My shih tzu had puppies on Friday and our male shih tzu is trying to breed her again. A friend mentioned to me something called puppy heat which I haven't heard of .. is that for real?

Yes, "puppy heat" refers to a situation where a female dog can go into heat as early as six months old, which may coincide with her having just given birth. However, it's important to note that a mother dog should not be bred again immediately after giving birth, as it can pose health risks to both her and the puppies. It's advisable to separate the male and female dogs until she has fully recovered and you are ready to breed her again responsibly. Always consult a veterinarian for guidance on breeding and caring for your pets.