On July 29, 1993 about 2000 central daylight time, a Cessna 170, N8163A sustained substantial damage when it nosed over after making an emergency landing. The pilot reported no injuries. The flight was operating in visual meteorological conditions under 14 CFR Part 91. The pilot was making a low pass from north to south to check his cattle when he hit a cow with the right main landing gear, killing the cow and tearing the gear from the aircraft. The pilot reported that the gear assembly and strut fell into a nearby oats field. He decided to land at his neighbors landing strip because his was too wet. When he landed without the right gear, the airplane ground looped, damaging the right outboard wing and wing tip. When asked to produce his pilot certificate and medical certificate, the pilot stated that he had no current medical, and had not planned to fly that day. When he was asked for his logbook, the pilot stated he had lost it sometime the previous year. When asked when his last biennial flight review was, he said he wasn't sure, and didn't know the name of the instructor who gave him the BFR. Examination of the aircraft logbooks found that the airplane did not have a current annual inspection. In the pilot report statement, the pilot said he applied 10 degrees of flaps and went in a low pass to investigate a calf lying by the water accumulated from heavy rains. The engine started sputtering, so he applied carburetor heat and tried to get power back. The plane started settling. When the power came back, he applied full power and started climbing. At the same time, the right main gear struck a cow. Postaccident examination revealed no evidence of pre-impact mechanical malfunction with airframe, engine or accessories.