This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.


A parasite is an organism that lives in association with another life form in a temporary or permanent relationship. This type of animal association is called parasitism.

In parasitism one partner (the parasite) benefits from the relationship, whereas the other partner (the host) suffers injury of some kind. This injury may be only slight, or it may manifest as disease.

Parasitism needs to be distinguished from other forms of animal association such as symbiosis and commensalism.

There are three main types of parasite 

  • Helminths - endoparasites (live inside the host) - eg roundworms and tapeworms
  • Arthropods - ectoparasites (live on the surface of the host) - eg ticks, fleas and lice
  • Protozoa - endoparasites

Some parasites of animals are transmissible to humans and vice versa. (See Zoonoses)


Last updated : October 2013