Giardia are single-celled protozoan organisms that live and thrive in the small intestine of dogs and cats. Infection caused by it is known as 'Giardiasis'. Although the parasite is prevalent in all parts of the world, many facts about the disease, including the life cycle are unknown. Veterinarians have not agreed on how to treat the disease, but they do agree that though the infection is common, the disease is rare.
A dog becomes infected by eating the cyst form of Giardia. The cyst opens in the small intestine and releases an active form of the parasite known as the trophozoites, which have flagella (hair like structures) that can move back and forward allowing the parasite to move around. These trophozoites attach themselves to the wall of the small intestine and reproduce by dividing into two. As time passes, the Giardia continues to multiply and slowly develops a wall around itself forming a cyst. The cysts are passed in the feces of the dogs that contaminate the environment, water, and infect other dogs and humans.
The trophozoites that continue to multiply at an alarming rate begin to interfere with the absorption of food, nutrients damaging the intestinal lining and interfering with digestion. The feces become light-colored, greasy, smelly, and soft, and in some cases the dog suffers from diarrhea that can be acute, chronic or intermittent. This occurs around the time when the cysts are shed. The animal will lose weight but the diet will remain constant. Additional symptoms include irritation of the large intestine, which leads to straining, and mucus in the feces. Increase in the eosinophils count and mild anemia is also seen.
Giardiasis is a very difficult disease to diagnose, because the protozoa are very small and are not passed in every stool. Tests have to be conducted on serial samples (one stool sample everyday for three consecutive days) to detect the organism.
To detect the active form of the organism, a small amount of stool is mixed with water on a microscope slide and examined under high magnification. As these parasites have flagella, they can be seen moving around the slide. These are commonly seen in loose stools. Cysts can be found in stools that are firm. Special solutions are used to separate the stool and the cyst.
A special diagnostic test using the ELISA technology became available in 2004. A small fecal sample is used and the results are obtained in 8 minutes. These tests are considered to be more adequate when compared to a fecal examination.
Several treatments are available for Giardiasis, but some of them have not been approved by FDA for use in dogs. Antiparasitic drugs like Fenbendazole and Metronidazole can help control giardia and kill intestinal worms. However, these drugs can cause physical defects in a growing embryo, and should not be given to pregnant animals. Hence, ensure that you consult the vet before administering any drugs to your dog.
Once a dog passes the cyst in its stool, the cyst can survive for several weeks in a wet and cold environment. Hence, lawns, parks, kennels, and other areas where there is a possibility of finding dog feces can be a source of infection for the dog. Keeping your dog away from these places can be a very difficult task.
If you hear about cases of Giardiasis in your neighborhood, then you can take preventive measures and give them a course of anti-parasitic medicines. Ensure that the kennel is clean and remove any organic matter that is present in and around. Further, cysts can stick to the fur and skin of the animals. Make sure the dog is bathed and cleaned thoroughly with a mild shampoo. Lastly, it is very important to remember that dogs can transfer the Giardia infection to humans. Ensure complete personal hygiene and wash yourself well after you clean the kennel. Use of gloves and boots is recommended.