Hypervitaminosis A is real... but I wonder how real it is when we
get our vitamin A from food (beef or sheep liver)...
get our vitamin D from sunshine and
get our vitamin K from kimchi, nattō and rich bone marrow... Maybe we don't need 20,000 IUs of vitamin A per day but we at least need an average of 5,000 per day to prevent disease... that means that we at least need to eat two servings of 4 to 6oz of liver per week... or take four to six capsules of desiccated liver per day.
Because the body holds onto them over time, it is possible to overdose on these vitamins (known as
hypervitaminosis), so it is important to monitor the amount your dog is
getting.