Giardia occurs when the dog in concern eats the cyst form of the parasite causing the disease. This usually spreads from the feces of infected dogs. Diarrhea is the symptom of Giardia, it may be acute, chronic or intermittent. The feces too become abnormally pale and have a strange smell.
Fenbendazole is an anti-parasitic drug which is used to treat this condition. Metronidazole is also used for the same purpose. Again proper hygiene and a clean environment can prevent your dog from contracting this dog feces disease.