Objectives: To determine incidence and identify predisposing factors for sterile hemorrhagic cystitis (SHC) in dogs with lymphoma that were treated with cyclophosphamide and to evaluate whether furosemide administered i.v. concurrently with cyclophosphamide decreased the incidence of SHC.
Design: Retrospective study.
Animals: 216 dogs with lymphoma.
Procedure: Medical records of dogs with lymphoma that received cyclophosphamide chemotherapy in accordance with 1 of 2 protocols, with or without concurrent i.v. administration of furosemide, were examined. Data for the 2 groups were analyzed to determine the incidence and predisposing factors (age, breed, sex, weight, previous or preexisting disease, previous or preexisting urinary tract infection, neutropenia, azotemia, dose, and number of cyclophosphamide treatments) for cyclophosphamide-associated SHC.
Results: Cyclophosphamide-associated SHC developed in 12 of 133 (9%) dogs that had not received concurrent administration of furosemide and cyclophosphamide treatments; of the 83 dogs that had received furosemide, only 1 (1.2%) developed SHC. Dogs receiving cyclophosphamide and furosemide concurrently were significantly less likely to develop SHC than dogs that did not receive furosemide. Dogs with previous or preexisting immune-mediated disease were significantly more likely to develop cyclophosphamide-associated SHC.
Conclusions and clinical relevance: Analysis of results suggested an association between i.v. administration of furosemide concurrently with cyclophosphamide and decreased incidence of cyclophosphamide-associated SHC. Incidence of cyclophosphamide-associated SHC was similar in treated dogs that did not receive concurrent furosemide to that observed for other studies in which cyclophosphamide was administered orally. Cyclophosphamide-associated SHC appeared to develop early during the course of chemotherapy when furosemide was not administered concurrently with cyclophosphamide.