Worming is one of those tasks people do out of habit without knowing what they are treating. The result is dogs treated for the wrong thing, and owners surprised when a problem turns up anyway.
Different worms need different drugs, and no single product covers everything.
Roundworm (Toxocara)
The most common, and the one with a human health angle.
Puppies are frequently born with them, having been infected in the womb or through the mother’s milk. Adults pick them up from contaminated soil.
Signs: a pot-bellied puppy, poor growth, dull coat, vomiting, diarrhoea, and sometimes visible spaghetti-like worms in vomit or faeces.
The human risk: Toxocara eggs shed in dog faeces can infect people, particularly children who put soil-contaminated hands in their mouths. In rare cases larvae migrate and can cause serious problems including eye damage. It is uncommon, and it is the reason picking up faeces and washing hands is more than tidiness.
Treatment: puppies need worming frequently — typically every two weeks from two weeks old until twelve weeks, then monthly until six months. Adults, according to risk.
Tapeworm
Segments look like grains of rice around the anus or in the bed.
The common tapeworm is transmitted by fleas — the dog swallows an infected flea while grooming. Which means tapeworm treatment without flea control is a cycle that repeats.
Another type comes from eating raw meat, offal or carcasses, so hunting dogs and raw-fed dogs need more frequent treatment.
Echinococcus is a tapeworm of particular importance in some regions because it can cause serious disease in humans. Many countries require treatment before entry.
Hookworm and whipworm
Picked up from contaminated ground. Hookworm attaches to the intestinal lining and feeds on blood, causing anaemia in heavy infestations, particularly in puppies. Whipworm causes large-bowel diarrhoea, sometimes bloody.
Whipworm eggs are notoriously persistent in soil, which is why reinfection is common in the same garden or kennel.
Lungworm (Angiostrongylus)
The one that has changed the picture in several countries over the last two decades, and the one many standard wormers do not cover.
Transmitted by slugs and snails, including accidentally swallowed tiny ones on grass, in water bowls left outside, and on toys left in the garden.
Signs: coughing, exercise intolerance, weight loss, and — the distinctive one — abnormal bleeding. Dogs with lungworm may bleed excessively from minor wounds, bruise easily, or bleed into the eye or gut, because the parasite interferes with clotting. Neurological signs occur in some cases.
It can be fatal. It is preventable with the right product, and the key point is that not all wormers cover it. Ask specifically.
Giardia and other protozoa
Not worms, but frequently lumped in.
Giardia causes soft, foul-smelling, sometimes greasy stool, often chronic and often in puppies and dogs who drink from puddles and streams. Standard wormers do not treat it; it needs specific medication and thorough environmental cleaning, and dogs often need bathing to remove cysts from the coat.
Diagnosis is by faecal testing. If your dog has persistent soft stool and routine worming has not helped, ask for a test.
How often to worm
There is no universal schedule, and the honest answer is that it depends on risk.
Puppies: every two weeks from two weeks old to twelve weeks, then monthly to six months.
Adults: at least every three months is the common general recommendation. Higher risk dogs need monthly treatment.
Higher risk means:
- Dogs who scavenge or hunt
- Dogs fed raw meat
- Dogs in households with young children
- Dogs who eat grass, drink from puddles, or spend time where slugs are present
- Dogs in areas with high lungworm prevalence
- Dogs who travel abroad
Pregnant bitches need a specific protocol — ask your vet, since timing matters and not all products are safe in pregnancy.
Faecal testing as an alternative
An increasingly common approach, particularly for low-risk adult dogs: test faeces regularly instead of treating blindly, and treat when something is found.
The argument for it is reduced unnecessary drug use and less environmental impact. The argument against is that tests can miss intermittent shedding, and lungworm prevention in high-risk areas is generally considered worth doing regardless.
Discuss which approach suits your dog.
Choosing a product
Ask specifically what it covers. Many supermarket wormers cover roundworm and tapeworm only, and miss lungworm and whipworm entirely.
Weigh your dog. Underdosing is a real and common problem, and it contributes to resistance.
Combination products covering fleas, ticks and several worms are convenient and reduce the number of separate treatments — but check what is actually in the combination rather than assuming.
Prescription products from your vet generally have broader and more reliable coverage than over-the-counter options.
Practical prevention
- Pick up faeces immediately, in the garden and on walks. This is the single biggest thing you can do
- Wash hands, and teach children to
- Control fleas, which breaks the tapeworm cycle
- Bring water bowls in at night, where slugs congregate
- Pick up toys from the garden overnight
- Discourage scavenging, and work on “leave it”
- Do not let dogs drink from puddles or stagnant water
- Cover sandpits
Signs worth a vet visit
- Visible worms or segments
- Scooting, which may be worms or anal glands
- Pot belly with poor condition, particularly in a puppy
- Persistent diarrhoea or soft stool
- Weight loss despite a good appetite
- Coughing or exercise intolerance
- Any unexplained bleeding or bruising — this one is urgent
And if you travel abroad with your dog, check the requirements well in advance. Some countries mandate specific treatments within a fixed window before entry, and missing it means being turned back.
