Have had several elderly friends with Alzhiemers - not sure if this is what the old lady has - but Alzhiemers has a great deal of short term memory loss involved ~ ~ she may not remember that you were there with the dog today - but she appreciated it yesterday, you can be sure.

One of the wierd things about memory situations like this is how they can click "on" and "off" - and you never know when - but in general (from those cases I have had acquaintence with) the happier in general the person is the better their memory and the easier they are to handle.