Isaac Newton Phelps Stokes (1867–1944) married fellow New Yorker Edith Minturn (1867–1937) in 1895. A friend of the couple commissioned as a wedding gift a portrait of the young bride from the acclaimed expatriate John Singer Sargent. Initially, the artist selected an evening gown for the sitting, but soon decided to portray Edith Minturn Stokes in sporty daywear with a Great Dane at her side. Her husband had "a sudden inspiration," he later recalled, when the dog became unavailable, and "offered to assume the role of the Great Dane in the picture." The compelling result was soon regarded as one of Sargent’s most important double portraits.
(https://www.metmuseum.org/art/collection/search/12140)