The image below shows me searching for 'calgary pet events'. You cannot tell from the results whether or link is for something that is going to happen or happened 5 years ago. Would help a lot if you could show the date either from when the page was created or when it was last indexed perhaps.
I know google shows you dates for some content (maybe just news sites?). They used to show the date the page was created (I think). That way you could weed out past events easily.