Garth competed internationally for South Africa but had resided in the United States for 21 years. An FEI level competitor, he earned his USDF Gold medal in 1999. He competed through Grand Prix and placed in the top finishers in CDI's on Wolkensong. His other mounts included Cartier, Abu Hassan, Landsberg, Bogart, and Paradox.

He trained with Jane and Christopher Bartle and Kathy Connelly. He cliniced with Rudolph Zeilinger and Arthur Kotas. In 1997 he served as a demonstration rider at the USDF Trainers Conference in Florida featuring Kyra Kyrklund.

Responding to the news of her friend's passing, instructor/trainer Kathy Connelly of Massachusetts said, "I'm deeply, deeply saddened by Garth's passing. He was such an ebullient spirit. I helped him with his horses for three years and was always impressed with his quest for the truth and his dedication to learning. He was a very talented rider, very insightful. He was an extremely bright and complex person with a brilliant wit and humor; also a very compassionate person. He was a very, very good friend. I will miss him terribly, and I am very grateful to have known him."

A USDF Certified Dressage Instructor through Fourth Level, Garth also was a USDF "L" Judge Program Graduate. He was the trainer of the 1995 North American Young Rider Individual Gold Medalist, Katherine Walsh. Among his other students were eight silver medalists and two gold medalist. He served as trainer at Paxton Farms for several years and was a popular horse show announcer.