Nematode Infection

Nematode is just the scientific name for roundworm, a whole family of parasitic worms with a round, tube-like body. It's a broad category, not one single parasite, and it covers several worms you may already recognise by name: intestinal roundworms, hookworms, whipworms, and the more dangerous heartworm and lungworm, which travel beyond the gut. Nematodes are the most frequently diagnosed worms in dogs and cats across Europe and North America, so most pets will encounter one of these at some point in their life.

Pets usually pick up nematodes by swallowing eggs or larvae left behind in soil, grass or another animal's droppings, or by eating an infected prey animal like a rodent. Puppies have an added route: roundworm larvae can cross the placenta before birth or pass through the mother's milk, which is why even very young puppies can already be carrying a heavy worm burden. Fleas can also transmit certain tapeworm-adjacent parasites, though that's a separate worm family from true nematodes.

What an infection looks like depends heavily on which worm and how many are present. Many infected pets show nothing obvious at all, especially with light burdens, which is exactly why routine deworming and faecal checks matter rather than waiting for symptoms. When signs do appear, they can include:

• Diarrhoea, sometimes with visible worms or blood
• Vomiting, occasionally with worms present
• A dull coat, weight loss or a pot-bellied look in puppies and kittens
• Pale gums from blood loss, particularly with hookworms
• Coughing or breathing trouble, which points more toward lungworm or heartworm rather than gut worms

Whipworms are notoriously tricky to catch on a standard stool sample because they shed eggs only occasionally, so a single clean test doesn't always rule them out.

A few nematodes, particularly the common roundworm Toxocara, can also infect people, especially young children who play in contaminated soil or sandpits. Picking up after your pet promptly and washing hands after gardening or handling soil are simple ways to lower that risk.

Diagnosis is usually straightforward for a vet: a faecal sample checked under the microscope, sometimes paired with a newer antigen test that can pick up infections standard floats might miss, or a blood test for heartworm. Treatment relies on anthelmintic medication chosen for the specific worm involved, since no single dewormer covers every type equally well. Because reinfection from the environment is so easy, most vets recommend a regular deworming schedule tailored to your pet's age, lifestyle and local risk, rather than a one-off treatment. If you're ever unsure what your pet's routine should look like, a vet can build a plan around where you live and how your pet spends its time outdoors.