In this post Q links to the video where HRC says that super-predator blacks need to be brought to heel.
Q makes sure we understand this is to be understood in the context of 'dogs' and their owners.
IMO, when POTUS calls O a dog, he is telling us that HRC owns O.
https://www.youtube.com/watch?v=j0uCrA7ePno
"Super-predator"
"Bring them to heel"
Define heel.
(of a dog) follow closely behind its owner.