" Dog heart murmur is the term used for hear-able vibrations produced by the heart or major blood vessels, due to a troubled flow of dog blood. Heart murmurs in dogs can also be produced due to any abnormality in a dogs cardiac features, such as the heart valves, cardiac leaflets or chordal structures. Canine heart murmurs can be minor or a normal cardiac behavior. A dog cardiac problem should be suspected in cases where there are accompanying symptoms such as lethargy, intolerance, obesity, cough, fainting and irregular breathing. Heart murmurs are important as part of a clinical examination for any dog heart disease, but confirmation of any underlying condition requires detailed procedures such as X-Rays, blood profiles, electrocardiography etc. Treatment for dog heart murmur is dependent upon a confirmatory diagnosis and requires either a specific surgical or medical approach along with a supportive care. "
Dog heart murmur is often minor in nature, a dog heart
condition which is called a
“physiological murmur” or “innocent murmur”. This kind of dog
heart murmur is usually produced on the outer surface of the heart or
major
blood vessels, which is caused by blood pressure blood on walls of the
heart. These are usually puppy heart murmurs which resolve by
the time the dog reaches 6 months of age. Minor dog heart murmurs is
also found in large and giant breed dogs, in dogs that are athletes,
and during illnesses such as canine hypoproteinemia (low levels of
blood protein), anemia and fever.
Physiological heart murmurs are hard to hear and are usually only noticed when a dog is panting after exercise, fear, excessive barking or running. On the other hand, a “pathological murmur” is a clearly audible cardiac vibration, which is produced inside the heart or major blood vessels due to troubled blood flow. Blood flow can be abnormal due to any problem in the valves, cardiac leaflets in the heart or congested blood flow in major blood vessels.
The comparison of normal to abnormal canine heart murmurs and severity of the cardiac problem is clinically analyzed on the basis of a physical examination with the help of a stethoscope and observation.
For a precise analysis, a heart murmur in dogs are usually identified and related with the intensity of the murmur, timing, pitch, location, quality, frequency and configuration of different vibrations observed in a clinic, during auscultation which means "listening for sounds."
Dog Heart murmurs are classified by their timing in the cardiac
cycle, intensity, location (or point of maximum intensity or PMI),
quality (subjective), phonographic configuration and frequency.
The veterinarian will grade the murmur based on subjective criteria
after listening to the loudness of the murmur. In many cases, a loud
murmur does not mean that there is a chronic heart disease.
Dog heart murmur grades are on a scale of I to VI (1 to 6)
Dog
Heart Murmur Grade |
Meaning |
I |
very
faint murmur requiring concentration and quiet room to be heard |
II |
soft
murmur that is consistently ausculted over only 1 valve area |
III |
moderate
intensity murmur, readily auscultable usually radiating to another
valve area. |
IV |
loud
murmur without a precordial thrill, usually radiates to both sides of
the chest |
V |
loud
murmur with a precordial thrill (palpating the vibration on the chest
wall caused by the murmur) |
VI |
loud
murmur with a precordial thrill and still audible with the stethoscope
off the chest wall |
Canine heart murmur is a clinical feature of a heart patient during diagnosis. Dogs with symptoms such as cough, lethargy, intolerance, fainting, loss of appetite and irregular breathing should be suspected for possible canine heart disease. A detailed clinical examination for the identification of symptoms and procedures like auscultation (listening) of heart sounds/murmurs can reveal a possible underlying problem.
Auscultation (listening) to dog heart sounds and murmurs can help a veterinarian in identifying the severity and nature of the dog heart problem. This is a clinical feature only, confirmation can only be done through other specific features like radiography and laboratory tests.
Breed is an important diagnostic factor when diagnosing a dog heart murmur. Here are selected canine cardiovascular disease predispositions:
Breeds |
Dog
Heart Diseases |
Cavalier King Charles
spaniel, dachshund, small breeds |
Mitral valve disease
(acquired) |
Bull terrier,
rottweiler |
Mitral valve disease
(congenital) |
Boxer, cocker spaniel,
Doberman pinscher, Great Dane, Irish wolfhound, Labrador retriever |
Myocardial failure |
Cocker spaniel,
English springer spaniel, German shepherd, Maltese terrier, poodle |
Patent ductus
arteriosus |
Boxer, cocker spaniel,
English bulldog, mastiff, miniature schnauzer, Samoyed, West Highland white terrier |
Pulmonary stenosis |
Boxer, German
shepherd, golden retriever, Newfoundland, rottweiler |
Subvalvular aortic
stenosis |
Labrador retriever |
Tricuspid valve
disease (congenital) |
English springer
spaniel |
Ventricular septal
defect |
Canine heart murmurs are a clinical feature for heart patients, on the basis of which a veterinarian will recommend different procedures for confirmation of the condition. A brief assessment of possible dog heart disease can be made on the basis of auscultation, but confirmation of any underlying condition can only be made through X-Rays, blood profiles, electrocardiography and echocardiography etc.
Click to listen to a dog heart murmur:
Once an underlying canine heart disease is diagnosed, specific treatment should be followed. Approaches can be either medical or surgical, based upon the age of a patient, the severity and nature of the diagnosis made. Canine heart murmur is a clinical feature, a symptom itself and a diagnostic tool which usually resolves on successful specific cardiac treatment.
Since, canine heart murmurs are related with abnormality in the physiology and strength of the heart muscles, valves and major blood vessels, a supportive therapy with supplements and tonics such as Heart and Circulation Tonic can help to improve a dog's clinical condition during treatment. These supplements and natural remedies can be used after recovery to maintain cardiovascular strength. Similarly, along with specific and supportive treatment, critical care is needed in the day to day routine of a dog with heart problems, such as regular use of prescribed medications and care regarding activities.
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Merck Veterinary Manual (Merck & Co.)
Veterinary Clinical Cardiology