Dogs with Giardia infections have diarrhea that persists for days, even after treatment. We managed canine giardiasis using two distinct approaches: treatment with the antiprotozoan secnidazole alone; and secnidazole plus a homeopathic product that is indicated for control of diarrhea in dogs. Treatment I: Ten beagle dogs showed clinical signs of severe diarrhea. Their feces revealed large numbers of cysts consistent with Giardia sp. Therefore, we treated the dogs with secnidazole (10 mg/kg, single dose) given orally. Five days after treatment, all dogs were negative for Giardia spp. Treatment II: Three months later, the same ten Beagles again presented with diarrhea. Feces were collected, revealing Giardia sp. in all dogs. This time, we treated them with an antiprotozoan (secnidazole, 10 mg/kg dose) combined with a commercial homeopathic drug for diarrhea control (3 g dose/animal at 12 h interval). We found that three to five homeopathic doses were needed to achieve normal fecal scores in all dogs. After 5 days of treatment, stool samples had normal consistency and were negative for Giardia. This is the first record of using secnidazole to control canine giardiasis associated with homeopathic drugs to prevent diarrhea.