Loss of balance

Hello, I have a 4 year old male house cat. He has a diagnosed heart murmur but has been otherwise fine until about 5 months ago when he started to have episodes of loss of balance. He will kick out with his back legs and stumble, sometimes completely falling over. It seems to affect his rear legs the most. He has had heart and brain scans done and both were relatively normal. My vet is treating it as idiopathic epilepsy but I am not convinced as he is alert and aware of his surroundings during these episodes. I have managed to video one of these episodes and wonder if I should get a second opinion before starting him on medication that he will not be able to come off. 

Hello!  It sounds as though your vet has reviewed the signs and data much more thoroughly than I have and come to this conclusion, but given that epilepsy is difficult to diagnose (there is no 'test' for it) you are wanting to rule out other causes of seizures before resorting to medication.  Have you spoken to your vet about what you can do to keep your cats as safe as possible in the meantime (as seizures can happen randomly at any time).  The best person to turn to for a second opinion would be a medical specialist and I wonder whether your vet can refer you to one eg at their local vet-school or referral centre.  Many specialist vets do consult online now.