google says > Vitamin D3 is good for humans at normal doses, but kills rats and mice because the high doses in rodenticides cause a life-threatening buildup of calcium in the blood, a condition called hypercalcemia, which leads to kidney failure, heart abnormalities, and tissue mineralization, resulting in death. While the basic mechanism is the same for all mammals, rodents are much more susceptible to toxicity from cholecalciferol (activated vitamin D3) due to their smaller body mass and the massive quantities of the substance in the bait
google says > Vitamin D3 is good for humans at normal doses, but kills rats and mice because the high doses in rodenticides cause a life-threatening buildup of calcium in the blood, a condition called hypercalcemia, which leads to kidney failure, heart abnormalities, and tissue mineralization, resulting in death. While the basic mechanism is the same for all mammals, rodents are much more susceptible to toxicity from cholecalciferol (activated vitamin D3) due to their smaller body mass and the massive quantities of the substance in the bait