below I copied off of copilot...
some commercial dog foods contain ingredients that mimic estrogen or interfere with hormone signaling.
Phytoestrogens (Plant Estrogens)
These are natural estrogen‑like compounds found in:
Soybean meal
Corn gluten
Flaxseed
Pea protein
Many mid‑tier dog foods use these as cheap protein sources.
Phytoestrogens can bind to estrogen receptors and confuse the reproductive system, causing:
Delayed heat
Silent heat
Weak or incomplete cycles
Missed breeding windows
? 2. Excessive Grain-Based Diets
High‑grain foods (corn, wheat, sorghum) can:
Spike insulin
Increase systemic inflammation
Disrupt the hypothalamus–pituitary–ovary hormone axis
This can lead to irregular estrous cycles or anestrus (no heat)
I will say this as well, back in the 1970-90's i didn't feed the expensive dog foods because the expensive dog foods back then were super expensive like almost a dollar a pound...it was a rich mans dog food...and i never had any issues breeding dogs back then with the cheaper feed...I remember some were thinking it was an iodine issue once these problems started popping up...
