It seems to be a rule for placenta to have dominantly E1 with only the exception of equine, which has equine-specific estrogens not found in any other animals... Considering the harm that premarin can do, I don't think I'd want to play with equine estrogens.

I am therefore still at a loss for where to get my animal estrogens. If anyone can think of anything, I'm all ears. Well, symbolically speaking.