OBJECTIVE: To characterize the biological behavior and prognostic factors associated with hemangiosarcoma in cats.DESIGN: Retrospective case series.ANIMALS: 53 cats with hemangiosarcoma.PROCEDURES: Data were retrieved from a state veterinary diagnostic laboratory, 3 veterinary colleges, and a private practice.RESULTS: Cutaneous and subcutaneous tumor locations were more common than visceral (abdominal and thoracic) and oral locations. Surgical excision was the primary treatment in 47 cats. Tumor-free surgical margins were more likely in cutaneous than subcutaneous lesions and were associated with longer survival times. Local recurrence was observed in 6 of 12 cats with subcutaneous lesions for which follow-up was available. Metastatic disease was detected in 5 of 13 cats with adequate staging at initial diagnosis. A sixth cat had pulmonary metastases at the time of euthanasia. In 4 of 10 cats with visceral hemangiosarcoma, the diagnosis was made at necropsy or they were euthanized at the time of diagnosis. Adjuvant therapy was uncommonly used. Eighteen of the 21 known deaths or euthanasias were tumor-related. Higher mitotic counts (> 3 in 10 hpfs) were associated with shorter survival times.CONCLUSIONS AND CLINICAL RELEVANCE: Subcutaneous hemangiosarcoma was more biologically aggressive than the cutaneous form and was more likely to recur locally and result in euthanasia or death of the cat. Metastatic potential of the cutaneous and subcutaneous forms may be greater than previously reported. Visceral hemangiosarcoma is associated with a grave prognosis.
Animals Behavior, Animal