Madeline Backus comes from an equestrian family – her mother Laura is a rider and trainer in Colorado running the Pendragon Equestrian Centre where she also breeds horses for eventing. Madeline was a member of the Pony Club, gaining her A test. In 2013, Madeline won the Junior training title at the American eventing championships on the homebred PS King of Hearts. Later that year she spent the summer as a working pupil for Jessica and Missy Ransehousen in Pennsylvania, and after leaving school returned to work for them full time.
After being awarded two the Rebecca Broussard National Developing Rider Grant and the inaugural Wilton Fair Grant, Madeline relocated to the UK for a year to train with William Fox-Pitt. Madeline completed her first CCI4* event in 2017 in Kentucky and competed at Badminton for the first time in 2018 at age 22.