Could A Small Dog Like A Havanese Mate With A Mastiff Or Great Dane?

All 3 dogs are scheduled to be fixed in 6-8 weeks of time(this is when the vet was available?
Could a Small dog like a Havanese mate with a Mastiff or Great Dane?
should they be kept separate when they are in heat?
They don’t socialize with other dogs just with each other,but is it safe to leave them together while one is in heat?
Thanks

What Is The Best Small Dog To Get. I Was Thinking Of Getting Either A Pomeranian, Havanese, Or A Maltese. Whic

I was thinking of getting either a pomeranian, havanese, or a maltese. Which one would be the best for me and what other breeds are good??

Why Do People Hate Small Dogs? And Call Them Stupid?

I have 2 dogs a small havanese and a golden retriever. They are both very smart dogs and are very well mannered why? Because I trained them. I taught them all their manners and I am not even a teenager yet. They are also not hard to train either. It is true that some small dog breeds mostly terriers are stubborn with commands but most arent usually stubborn when it comes to manners. So why do people think dogs that are small dont deserve to be dogs? Why do they think they are stupid I mean I know people spoil them but stupid I have no idea how anyone would come up with that. I mean my havanese is anything but stupid he can open his crate,open doors,open cabinets,get on top of things with out jumping,makes up his only “agility course” out of furniture,and is a genius at pit-pocketing(He oddly likes stealing paper to shred)

What Small Breed Of Dog Do You Suggest?

I want a dog but i do not want one that will bark at everything that moves. I was leaning towards a Havanese, Yorkshire Terrier, Maltese, Bichon Frise, or something along those lines…or do you have any tips on training dogs to not bark that much unless necessary?