Intestinal Worms

Intestinal worms are not the most pleasant topic of conversation, however they are very common parasites.  There are two main categories of intestinal worms found in dogs: roundworms and tapeworms.


German Shepherd feeding puppiesRoundworms are extremely common and will affect most dogs at some point in their lives.  There are two common roundworms found in dogs: Toxocara canis and Toxascaris leonina.

How do dogs get roundworms?

There are three main ways that dogs get infested with roundworms:

  • Eating eggs directly from contaminated environment (e.g. soil)
  • Eating prey which has eaten eggs from the contaminated environment (e.g. mice, rats)
  • From their mother – this is a very common route of infection and all puppies are likely to have some level of roundworm burden via this route.  The roundworm larvae cross the mother’s placenta during pregnancy and will also be found in the milk.

Why are roundworms a problem?

Children playing in sandIn most cases, intestinal roundworms do not cause significant disease to your dog.  However, if the number of worms present is very high, or if your dog is very young, or unwell, they can lead to weight loss, diarrhoea, and intestinal blockages.

Roundworms are also a human health risk, most commonly affecting young children who come into contact with animal faeces, either directly or through contaminated soil.  In severe cases, the roundworm larvae can affect the liver, lungs, brain and eyes, potentially causing blindness and seizures (fits).

How often should I treat for roundworms?

Roundworms have a pre-patent period (the time between ingestion of the eggs and when the adult worms start to produce eggs) of 6-10 weeks.  Because of this, it is advisable to treat dogs against roundworms monthly.  Treating every 3 months should be a minimum for dogs at low risk of infection.  Puppies should be wormed every 2 weeks from the age of 2 weeks until they are about 8 weeks old.  Worming the mother during pregnancy can help to reduce the number of worms infecting the puppies across the placenta.


The most common tapeworms that affect dogs in the UK are Taenia species, Dipylidium caninum and Echinococcus granulosus.  They are long flat worms made up of segments.  Segments containing eggs are passed in the faeces and can look like grains of rice in the faeces, on hair around the anus or on bedding.

A tapeworm called Echinoccoccus multilocularis is currently not present in the UK but is in Europe and can cause serious human disease.  This is why there is a requirement for tapeworm treatment before travel from Europe to the UK.

How do dogs get tapeworms?

Border Collies working sheepTapeworms are not transmitted directly to dogs, their life-cycle requires an intermediate host – something which eats the tapeworm eggs and is then itself eaten by the dog.

The intermediate host of Dipylidium caninum is the flea.  Any dog with fleas is likely to also have this tapeworm.

The intermediate hosts of Taenia species and Echinococcus granulosus are livestock such as sheep, cows and pigs, rabbits and small rodents.  Dogs who scavenge, hunt or are fed raw meat or offal are at risk of this worm.

Because of this need for an intermediate host, tapeworms are less common in puppies, although they may be found if the puppy also has fleas.

Why are tapeworms a problem?

Tapeworms rarely cause severe disease in dogs but can cause irritation, weight loss and diarrhoea.  They are a particular risk in older and immunosuppressed animals.  Echinococcus species are a risk to human health.  Taenia and Echinoccoccus can cause disease in livestock and may lead to financial loss for farmers as the affected carcasses will be deemed unfit for consumption.

How often should I treat for tapeworms?

Frequency of treatment depends on the risk.  If your dog has fleas, tapeworm treatment is advisable monthly until the fleas are eradicated.

If your dog is a hunter, scavenger, or fed on raw meat, regular tapeworm treatment is advisable (at least every 3 months).

If your dog is regularly walked on farmland, particularly around sheep, tapeworm treatment should be given at least every 3 months, possibly monthly.


Mother dog with puppies

Hookworms are fairly rare in dogs in the UK but can cause more serious disease when they do occur.

How do dogs get hookworms?

Hookworms are transmitted through eating larvae in contaminated grass, or they can also burrow through the skin.

Why are hookworms a problem?

Hookworms cause damage to the lining of the intestine and can lead to anaemia and protein loss.  They can also lead to skin irritations.

How often should I treat for hookworms?

As they are quite rare, treatment every 3 months should be sufficient against hookworms.


RottweilerWhipworms are fairly rare in dogs in the UK but can cause more serious disease when they do occur.

How do dogs get whipworms?

Whipworms are transmitted through eating eggs in contaminated environments (e.g. soil and grass).

Why are whipworms a problem?

Whipworms cause damage to the lining of the intestine and can lead to bloody diarrhoea.

How often should I treat for whipworms?

As they are quite rare, treatment every 3 months should be sufficient against whipworms.

Worming treatments

Please speak to your vet about the most appropriate worming regime for your dog.  Below is some information about the products available and which worms they target.

Active ingredients Brand names Intestinal worms Other parasites Method of administration Prescription-only?
Fenbendazole Panacur, Granofen Roundworms, Tapeworms Protozoa Liquid, paste or granules No


Advocate, Prinovox, Moxiclear, […] Roundworms, Hookworms, Whipworm Multiple Spot-On Yes


Nexgard Spectra Roundworms, Hookworms, Whipworm Multiple Tablet Yes
Milbemycin/Lufenuron Program Plus Roundworms, Hookworms, Whipworms Fleas, Heartworm Tablet Yes
Praziquantel Droncit Tapeworms Tablet No


Drontal, Prazitel, Cazitel,  […] Roundworms, Tapeworms Hookworms, Whipworm Tablet No


Milbemax, Milbactor, […] Roundworms, Tapeworms, Hookworms, Whipworm Tablet Yes
Pyrantel/Febantel Drontal for puppies Roundworms, Hookworms, Whipworm Liquid No
Selamectin Stronghold Roundworms Fleas, ear mites, heartworm Spot-On Yes

Always discuss the best parasite control regime for your dog with your vet.

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