A veterinary physician is necessary for the prevention of a variety of diseases and problems in diverse animal species. He or she is crucial in illness diagnosis and therapy planning. All situations when surgery is not required must be handled solely by a physician. Because many illnesses (zoonoses) may be passed from animal to human, chemists and doctors are continually checking on veterinary medicine to see how they might adjust human medications and vice versa. Vets take their duty extremely seriously in order to safeguard both the health of animals and the safety and wellness of the human-animal relationship. Shepard's utilized human medication and human medical advice to treat dogs thousands of years ago, and it typically worked.