Aortic stenosis (AS) is a "narrowing" just above or below the aortic valve, or (rarely) of the actual valve, causing a partial obstruction of blood flow from the left ventricle of the heart, through the aortic valve, and into the aorta.
* Subvalvular aortic stenosis is the most common form of AS.
The defect is located just below the aortic valve.
* Supravalvular aortic stenosis is not so frequently seen.
The defect is located just above the aortic valve.
*Valvular aortic stenosis is rare.
The defect is located within the aortic valve.
The stenosis (narrowing) is caused by the abnormal formation of nodules, or a fibrous ridge or ring of tissue. The heart therefore has to work harder to pump an adequate supply of oxygenated blood through the stenosed (narrowed) part.
Is AS hereditary? Some say yes but there is no definite conclusion.
Canine geneticist Bruce Cattanach writes:
"The problem is that the mode of inheritance of Aortic Stenosis has not been clearly established even in the researched breed, the Newfoundland. In this breed some evidence was obtained that a single dominant gene was responsible but this became confused upon crossing to another breed. From my background in genetics I would expect that a single gene is primarily responsible for the condition but this is not to say that any other genes, such as those playing a role in heart development, blood vessel walls, elasticity of the wall, or the biochemical milieu behind the nodule and fibrous ring formation that leads to AS, etc., do not play a part."
How are canine heart murmurs graded?
Heart murmurs are graded from 0 to 6, according to the severity of the murmur:
Grade 0/6 denotes no murmur.
Grade 1/6 and 2/6 murmurs are generally considered to be "mild".
Dogs with Grade 1/6 and 2/6 murmurs are very unlikely to develop any symptoms as a result of their aortic stenosis and should lead perfectly "normal" lives.
Grade 3/6 and 4/6 murmurs are generally considered to be "moderate".
The majority of dogs with Grade 3/6 and 4/6 murmurs are also unlikely to develop any symptoms, but a small number will go on to become symptomatic.
Grade 5/6 and 6/6 murmurs are generally considered to be "severe".
Dogs with Grade 5/6 and 6/6 murmurs are most at risk of developing symptoms - (see below).
X-ray looks at the shape and size of the heart and can identify abnormal enlargement of the heart chambers e.g. left ventricle in severe AS.
Electrocardiography measures the electrical impulses of the heart and can identify any abnormal heart rhythms e.g. VPCs (ventricular premature contractions) in severe AS.
Ultrasound with Doppler studies:
Ultrasound enables the vet to measure all the internal dimensions of the heart, in particular the thickness of the left ventricular wall with regard to aortic stenosis.
Doppler studies allow the vet to measure the speed of blood flow through the heart valves i.e. from one chamber to another or, in the case of aortic stenosis, specifically from the left ventricle to the aorta via the aortic valve; this is the aortic outflow velocity.
CVD - Heart valves can lose their ability to close properly, causing abnormal blood flow - Chronic Valvular Disease (CVD)
DCM - The muscular walls of the heart become thinned and weakened - Dilated Cardiomyopathy (DCM)
Heart Failure - DCM and CVD can result in the same serious condition - heart failure Canine heart failure is caused by one side of the heart being required to do more than it is physically able causing the muscles to fail.
Because the heart must pump harder to eject blood, the muscular walls of the left ventricle grow thicker and become abnormal. Many of the problems associated with SAS are due to this thickened heart muscle.
Heart murmurs can occur with basically any dog and for any number of reasons. Not all reasons point to genetics. If the parents are not presenting signs of a heart defect or heart murmur, such can still occur in the offspring during the fetal stage for a variety of reasons. See up above.
We have never had any heart issues with our personal dogs....ie...either the Poodle or the Golden Retriever. That does not mean that offspring Goldendoodles or Poodles or Golden Retrievers could not at some time, have an early development issue during the fetal stage. Unless a heart murmur is detected during a routine vet check at an early age, heart murmurs can go undetected if they exist. Should a heart murmur be detected in a very young puppy, it is possible for the heart murmur to disappear as the puppy ages and grows. Should a puppy have a heart murmur, it does not necessarily mean a death sentence. Canine who have a heart murmur can live a very normal life so long as the murmur has a low grade. (see up above). Low grade heart murmurs mean that your puppy or dog should be observed during playtime and as with even a normal canine, during the hot weather, strenuous activity should be limited. Maintaining a normal weight for your canine is essential and not allowing your puppy or dog to eat fatty foods or too many treats will help keep your Goldendoodle fit, trim and healthy. As a Goldendoodle creator, we recommend to our doodle owners, that if your puppy has been diagnosed with a low grade heart murmur, and so long as it is not life-threatening....to continue with your routine vet visits as you normally would.....continue with your puppy's daily life style with the exception of not "over doing things" and watch your puppy or dog for maintaining his or her normal weight. Don't place your dog on diets or strict intakes on food....just maintain a normal healthy balance of eating right with proper exercise.
In the winter or summer months, use common sense. Don't allow your puppy or dog to exercise heavily in the heat or to remain outdoors in the heat for long periods of time. In the winter months, limit exposure to extreme cold temperatures with normal walks....playtime or using the bathroom.
Should one of our Goldendoodles or other pups purchased with a genetic health warranty have a life threatening issue with a heart murmur....providing we have supporting documentation from the puppy's first vet check up (within 48 hours of possession) and we have evidence and information from your vet as soon as this issue has come to light, we will replace the canine should a death occur, due to a heart issue, during your warranted time frame. Canine can have heart issues that is completely unrelated to a known heart murmur which is why we do not offer any warranty for the life of the dog or beyond any purchased warranted time frame. Health issues for aging pets occur regardless of breed, regardless of how it was bred, regardless of the breeder and regardless of where it came from. If a customer has purchased a puppy from us without a genetic health warranty and paid for a health check up and a heart murmur is detected during the health check up, the customer does have the option of accepting the puppy "as is" or accepting a different puppy upon availability. If a customer has not paid for their puppy to be vet checked prior to possession, we have no way of knowing if a puppy has a heart murmur or any other health issue that is not noticeable upon personal observation. As stated above, low grade heart murmurs detected in a young puppy have the ability to disappear as the puppy ages.
What are DNA markers?
DNA Markers are short regions of DNA that differ between individuals. If you look at the total DNA sequence of one dog and compare it to the DNA sequence of any other dog, you would find that the vast majority of the nucleotides or bases, which are the letters that make up the genetic code, are absolutely identical between the two individuals. But you would also find a certain degree of difference. On the average, between one out of 1,000 to one out of 100 of these bases tend to be different. These differences are called different polymorphisms or markers. They can be the particular nucleotide, which occupies a given position.
**Because we believe it will eventually be possible to rule the Golden Retriever and the Poodle out as silent carriers for certain defective genes that can affect their offspring, we require all of our Goldendoodle owners to submit their doodle's DNA to a laboratory called VETGEN. This company can store their dogs' DNA for up to ten years for a very low, one-time fee. Your Goldendoodles' DNA can be tested if a health issue occurs that your vet has claimed has a genetic component and can help to either prove or disprove a direct genetic link. Some vets believe all health issues have a genetic component/link. This is not always true. When a customer is told by a vet that the health issue is genetic, they believe their vet. Please know that a veterinarian is NOT a geneticist and has NO WAY OF KNOWING 100% if your canine's illness if genetically related or not unless the canine's DNA has been submitted to a genetic lab for study and testing. WE REQUIRE ALL PUPPIES TO BE DNA TESTED with proof of a genetic link submitted to us before a decision will be made regarding a replacement. A health issue must occur within a purchased warranted time frame before any puppy or dog is replaced. Health issues that occur beyond a purchased warranted time frame will not be replaced. If a customer refuses to submit their Goldendoodles' DNA to VETGEN for storage or testing, then we can not assist the customer in any way with regards to a possible genetic health issue. As they say "the proof is in the pudding". Unfortunately some people do not take into consideration the age of their dog when health issues arise. A dog who is 12 years old and beyond are going to have health issues to include heart issues based on age alone. While 12 years old does not seem but a "tween" to humans....a dogs' internal organs age much quicker than that of a human and a dog who is 12 and older is a senior, elder dog. As with most elderly people, health issues occur more frequent and more problematic just as with dogs. It is very common to see aging dogs begin to have health issues and it has nothing to do at all with the dogs' breeder's method of breeding or the dogs' genetic make-up. There are other factors to consider as well to include the dogs' diet....how it was maintained, etc.
In the mildest form, the condition is undetectable and will not cause any problems for the dog. However the defect may still be passed on to offspring, so we highly recommend spaying or neutering any dog that has been diagnosed with a heart murmur...period. The challenge for breeders and veterinarians is to identify affected dogs with very mild or no clinical signs of the disorder. Dogs can be silent carriers and not show signs or symptoms of genetic ailments...hence, why we desire all of our Goldendoodle owners to submit their doodles' DNA to VETGEN.
In dogs with mild aortic stenosis,there is no special treatment required. The dog should not be used for breeding and littermates should be carefully screened. Your veterinarian may suggest antibiotics in certain circumstances as a precaution against infection of the abnormal valve tissue.
With moderate to severe stenosis, the dog's exercise should be restricted. Beta-blocking drugs may be prescribed by your veterinarian to try to minimize the effects of left ventricular hypertrophy. Your veterinarian will recommend other therapy if required to manage congestive heart failure. Medical management for congestive heart failure is similar no matter what the cause, and consists of medications to support the heart muscle and decrease the work load of the heart, together with dietary recommendations.
Various surgeries have been attempted to alleviate the obstruction with limited success. The surgery itself carries a high risk, and there is little, if any, increase in survival rates compared with dogs whose condition is managed medically.
**Photo courtesy by Debbie** **Billy...a Chinese Crested Hairless**
