Internal and External Parasites - Dogs and Cats

Intestinal Worms

As their name suggests, intestinal worms are parasites that live inside your pet’s intestines. These worms range in size from small to surprisingly large (up to 18cm in length). Regardless of their size however, they all have negative, and potentially deadly effects.


Most species of animal, as well as humans, can be infected with intestinal worms including dogs, cats, rabbits, horses, fish, birds and reptiles.


Common intestinal worms in Australian pets are roundworm, tapeworm, whipworm and hookworms. If your pet has a large number of worms you may find it difficult to put weight on them, they may develop a pot belly or drag their bottom on the ground. In some cases worms can cause vomiting, diarrhoea and even anaemia (a low red blood cell level). Occasionally, heavy intestinal worm burdens can cause death. Young animals are highly susceptible to developing intestinal worms.


Worms can have complex lifecycles which involve a period of existence and development outside your pet. Understanding the life cycle of a specific worm is important so that strategies for treatment and prevention can be designed and implemented. For instance, some tapeworms need to pass through fleas to complete their lifecycle, so flea prevention is an important method of controlling tapeworms.


It is important to maintain a worming treatment routine for your pets to reduce the incidence of infection and to reduce environmental contamination. There are many worming treatments available for the various worm infections that occur in our pets. These are available as tablets, spot-on treatments, or pastes. Re-infection is a common problem, particularly in pets that are in contact with a heavily contaminated environment. Another very important reason to worm your pets is to protect your family; as children in particular can become infected with certain dog and cat worms.


Below are some tips to consider regarding worm prevention:

  • Promptly clean up pet faeces.
  • Practice good hygiene, always encourage children to wash their hands regularly (especially after playing in dirt or sandpits, playing with pets or prior to eating).
  • Prevent children from playing where the soil may be contaminated with faeces.
  • Keep your pet's environment clean.
  • Always dispose of dog faeces in public parks and playgrounds.



Heartworm, or Dirofilaria immitis, is a parasite that is spread by mosquitoes and which causes disease in both dogs and cats. There is animal-to-animal  transmission so your pet does not even need to be in contact with other pets to become infected!


Heartworm has a complicated life cycle. Infected dogs / cats have microfilariae (an immature form of heartworm) circulating in their bloodstream. Microfilariae are sucked up by mosquitoes when feeding on the blood of infected animals. The immature parasites develop into heartworm larvae inside the mosquito, then a single bite from a carrier mosquito can infect your pet.


Heartworms mature in the heart of their infected host pet. They can cause a physical blockage as well as thickening of the heart and associated blood vessels. In the early stages of infection there may be no visible signs, however, infection may eventually lead to signs of heart failure (reluctance to exercise, lethargy, coughing, collapse) and even death. Heartworm is present throughout most of Australia (except Tasmania and arid areas where there are no mosquitoes).


Thankfully, heartworm is very easy to prevent and should form part of your routine pet health care. We have very effective preventative treatment options available including tablets, chews, spot-on's and even an annual injection for dogs administered by one of our veterinarians. If your pet has not been on heartworm prevention we strongly recommend a heartworm test prior to starting a prevention program.


Flea Control

Fleas are most often seen during the warmer months but as we keep our homes nice and warm throughout winter, we see fleas all year round.


Only a small part of the adult flea population actually lives on your pet. The fleas’ eggs and larvae live in the environment and can survive for up to a year, so it is important to not only treat your animal directly for fleas but also decontaminate the environment as well. Wash your pet’s bedding using the hottest cycle and regularly vacuum / clean carpets. We do not recommend flea collars or flea shampoos alone as they fail to address the environmental flea infestation, they are also highly inefficient.


Fleas will tend to jump onto your pet only to feed and then jump off again. Dogs and cats can have a reaction to flea saliva resulting in a skin condition called Flea Allergy Dermatitis or FAD. It only takes 1 flea in an allergic pet to set-off a flea allergy episode. Treatment of FAD can be complicated and veterinary consultation is recommended.


Some signs that your pet may have fleas include scratching, biting, hair loss and scabs especially at the base of the tail and rump. You may see fleas (especially over the rump and in the groin region) although sometimes it can be difficult, especially in FAD patients and cats. In that case it is recommended to check for flea dirt i.e. flea faeces. Simply moisten a cotton ball, part your pet’s fur and place the cotton ball on the skin over the rump. If the cotton ball takes on black specs surrounded by a reddish area, this may be flea dirt and can indicate that your pet has fleas.


Warning: Some non-veterinary brands of flea treatments for dogs are potentially lethal when applied to cats. Always seek veterinary advice about the best flea treatments for your pet.


Please call us to discuss an appropriate flea control program for your pet.