Being one of the largest breeds around, the Newfoundland is an impressive looking dog and one that's captured the heart of many an owner all thanks to their super kind natures. However, the breed like so many other large pedigree dogs has its fair share of genetic health issues to have to deal with. One of which affects their hearts and if the condition is severe, it could be life-threatening. The disease is called subvalvular aortic stenosis or SAS for short and it's a condition that's all too commonly seen in Newfoundlands as well as other dogs.
SAS is a congenital heart disease that affects these lovely dogs. Researchers have found that it's one gene mutation that is responsible dogs inheriting the condition from their parents although certain proteins are also thought to be involved. Studies into the disease have helped vets understand how to best treat dogs with the condition although a lot more research is still needed into what can only be described as a heartbreaking and all too often lethal heart condition that claims the lives of so many Newfoundlands throughout the world.
The gene responsible for SAS is known as PICALM which vets now understand is the same as the one responsible for people who develop Alzheimer's disease. Only one of the parent dogs needs to carry the gene for it to be passed on to puppies although research has established that it's a bit "hit and miss" as to whether a puppy would inherit the gene or not.
The condition impacts the aortic valve which is found in a dog's heart. Abnormal tissue growth forms around the valve which then means blood cannot flow properly out of the heart and out into the aorta. The problem vets often face when attempting to diagnose and treat the condition is that some dogs only develop mild symptoms whereas others develop a lot more serious forms of SAS. When a dog suffers the more severe form, they may suddenly keel over and die without having shown any symptoms or signs of having developed the disorder at all.
Occasionally, a vet might pick up on the fact a Newfoundland has the condition when they investigate a dog's heart murmur which leads to them carrying out x-rays of the dog's chest only to discover the dog is indeed suffering from SAS. Should a dog have just developed the mild form of the disease, the chances are they will live out their normal lifespan. However, should the condition be more severe, they are more likely to succumb to this heart disease as early as when they are just over 4 years old even if they have been given all the right therapeutic treatment.
Children can also suffer from SAS and if diagnosed with the condition, doctors would surgically remove the offending tissue growth around an aortic valve. However, with dogs this type of surgery is very rare and the prognosis is never very good should a vet decide to go down this anyway.
Newfoundlands can be tested to see if they carry the gene mutation and reputable, well established breeders would always have any and all their dogs tested before using them in a breeding programme. This is the only way of reducing the risks of any puppies inheriting this congenital heart disease from their parents. However, it's important to bear in mind that puppies can inherit any genetic health disorder because gene mutations are able to skip a few generations, but carefully selecting dogs that don't carry the gene does reduce the chances of their offspring developing SAS which is why it's still so worthwhile testing all Newfoundlands.
When a Newfoundland is tested for SAS the results are given to the breeders/owners, vets and other people involved namely the cardiologists. These tests show up any heart murmur that may be present which is then graded from 1 - 6 out of a total score of 6. Should a dog's murmur be slight, it would be graded as a 1/6 whereas if the murmur is a lot more severe, it would be graded as a 6/6. The test is carried out by a veterinary cardiologist using a stethoscope and should there be no murmur detected at all, a grade of 0/6 would be given in the report. This indicates that a Newfoundland's heart functions normally. Often a vet would recommend that an echo-Doppler heart test be carried out to confirm whether a dog has developed SAS and would study the results in depth to see whether their heart is working normally or not.
Newfoundlands are prone to develop heart murmurs and even when detected, neither the vet nor the cardiologist would know why the disorder has occurred. With this said, an experienced veterinary cardiologist would have a good idea of what the underlying cause of the heart disorder may happen to be simply by reviewing the characteristics of the murmur. However, to establish the root cause an echo-Doppler heart test would need to be carried out on a dog's heart. Murmurs can develop for a variety of reasons which are explained below:
Dogs with narrowed heart valves are more prone to develop a heart murmur simply because blood flow through the heart is restricted. This could be due to heart conditions like aortic, sub-aortic and pulmonic stenosis being the cause of the narrowed valves.
When blood is allowed to leak through a valve it causes a heart murmur because blood flow is more turbulent as it passes through the valve. Conditions like tricuspid and mitral regurgitation are often the cause of leaky valves in a dog's heart.
If a Newfoundland has any sort of heart defect which could be a hole in either the right or the left ventricle, it allows blood to flow through them which then results in a dog developing a heart murmur.
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