Canine subvalvular aortic stenosis (SAS) is an abnormal, congenital heart murmur caused by subaortic stenosis (SAS) that has been detected in Goldens. There is very good evidence that it is heritable and thought to be multifactorial, so that the inheritance is complex. A dog might carry the genes for SAS yet have no actual sign of SAS. Also, a dog might have signs of SAS and yet offspring with signs of SAS may not be seen for a couple of generations. Any animal that has SAS should not be bred, because they can definitely pass the defect on to future offspring. Known for being highly complex genetically and therapeutically, SAS has a history of taking the lives of seemingly healthy dogs, robbing them of a chance for treatment in their prime.
Part of the problem is that severely affected dogs may not show signs of disease. Additionally, owners may not know or recognise their dogs decreased exercise ability or the possibility of their fainting or collapsing from excitement. When these dogs die suddenly, their owners are left pondering the cause. Even for dogs lucky enough to be diagnosed with severe SAS, treatment options that increase quality of life and longevity have been slim. Discovery of the heart defect usually comes after a veterinarian detects a heart murmur, leading to definitive diagnostic testing. The risk in breeding a dog with SAS is that the heart defect easily can be passed on to offspring regardless of the genetics of the breeding partner. The dramatic life-shortening potential of severe cases of SAS is reflected in the median 19-month survival for dogs that do not receive treatment. The median survival for dogs receiving medical therapy, consisting of beta blockers to help slow the heart, is 56 months. Dogs with mild to moderate cases of SAS typically live much longer, possibly having normal life spans, although scientific data for life estimates is not available. Concerns about SAS have prompted the Golden Retriever Clubs to recommend breeders have their dogs examined by a veterinary cardiologist for heart murmurs. A dog which auscultates normally at 12 months of age is considered to be free of congenital heart disease; and a clear certificate is issued.
Despite the challenges, good news has come in bits and pieces. Veterinary cardiologists are tackling SAS from a preventive and treatment approach. A novel treatment option being developed and investigated for dogs with SAS is cutting balloon valvuloplasty. This procedure, used for treating coronary artery disease in adults and branch pulmonic stenosis in children, has proved successful in the short term in the majority of dogs with severe SAS that were part of a recent study. The long-term outcome of these dogs continues to be monitored. Genetic researchers are working to find the causative gene mutation and develop a genetic test. Current research focuses on a region of chromosome 21, where an association appears likely in Rottweilers and Golden Retrievers.