This product is from Rx Vitamins. You will need to have a blood sample drawn and spun down at your veterinarian's office.
With recent excesses of Vitamin D in many commercial pet foods, testing may be a life-saver!
Many older pets, pets with cancer, and pets on home-made diets suffer from low vitamin D.
Testing is simple and results will tell you exactly how much vitamin D is needed to get your pet into the normal range.
Recommended at annual check-ups or just to get a baseline. Can be used for cats or dogs.