Band Neutrophils Are Observed in Dogs Undergoing Multiagent Chemotherapy Including Vincristine

Chemotherapy is known to cause significant neutropenia, though concomitant left shift (also known as bandemia) has yet to be documented in dogs. The objective of this study is to assess the prevalence of band neutrophil elevation in dogs undergoing multiagent chemotherapy and identify factors influencing bandemia development. Medical records were retrospectively reviewed between 2018 and 2022 for dogs that started multiagent chemotherapy with at least one follow-up visit. Records were analyzed for body surface area (BSA), white blood cell count, segmented neutrophil count, band neutrophil count, and the previously administered chemotherapy drug (vincristine, cyclophosphamide, or doxorubicin). A generalized linear mixed model was used for statistical analysis. Ninety dogs with 530 nadir complete blood counts (CBCs) were identified. Band neutrophils were present in 20.2% of nadir CBCs, and increased band neutrophils occurred in 13.6%. Smaller BSA was associated with higher bandemia prevalence. Bandemia prevalence was 6% higher after vincristine (Risk Difference, 95% CI = [1%, 11%], <i>p</i> = 0.026) or doxorubicin (Risk Difference, 95% CI = [-1%, 13%], <i>p</i> = 0.115) administration than when patients received cyclophosphamide. Limitations include a lack of standardization of protocol, evaluation of underlying conditions that could contribute to bandemia, and opportunity for laboratory error. This study demonstrates that band neutrophils are present in dogs receiving chemotherapy, with a negative relationship between bandemia and BSA. Bandemia was most common following vincristine and doxorubicin administration.