puppy and parasites

Parasites and Your Puppy

March 23rd marks National Puppy Day; a chance to show our love for those gorgeous bundles of cuteness in our lives (as if we needed an excuse for that!). If you’ve recently welcomed a brand-new puppy into your home, it’s likely that you’ve had friends and family (and probably pretty much everyone else you’ve ever met!) queuing up for a cuddle. But your two-legged visitors aren’t the only ones that are keen to spend time with your new arrival; creepy crawly parasites like worms, fleas and ticks can target your pooch and make them quite unwell. We want to help you learn more about parasites and your puppy. 

We’re here to give you the lowdown on these pesky parasites and your puppy, and more importantly, to share some top tips to help you protect your pup, so they can get on with growing into those paws and enjoying their puppy-hood!

First Encounters

Your puppy’s first encounter with a parasite is likely to have taken place earlier than you may imagine, as the roundworm, Toxocara, can infect our fur babies before they’ve even been born.


When adult dogs are infected with roundworm, some of the larval stages of the parasite become trapped in our pet’s tissues, where they remain dormant. When a bitch becomes pregnant, these larvae reawaken (horror movies have been based on less terrifying thoughts!), and some travel to the placenta, where they pass across to the developing pups. Others make their way to the mammary glands, ready to infect the new born pups when they’re suckling milk, providing a continual source of infection every time your puppy feeds. Whichever way you look at it, your pup really doesn’t stand much of a chance of avoiding this pest!

Roundworms can be an issue for any animal, but for youngsters like puppies, they can be really dangerous. Puppies with roundworms  often have a pot belly and their coat may be dull and lacklustre. Pups may show signs of vomiting and diarrhoea, and generally don’t grow and thrive as you’d expect (no small wonder, as these wriggling creatures steal vital nutrients from your pup’s guts as they feed). Even more seriously, these worms  (that can grow up 18cm long inside your pooch!1) can cause a blockage in your pup’s guts, which, if left untreated, can prove fatal.

To add insult to injury, roundworms can cause disease in people too, so treating our pups against this parasite is crucial to protect not just them, but ourselves and our families, too.


Early Days

As well as the ongoing threat from roundworms, pups are at risk from other parasites from an early age, too. 


Another common pest that targets our pups, is the infuriating flea. These small, wingless insects can hop onto your puppy’s coat, where they burrow down to their skin and bite your pup to feed on their blood. Puppies can pick these irritating critters up from their mum or litter mates, and will continue to be at risk of an infestation when they start to venture outside.

And fleas can do more than just bite! If pups are infested with high numbers of these crawling critters, they can lose enough blood to become anemic, a condition that can be really serious if not treated early. Some pups are allergic to flea bites, which means that just a single bite can lead to a severe (and very itchy) skin reaction. Fleas can even pass a whole extra parasite onto your pooch- which brings us onto the next creepy crawly on our list: the tapeworm!





Fleas are carriers of the immature stage of the tapeworm, Dipylidium caninum. When pups swallow infected fleas, which, unpleasant as it sounds, happens quite naturally when they groom themselves, they can wind up with one of these wriggling creatures growing inside their guts. As if the thought of a worm living inside your pet wasn’t revolting enough, these worms up the ante by releasing small white segments , packed full of worm eggs, that can often be spotted crawling in the fur around an infected pet’s bottom. As you can imagine (not that you want to!), this causes a lot of irritation, so if you notice your pet scooting their bottom along the ground, there’s a decent chance that a tapeworm has taken up residence inside your pet!


Out and About

Around two weeks after puppies have completed their course of vaccinations, they can start venturing outside. It’s an exciting time for you both, but these new adventures can bring your still-vulnerable furry friend into contact with an array of novel parasites.

Roundworms and tapeworms will continue to pose a risk to your pup throughout their lives. Pets can swallow roundworm eggs from the soil, and can contract both round and tapeworms from hunting or eating undercooked meat. To keep us all on our toes, there are some other pesky parasites that pets might stumble across once they’re exploring outside, too.


Snuffling around in the great outdoors is one of the simple joys of puppyhood, but there are some unseen dangers hiding out in even the most innocent-seeming places. Hookworm larvae can be present in the soil; and if pups swallow these while they’re exploring, they can end up with a fully-fledged hookworm living inside their guts. Parasites aren’t pleasant at the best of times, but hookworms take this to a new level, biting your pooch’s gut wall in order to feed on their blood.

Hookworms in puppies can cause diarrhoea, and even anaemia if worm numbers are high. And, believe it or not, there’s another, even more gruesome side to this parasite! Hookworm larvae in the soil don’t just wait to be eaten; they are also able to burrow into the skin of passing feet, causing intense irritation! This doesn’t just affect our pets, either …so if you love the feel of grass beneath your bare feet, be warned, especially if you’ve not wormed your pooch recently!



Another, less than delightful pest that your puppy might encounter on their travels is the whipworm. This creature, named for its whip-like shape, lives in an infected dog’s large intestine, and your pet can become infected if they swallow whipworm eggs when they’re exploring outside. The worm burrows its head into the lining of your puppy’s gut wall, and feeds on the resulting blood; so, like many other blood-feeding parasites, it has the potential to cause anaemia in young puppies. Pups that are infected with high numbers of worms might also have diarrhoea containing blood, and may suffer from weight loss too.


Ticks hide out in areas of long grass and woodland, and can leap onto your pup as they brush past. These  eight-legged creatures embed their mouthparts into your pet’s skin in order to feed on their blood, and once attached they will stay in the same spot for days or even a week or more, growing hugely in size as they feed. Like fleas, ticks aren’t too fussy about where their meals come from, and will happily attach to people as well as to pets, to get their fill of blood. Ticks are notorious for their ability to spread diseases; Lyme Disease for example can be spread to both dogs and people from an infected tick bite, and can be a debilitating condition if left untreated. 

Speak to Your Vet

Depending on where in the country you and your pup live, there may be other parasites that pose a threat to your pet. It’s always a good idea to chat to your vet about the specific risks in your own area, so that you can make sure your pooch is protected against any local threats. 


Protecting Your Pup

Delving into the world of parasites can make it feel like there’s a threat around every corner- but luckily, protecting your puppy is simpler than you might think.

If you’re welcoming your pup into your home at around 8 weeks of age, they should have already started a course of worming treatment; current guidelines  recommend worming pups with a suitable wormer at two weeks of age, and then every two weeks until two weeks after they’ve weaned.2 Your breeder should let you know what wormer they’ve given already, and when your pup’s next dose is due.  

Once puppies have left their mums, worming should continue monthly until they’re six months old2, and most dogs should then be wormed at least every three months throughout their lives.

Prazitel Plus makes worming simple: this worming tablet is specially formulated for dogs, has a tasty pork flavour, and kills all types of intestinal worm commonly affecting UK dogs- including roundworms, tapeworms, hookworms and whipworms. 

For those creepy crawly fleas and ticks, Fipnil Plus is a simple spot-on that kills both fleas and ticks, and can be used on a monthly basis on pups from 8 weeks of age.

Welcoming a new pup into your family is a truly special time, so don’t let parasites get in the way! Treating your puppy on a regular basis against fleas and worms helps keep them happy and healthy, and lets you focus on snuggling up with your gorgeous new bundle of energy, free from the worry of these creepy crawlies! 



1. Taylor MA, Coop RL, Wall RL. 2007. Veterinary Parasitology, Third Edition. Blackwell Publishing Ltd.

2. Esccap Guidelines: Worm Control in Dogs and Cats.  Sixth Edition, May 2021