
Getting frustrated by 'treatment' for one of my girls who was, it turned out, terminal cancer, I phoned my vet across country for her opinion (without seeing her) and then went to see my sister's vet. I told the vet who had been seeing my girl which produced the Senior Partner who FINALLY x-rayed her (which the first vet refused to do saying scanning was good enough) and sadly discovered the original cancer (probably in her bladder) had spread to her lungs.
Sometimes taking a second opinion (and my sister's vet didn't want, or need to see her medical history - he went straight to saying why no x-ray - as my vet across country had also said) gives a vet a kick up the backside!
It can help in these cases, when there are multiple vets in the same Practice - you get multiple opinions without needing to go outside the Practice.