Canine Giardiosis is a zoonotic disease, considered a cosmopolitan parasitosis, which has shown resistance to various treatment protocols. The objective was to evaluate the effectiveness and safety of nitazoxanide in the treatment of canine Giardiosis, in Caldas, Antioquia kennel. Sixteen dogs were selected, crossbreed, both sexes diagnosed with Giardia by directs mear and zinc sulfate flotation. All received nitazoxanide 10 mg/kg oral sid for three days (d). Measuring presence of the parasite was performed at times 0, 8 and 30 d of treatment, further blood count, alanine amino transferase and creatinine eat the same times was evaluated. The data were processed in Statgraphics Centurion XV®, with a confidence level of 95% and made Chi2 and Tukey test. After 8 d of treatment 56.25% of canines showed Giardia spp while 43.75% showed negative presence of the parasite, 30 d 87.5% of dogs have no Giardiosis and 12.5% were positive, showing low effectiveness at 8 d and more 30 d. No relationship between the presence of Giardia spp and variables fat, starch, mucus, blood and vegetable fibers found in feces (P=0.10). All patients had normal full blood count during the three times evaluated and alanine amino transferase ALT normal creatinine in the same period, indicating that the drug in this study was safe for canines. Nitazoxanide is effective in treatment of canine lodge situation Giardiosis in long term drug.