You spot them on the blanket. Small pale things, rice-sized, and one of them is moving.
It’s a grim moment and it’s an extremely common one. Every dog encounters parasites; the question is only whether they’re being dealt with. Worming gets treated as a chore to be got through, which is a shame, because understanding what you’re actually treating makes the difference between a schedule that works and one that misses the thing your dog has.
Two things before the detail
Prevention beats treatment, and it isn’t optional. A dog carrying a parasite burden has a disrupted gut, absorbs less from his food, and in the case of lungworm may be in genuine danger. Nothing in this article is an argument for waiting until you see something.
And worming is hard on the digestive system. It kills organisms inside the gut, and a day or two of loose stools afterwards is common. That’s an argument for supporting the gut around it rather than skipping it – daily Probiotic Dog Treats being worth having in place before treatment rather than after it, so the population goes into the process in decent condition instead of recovering from a standing start.
With that established, here’s what you’re actually dealing with.
The ones that matter in the UK
Roundworm. The most common. Almost all puppies are born with it, passed from the mother before birth or in her milk. Adults pick it up from contaminated ground. Looks like pale spaghetti in stools or vomit. Causes a pot belly, poor coat and soft stools in puppies. Transmissible to humans, and that matters most for young children.
Tapeworm. The rice grains on the bedding. Segments break off and crawl out, which is how most owners find them. The commonest type is transmitted by fleas – the dog swallows an infected flea while grooming – so a tapeworm problem is very often a flea problem nobody had noticed.
Hookworm and whipworm. Less common, more troublesome. Whipworm in particular causes large-intestinal diarrhoea with mucus and blood that looks exactly like colitis, and it’s frequently missed because the eggs are shed intermittently.
Lungworm. The one to take seriously. Spread by slugs and snails, and by the slime trails they leave on grass, toys and water bowls left outside. It’s spread across much of the UK over the last two decades. Signs are vague – coughing, breathlessness, tiring easily, and crucially, unexplained bleeding or bruising, because it interferes with clotting. It can kill, ordinary wormers don’t cover it, and prevention needs a specific product from your vet.
Giardia. A protozoan rather than a worm, picked up from puddles, streams and contaminated ground. Causes persistent soft, foul stools and wind in a dog who’s otherwise well. Needs specific treatment.
What worming does to the gut, and why it’s still worth it
Worming is not gentle. It kills organisms inside the digestive tract, and it’s common for dogs to have a day or two of softer stools afterwards.
That’s a reason to support the gut around it rather than a reason to skip it. A dog carrying a worm burden has a considerably more disrupted gut than one who’s just been treated, and there’s no version of leaving parasites in place that ends well.
Practically: give the wormer with food unless the label says otherwise, and keep daily support running through it. The point is that the population is in reasonable condition before the treatment rather than being asked to recover afterwards from a standing start.
The schedule, and why “every three months” is a rule of thumb
Most adult dogs are wormed quarterly. It’s a reasonable default and it isn’t a law of nature.
Puppies need much more: typically every two weeks from around two weeks old to twelve weeks, then monthly to six months. Follow your vet’s schedule exactly rather than approximately.
Adults at higher risk need more frequent treatment – dogs who scavenge, dogs who eat faeces, dogs who hunt or eat raw prey, dogs in households with young children, and dogs who swim in or drink from standing water.
Lungworm prevention is separate. It’s usually monthly and it isn’t covered by most standard wormers. If you’re in an area where it’s present – which is now most of the UK – that’s a specific conversation with your vet.
The alternative to blanket worming is testing. Pooled faecal samples across three consecutive days, a few times a year, and treat when something’s found. It’s a legitimate approach, it reduces unnecessary medication, and it costs more in vet visits. Worth discussing rather than assuming quarterly tablets are the only option.
Fleas, and why they belong in this conversation
You cannot manage tapeworm without managing fleas.
Every animal in the household needs treating, year-round, with something reliable. Central heating means fleas no longer take a winter off, and treating only the dog while the cat goes untreated achieves very little.
The environment matters too. The large majority of a flea population is in the carpets and bedding as eggs and larvae rather than on the animal, so treatment usually needs to cover the house as well as the pets. Hot-wash bedding, vacuum thoroughly and empty the cylinder outside.
Supermarket spot-ons are a common source of frustration – resistance is widespread and results are often poor. Vet-supplied products cost more and generally work.
Signs worth noticing
Visible worms or segments, in stools or around the back end.
Scooting and licking, though soft stools and anal gland trouble are the more common explanation for that.
A pot-bellied appearance in a puppy, particularly alongside poor growth.
Dull coat, poor condition, a big appetite with no weight gain.
Persistent soft stools, mucus, or intermittent diarrhoea with no dietary explanation.
Coughing, breathlessness, unusual tiredness, or any unexplained bruising or bleeding – lungworm, and that’s an urgent appointment rather than a routine one.
Plenty of infected dogs show nothing at all, which is precisely why routine prevention exists.
The human side
Roundworm is the one that matters, and it matters most for children.
Practical measures: pick up faeces immediately in the garden and on walks, wash hands after handling the dog and before eating, keep sandpits covered, and don’t let dogs lick faces – particularly children’s.
None of that is a reason for anxiety about having a dog. It’s a reason to keep worming current and be sensible about hand-washing.
Raw feeding and parasite risk
Worth its own note, because it changes the calculation.
Raw diets carry a higher parasite risk than cooked or processed food. Tapeworm species transmitted through raw meat and offal are the main concern, and freezing reduces but does not reliably eliminate the risk for all of them.
Dogs fed raw generally need worming more frequently than the standard quarterly schedule. That’s a conversation with your vet about your specific diet and sourcing rather than a blanket number.
The same applies to dogs who hunt – rabbits, rodents, birds – and to dogs who eat raw prey on walks whether you’ve offered it or not.
None of this is an argument against raw feeding. It’s an argument for adjusting the schedule to the actual risk rather than following a generic one.
When worming doesn’t seem to be working
You’ve treated, and a fortnight later there are still soft stools, still segments, still a dog who isn’t right.
Work through it in this order.
Check the dose against current weight. Underdosing is the commonest reason, especially in growing puppies and in dogs who’ve put weight on since the last treatment.
Check what the product actually covers. Many over-the-counter wormers don’t cover tapeworm and almost none cover lungworm. If you’re treating for the wrong thing, the dose is irrelevant.
Check every animal in the house was treated, on the same day.
Check for fleas. Persistent tapeworm almost always means an ongoing flea problem somewhere.
Then ask for faecal testing – pooled across three consecutive days, because shedding is intermittent and single samples miss a great deal. Giardia and whipworm in particular are routinely missed this way.
And if testing comes back clear and the stools still aren’t right, the problem probably isn’t parasites at all. That’s the point to look at diet, dysbiosis and food-responsive disease instead of worming again.
Practical points people get wrong
Dose by current weight. Puppies outgrow their dose in weeks, and underdosing is one of the main reasons treatment appears not to work.
Not all wormers cover everything. Many don’t cover tapeworm; almost none cover lungworm. If you’re buying over the counter, check what’s actually in it.
Faecal testing is worth more than most owners think, particularly for chronic soft stools that haven’t responded to anything. Giardia and whipworm are missed constantly, and both need pooled samples rather than a single one.
Treat every animal in the house at once. Treating one dog in a household of three achieves very little.
Write the dates down. Nobody remembers when they last wormed. A note on the calendar or a phone reminder is the difference between a schedule and a good intention.