Summer is likely the only daughter of the Elite Trakehner stallion E.H. Itaxerxes in the United States. E.H. Itaxerxes was champion of his approval year in Neumünster and was also champion of his performance test in a group of 23 competitors from all breeds at Warendorf in 1985. He received an index of 132 for rideablity and 129 for jumping with an overall index of 135. He is accepted for breeding in Germany by the Hanoverians, Rhinelanders, Westphalians and Rhineland-Pfalz-Saar. In 1995, E.H. Itaxerxes was awarded the title of "Elite stallion" by the German Trakehner Verband.

E.H. Itaxerxes is the son of E.H. Tenor, the vice champion of the 1980 Trakehner approvals, and grandson of Tümmler, who was an internationally successful three-day event horse. E.H. Itaxerxes' dam is a states premium mare out of the premier Isolda line which produced four approved sons, including Ibikus, one of the top stallions in the breed. This outstanding dam line originated from the principal stud of Trakehnen.

The dam of Summer is an imported German Trakehner mare out of Sherazare, a half sister to the Approved Trakehner stallion, Sedar, who stands in Germany.

Summer was approved for the ATA Official Stud Book in 2001. She was bred in Canada with frozen semen.