Once you have the main concepts, you can then start to put together a search strategy with AND/OR/NOT. For more information about using AND/OR/NOT see the Library Research Process Guide or see below.
Searching (Dog OR Canine) would get you more, relevant results. Different authors may refer to dogs as canines in their article or specifically the breed German Shepard. You want to make sure you get all the possible relevant articles.
AND ties the concepts together that will decrease the number of results, but makes the results more relevant.
A short search strategy may look like this: Therapy animal AND (dog OR canine OR German Shepard) AND (elderly OR senior citizen OR 65+)
Taking your topic to a search - This document provides a template on how to format your research question as well as how to break down your main concepts into a table like the one seen above. This method will help you to identify the best words to search to find relevant articles.