Intestinal Worms

Dogs pick up worms constantly - from soil, grass, prey animals, flea bites, and, in the case of puppies, from their mothers before birth. Most worm infections in healthy adult dogs cause no obvious symptoms. This makes them easy to miss and easy to dismiss - but worm burdens accumulate, and some species carry significant risks to both dogs and humans.

Logging treatment history is the most practical thing you can do here. Worming on schedule, with appropriate products, is straightforward preventive care.

Types of worms in the UK

Roundworms (Toxocara canis) are the most common. Almost every puppy is born infected or acquires roundworms through their mother's milk. Adults can carry them without visible symptoms. Roundworm eggs survive in soil for years - 86.6% of soil samples from UK and Irish parks contained Toxocara eggs in the WormWatch national surveillance study (Airs et al., Veterinary Record 2023; cited by NOAH). This is a genuine public health concern: children who ingest eggs can develop visceral larva migrans, a serious condition.

Tapeworms (Dipylidium caninum) are spread through fleas - a dog ingests an infected flea while grooming, completing the tapeworm's life cycle. This is one reason flea control and worming are linked. Other tapeworm species exist; Echinococcus is rarer but requires specific treatment.

Lungworm (Angiostrongylus vasorum) is increasingly prevalent in the UK, particularly in southern England and the Midlands. It's spread through slugs and snails - dogs ingest them directly or contact slime trails. Standard over-the-counter wormers do not cover lungworm. A prescription product that specifically lists lungworm is required. Signs include coughing, breathing difficulty, lethargy, and in severe cases, bleeding disorders (lungworm can interfere with clotting).

Hookworms and whipworms are less common in UK-resident dogs but relevant for dogs that have travelled abroad.

Treatment schedule

| Life stage | Recommended frequency | | ---------------------- | --------------------- | | Puppies under 3 months | Every 2 weeks | | Puppies 3–6 months | Monthly | | Adults (low risk) | Every 3 months | | Adults (high risk) | Every 4–8 weeks | | Pregnant / nursing | Consult your vet |

High risk includes: dogs that regularly scavenge, live in multi-dog households, live with young children, or spend significant time in parks and woodland.

What to monitor

Weight changes. A heavy worm burden - particularly in puppies - causes weight loss and a pot-bellied appearance. Unexplained weight loss in an adult dog warrants investigation.

Coat and energy. Chronic worm burden causes a dull coat, lethargy, and gradual condition decline. Log any unexplained changes in energy or coat quality.

Stools. You may occasionally see segments (tapeworm), rice-like white fragments near the tail, or in heavy roundworm infestations, worms in vomit or faeces. Log what you see and when.

Coughing or breathing changes. These are a key lungworm red flag. A dog that develops a cough - especially if young, previously healthy, and not vaccinated against kennel cough - should be assessed promptly for lungworm.

Treatment dates. Log every worming treatment: product name, date, dose. Gaps in treatment history are significant information for your vet.

Choosing the right product

Prescription products tend to have broader spectrum coverage - including lungworm - and are the safest choice if you want comprehensive cover. Worth discussing with your vet given your dog's specific risk profile.

Over-the-counter products typically cover roundworm and tapeworm but not lungworm. Adequate for low-risk adult dogs; insufficient for dogs in high-risk environments or those in areas with known lungworm prevalence.

Natural or herbal wormers - the evidence base for these is weak. Use a licensed veterinary product.

Logging for your vet

The most useful thing you can bring to a vet appointment for a suspected worm problem is a treatment history: what product you've used, how often, and when the last treatment was. This prevents unnecessary repeat treatments and helps identify whether the current product may have failed.