I'm not knowledgeable about heart murmurs, but since no one else has posted, I'll offer my thoughts:

I'd challenge the vet with the same arguments you've listed here-
no food, POed cat, etc.

I'd also get a 2nd opinion, ideally from a good veterinary college.

If he were my cat, I would do everything I could to keep from stressing him with extra tests unless someone offered me a *very* good reason in favor of them.

I wish you the very best.

I agree with everything sylviatexas said!

Two years ago when I had my one cat to a regional veterinary collage/animal hospital to be seen by specialists (three days spent at the hospital there!) to help diagnose a GI disorder, this 11 year old cat suddenly had a murmur for the first time while a patient at the hospital! They did an echocardiogram because they had to before they would anesthetize him for an upper GI scope, and the echocardiogram showed nothing was wrong! The vet there (a vet cardiac specialist) said that it is not unusual at all for cats to suddenly get a murmur when they are really stressed out! He said, in those instances, the murmur is really stress related and goes away when the stress does!

I too would be very reluctant to stress any cat out any more with further tests since this murmur was something new and seems to have a definite cause and effect! I really question your vet's judgement on this and sometimes it seems some vets, like some doctors, will go strictly "by the book" without considering common sense factors. All I know is, our poor pets just don't know what is going on and are scared to death when we take them in to be treated, and unless I feel it is for their good and absolutely necessary, I can't see doing something purely for the sake of being someone's "science project".

Thank you very much for your responses. I will need more convincing before I subject Owen to the echocardiogram. At the moment he is resting his eyes while laying in a brown paper bag and is the picture of contentment.

No, but my schnauzer developed one when he was older. The doctor followed it with each visit, as he had no outward symptoms and needed no medication for it until the day we had him put to sleep for advanced age, arthritis, deafness, and myriad other causes where his quality of life had declined to a struggle.........all non-heart related, and having lived four years past his expected life span. The doc said his heart sounded like a wash machine.

I can't tell you to disregard your vet's advice. Your kitty could expect to live for another eight years or more with your good care. I would be curious what that would involve with a cat. They are non-invasive, aren't they? But, I'm wondering whether a cat would be cooperative enough to do one without sedation? I suppose the test would be the only way to know if it's innocent or a valvular problem.

An echocardiogram is just an ultrasound of the heart. It is completely painless, non-invasive, and unless your cat is a total pistol, he shouldn't need any sedation.

It is impossible to tell without an echocardiogram if the heart murmur is a problem or not. The best news you can get is no problem- that is certainly worth it to me! Some cats do develop innocent murmurs with higher heart rates; other murmurs heard at higher heart rates can be indicative a potentially fatal disease. The only way to know is through an echocardiogram.

You don't treat a heart murmur per se- you treat the disease causing the murmur if there is one. The treatment depends on the disease. Not all diseases are as treatable as others. Endocardiosis is relatively treatable compared to hypertrophic cardiomyopathy, for example.

Hopefully there is nothing wrong and it was just a stress murmur. I for one would want to know for sure, especially given the procedure is very easy on the cat.

Thank you, again.