How Aortic Stenosis Affects Dogs
Subaortic stenosis (SAS) typically develops after a puppy is born, during the first weeks to months of its life. However, clinical signs of the disorder often do not appear until later. The onset of noticeable signs of SAS can happen at any age and depends largely upon the severity of the blockage or obstruction of blood outflow from the left ventricle into the aorta. In most cases, the disorder can be identified by the time the puppy reaches about one year of age. It is hard to say whether affected dogs are consciously hindered by the condition before they develop symptoms of disease. However, at some point, they most likely will become extremely ill and may die suddenly from the condition.
Symptoms of Aortic Stenosis
The signs of SAS range from none (subclinical disease) to the signs of full-blown congestive heart failure. In most cases, the condition is diagnosed when a veterinarian detects a heart murmur in a young, large breed dog on a routine physical examination, or when the dog is in the veterinary clinic for some unrelated reason. When symptoms are present, may include one or more of the following:
- Difficulty breathing (dyspnea)
- Rapid breathing (tachypnea)
- Fainting episodes (syncope)
- Exercise intolerance
- Heart murmur (most prominent after 2 months of age)
- Irregular heart beats (arrhythmias)
- Weak femoral pulses (the femoral artery is the large artery that is palpable [can be felt] on the inside of a dog’s upper thigh)
- Stunted growth
- Sudden death
Unfortunately, if SAS is not properly diagnosed in an affected young dog, its owner may only learn of the existence of the disorder when the dog literally “drops dead,” which usually occurs during a period of exercise or exertion.
Dogs at Increased Risk
SAS is among the most common of the congenital heart defects seen in domestic dogs. It certainly is the most common congenital heart defect of large and giant breeds. SAS is commonly seen in Golden Retrievers, German Shepherd Dogs, Newfoundlands, Boxers, Bull Terriers, Rottweilers, German Shorthaired Pointers, Bernese Mountain Dogs and the Bouvier des Flandres. Other breeds with a heightened risk of developing SAS include Great Danes, Samoyeds, Bull Terriers and English Bulldogs.