One of the drawbacks of the 8-Track tape format is that they played on an infinite loop, automatically switching through the four stereo tracks and then starting over again. Often, the switchover—heard as a click and then pause—would happen in the middle of a song so engineers would just fade out the song in the middle and then fade it back in. Also frequently, artists and engineers would change the song sequence compared to LP or cassette releases to better align with the 8-track format. On Animals (1977), Pink Floyd took it a step further by adding a guitar solo specifically as a bridge between Pigs on the Wing Part 1 and Part 2, making them essentially a single song. That guitar solo would be heard nowhere else until the Internet. From The Blind Man Sees All:
Given the nature of the 8-track format, the band decided to record a guitar solo that would connect the 2 halves of the song and explicitly bring the album back full circle. Floyd associate Snowy White was assigned the task after David Gilmour's take was accidentally erased, and the resulting "complete" version of "Pigs on the Wing" was included exclusively on British and American pressings of the 8-track tape when the album was released.
As time passed and the 8-track went extinct, though the Floyd remained as popular as ever well on through the beginning of the CD era, this solo slipped out of the discography as the catalog was standardized to reflect the more familiar tracklisting associated with the original LP. As time went by, Snowy White's solo took on mythic stature among the band's fanbase, particularly as reissues continued and it became the only commercially unavailable piece of music the band had ever officially released.