Download Heart Murmurs and Congestive Heart Failure

East Doncaster Veterinary Hospital
Cnr Peach Way and Blackburn Rd
Templestowe, Vic 3106
Ph (03) 9842 8833, Fax (03) 9842 0233
Webpage: www.edvh.com.au
Dr Jedda McDonogh BVSc, MVS, MACVSc (Small Animal Surgery)
Dr Laura Lim BAniSci, BVSc (Hons)MACVSc(Medicine), Dr Meg Richardson BVSc
Heart Murmurs and Congestive Heart Failure
How are heart murmurs detected?
When examining a patient the Vet will listen carefully to the Right and Left heart sounds
to detect any arrhythmias (skipped or extra beats), any muffling or enlargement of the
heart and any “whooshing” noises (murmurs). Usually the heartbeat is a distinct “lup dup, lup - dup” noise but when the heart valves are abnormal we hear a murmur - “lush dush, lush - dush.”
Why does it happen?
Approximately 5% of heart murmurs are congenital - present at birth. This can be due to
blood flowing through a “hole in the heart”, failure of the foetal blood vessels to close,
malformed heart valves or a narrowing in a large artery due to a ring of fibrous muscular tissue. These murmurs can be more common in particular purebred pups. At an
early age, we can organise an ultrasound to be performed at the clinic or at a specialist
centre with advice on corrective surgery.
Wear and tear valve disease is the most common cardiac disease of middle aged and
older dogs, often toy and miniature breeds. It is a combination of thickening of the heart
valves and their connecting muscles, narrowing of the coronary arteries and overloading
of heart chambers leading to possible heart attack.
Why does heart failure occur?
The 4 valves inside the heart maintain a one - way blood flow through the heart - “blue”
venous blood returns from the body to the heart to be pumped to the lungs. If the valves
are worn they do not close completely whilst the heart muscle is pumping (contracting).
The blood can then flow backwards - from the heart towards the body or towards the
lungs.
If the backwards flow is less than 50% of the total volume, the heart will compensate and
there will be no external signs of heart failure. In advanced cases, backwards blood flow
may be up to 80% and the heart murmur noise becomes louder and is classed as a higher
grade out of 6. Severe cases may develop an abnormal heart rhythm - the Vet will feel for
the strong pulse on the inner thigh, the femoral artery, keeping in time with the heartbeat.
An enlarged heart can push upon the windpipe causing a harsh, dry cough. More blood
flowing backwards towards the lungs can cause a moist, productive cough and faster
breathing. Fluid can accumulate in the liver and abdomen, around the lungs and the
patient may run out of energy when exercising or even faint.
What happens next?
When a heart murmur is detected in your pet, in combination with coughing, low energy,
weight loss and increased breathing effort, we recommend x-rays to stage the severity of
heart swelling and fluid accumulation in the lungs. An ECG (electrocardiograph) can be
conducted in a conscious patient to observe abnormal heart rhythms and unusual or
severe cases should have an ultrasound (echocardiography) to visualise the heart valves
working.
What treatments are available?
In patients with a mild heart murmur and no heart enlargement or signs of breathing
distress, monitoring at home and six monthly check ups may be sufficient.
In more advanced disease, medication can be commenced to assist with blood pressure,
increase the oxygenated blood flow to the heart muscle and help remove excess fluid
from the lungs or abdomen. Weight loss can help some patients and low salt diets are also
recommended. Diuretic drugs, which promote excess fluid loss by increasing kidney
work, must be balanced with free access to water, more toileting and regular blood or
urine tests on kidney function. Regular checkups are necessary so that dose rates of
medication can be tailored to progress.
Unstable heart failure patients may require initial therapy in hospital with intravenous
diuretics, oxygen supplementation, blood pressure medication to help heart muscle
contraction and slow IV fluids. Oxygen in a humidicrib or via nasal tube and any fluid
drainage from the chest may be initiated at the clinic and continued overnight at the 24
hour, Animal Emergency Centre.
The aim is to stabilise the patient to continue oral medication, sometimes up to 3 types, at
home. This must be balanced with weight control, gentle exercise, minimising side
effects and ensuring a good quality of life.
© to edvh