Newfoundlands and SAS: Understanding Heart Disease Risks

Being one of the largest breeds around, the Newfoundland is an impressive and beloved dog known for its gentle and kind nature. However, like many large pedigree dogs, Newfoundlands are prone to certain health problems, including a serious congenital heart condition called subvalvular aortic stenosis (SAS). This disease impacts the heart‟s function and can, in severe cases, significantly shorten a dog‟s life if left unmanaged.

What is Subvalvular Aortic Stenosis (SAS)?

SAS is a hereditary disease characterised by the abnormal narrowing just below the aortic valve in the heart. This narrowing is caused by fibrous or cartilaginous tissue growths that restrict blood flow from the left ventricle into the aorta—the main artery carrying blood to the body. The severity of SAS varies widely: some dogs have mild, subclinical forms while others develop severe obstruction leading to serious heart complications or sudden death.

Scientific research has identified a specific gene mutation in the PICALM gene that is strongly associated with SAS in Newfoundlands. Intriguingly, this gene mutation is related to the same gene implicated in Alzheimer‟s disease in humans. SAS inheritance is typically autosomal dominant with incomplete penetrance, meaning not all dogs carrying the mutated gene develop the disease but can still pass it on genetically.

How Does SAS Affect Newfoundlands?

The disease affects heart valve function, causing turbulent and restricted blood flow. This disturbance can produce a heart murmur, which vets detect during physical examination using a stethoscope. The murmur's loudness is graded from 0 (no murmur) up to 6 (severe). Mild SAS may allow a dog to live a normal lifespan without symptoms, while severe cases often cause heart failure or sudden collapse even in relatively young dogs, sometimes as early as four years old.

Diagnosing SAS often involves follow-up testing such as echocardiograms (echo-Doppler studies) to visualise heart structures and function in detail. Unfortunately, surgical treatment options are limited and rarely employed in dogs, unlike humans where surgery can remove the obstructive tissue around the aortic valve.

Testing for SAS and Responsible Breeding

Genetic testing for the PICALM mutation is available and plays a crucial role in responsible breeding practices. Reputable Newfoundland breeders test their breeding stock to identify carriers of the gene. Breeding decisions aim to reduce the incidence of SAS in puppies without compromising genetic diversity, which is essential for the long-term health of the breed.

Because SAS demonstrates incomplete penetrance, puppies may inherit the gene without showing symptoms immediately or ever, so careful selection and ongoing monitoring are vital. Breeding a carrier dog only to a clear partner and testing offspring can gradually decrease the likelihood of puppies developing this heart condition.

Understanding Heart Murmur Tests in Newfoundlands

When a vet detects a murmur, they evaluate its grade to gauge severity. A grade of 0/6 confirms a normal functioning heart, while grades from 1/6 to 6/6 indicate increasing severity of turbulent blood flow. Cardiologists may perform echocardiograms to confirm the diagnosis and assess heart function thoroughly.

Other Causes of Heart Murmurs in Newfoundlands

While SAS is a common reason for heart murmurs in Newfoundlands, other cardiac abnormalities can also cause murmurs. These include:

• Narrowed Heart Valves: Conditions such as pulmonic stenosis also restrict blood flow, leading to murmurs.
• Leaky Heart Valves: Regurgitation through valves like the mitral or tricuspid can cause turbulent flow detectable as murmurs.
• Abnormal Shunts: Structural defects such as holes in heart chambers allow abnormal blood flow and murmurs.

Confirming the exact cause requires specialist cardiac evaluation and imaging.

Conclusion

Subvalvular aortic stenosis is a significant inherited heart condition particularly affecting Newfoundlands. Thanks to identification of the PICALM gene mutation, genetic screening can help breeders responsibly reduce SAS risk while protecting the breed‟s genetic health. Early diagnosis through murmur detection and specialist cardiac tests can improve management outcomes for affected dogs. Prospective owners should seek puppies from breeders who perform health screenings, and owners with Newfoundlands should maintain regular veterinary check-ups to monitor heart health.

By understanding and managing SAS proactively, we honour our duty to these magnificent dogs, ensuring they live full, happy lives as cherished companions.