Vincristine, one of the anti-cancer drugs used in veterinary practice, has adverse hematological and gastrointestinal effects in dogs. Juzen-taiho-to is a traditional Chinese medicine used for patients with anorexia in human medicine. However, the protective effects of Juzen-taiho-to against anti-cancer drug-induced toxicity in dogs have not been investigated. We therefore examined whether the administration of Juzen-taiho-to to dogs affects gastric motility, and vincristine-induced gastrointestinal and hematological toxicity. The study was composed of three trials. In the first trial, Juzen-taiho-to (450 mg/kg/day) was orally administered to five dogs. In the second and third trials, vincristine (0.75 mg/m²) was intravenously administered to each dog in the absence or presence of Juzen-taiho-to (450 mg/kg/day). During these trials, gastric motility and blood parameters were assessed. Juzen-taiho-to increased gastric motility and improved vincristine-induced gastrointestinal, but not hematological, adverse effects in dogs. This study suggested that Juzen-taiho-to may be applicable for gastrointestinal care in dogs receiving chemotherapy.