P2RY12 receptor platelet disorder is an inherited bleeding disorder affecting Greater Swiss Mountain Dogs. Affected dogs have abnormal platelet activity. Platelets are blood cells that are necessary for the normal clotting of blood. Affected dogs typically appear healthy but can have nosebleeds and bleed from the mouth when juvenile teeth are lost. Affected dogs are often not identified until a surgery is performed or trauma occurs at which time excessive bleeding is noted. Veterinarians performing surgery on known affected dogs should have ready access to blood banked for transfusions. Dogs can have a normal lifespan with this condition although they are susceptible to life-threatening bleeding with an accidental injury or any surgical procedure.