Quite probably the deed is done by now, but it should be noted that the question was not which side of the dog the heart is on, but which side of the dog the vet wanted shaved for the procedure he will use.

"a scan of his heart" is a rather ambiguous specification, since x-ray, tomography, sonography, etc are all possible meanings of "a scan," but the various procedures may have slightly different requirements for a best result.

As we're into "the next day," we're now waiting for the report, and holding forth our best wishes and support for the patient - and for the concerned caretakers and caregivers.

John