensure they stay happy and healthy throughout their life.

Worms in Pets FAQs

Worms are a nuisance, but the damage they can do to you and your pet is rarely worth the risk.

The best action is to keep your pet up to date with their routine flea and worming treatments to keep them healthy and parasite-free! If you’re looking for the perfect worming solution for your pet, check out our full range of wormers for dogs and cats below and keep them worm-free for less.