Resumen de Risk factors for perioperative death in dogs undergoing splenectomy for splenic masses: 539 cases (2001–2012)
Objective—To determine the perioperative mortality rate, causes of death, and risk factors for perioperative death in dogs undergoing splenectomy for splenic mass lesions.
Design—Retrospective case series.
Animals—539 dogs.
Procedures—Medical records of dogs that underwent splenectomy for known splenic masses were reviewed. Perioperative mortality rate and causes of death were determined. Associations between potential prognostic factors and perioperative death were evaluated by multivariable logistic regression analysis.
Results—41 of 539 (7.6%) dogs died during the perioperative period. Thrombotic and coagulopathic syndromes and uncontrolled bleeding from metastatic lesions were the most common causes of death. Of the variables selected for multivariable analysis, platelet count at admission, whether PCV at admission was < 30%, and development of ventricular arrhythmias during surgery were significantly associated with outcome. For each decrease in platelet count of 10,000 platelets/μL, odds of death increased by approximately 6%. For dogs with PCV < 30%, odds of death were approximately twice those for dogs with PCV ≥ 30%, and for dogs that developed intraoperative arrhythmias, odds of death were approximately twice those for dogs that did not.
Conclusions and Clinical Relevance—Marked preoperative thrombocytopenia or anemia and development of intraoperative ventricular arrhythmias were identified as risk factors for perioperative death in dogs with splenic masses. The risk of death may be limited by efforts to prevent thrombotic and coagulopathic syndromes and to control all sources of intra-abdominal hemorrhage.
Splenic masses are a common and potentially life-threatening condition in older dogs. Approximately 48% to 59% of splenic masses in dogs are malignant, and 51% to 73% of malignant masses prove to be hemangiosarcoma,1,2 a highly metastatic tumor associated with a poor prognosis for long-term survival.2–5 Other differential diagnoses include common nonneoplastic lesions, such as hematoma and nodular hyperplasia, and less common malignancies, such as leiomyosarcoma, fibrosarcoma, and histiocytic sarcoma.1,5–8 The decision whether to elect surgery for a dog with a splenic mass can be difficult for owners because the long-term prognosis varies substantially with the histopathologic diagnosis,8 which is usually not known prior to surgery, and because surgery and aftercare for dogs undergoing splenectomy are expensive. The decision often must be made quickly and without warning because many dogs, particularly those with hemangiosarcoma, are brought to a clinician because of acute and severe clinical signs caused by sudden intra-abdominal hemorrhage.2,4,9–13 Short-term survival prospects are likely influenced by the severity of any resultant changes in blood pressure, tissue perfusion, oxygen carrying capacity, and coagulation; by the potential for very large masses to partially obstruct blood flow in the caudal vena cava and portal vein; and by the systemic effects of general anesthesia.14 Factors such as age and general health of the dog may also influence the risk of death in the perioperative period.
Although long-term survival prospects for dogs undergoing surgery for various types of splenic masses have been well characterized,1,2,4,8,10,15 relatively little information pertaining to perioperative death is available. In a study1 conducted in a large group of primary care practices that used the services of a single pathology laboratory, 31 of 203 (15%) of dogs with nonneoplastic lesions and 38 of 115 (33%) of dogs with hemangiosarcoma failed to survive to discharge; however, details regarding causes of death or reasons for euthanasia were not reported. Three studies9,12,13 have reported perioperative mortality rates among dogs with acute nontraumatic hemoabdomen of various causes including splenic masses. In 2 of these studies, reported perioperative mortality rates among dogs with splenic masses were 6 of 1213 and 16 of 52 (30.7%)9; however, these results included dogs that were euthanized intraoperatively because of suspected metastatic disease. The third study12 included 83 dogs with hemoabdomen, 67 of which underwent splenectomy. The overall perioperative mortality rate was 16%; however, a mortality rate for dogs that underwent splenectomy was not reported. Factors associated with perioperative death for all dogs included tachycardia, a requirement for massive transfusion with blood products, and development of respiratory disease secondary to suspected pulmonary thromboembolism or acute respiratory distress syndrome.12 Although the perioperative mortality rates reported to date are discouraging, to our knowledge, a large study confined to dogs undergoing splenectomy for a known splenic mass in a high-volume referral practice has not been performed.
The purposes of the study reported here were to determine the perioperative mortality rate and causes of death for dogs that underwent splenectomy for splenic mass lesions at an academic referral practice, to perform a multivariable analysis to identify clinical variables commonly measured prior to surgery that are independently associated with the risk of perioperative death, and to perform a second multivariable analysis that also considered commonly collected data that become available during surgery or in the early postoperative period.
