Splenic mass diagnosis in dogs undergoing splenectomy according to breed size

Various splenic diseases can result in a splenic mass and necessitate splenectomy. The objective of this study was to compare the prevalence of malignant and benign splenic diseases, and type of malignant disease, in dogs categorised by breed size. It was hypothesised that the prevalence of splenic disease would be significantly different in small versus large-breed dogs. All dogs had a splenic mass identified with ultrasonography or CT, and had a confirmed diagnosis. Dogs were categorised as small, medium and large breeds according to breed standards. There were 54 small, 139 medium and 41 large-breed dogs; 129/234, 55% (95% CI 49% to 61%) had malignant disease versus 105/234, 45% (95% CI 39% to 51%) with benign disease (P=0.117). The prevalence of malignant versus benign disease was not significantly different for small (P=0.276), medium (P=0.074) or large-breed dogs (P=0.080). Small-breed dogs were 2.3 times more likely than large-breed dogs to have benign disease. Small-breed dogs with malignant disease were one-third as likely as large-breed dogs to have haemangiosarcoma. In conclusion, the overall prevalence of malignant and benign diseases was 50:50; however, compared with large-breed dogs, small-breed dogs are more likely to have benign disease. When small dogs do have malignant disease, they are, however, less likely to have haemangiosarcoma. This information is important to consider in early discussions with owners of dogs of various breed sizes.