Tapeworms in Dogs

What are tapeworms?

Tapeworms as their name suggests are flattened intestinal worms that are actually made up of many small segments about 3-4 mm long. Unlike roundworms which live freely in the bowel, tapeworms attach to the wall of the small intestine by hook like mouth parts. 

The most common tapeworm of dogs (and cats) is Dipylidium caninum caninum (known as the Flea Tapeworm). The adult worms may reach 20 cm. in length. The individual segments are developed from the head end and gradually mature, finally being shed at the opposite end, either singly or in short chains.  These segments are passed out on the faeces when the dog defaecates. They are about 3 mm long and look like grains of rice. Occasionally they can be seen moving on the hairs around the anus or on freshly passed faeces. As the segment dries it becomes golden in colour and the fertilised eggs are released into the environment.

Unlike with roundworms dogs cannot be infected by eating the fertilised eggs. These have to pass through an intermediate host. In the case of Dipylidium caninum this is a flea.

How do dogs pick up tapeworms?

When the infected eggs are released into the environment they have to be swallowed by immature fleas (larvae) in the environment. Once inside the larval stage of the flea, the tapeworm egg then develops to become fully infective in the adult flea. During natural grooming or biting to allay irritation the dog can ingest the flea and so the life cycle is completed.

Are tapeworms dangerous for my dog?

Usually the worms do not cause too many problems in the dog. It is mainly the appearance of mobile segments crawling round the anus that causes aesthetic concern. Occasionally dogs will drag their bottoms on the ground (scooting) in order to allay this irritation but this behaviour can, of course, be for other reasons, such as impacted anal sacs.

"Usually the worms do not cause too many problems in the dog. It is mainly the appearance of mobile segments crawling round the anus that causes aesthetic concern."

In puppies heavy tapeworm infestation can be more serious. Lack of growth, anaemia and sometimes blockage of the bowel can occur. Occasionally contact with the bowel wall is lost by the head of the tapeworm (scolex). The worm can then be passed either in the faeces or be vomited.

How is diagnosis made?

Clinical diagnosis is usually as the result of the white mobile segments being seen crawling around the anus. Sometimes the yellowish dried segments are found in the dog’s bed. They look like grains of rice.

Tapeworm segments are only passed intermittently and therefore are often not diagnosed on routine faecal examination. However if you do find any segments, white or golden colour, bring these to us for a definitive diagnosis.

What is the treatment?

With modern drugs treatment is simple and very effective. The parasiticide may be given either in the form of tablets or by injection. It causes the tapeworm to dissolve in the bowel and so evidence of effective treatment will not be available.

These drugs are very safe and should not cause vomiting or diarrhoea or any adverse side effects.

Combined tablets are available which will be effective also against roundworms seen in the dog. Please consult us for further advice.

Is there anything else I should do?

Control of fleas is very important in the management and prevention of tapeworm infection. Flea control involves treatment of your dog, and the environment. We will be happy to supply a separate fact sheet on this subject. If the dog lives in a flea infested environment reinfection with tapeworms may occur in as little as two weeks. Since tapeworm medication is so effective, bear in mind return of tapeworms in your dog is almost always due to reinfection from the intermediate host and not from failure of the product.

Can we catch canine tapeworms?

Infection is not common or likely. Dipylidium caninum, the most common tapeworm of the dog, depends on the flea as the intermediate host. This has to be swallowed by a person if infection is to occur. A few cases have been reported in children. Just as control in dogs depends upon vigorous flea eradication, this strategy will also eliminate any risk of children in the environment becoming infested.

Although Diplylidium species are the most common tapeworms in dogs, other Cestodes are also important particularly in certain areas.

Taenia species. These are tapeworms that the dog acquires when eating prey or offal containing the infective larval stage. These are very much larger tapeworms, often up to one metre in length. Intermediate hosts include rabbits and sheep. The intermediate stages develop hydatid cysts in various organs. Very efficient anthelmintic preparations are available.

Echinococcus species (known as Hydatid tapeworm). By contrast these are very small tapeworms. They consist of only three or four segments and are usually less than 1 cm. in length. Intermediate hosts can be sheep, horses or occasionally man. Infection is by ingesting eggs that have originated from the faeces of dogs, foxes or kangaroos harbouring the adult tapeworm. In the Australia, Echinococcus problems are localised to mainly sheep grazing rural areas. Fortunately de-worming preparations, particularly those containing praziquantel are very effective for eliminating the Cestode from the dog.

Control measures involve avoidance of uncooked or partially cooked meat or offal. If you live in an area where Echinococcus is a problem we are more than ready to help and advise.