Vitamin D is a fat-soluble vitamin necessary for the proper absorption of calcium and phosphorous in the body. Diet is the primary source of vitamin D in dogs and cats. All pets should be tested to determine their vitamin D levels at least once per year. VDI labs has shown that optimal levels are 100 to 150 ng/ml on blood testing. Pets with levels below 40 ng/ml are much more likely to suffer from a variety of diseases. Vitamin D insufficiency is easy to test. The results and further action potentially required may be determined by the pet’s species, weight, age, intact status, diet, and other factors. Testing is simple and cost effective using the VDI Vitamin D test. A blood sample from the pet is applied to a device and simply mailed by common carrier. Recommendations for supplementation is provided on the report detailing the result and D3 supplementation required for the cat or dog, along with supplements that can be found at drjudymorgan.com. Directions for The Pet Owner: Take this kit (unopened) to your veterinarian with your pet Give to vet staff & discuss the need for a serum blood draw Provide contact information to vet staff Don't worry, there are directions & information on the included card that direct veterinary staff as to the next steps! *Not an at-home test. Requires a serum blood draw from a vet clinic. *Fasting recommended (8 hours) These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.