If your dog has long hair around his eyes, this could be the problem. I have a Shih Tzu and when I mentioned this same problem to my vet, he told me to try to keep the hair cut around the eyes, the hair tickles the eyes and causes them to water. If this does not help, there is eye drops that you can get from your vet to help with this problem. I am going to ask for the drops next time my baby is at the vet, keeping the hair cut short around his eyes is really not helping.