Whilst on holiday Heiko kept scratching his ear and shaking his head, so we took him to a vet who said he had infection and prescribed (Canaural) one drop daily for five days, after a couple of days he seemed a lot better and his ear wasn’t bothering him but we continued drops for five days. When we got home it didn’t twig at first, but little things began to make we wonder about his hearing, OH shouted his name ‘nothing’ tried clapping hands ect : nothing, that is when my suspicions were confirmed he was deaf. He never showed any signs like loss of balance ect: I went online and put in ear drops causes deafness and was shocked to find, it was quite common for dogs to go deaf, after using ear drops.https://www.dailydogdiscoveries.com/ear-drops-may-be-making-your-dog-deaf/ There is no warning on outside of box and vet didn’t mention about it either. I am now blaming myself for not reading the small print where it does say, that in geriatric animals use of auricular preparations can cause hearing loss which may be transient or prolonged. So it’s a waiting game to see if he will get his hearing back.