Are parasites contagious in dogs

Diarrhea in dogs and cats can have many causes, including an infection with giardia. These protozoa are - besides Roundworms - the most common intestinal parasites in dogs and cats. Humans can also, albeit rarely, become infected with Giardia.

Around every fourth dog and every sixth cat are infected with the unicellular organisms. The infestation rate in puppies and young animals can be up to 70%. There is also evidence that giardia is the cause of diarrhea in 22% of dogs and 23% of cats.


After infection and colonization of the intestine, large numbers of contagious Giardia cysts are excreted in the faeces of the animals and can lead to contagion for a long time in the environment (in water and a moist environment the cysts can remain contagious for three months, in the faeces for about a week).

Dogs and cats can become infected if they ingest cysts from water contaminated with feces (drinking from lakes, ponds, and puddles) or food. A smear infection on contact with infected animals is also possible. Just a few of the cysts are sufficient for infection.

Symptoms of Giardiosis

Giardiosis (infection with Giardia) often runs without symptoms in adult animals. In puppies and young animals, it can lead to chronic or recurring diarrhea, which can be thin or watery, foul smelling and slimy or bloody. Vomiting and weight loss are also possible. The animal can be appetite and apathetic. This can lead to chronic bowel inflammation.


Since the risk of infection for other animals is high and humans can also become infected, the feces of dogs and cats should be examined for the parasite if giardiosis is suspected. The most reliable proof is the examination of a collective faeces sample with a so-called ELISA antigen test.


If giardiosis is detected, all animals in the household must be treated, even if they do not show any symptoms. The choice of preparations and the duration of treatment are decided on a case-by-case basis. After therapy, the feces should be re-examined to ensure that the treatment was successful.

Hygiene measures in case of giarid infestation

To avoid re-infection, you should take the following measures during treatment:

  • Pollution of the environment with the contagious feces should be avoided at all costs. Always dispose of dog waste in a sealed bag.
  • Wash dogs and cats thoroughly with shampoo at the beginning and end of treatment. Especially with long-haired animals, the fur in the anal area should be shortened. This will prevent cyst-contaminated faeces from remaining in the animal's fur.
  • Litter box: Remove the feces as soon as possible and clean the litter box daily with hot water and dry it well, as Giardia can survive particularly long in water and a damp environment.
  • Clean food and water bowls daily with boiling water (or in the dishwasher) and dry them thoroughly as well.
  • Always offer fresh water and prevent the contamination of water and food by flies (flies can be carriers).
  • Wash beds, blankets and pillows at a temperature of at least 65 ° C.
  • Wash toys with boiling water at the beginning of treatment. Also clean cat scratching posts.
  • Treat solid floors with a steam jet (warmer than 60 ° C).