The solo student pilot reported that he was practicing a stop-and-go landing on the asphalt runway. He recalled that, while on the downwind leg of the approach pattern, he was headed into a bright sunset. On short final, "a medium sized, reddish brown animal ran across the runway near the numbers from right to left." The student overflew the animal, and the airplane bounced upon touchdown. He applied full power to abort the landing, but the airplane veered left and exited the left side of the runway. About 40 ft from the runway, the airplane encountered soft soil and nosed over. During a conversation with the National Transportation Safety Board investigator-in-charge, the student pilot stated that he may have become fixated on the animal during the approach. He could not recall whether he manipulated the yoke to avoid the animal. The airplane sustained substantial damage to the left-wing strut. The student reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.