There is an old black man that works with my dad on the farm some. He has a female lab and he said he ground up 2 400mg Tylenol in her food and it keeps her from coming in heat. I don't know if that was a one time fix or he does it everytime. I DO NOT RECOMMEND THIS. I just thought it was funny. He lies alot too. PLEASE DON'T TRY IT!!!
Yeah, that would be a HUGE NO-NO! It can prevent a heat alright, by killin the bitch! lol