Giardia in Dogs
Giardia in dogs (canine giardiasis) is caused by a protozoan of the giardia species. It affects the dog’s digestive system resulting in symptoms such as diarrhea and vomiting. Read on to learn more about the symptoms and treatment of canine giardiasis.

Giardiasis is an infectious parasitic disease caused by a protozoa of the giardia species. Many people refer the disease simply to “Giardia”.

Canine Giardia affects the dog’s digestive system.

Transmission of the disease is through contact with infected fecal material. (The giardia cyst resides in the fecal matter of infected dogs.)

Dogs acquire the infection by drinking contaminated water from streams and other sources with infected animal feces. It is possible for a giardia cyst to survive for several months, when provided with a warm water-based environment.

When the giardia cyst gets inside the small intestine of a dog, it opens up and out comes the active form of the giardia parasite, which then attaches itself to the dog’s intestinal wall.

Reproduction of the parasite is by the process of cell division. Finally, after reproduction, the parasite encysts itself one more time. The cyst then emerges in the dog’s fecal matter.

In adult dogs, most infections are not serious unless the infected dog has a compromised immune system. Puppies and young dogs tend to have a higher rate of being infected.

Dogs most susceptible to infection are those in shelters and boarding kennels.

Symptoms of Giardia in Dogs

As mentioned above, most cases of Giardia in adult dogs are mild and some dogs do not show any visible clinical symptoms.

In more serious cases, an infected dog will show some symptoms in around seven to ten days of ingestion.

The most evident symptom of Giardiasis is diarrhea. In particular, an infected dog will pass a large amount of foul-smelling, watery or grease-like stools. The diarrhea can be acute or chronic, and it can be intermittent or persistent.

Besides diarrhea, there may be other symptoms such as:

Diagnosis and Treatment of Giardia in Dogs

Diagnosis of Giardiasis is made by fecal examination. Identifying the cysts of giardia gives a positive diagnosis.

However, since an infected dog will not pass cysts in every bowel movement, absence of cysts in the fecal sample does not exclude Giardia. Giardia infection can be ruled out ONLY IF there are 3 negative fecal examinations (the samples should be collected at least two days apart.)

Another diagnostic test is the use of serology tests, such as ELISA.

Conventional treatment of Giardia in dogs includes using antibiotics and/or dewormers, such as Metronidazole, Fenbendazole, and Albendazole.

Metronidazole (Flagyl), an antibiotic, is most commonly used but it can cause fetal malformations, so pregnant dogs should not be given this drug. Possible side effects include nausea, diarrhea, itching, dilated pupils and vomiting. It can also cause liver damage.

Fenbendazole (Panacur), a dewormer, is safer than metronidazole but can cause nausea and vomiting.

Metronidazole and Fenbendazole are about 70% effective in treating giardia in dogs. Albendazole (Albenza) is sometimes used if the above medications are ineffective.

However, the drug can also cause side effects such as fever, nausea, vomiting, and temporary hair loss. More seriously, it may cause bone marrow toxicosis.

Home Remedies for Giardia in Dogs

For mild cases of canine giardiasis, home remedies such as the following may be used instead of conventional medications to avoid possible side effects:

Grapefruit Seed Extract (GSE)

GSE is effective in treating Giardia in dogs but consistent use for up to 14 days is needed. (Dosage: 10-15 drops of GSE/10 lbs of body weight, 3 to 5 times daily.) Dilute the GSE with water and give it to the dog using a needle-less syringe.

Digestive Enzymes

Dr. Jean Hofve, a veterinarian in Colorado, suggests using digestive enzymes such as
Prozyme to treat giardia. For this to be effective, the enzymes should be given on an empty stomach.

(Dosage: 1/4 to 1/2 teaspoon, or one capsule, of enzymes mixed with a bit of water, given to the dog by mouth using a needle-less syringe).

Here is a suggested treatment schedule:

  1. For the first 8 days, give 3 doses daily to the dog – one dose each 60 minutes before morning and evening meal, and one dose before bed.
  2. After 8 days, stop giving the enzymes for one week.
  3. Repeat enzyme treatment for another 7 days.

The reason why the digestive enzyme treatment is effective if given no an empty stomach is that, with no food in the digestive system, the enzymes proceed to digest the parasites (such as giardia) in the intestines.