Smith, who is expected to play a key role for the Boks when the Lions arrive in South Africa this summer, collapsed in the away dressing room following a 22-3 reverse that leaves the Cheetahs bottom of the table.
The round three clash between two previously winless sides was played in temperatures of more than 32 degrees Celsius and humidity of more than 66%.
The fixture kicked off at 4pm on the East Coast of Australia and, although afternoon games are rare in the Super 14, the incident has highlighted calls to review competition timings.
