Check the CMHS website to see what animals are currently available for adoption. When we adopted our dog two months ago, I saw some guinea pigs there.
My children and I were there a couple of weeks ago and they had two male guinea pigs in their small animal room. I am unsure if they were adopted or not but it is worth giving them a call! Best of luck to you!
They do have smaller animals (rabbits and the like) but as far as what they have currently you would have to call or visit to see for sure.
Thanks! Your answer is awaiting moderation.