Unexpected neurotoxicity in dogs receiving a cyclophosphamide, dactinomycin, and 5-fluorouracil chemotherapy protocol

An inexpensive combination chemotherapy protocol containing cyclophosphamide, dactinomycin, and 5-fluorouracil was evaluated in dogs with carcinomas. Fifteen dogs were entered in this study, and there were 1 complete response and 2 partial responses among 12 evaluable dogs. However, 6 of 15 dogs (40%) developed neurotoxicity. The neurotoxicity of this protocol was compared with a previous 5-fluorouracil-containing protocol and found to be significantly higher. Due to the unacceptably high rate of neurotoxicity, this protocol cannot be recommended for use in dogs with cancer.