Natural History of Subaortic Stenosis in 166 dogs (1999 – 2011)

Abstract Introduction Subaortic stenosis (SAS) is one of the most common congenital cardiac diseases in dogs. The objective of this study was to provide survival times on a large population of dogs with SAS and to propose a redefined pressure gradient (PG) scale to include a mild, moderate, severe and very severe disease group. Animals, materials and methods Dogs were divided into four groups based on the Doppler-derived PG across the stenosis. Disease severity was defined as follows: mild = PG   130 mmHg. Over the study period (1999–2011), 166 client-owned dogs were diagnosed with SAS of which 129 had follow-up information available. Results Unadjusted median survival time for severity groups were as follows: mild 10.6 years; moderate 9.9 years; severe 7.3 years; and very severe 3.0 years. Univariable analysis examining the effect of the PG, age at diagnosis and sex found only the PG and age at diagnosis had a significant effect on survival. Adjusted survival curves showed that the survival time in the very severe group was decreased compared with all other groups. Conclusion Based on the results of this study, a revised SAS classification system with four PG groups is appropriate. Dogs with a PG > 130 mmHg were identified as those with the lowest median survival time.