# Band Neutrophils Are Observed in Dogs Undergoing Multiagent Chemotherapy Including Vincristine

## TL;DR

This study found that band neutrophils appear in dogs undergoing chemotherapy, especially after vincristine or doxorubicin, and smaller dogs are more likely to show this effect.

## Contribution

The study is the first to document band neutrophil presence in dogs receiving multiagent chemotherapy in veterinary medicine.

## Key findings

- Band neutrophils were present in 20% of complete blood counts in dogs undergoing chemotherapy.
- Smaller dogs had higher band neutrophil counts, showing a negative relationship with body size.
- Band neutrophils were most common after vincristine or doxorubicin administration compared to cyclophosphamide.

## Abstract

Neutrophils are white blood cells involved in the first line of immune defense. In times of increased neutrophil need, immature band neutrophils are released from the bone marrow. Chemotherapy causes a low neutrophil count, which leads to rapid replenishment, though the presence of band neutrophils in these patients has not been documented in veterinary medicine. This study retrospectively evaluated 90 dogs undergoing multiagent chemotherapy. We evaluated 530 post-chemotherapy complete blood counts for the presence of band neutrophils. We found that band neutrophils were present in 20% of complete blood counts, and increased band neutrophils occurred in 14%. Smaller dogs were more likely to experience increased band neutrophil counts. Band neutrophils were 6% higher after vincristine or doxorubicin chemotherapy 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 band neutrophil count and dog size. Band neutrophils were most common following vincristine and doxorubicin administration.

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%], p = 0.026) or doxorubicin (Risk Difference, 95% CI = [−1%, 13%], p = 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.