Giardia in Dogs, Symptoms, Treatment, Life Cycle, Vaccine

Giardia in Dogs

giardia in dogs

Giardia in dogs is a particularly nasty infection of the intestine caused by a single celled organism (parasitic protozoan) referred to as Giardia Lamblia. These single celled organisms are actually present in many adult dogs intestines with some experts estimating that fourteen percent of all older adult dogs and a massive thirty percent of dogs below the age of one year old have the parasite in their intestine.

Although the Giardia Lamblia protozoan is found within a dogs intestine it can also be found floating in the mucous that lines the intestine. Of course if this parasite is present in a dogs intestine then it can be transmitted to other dogs which will then cause a variety of symptoms (more on this below).

Is Giardia Contagious?

This parasitic infection is highly contagious and after it has reproduced within it’s chosen host it will develop into highly infectious cysts which are then passed out in a dogs poop. The cysts can survive outside of the host in specific environmental conditions i.e. wet and damp environments. The cysts can actually survive in these conditions for months on end. Of course while the cysts are alive they can then be transmitted to other dogs through ingestion possibly through infected water, food or anything that has the right temperature where the cysts can survive. Interestingly new research has found the Giardiasis can also be passed on through sexual intercourse.

Although many bacterial infections need the main host to ingest many thousands at at time for the host to exhibit symptoms with Giarda it is possible for a dog to only ingest one cyst or more for symptoms to develop after the parasite has reproduced.

Giardia in Dogs – Life Cycle

The life cycle of the Giardia infection comes in two stages – during one stage which is referred to as ‘non-motile’ (this basically means that the cyst does not move) – this is when the cyst (Giardia) is passed in a dog’s poop. The other stage is referred to a ‘motile’ (this means that the cyst is capable of moving). During the motile stage the cyst will live and infect a dog’s intestine.

It will start in the smaller intestine before passing through your dog and either going it in the poop or continuing it’s journey to the large intestine. During the early stage of infection the cysts will continue to multiply.  If the cysts are passed out in a dog’s poop as long as the environmental conditions are damp and perfect for the Giardia infection to thrive it can live for several months. Cysts are also referred to as Trophozoites.


To prevent your dog getting the disease or passing it on to other animals is vital that you put some gloves on, pick up the stool sample and get rid it immediately.

Do not allow your dog to drink from areas where other dogs have pooped – always provide safe and clear, clean drinking water for your dog.

It is important to mention that dogs can actually reinfect themselves due to the fact that the cysts might stay attached to the anus after excretion – this is why regular grooming and bathing is important.

Giardia in Dogs – Symptoms

The symptoms of a Giardia infection in dogs can include severe diarrhea. Basically due to the constant multiplication and reproducing cysts the intestine will start to become more blocked. This will stop food and waste products from moving effectively down into the lower digestive tract – the resulting symptoms will include diarrhea. The diarrhea can vary – in some circumstances it can be relatively mild but in more severe cases it can be chronic. Giardia in dogs can also cause some of the following symptoms…

  • Weight loss
  • Restlessness
  • Poop might appear light in color
  • Your dog’s poop might have mucus in it.
  • Your dog’s poop might also have blood in it. 
  • Expect your dog to also be very tired and lethargic
  • In some cases your dog might start vomiting
  • Your dog’s poop might also have a particularly foul odor
  • In very serious cases the condition can be deadly.

Giardia in Dogs – Diagnosis

Diagnosis of this condition can be a little difficult mainly because the cysts are not passed in every single stool that your dog excretes. This will mean the diagnosis by microscope will need to be done over a few days with lots of stool samples. The Giardia infection is very hard to diagnose through stool samples.

Some vets are now using a very cheap technique referred to as ELISA – this is a new and highly effective.


Treatment for Giardia in dogs can depend on the vet – below is a list of medications that might be prescribed to treat the condition.

  • Metronidazole – this is one of the most common treatments for the infection with the treatment lasting five days. This treatment is not always effective and may not work in 33% of dogs infected.
  • Furazolidone – this treatment can be up to ten days.
  • Tinadazole – this treatment will last seven days.
  • Fenbendazole – this treatment will last three days.
  • Albendazole – this treatment will last about two day.

Return from Giardia in Dogs to Free Vet Advice

Return from Giardia in Dogs to Dog Obedience Training Online Home Page