Worming Your Pet: What, When and Why

Worming sits in the category of pet care that most owners do occasionally, without being entirely clear what they are treating or how often it should happen.

That vagueness matters more than it used to, because one particular parasite has spread across Britain over recent decades and can kill an otherwise healthy dog.

Here is what you are actually treating and when.

Roundworm is the most common.

Roundworms are the parasite most people picture. Puppies and kittens are frequently born with them or acquire them through their mother's milk, which is why young animals need worming far more frequently than adults.

Heavy infestations in young animals cause a pot-bellied appearance, poor growth, diarrhoea and vomiting.

Roundworm also matters for human health. Toxocara eggs passed in faeces can, rarely, infect people, particularly young children, and can cause serious illness including damage to the eye.

That is the reason behind dog fouling laws and the advice about handwashing after handling pets and before eating. Picking up promptly genuinely reduces risk to other people.

Tapeworm is linked to fleas.

Tapeworms are long, flat and segmented, and the segments passed in faeces or found around the animal's rear look like grains of rice.

The most common tapeworm in dogs and cats is transmitted by fleas, which is why flea and worm control are connected. An animal that swallows an infected flea while grooming will acquire tapeworm.

Cats that hunt also acquire tapeworm from prey, which is why hunting cats need worming more frequently than those that stay indoors.

Lungworm is the serious one.

Lungworm, caused by the parasite Angiostrongylus vasorum, has spread widely across Britain over recent decades, having previously been confined to a few southern areas.

Dogs acquire it by eating slugs and snails, deliberately or accidentally. Dogs that eat grass, drink from puddles, chew toys left outside overnight or lick surfaces where slugs have travelled are all at risk.

The parasite affects the lungs and the blood's ability to clot. Signs can include coughing, breathing difficulty, tiredness, unexplained bruising or bleeding that will not stop, and behavioural changes. It can be fatal.

Crucially, not every worming product treats lungworm. Many shop-bought wormers do not, and treating monthly with the wrong product provides no protection at all. This is the single most common gap in home worming routines.

Ask your vet specifically about lungworm cover.

Frequency depends on lifestyle.

General guidance is that adult dogs and cats should be wormed at least every three months, but that is a baseline rather than a rule.

More frequent treatment is usually recommended for animals that hunt, scavenge, eat raw food, have contact with young children, or live in households with immunosuppressed people.

Puppies and kittens follow a much more frequent schedule during their early weeks, and pregnant and nursing animals have their own requirements.

Lungworm prevention generally requires monthly treatment rather than quarterly, which is another reason the standard three-month habit may not be sufficient.

Prescription products differ from shop ones.

Wormers sold in supermarkets and pet shops are not the same as those supplied by vets.

Prescription products generally cover a broader range of parasites, including lungworm, and are dosed by accurate weight. Many combination products treat fleas and worms together, reducing the number of treatments to remember.

Dosing by weight matters. Underdosing is ineffective and contributes to resistance, and guessing an animal's weight is unreliable. Most practices will let you weigh your pet on their scales without an appointment.

Never give a dog product to a cat without checking, as some are toxic to cats.

Signs worth acting on.

Visible worms or segments in faeces or around the rear, scooting along the floor, unexplained weight loss despite normal appetite, a dull coat, vomiting, diarrhoea or a pot-bellied appearance in a young animal all warrant a vet visit.

Many infected animals show no signs at all, which is precisely why routine treatment exists rather than treating only when symptoms appear.

If your dog develops breathing difficulty, persistent coughing or unexplained bleeding, contact a vet urgently and mention lungworm specifically.

Worming is not the same as flea treatment.

A common misunderstanding is that a single product covers everything. Many do not, and the combinations vary considerably between brands.

Some spot-on treatments cover fleas and certain worms but not tapeworm. Some tablets cover a broad range of intestinal worms but nothing external. Very few single products cover everything an at-risk dog needs.

Ask your vet to write down exactly what your product covers and what it does not, and keep that note with the packaging so you are not guessing three months later.

Practical points for the North East.

Slugs and snails are abundant across the region, particularly in wet weather, which is most of it. Gardens, allotments and long grass all present exposure.

Bringing water bowls and toys indoors overnight reduces the chance of a slug crossing them, which is a small habit with a real effect.

Grazing land across Northumberland and County Durham brings additional considerations, and tapeworm species affecting livestock make worming dogs walked on farmland particularly important.

Setting a recurring reminder on your phone is the simplest way to keep a routine going, since worming is the treatment owners most commonly forget.

Share your thoughts.

Did you know your wormer might not cover lungworm?