My dog is in heat and has been dropping huge blod clots, is this normal?

This is my first time as a female dog owner. A friend of ours gave her to me, she is about 2 years old, pure husky and she has been bleeding since the day she came to us about 1.5 week ago. Twice already she has dropped very large blod clots and I do not know if this is normal or if I should rush her into the vt. Please help me?