Final answer:
A veterinarian is the properly licensed medical professional who performs spay surgeries on dogs, to prevent them from having puppies and to confer certain health benefits.
Step-by-step explanation:
The medical professional licensed to spay a dog so that she cannot have puppies is a veterinarian. Spaying is a surgical procedure known as ovariohysterectomy, which involves the removal of a fe_male d_og's reproductive organs. This procedure is not only for preventing unwanted litters but also has health benefits, such as reducing the risk of certain cancers and diseases. Veterinarians complete extensive education and clinical training to perform such surgeries professionally and safely.