Canine subvalvular aortic stenosis (SAS) is an abnormal,

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

heart murmur Heart murmurs are unique heart sounds produced when blood flows across a heart valve or blood vessel. This occurs when turbulent blood flow creates a sound loud enough to hear with a stethoscope. Turbulent blood flow is not smooth. The sound di ...

caused by subaortic

stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture). ''Stricture'' ...

(SAS). There is a high incidence of this condition identified in large and giant breed dogs like the

Rottweiler The Rottweiler (, ) is a breed of domestic dog, regarded as medium-to-large or large. The dogs were known in German as , meaning Rottweil butchers' dogs, because their main use was to herd livestock and pull carts laden with butchered mea ...

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

Golden Retriever The Golden Retriever is a Scottish breed of retriever dog of medium size. It is characterised by a gentle and affectionate nature and a striking golden coat. It is commonly kept as a pet and is among the most frequently registered breeds ...

Boxer Boxer most commonly refers to: * Boxer (boxing), a competitor in the sport of boxing *Boxer (dog), a breed of dog Boxer or boxers may also refer to: Animal kingdom * Boxer crab * Boxer shrimp, a small group of decapod crustaceans * Boxer snipe ee ...

German Shepherd The German Shepherd or Alsatian is a German breed of working dog of medium to large size. The breed was developed by Max von Stephanitz using various traditional German herding dogs from 1899. It was originally bred as a herding dog, for he ...

English Bulldog The Bulldog is a British breed of dog of mastiff type. It may also be known as the English Bulldog or British Bulldog. It is of medium size, a muscular, hefty dog with a wrinkled face and a distinctive pushed-in nose.Great Dane The Great Dane is a large sized dog breed originating from Germany. The Great Dane descends from hunting dogs from the Middle Ages used to hunt wild boar and deer, and as guardians of German nobility. It is one of the largest breeds in the world ...

German Shorthaired Pointer The German Shorthaired Pointer (GSP) is a medium to large sized breed of pointing dog developed in the 19th century in Germany for hunting. A versatile hunting breed, being an all-purpose gun dog suitable for both land and water, they are streaml ...

, and

Bouvier des Flandres The Bouvier des Flandres is a herding dog breed originating in Flanders, Belgium. They were originally used for general farm work including cattle droving, sheep herding, and cart pulling, and nowadays as guard dogs and police dogs, as well as ...

. It is a common

heart defect that consists of abnormal tissue located just below the

aortic valve The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. The ...

that creates an obstruction the heart has to overcome to pump blood out to the body. As a result, the heart muscle can become thickened. The blood is pumped at a higher speed and pressure across the stenosis into the

aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...

, creating a

. This genetic trait is

polygenic A polygene is a member of a group of non-epistatic genes that interact additively to influence a phenotypic trait, thus contributing to multiple-gene inheritance (polygenic inheritance, multigenic inheritance, quantitative inheritance), a type of ...

. An animal might have the genes for SAS, yet have no actual sign of SAS. Also, an animal might have signs of subaortic stenosis, and yet offspring with SAS may not demonstrate clinical signs for a couple of generations. Any animal that has subaortic stenosis should not be bred because they can pass the defect on to future offspring.

Symptoms

In many cases, affected dogs do not show any signs. Aortic stenosis is often initially detected upon hearing a heart murmur during a routine physical examination by a veterinarian. In dogs with severe disease, you may observe signs related to heart dysfunction. These signs include lethargy, exercise intolerance, shortness of breath, and fainting. Signs of heart failure may also be seen in severe cases of aortic stenosis. These signs include coughing, increased breathing effort, and open-mouth breathing. Puppies and adult dogs diagnosed with subaortic

can suffer from heart failure and sudden death. If a dog with SAS develops heart failure, medications can be prescribed to alleviate the clinical signs (sudden/strong lethargicism, continuous heavy panting, rise in temperature etc.)

Diagnosis

SAS is diagnosed via

echocardiogram An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound of the heart. It is a type of medical imaging of the heart, using standard ultrasound or Doppler ultrasound. Echocardiography has become routinely used in th ...

with Doppler performed by a veterinary cardiologist. This allows visualization of the four heart chambers and valves as well as the anatomy of the subaortic area. Doppler allows estimation of the pressure created in the heart by the stenosis. An electrocardiogram (ECG) may be required in patients with an irregular heart rhythm. Heart murmurs are graded on a scale of one to six, with one being very mild and six being very serious. Murmurs can exist due to a large number of heart problems (infection, trauma,

anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...

, etc.). Conversely, some murmurs are benign and do not indicate cardiac pathology. The

Orthopedic Foundation for Animals The Orthopedic Foundation for Animals (OFA) is a nonprofit organization based in Columbia, Missouri, that aims to research and prevent orthopedic and hereditary diseases in companion animals. As a private not-for-profit foundation, the OFA has f ...

(OFA) has established a Congenital Heart Registry whose guidelines were established by veterinary cardiologists. A dog which auscultates normally at 12 months of age is considered to be free of

congenital heart disease A congenital heart defect (CHD), also known as a congenital heart anomaly and congenital heart disease, is a defect in the structure of the heart or great vessels that is present at birth. A congenital heart defect is classed as a cardiovascular ...

; upon confirmation of this, OFA will issue a certificate.

Treatment

Prognosis of canines with aortic stenosis depends on the severity of the disease. Mild stenosis usually does not affect longevity; however, the possibility of aortic

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or the ...

exists. Administration of

beta-blockers Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack after a first heart attack (secondary prevention). They are al ...

can decrease heart rate and prolong

diastole Diastole ( ) is the relaxed phase of the cardiac cycle when the chambers of the heart are re-filling with blood. The contrasting phase is systole when the heart chambers are contracting. Atrial diastole is the relaxing of the atria, and ventric ...

and coronary filling, thereby reducing

myocardial Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that ...

hypoxia Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the tis ...

and protect against

arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

. Dogs do clinically well on beta-blockers; however, a study proved no benefit in terms of survival versus untreated dogs with severe SAS.

References

{{DEFAULTSORT:Subvalvular Aortic Stenosis Dog diseases