The pilot reported that during the landing, the left main landing gear wheel separated from the landing gear assembly. The pilot had made a three point landing, and stated that "I may have hit a deer," because he "saw 5 or more deer on south side of runway centerline," prior to landing. He reported that the "airplane traveled to left side of runway despite brake and full right rudder." The bi-plane departed the left side of the runway and nosed over, sustaining substantial damage to the right wing and both the right and left wing struts. A postaccident examination of photographs of the landing gear provided by the pilot, showed that the wheel separated from the landing gear assembly along a welded joint. There was no evidence of impact prior to the separation. The pilot reported there were no pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.