My dad and step dad both have dementia and I know how hard it is for sufferers to maintain independence and pleasure in life, and this post is in that context and with an understanding that people with dementia in the community are vulnerable to the risk of an adverse reaction to their actions. Yesterday I allowed my puppy of 4 months to say hello to a dog (with a wagging tail) being walked by an elderly man. When, after a couple of seconds I pulled my dog away the other dog attacked my pup. The gentleman did nothing at all to control his dog, and I had to wade in and rescue my dog who was upset, but thankfully (and having been checked by a vet) appears to be physically unscathed, though was noticeably cautious with other dogs today. It turns out the gentleman has dementia and I'm sorry to say, not realising it and being quite shaken myself, I shouted at him that he should have pulled his dog off. I am now worried that the dog could attack another dog, or even a child, and that in that situation the gentleman is at risk as well as the third parties. I believe a passer by who intervened made the gentleman's carer's aware and presumably they will (or should) log the incident, but have no certainty of this. Should I inform someone in authority, and if so who?