Previous research pertaining to dog memory and cognition has been confined mainly to samples of colony dogs and therefore can be hard to generalize to a larger population of pet dogs and varying breeds. The present study focused entirely on pet dogs of many different breeds, rather than colony or laboratory animals for the purposes of accessibility, affordability, and novelty. Methods: We presented the dogs with a memory task in the form of a game in which the dogs chose to search for food at one of two locations at varying delay intervals, with a maximum time limit of one hour per dog. We expected our data to show a significant decrease in memory capacity and an increase in error rates among older dogs as compared to younger dogs; these results would allow us to conclude that it is likely many dogs, much like humans, experience various cognitive deficits as a function of increasing age. Results: Using one-factor ANOVA and linear and curvilinear regression analyses, we examined the relationship between the independent variable, age (individual dog ages as well as three generalized age categories), and three dependent variables. The dependent variables were: (a) percentage of correct choices at a 60 second delay interval, (b) maximum delay interval attempted (MDIA), and (c) the maximum delay interval that was completed above chance level (50%) (MDAC). We found significant results to support our hypotheses that aged dogs show spatial memory and cognitive deficits in comparison with young and middle-aged dogs, and that age can be considered a marginally significant predictor of spatial memory capacity.