I got these socks as a gift for me and my dog, but the socks are too small for my dog!

I think these are actually meant for puppies, so I would assume XS- S size for dog feet. Perhaps even a XXS. They are meant for small dogs. My dog is a medium.

I detached a sock to try and put it on my dog, but it just wouldn't go. That's why one of the socks is loose. Other than that, it's new.

The adult sock there's no information on what size it is supposed to be, I'm a size 7. So I would assume that the sock would fit at least a size 7 person. But again, there's no info on what size it is. The only thing I can think of is if it's meant to be a "one size fits all" sock.