Why do vets take blood samples at check-ups? When you take your cat, dog, or other pet for a check-up, the veterinarian wants to make sure there aren’t any new or hidden illnesses. The blood sample is an important part of this process. Particularly cats are experts at hiding illness, but dogs can be very good at it too. Faking health may work on pet parents, but won’t trick laboratory results. Common blood tests include the blood-chemistry panel. This is a way for the veterinarian to measure various elements in a pet’s blood, and helps ensure liver, kidneys, pancreas, and other organs are functioning as they should. If there is an issue, early detection improves the pet’s prognosis. For instance, if a pet shows a deficiency in albumine, there might be an issue with the liver. A blood count determines how many blood cells and platelets are in the pet’s blood. Results outside the normal range can indicate infections, allergies, and even leukemia. Veterinarians also check urine samples and stool samples. The sooner a problem is discovered, the easier it is to treat.