Retrospective analysis of carboplatin-induced cumulative neutropenia in cancer-bearing dogs

This is the authors' abstract. We don't add key points for this paper.

OBJECTIVE To determine the clinical significance of performing repeated postchemotherapy CBC for cancer-bearing dogs receiving ≥ 4 carboplatin treatments. The secondary aim was to identify risk factors associated with cumulative carboplatin-induced neutropenia in those dogs. ANIMALS 40 client-owned dogs diagnosed with cancer. METHODS A retrospective study using medical records from a single academic institution during 2012 to 2023. Dogs that received ≥ 4 doses of carboplatin with pre- and postchemotherapy CBCs available were included. Signalment and possible risk factors were recorded. Veterinary Cooperative Oncology Group–Common Terminology Criteria for Adverse Events was used for neutropenia grading. RESULTS 40 dogs met the inclusion criteria, with a total of 206 prechemotherapy and 188 postchemotherapy CBC results available. The median carboplatin dosage was 300 mg/m 2 (range, 200 to 300 mg/m 2 ). The median interval between carboplatin administration and the postchemotherapy CBC was 10 days (range, 6 to 38 days). Eleven dogs developed a grade 2 or higher neutropenia, with 5 dogs developing multiple neutropenic events, for a total of 18 separate events (18/394). Only 2 of 18 neutropenic events were recorded at the 10- to 14-day postchemotherapy CBC. The yield of detecting neutropenia at a postchemotherapy CBC at any carboplatin chemotherapy after the second dose was < 1% (1/149). Dogs that developed neutropenia at the pre-2nd chemotherapy CBC had a significantly higher risk of developing another neutropenic event at subsequent prechemotherapy CBC ( P < .001). CLINICAL RELEVANCE The incidence of cumulative neutropenia after 4 to 6 doses of carboplatin is low in cancer-bearing dogs. If a grade 2 or higher neutropenia is observed at or before the second prechemotherapy CBC, the dog is at a higher risk of developing neutropenia following future treatments.