Worms in dog and cat stool — a UK identification guide (with what to do)

Quick answer. Tapeworm segments look like flat, rice-grain-sized white or cream-coloured pieces around the rear, on bedding, or in fresh stool — they sometimes move. Roundworms look like pale, spaghetti-like worms 5–15 cm long, often coiled, sometimes visible in vomit or stool. Hookworms are usually too small to see without a microscope. Whipworms are rare in UK dogs and rarely visible. Most of what owners describe as “worms” in stool is actually tapeworm segments — and finding them does not mean the regular wormer failed; it usually means the cat or dog has been treated for fleas recently or has had access to prey.

If you’ve found something in your dog or cat’s stool and you want to know what it is, this guide is the visual reference. We walk through the five worms UK pets actually get, what each one looks like in stool, what it usually means, and which product treats it.

The five UK worms in one table

Tapeworm segments — by far the most-found

The single most common “worm” UK owners report finding is a tapeworm segment, almost always Dipylidium caninum — the flea tapeworm.

What it looks like: flat, off-white or cream-coloured, roughly the size and shape of a grain of cooked rice or a cucumber seed. Fresh segments are visibly moving — they slowly extend and contract. Dried segments look more like sesame seeds and don’t move.

Where you’ll see it: stuck to the fur around the cat’s or dog’s rear (especially under the tail), on bedding or where the pet sits, around the litter tray, or sometimes in fresh stool.

What it means: Dipylidium needs a flea to complete its lifecycle. The cat or dog must have ingested an infected flea (almost always while grooming). Finding segments means the pet has had fleas recently, even if you haven’t seen the fleas themselves. Tapeworm cysticercoids can survive inside the flea for weeks, so the flea exposure may have been a month or more ago.

What treats it: any praziquantel-containing wormer clears Dipylidium effectively. That includes Biheldon, Drontal Cat, Drontal Dog Tasty Bone, and Milbemax. Panacur (fenbendazole alone) does not cover Dipylidium — this is one of the major limitations of using Panacur as a standalone wormer.

What else to do: if you’ve found tapeworm segments, treat the cat or dog with a praziquantel-containing product, AND start (or restart) consistent flea control. Worming alone without addressing the fleas means the pet will re-acquire tapeworm within weeks.

Taenia tapeworm segments — for hunting cats and raw-fed dogs

A second tapeworm type, Taenia species, is acquired by eating infected prey — mice and voles for hunting cats, rabbits and small rodents for dogs. Raw-fed dogs and cats can also acquire Taenia from raw meat that contains cysticerci.

What it looks like: rectangular, slightly larger than Dipylidium segments (5–10 mm vs 2–5 mm), white-ish. Usually less mobile than Dipylidium segments by the time you see them.

What it means: the pet has eaten prey or raw meat carrying Taenia cysticerci.

What treats it: praziquantel-containing wormers (Biheldon, Drontal, Milbemax). Panacur (fenbendazole) covers Taenia — this is the one tapeworm Panacur does treat, but it doesn’t cover Dipylidium.

Roundworms — pale spaghetti, mostly in puppies and kittens

Toxocara canis (dog roundworm) and Toxocara cati (cat roundworm) are the worms most people picture when they think “worms”.

What it looks like: pale cream or off-white, smooth, like very thin spaghetti. Adults are typically 5–15 cm long. Often found coiled or knotted. You may see them in vomit (cats and dogs with heavy burdens sometimes vomit live worms) or in stool.

What it means: in puppies and kittens under 6 months old, roundworms are extremely common — vertical transmission from the dam (transplacental in dogs, trans-mammary in cats) means most are born already infected. In adult dogs and cats, visible roundworms usually indicate a heavier-than-typical burden, either because worming has been delayed or because of significant environmental re-exposure.

What treats it: all UK-licensed wormers cover roundworms — Biheldon, Drontal (any), Milbemax, Panacur, Bob Martin Clear, Stronghold spot-ons. For puppies and kittens, the standard schedule (every 2 weeks from 4 / 3 weeks of age until 12 weeks) is the right approach.

What else to do: if you see roundworms in stool, give the next scheduled dose now rather than waiting. For puppies and kittens, also worm the dam concurrently — she will be re-shedding from her own larval reservoir.

Hookworms — rarely visible

Ancylostoma caninum and Uncinaria stenocephala in dogs (less common in UK cats) live in the small intestine and bite into the gut wall to feed on blood.

What it looks like: small (1–2 cm), thin, dark-coloured worms. You will not usually see them in stool — adult hookworms attach tightly to the gut wall and aren’t shed alive in the way roundworms or tapeworms are. You’d more likely see hookworm eggs on a faecal exam at the vet (not visible to the naked eye).

What it means: if you do see what you think is a hookworm in stool, you’re more likely seeing an immature roundworm. If you see clinical signs of hookworm — pale gums (from blood loss), dark tarry stools (digested blood), weight loss in a dog who isn’t otherwise unwell — see a vet for a faecal exam.

What treats it: all UK-licensed wormers cover the common hookworm species. Biheldon, Drontal, Milbemax, Panacur.

Whipworms — rare in UK dogs

Trichuris vulpis in dogs is the UK whipworm. It is uncommon in the UK pet dog population — much less common than roundworm or tapeworm. Cats don’t get a clinically meaningful whipworm in the UK.

What it looks like: whip-shaped — a thicker rear end with a long, narrow, whip-like front end that the worm uses to anchor into the gut lining. ~5 cm long. Rarely visible in stool; usually diagnosed by faecal egg count.

What it means: whipworm is associated with dogs in kennels, multi-dog households where one animal has had a confirmed infection, or dogs with regular access to contaminated soil. Symptoms when present include chronic intermittent diarrhoea, often with mucus and occasionally blood.

What treats it: Biheldon and Drontal Cat do NOT cover whipworm. The products that do are Drontal Dog Tasty Bone (via febantel), Milbemax (via milbemycin oxime), or Panacur (fenbendazole). If your vet has confirmed whipworm on a faecal egg count, you need one of those products — not Biheldon.

Lungworm — not visible in stool

Lungworm (Angiostrongylus vasorum in dogs, Aelurostrongylus abstrusus in cats) lives in the heart and pulmonary arteries (dogs) or the lung tissue (cats), not the gut. Adult lungworms are not visible in stool. The first-stage larvae are microscopic and visible only on a Baermann faecal test at the vet.

If your dog has respiratory symptoms — persistent cough, breathing difficulty, exercise intolerance — or unexplained bleeding, see our lungworm guide. Lungworm is the UK parasite that most warrants vet attention rather than at-home worming.

What if I don’t see worms in stool — does that mean my pet is clear?

No. The absence of visible worms in stool does not mean the pet is parasite-free. Most adult dogs and cats with low-level worm burdens shed only eggs (microscopic) and not adult worms. Faecal egg counts — where your vet examines a small stool sample under a microscope — are the only reliable way to confirm what’s actually present.

This is also why ESCCAP UK recommends routine worming on a schedule (every 3 months minimum) rather than waiting for visible evidence. By the time you can see worms in stool, the pet has been carrying them for some time and the household has been exposed to eggs.

When to see a vet rather than worm at home

For most cases of visible worms or segments, treating with the appropriate product at home is fine — assuming your pet is otherwise well, eating, drinking, and behaving normally. See a vet first if:

• Worms are visible alongside any of these: persistent vomiting, lethargy, blood in stool, breathing difficulty, unexplained bruising
• The pet is under 6 weeks old — dosing very young animals is sensitive and benefits from vet input
• The pet has a known underlying condition — liver/kidney disease, GI sensitivity, post-surgical recovery
• You’re not sure what you’re looking at — a phone photo to your vet practice usually gets you a quick identification

The bottom line

Most “worms” UK owners find are tapeworm segments, most often Dipylidium caninum from flea exposure. The treatment is a praziquantel-containing wormer (Biheldon, Drontal, Milbemax) plus consistent flea control. Visible roundworms in puppies and kittens are normal and treated with the standard puppy/kitten schedule. Hookworm and whipworm are rarely visible to the naked eye and usually diagnosed at the vet on faecal egg count.

If your pet looks well and you can identify what you’ve found, treating at home is appropriate. If anything else looks off, the vet is the right next step.

See Biheldon’s full parasite coverage on the product page, the Biheldon vs Drontal comparison for the whipworm-cover difference, and the worming frequency pillar guide for the routine schedule.

Tags: #dogs#cats#identification#tapeworm#roundworm