LAUSANNE, Switzerland — Brazil's Rufus became the sixth horse to test positive for doping during the Beijing Olympics.

Rufus, ridden by Rodrigo Pessoa, tested positive on Aug. 23 for nonivamide, a substance prohibited for its pain-relieving properties, equestrian's governing body said Monday.

Pessoa was fifth in the individual jumping final. The International Equestrian Federation (FEI) said it suspended him Friday after an initial hearing, and added that the backup "B'' sample will be tested Tuesday in Hong Kong — the site of the Olympic equestrian competition.

The FEI said Rufus' test is the last of a series of probes at the games.

Four horses were previously found to be positive during the games, and a fifth positive test was announced last week.

The six horses match the number of doping cases among athletes in other sports during the Beijing Games.