Introduction

Many case reports of chemotherapy overdoses (ODs) exist in both human and veterinary literature, though anthracycline ODs have been uncommonly described.

Methods

This study was performed as a multicenter retrospective analysis. The American College of Veterinary Internal Medicine oncology and internal medicine listservs were solicited for cases in which a chemotherapy OD occurred.

Results

Thirty-one (31) chemotherapy OD submissions were collected. Of these, there were 16 canine anthracycline ODs, including 12 mitoxantrone and 4 doxorubicin. More anthracycline ODs occurred secondary to an error in chemotherapy preparation (n=9) than due to a dose miscalculation (n=7). Most ODs were identified immediately after administration (n=11) and supportive care was initiated. In the remaining patients, supportive care was initiated when clinical signs appeared.

The overall median overdose (n=16) was 1.9x (range: 1.4–10x) the prescribed amount. Clinical signs for all patients included diarrhea (63%), anorexia (56%), vomiting (38%), and nausea (25%). Five patients also experienced lethargy (31%). Hematologic abnormalities for all patients included neutropenia (94%), of which 12/15 (80%) were grade IV, thrombocytopenia (88%), and anemia (63%). Most patients were hospitalized (n=11) and all but 2 patients survived the OD.

Conclusion

This is the largest data set to describe the outcomes of accidental anthracycline ODs in canine patients. All patients received supportive care after identifying the OD and death was uncommon. High grade myelotoxicity was common and may not have been mitigated with the administration of filgrastim. Further evaluation is needed to determine ideal therapeutic guidelines for treatment of a chemotherapy OD.