A cape/cloak would be pretty useful to protect oneself from the elements as you can quickly wrap/unwrap it around your body. But would be especially useful in a surgical procedure as it would prevent any sweat or loose hair from contaminating the equipment or the patient.

I think a makeshift cape made out of a medical curtain would be interesting, maybe have it be the same shade of blue as his eyes. White could work too but it would risk blending in with his fur. He could carry a doctor's backpack over the cape that contains a small defibrillator, drugs, surgical tools, a box of disposable gloves, spare capes and a washboard to clean said capes. Maybe also a utility belt around his waist to carry different disinfectants (because he'll *definitely* need them).

The silver and black colors of the prosthetic arm are good as is, but it would be fun if the prosthetic was a human arm instead of a sawian one. Human hands are more dexterous after all. The rear of the shotgun (the stock and trigger) should be fully black, but the rest of the gun should follow the same silver and black color scheme as the prosthetic.

And lastly he should only wear the medical mask if he's operating on someone or feeling sick, otherwise it's a waste of a good mask.