Incidence of sterile hemorrhagic cystitis in dogs receiving cyclophosphamide orally for three days without concurrent furosemide as part of a chemotherapeutic treatment for lymphoma: 57 cases (2007-2012).

OBJECTIVE

To evaluate the incidence of sterile hemorrhagic cystitis (SHC) and other adverse effects in dogs following oral administration of the single-day, maximum-tolerated dose (MTD) of cyclophosphamide divided over 3 days as part of a multiagent chemotherapy protocol for treatment of lymphoma without concurrent administration of furosemide.

DESIGN

Retrospective case series.

ANIMALS: 57 dogs.

PROCEDURES: Medical records were reviewed to identify dogs with lymphoma that underwent the described cyclophosphamide treatment. Information was obtained regarding signalment, lymphoma stage, concurrent diseases, cyclophosphamide doses administered, adverse effects (including SHC), remission rates, and outcomes. The incidence of SHC was compared with that of literature-derived historical control groups that received the MTD of cyclophosphamide as a single, 1-day dose with or without furosemide treatment.

RESULTS

None of the 57 dogs developed SHC during the study period. Forty-seven of 57 (82%) dogs had complete remission of lymphoma. Other adverse effects were uncommon and self-limiting; no dogs had myelosuppression, and only 5 had mild gastrointestinal effects. Incidence of SHC was significantly lower than that reported for historical control dogs that received cyclophosphamide as a single dose without furosemide (24/219) and was not significantly different from that for historical control dogs that received cyclophosphamide as a single dose with furosemide (2/139).

CONCLUSIONS AND CLINICAL RELEVANCE: No dogs in this study had SHC following oral administration of the single-day MTD of cyclophosphamide divided over a 3-day period without furosemide administration. Further research is needed to confirm whether this method of cyclophosphamide administration is equivalent or superior to the current single-dose administration method.