It seems unbelievable that there isn't already one in existence, but peripheral manufacturer, Razer, claims to have launched the first ever left-handed mouse for gamers.

The Razer DeathAdder Left Hand Edition was created specifically for lefties and features five programmable Hyperedponse buttons, a 3.5G infrared sensor that it claims offers four times more precision than a standard 800dpi mouse, and an ergonomic design so it sits comfortably in your hand.
"Not many gamers know this, but I am a southpaw myself and feel truly excited to have a mouse that fits perfectly in my left hand. There is really no substitute for gaming with your naturally dominant hand," said Robert "Razerguy" Krakoff, president of Razer USA in the official press release.
The Razer DeathAdder Left Hand Edition has a recommended retail price of $59.99 in the US and ?59.99 in Europe.
You can check out a picture of the new mouse below.