Overuse of antibiotics can trigger the development of multidrug resistant bacteria. The World Health Organization (WHO) declared multidrug resistant (MDR) bacterial infections one of the most urgent concerns of modern medicine. Therefore, prudent antimicrobial usage is important for all healthcare professionals. This becomes especially important in cases where antibiotics are given to patients that do not currently have a bacterial infection, as can be seen in dogs undergoing surgery. This prophylactic usage is common to try to prevent infections after surgery, but it is unproven, the side effects are unknown, and it can contribute to the development of bacterial resistance. It is known that antibiotic usage can cause lasting changes in the gut bacteria, leading to disease later in life. This study seeks to investigate how profound the negative effects of antibiotic usage are in dogs undergoing spays and gastrointestinal surgeries. It will help us acknowledge the potential risks of prophylactic antibiotic usage in dogs.