im trying to fond out info for someone whose been told their pup has a grade 4 murmur (it ws scanned), small hole in heart. Anyone had experience of this and thoughts on prognosis?

Is it still a pup?  As in human children the holes can close up before adulthood.

My last Border T, had a heart murmur from 6 weeks, and lived to 15yrs old, depending on how severe they are I expect, his was picked up when he was vet checked, he was checked yearly after that.

Investigations

There are several investigations, which may be undertaken by a veterinary cardiologist, to diagnose and evaluate aortic stenosis and other heart conditions.

Heart murmurs are graded from 0 to 6, according to the severity of the murmur:

Grade 0/6 denotes no murmur.

Grade 1/6 and 2/6 murmurs are generally considered to be "mild".
Dogs with Grade 1/6 and 2/6 murmurs are very unlikely to develop any symptoms as a result of their aortic stenosis and should lead perfectly "normal" lives.

Grade 3/6 and 4/6 murmurs are generally considered to be "moderate".
The majority of dogs with Grade 3/6 and 4/6 murmurs are also unlikely to develop any symptoms, but a small number will go on to become symptomatic.

Grade 5/6 and 6/6 murmurs are generally considered to be "severe".
Dogs with Grade 5/6 and 6/6 murmurs are most at risk of developing symptoms - (see below).

X-ray looks at the shape and size of the heart and can identify abnormal enlargement of the heart chambers e.g. left ventricle in severe AS.

Electrocardiography measures the electrical impulses of the heart and can identify any abnormal heart rhythms e.g. VPCs (ventricular premature contractions) in severe AS.

Ultrasound with Doppler studies:
Ultrasound enables the vet to measure all the internal dimensions of the heart, in particular the thickness of the left ventricular wall with regard to aortic stenosis.
Doppler studies allow the vet to measure the speed of blood flow through the heart valves i.e. from one chamber to another or, in the case of aortic stenosis, specifically from the left ventricle to the aorta via the aortic valve; this is the aortic outflow velocity.

yes i think hes about 14 weeks old......apparently hes a bit thin and not overly lively, hence they went to vet....although previous checkes by 2 vets never picked anythin up....this one did so had it xrayed, and told grade 4. They are not really dog people and are worried sick so I said id try nd find more info. Kenya, thanks fr your help.

Go to http://www.boxerbreedcouncil.co.uk/as.htm if the vet has diagnosed aortic stenosis.
It's good info.

Also read the link puppy handout sheet too.