Not as a breed of dog, they don't. I remember seeing a three legged dog some years ago. It had had a leg amputated, and had no trouble moving about on three legs. So, three legged dogs exist only in the capacity of an amputee.
Charlie the Three Legged Dog - 2011 was released on: USA: 11 June 2011 (Delray Beach Film Festival)
The three-legged dog is named Cody.
A three-legged dog named "Trowser".
Edward Steichen.
I came to get the man who shot my paw!
You should probably take your dog to a veterinarian, particularly if your dog became three-legged through an amputation to control cancer or infection - the cancer or infection may have spread to the back leg she now can't walk on.
Dog Tales - 2007 Adopting Three Legged Dogs Pug Profile 1-7 was released on: USA: 15 October 2007
Youtube is your best bet.
Three legged stands are often called stools. In photography a three legged stand is called a tripod.
tri-pod limp bizkit trace (tres-3 in spanish)
this is quite common in small dogs, eg jack russell. it is called patella luxation which is where the kneecaps dislocate causing a three legged hop for a step or two. there is nothing to worry about, but you can get it corrected with surgery.
Three Legged Cross's population is 1,500.