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 cats: roundworms and tapeworms.


Very young tabby kittensRoundworms are extremely common and will affect most cats at some point in their lives.  There are two common roundworms found in cats: Toxocara cati and Toxascaris leonina.

How do cats get roundworms?

There are three main ways that cats 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)
  • Through their mother’s milk – this is a very common route of infection and all kittens are likely to have some level of roundworm burden via this route

Why are roundworms a problem?

Children playing in sandIn most cases, intestinal roundworms do not cause significant disease to your cat.  However, if the number of worms present is very high, or if your cat 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 cats against roundworms monthly.  Treating every 3 months should be a minimum for cats at low risk of infection.  Kittens should be wormed every 2 weeks from the age of 2-3 weeks until they are about 8 weeks old.


The most common tapeworms that affect cats in the UK are Taenia taeniformis and Dipylidium caninum.  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 cats get tapeworms?

Black and white kitten stalking mouseTapeworms are not transmitted directly to cats, their life-cycle requires an intermediate host – something which eats the tapeworm eggs and is then itself eaten by the cat.

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

The intermediate hosts of Taenia taeniformis are small rodents such as rats, mice and voles.  Cats who hunt are therefore at high risk of this tapeworm.

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

Why are tapeworms a problem?

Ginger kitten licking its motherTapeworms rarely cause severe disease but can cause irritation, weight loss and diarrhoea.  They are a particular risk in older and immunosuppressed animals.

How often should I treat for tapeworms?

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

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


Tabby and white cat walking

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

How do cats get hookworms?

Hookworms are transmitted through eating larvae in contaminated soil, eating an intermediate host such as a rodent, 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.

How often should I treat for hookworms?

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

Worming treatments

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

Active ingredients Brand names Intestinal worms targeted Other parasites targeted Method of administration Prescription-only?
Imidacloprid/Moxidectin Advocate, Prinovox, Moxiclear Roundworms, Hookworms Fleas, ear mites, lungworm, heartworm Spot-On Yes
Praziquantel Droncit Tapeworms Spot-On, Tablet No
Praziquantel/Pyrantel Drontal, Prazitel, Cazitel, WORMclear, Anthelmin Roundworms, Tapeworms Tablet No
Praziquantel/Emodepside Profender, Dronspot Roundworms, Tapeworms, Hookworms Lungworm Spot-On Some
Praziquantel/Milbemycin Milbemax, Milbactor, Milpro, Milprazon Roundworms, Tapeworms, Hookworms Tablet Yes
Praziquantel/Eprinomectin/ Fipronil/(S)-methoprene Broadline Roundworms, Tapeworms, Hookworms Fleas, ticks, heartworm Spot-On Yes
Fenbendazole Panacur, Granofen Roundworms, Tapeworms Protozoa Paste or granules No
Selamectin Stronghold Roundworms, Hookworms Fleas, ear mites, heartworm Spot-On Yes

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