Do I need to track my rankings on the keywords "dog" and "dogs" separately? Or does Google group them together?

[Fairstone]

I'm creating an SEO content plan for my website, for simplicity's sake lets say it is about dogs.

Keeping SEO in mind, I want to strategically phrase my content and monitor my SERP rankings for each of my strategic keywords. I'm only given 150 keywords to track in Moz, do I need to treat singular and plural keywords separately?

When I tried to find estimated monthly searches in Google's keyword planner, it is grouping together "dog" and "dogs" under "dogs"... and similarly "dog company" and "dog companies" under "dog companies".

But when I use Moz to track my rankings for these keywords, they are separate and my rankings vary between the plural version and singular version of these words.

Do I need to track and treat these keywords separately? Or are they grouped together for SEO's sake?