Heart murmurs in dogs


Heart murmurs in dogs

Heart murmurs in dogs are the signs and symptoms of ailments either cardiovascular or extra cardiac in pathology. When the unidirectional flow of blood through cardiac valves is interrupted, then the turbulence triggers murmuring sound.

The Grades of Heart Murmurs in Dogs:

The murmurs range from mild to intense grades; the veterinarians use I-IV grade scale to mark the extent of severity.

Grade I heart murmurs are usually localized in a particular area of chest, very mild and murmuring frequency is lower and irregular.

Grade II heart murmurs are characterized with considerable sound, though localized akin to Grade I heart murmurs, the pattern of murmur is regular.

Grade III heart murmurs are apparent in different parts of chest, the decibels are greater than Grade I & II scale but the pattern of murmur is regular, similar to that of Grade II murmurs.

Grade IV heart murmurs are so intense, heard through stethoscope as well as felt over hand during palpitation; it is also manifested in pulse rate anomaly throughout the body.

Causes of Heart Murmurs in Dogs:

The etiology of heart murmurs are as follows:

1. Physiologic or harmless/innocent heart murmurs

2. Pathology – either acquired or congenital cause

3. Ailments of cardiac muscle fiber and cardiac valve in heart functioning

4. Extra-cardiac, i.e., conditions not involving heart

Physiological heart murmurs; also called as innocent heart murmurs at times. It’s felt in 6-8 weeks old puppies during the postnatal development of heart & valves. But gradually disappears when they turn 4-5 months old. It’s harmless, graded between I & II.

Structural problem is related to unhealthy muscle fibers of heart or abnormalities in cardiac valves that may be either acquired or congenital.

The cardiac valves enable unidirectional blood flow; defects in valves like mitral valves diffuses unidirectional flow resulting in murmuring sound and this condition is termed as mitral insufficiency.

In pathological factors, bacterial endocarditis in older dogs gives rise to heart murmurs.

Extra-cardiac heart murmurs are also called as “functional heart murmurs”. It does not affect cardiac health though ailments are not related to heart but it’s potential to trigger cardiac murmur. Infection, pregnancy, anemia or hypoproteinemia, fever, weight loss are the conditions associated with lowering of blood viscosity likely to cause murmuring sound, however heart remains unaffected as such. Anemia is closely related to parasites, flees, worms and ticks wherein the treatment is not directly towards mitigating heart murmurs but to kill these vectors.

Anemic or hypovolemic blood due to blood loss is serious though extra-cardiac ; adults dogs are more vulnerable to such conditions.

Diagnosing and Treating a heart murmurs:

It’s easier to diagnose heart murmurs. Stethoscope over the chest would enable you to listen to murmuring decibels. But it’s your vet who will tell you the grade ranging from I-IV, within which your dog falls and also the consequent measures to get well! The intensity of murmurs and the area over the chest where it is palpitated would be monitored periodically by your vet reducing the case history in his medical chart. So your dog has to be shown to him for follow up. But murmurs in puppies are not a factor to worry, your vet will definitely advise to wait for disappearance of murmurs as the puppies grow and attain 4-8 months old.

The Psychological tenor also gets reflected in dog’s heart. Uncontrolled excitement or heavy depression cause heart murmur but things go right with the way your dog is taken care as there is no requirement of medicines.

When your dog falls under grade IV of heart murmur scale, either it may be attributed to structural heart problem or extra-cardiac, the symptoms are more severe which s an indication of deteriorating health.

  • Weight loss
  • Fatigue even after minimal exertion
  • Gums turning paler
  • Intensive coughing
  • Abnormal heart rate with irregular cardiac rhythm
  • Faintness or collapsing episodes
  • Loss of appetite

Structural heart problems and extra-cardiac ailments are diagnosed through sophisticated medical equipments like ultrasound scanning, electro and echocardiograms and X-rays. Doppler test is the best for diagnosing structural cardiac problems which involves ultrasound, a type of echocardiogram. This easily helps to view heart and watch its movements, the status of cardiac valve and the rate of blood flow wherein the accuracy in diagnosis is ensured.

The treatment of structural as well as extra-cardiac heart murmurs are through “SMS’” S- Specialized diet, M- medications, S-Supportive care or a sweet combination of all the three.

Congenital heart defects like pulmonic stenosis or patent ductus arteriosis require surgical correction.

Outlook for dogs with heart murmurs:

It is your vet, who will assess your dogs appropriately and advise whether to opt for treatment or to go for conventional and conservative measures:

  • Physiological/innocent hart murmurs usually don’t require treatment. Prognosis is always better to get well quickly.
  • Congenital heart diseases involving abnormalities in cardiac valve demand surgical correction, following which prognosis is highly appreciable.
  • Mitral insuffiency is treated successfully but continuous medication after it is unavoidable.
  • Bacterial endocarditis and dilated cardiomyopathy resulting in cardiac murmurs may be fatal and even when medical attention is given to counter death, prognosis is poor.

If your dog murmurs, then you may try to understand its language. But when your dog’s heart murmur, your vet may be called as he is specialized to understand it accurately. Physiologic/innocent cardiac murmurs disappear as days progress and get completely obliterated during successive visits to clinic after regular intervals. Your vet would catch-up the ailing murmurs and gives a successful treatment. So take care of your dog and help them to visit their vets regularly in order to avert fatal ailments to an unfolding extent.


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