Pathologic Factors Affecting Postsplenectomy Survival in Dogs

Abstract

The apparently high prevalence of splenomegaly in dogs, along with the surgical accessibility of the spleen, results in a relatively large number of splenectomies in dogs in clinical veterinary practice. Splenic nodular lesions are widely considered t o be indicative of hemangiosarcoma and thus a disease that is ultimately fatal. This study correlates the results of complete pathologic evaluation and classification of 500 spleens obtained by splenectomy with survival information for each dog. Among the spleens examined, 257 of 500 (51.4%) were classified nonneoplastic and 241 (48.2%) were neoplastic; 2 (0.4%) were unclassified. Miscellaneous nonnodular splenomegaly accounted for 46 of 257 (18%) of the nonneoplastic lesions; nodular splenomegaly accounted for 206 of 257 (79%) of nonneoplastic splenic lesions and was composed of lymphoid hyperplastic nodules and associated hematomas, hyperplastic lymphoid nodules alone, or hematomas with no apparent underlying cause. Nodular neoplastic diseases of the spleen were divided among benign he canine spleen is readily accessible during physical T examination through abdominal palpation, radiography, and ultrasonography. Splenectomy is a routine surgical procedure that is undertaken in dogs most frequently because of abdominal discomfort and hemorrhage in the presence of splenomegaly. The surgical approach to the spleen is simplified by its peripheral location in the abdomen, loose mesenteric attachment, and relatively long vascular pedicle. ' From the perspective of the veterinary pathologist, the prevalence of splenic disease in dogs, as indicated by splenomegaly and subsequent splenectomy, is relatively high. Conventional surgical wisdom implies that splenic hemangiosarcoma is the most prevalent and lethal form of ~p l e n o m e g a l y ,~-~ even though recent publications suggest that hemangiosarcoma is relatively less important. On the contrary, many other forms of splenic pathology are not only more prevalent than hemangiosarcoma, but less lethal and consequently bear a considerably better These considerations can adversely affect not only the prognosis given to the dog's owner, but also the ultimate outcome of the illness. Hemangiosarcomas represented only 51% (122 of 241) of all neoplasms observed in the spleen and less than 25% (122 of Materials and MethodsThese data represent the result of gross and microscopic examination of 500 spleens consecutively submitted to the laboratory (IDEXX Veterinary Services, Inc) during a 4-year period (1988)(1989)(1990)(1991). Spleens were received by the laboratory whole and refrigerated; the overall length was measured, and the diameter of any nodular distortion was noted. Each spleen was described grossly and sectioned at 0.5-to 1-cm intervals. Sections for microscopic examination were selected from various regions of the gross specimen; generally multiple sections were obtained from the margin of any nodule and adjacent unaffected splenic parenchyma. Microscopic evaluation of multiple selected sections was accomplished fro...

Splenic Myeloid Metaplasia, Histiocytosis, and Hypersplenism in the Dog (65 Cases)

“…However, the patterns of thrombosis, infarction, and myeloid metaplasia seen in the spleens of this study were seldom observed in splenomegaly associated with other splenic diseases. 18 Microscopically, the pattern of histiocytosis, extramedullary hematopoiesis (myeloid metaplasia), and excessive erythrophagocytosis was unique among the spleens examined for this study. 18 In this context, the presence of multinucleated giant cells was reliably predictive of a fatal outcome for those dogs in which giant cells were demonstrated.…”

“…18 Microscopically, the pattern of histiocytosis, extramedullary hematopoiesis (myeloid metaplasia), and excessive erythrophagocytosis was unique among the spleens examined for this study. 18 In this context, the presence of multinucleated giant cells was reliably predictive of a fatal outcome for those dogs in which giant cells were demonstrated. However, some dogs lacking giant cells also experienced fatal outcomes.…”

Splenic malignant mesenchymoma in a dog - immunophenotypic features and clinicopathological ramifications: a case report

“…Sonographic evidence of multiple nodular splenic changes is often associated with malignancy, but is not specific for any particular disease (Hanson et al 2001;Ballegeer et al 2007). Mesenchymomas represent 4% of all splenic malignancies (Spangler and Kass 1997); however, the relative size and morphological appearance makes it difficult to differentiate malignant mesenchymomas from other mesenchymal tumours (Johnson et al 1989;Spangler et al 1994). Pre-operative sonographical evidence of local spread in regional lymph nodes or other organs is important to determine prognosis in aggressive malignant sarcomas.…”

“…Benign and malignant mesenchymal neoplasias are well described in the veterinary literature (Spangler and Culbertson 1992;Spangler and Kass 1997;Miller et al 2005;Liptak and Forrest 2007;Eberle et al 2012). Only a small number of case reports describe sarcomas, which were previously referred to as unclassified mesenchymomas with heterologous differentiation.…”

A literature review on the welfare implications of gonadectomy of dogs

“…16,30,78,89 The overall prognosis for dogs with hemangiosarcoma is extremely poor, with ≤ 10% surviving for 12 months, even when receiving adjunctive chemotherapy after surgery. [89][90][91][92] Although age at gonadectomy was unknown, a retrospective study 9 of splenic hemangiosarcoma and hematoma in various breeds revealed that spayed females have a significantly increased likelihood of developing hemangiosarcoma (OR, 2.2) when compared with the likelihood for sexually intact female dogs.…”