Vernon's stepson John Fitzpatrick, the Earl of Upper Ossory (1745-1818) purchased Otho early in 1767, the last and most successful year in Otho's racing career. He had several victories at Newmarket that year, and this painting was presumably commissioned to celebrate these. It is not known whether John Larkin, the jockey, rode Otho on each successful occasion, as Racing Calendars of this period do not record jockeys' names. The setting for the picture is Newmarket racecourse, with one of the rubbing-down houses shown on the right (see Newmarket Heath, with a Rubbing-Down House, c.1765, Tate Gallery T02388), and a view of St Mary's Church and Newmarket town in the middle distance. Otho was subsequently retired to stud at Ampthill Park, Lord Ossory's seat in Bedfordshire. He commanded high stud fees and his progeny included Comus, Dormant, Coxcomb and Saturn.
Judy Egerton, British Sporting and Animal Paintings 1655-1867, London 1978, p.80, reproduced pl.30
Judy Egerton, George Stubbs 1724-1806, exhibition catalogue, Tate Gallery, London 1984, reprinted 1996, pp.88-9, reproduced in colour