Worms and Your Dog

Separate fact sheets are available on roundworms, tapeworms and heartworms.  This fact sheet gives a general overview of the problem.

Are there different sorts of worms?

Broadly there are two types of worms that cause problems in the dog, nematodes (roundworms),and cestodes (tapeworms).Common nematodes are Toxocara canis (intestinal roundworm)and Diarofilaria immitis (the heart worm). Important cestode parasites include Dipylidium caninum (the flea tapeworm) , Taenia species and Echinococcusspecies (hydatid tapeworm) and Ancylostoma species (hookworms).

Heartworm disease

This is a condition which once was common in Australia (especially after dispersion of infected dogs after cyclone Tracey) but is now decreasing in prevalence, presumed due to effectiveness of preventative medications. There is some concern that this disease may become more common however if  prevention is not continued.

Transmission depends upon mosquito types found commonly in most parts of Australia.

Heartworms are a major problem in this country especially for dogs not on preventative medications.  They are large worms, adults reaching 16 cm.  They are chiefly located in the right ventricle of the heart and adjacent blood vessels.

The period of development to the adult stage is about six months after infection following a bite by a mosquito carrying the infective larvae (microfilariae).  The typical signs are fatigue on exercise, coughing and poor condition. It can lead to heart and other organ failure.

Roundworms

No intermediate host is required.

Nematodes (roundworms) are free living in the bowel.  In puppies they can present problems if not controlled.   In large numbers they can stunt growth, cause serious digestive upsets and result in a lot of gas formation.  This results in a typical ‘pot bellied’ appearance.  Roundworms can be spread directly from dog to dog via infective eggs.

Tapeworms

An intermediate host is required.

Dipylidium caninum (Flea Tapeworm) is the common tapeworm of the dog in Australia.  It causes few problems in the adult host but in the growing puppy can result in digestive upsets and stunting. Diplylidium is spread by the flea as intermediate host and effective treatment also must cover environmental flea eradication.

Echinococcus spp, (Hydatid tapeworm) , is important because it is zoonotic, i.e. we can be infected.  Sheep, kangaroos and sometimes man can act as the intermediate hosts in which the immature forms of Echinococcus develop inside cysts which grow in various organs.  In man the usual organs affected are lungs or brain.

Control measures involving regular deworming of the dog together with avoidance of feeding raw or under-cooked offal are obvious precautions.

Tapeworms found in adult dogs usually cause few problems.  However occasionally puppies are infested and depending on the type of worm involved, their sheer volume can cause serious blockages to the bowel.

Hookworms

Hookworms, particularly Ancylostoma species are one of the most pathogenic parasites of the dog.  , This tropical hookworm, approximately 1-2 cm long, attaches itself to the lining of the bowel and as a result of blood sucking activities can cause severe anaemia. The infective larvae enter the host either by mouth or through the skin (particularly of the feet).  Eczema and secondary bacterial infection can result due to irritation as they burrow through the skin.

Treatment against worms

Today many effective drugs are available to control worms in the dog.  Many of these are available “over-the-counter” without prescription.  Effective worm control in the dog however involves the choice of an appropriate preparation which has to be regularly repeated.  Please contact us and we will be happy to advise and supply a suitable preparation together with appropriate dosing instructions.