I don't know the answer to your question, friend. Why do anything unless it's necessary? The Lab is one of the most tractable breeds. I've owned only male Labs for the past 40 years and have had no reason to consider the question.

Any male is going to act naturally with a female in heat. I always put my dog in the kennel when anyone is foolish enough to bring a female in heat to my premises, knowing I don't let my dog "play" under those conditions.