A Salty Dog has an ostensibly nautical theme, as indicated by its cover (a pastiche of the famous Player's Navy Cut cigarette pack), interspersed with straight rock, blues and pop items, A Salty Dog showed a slight change of direction from its predecessors, being thematically less obscure. The title track itself was the first Procol track to use an orchestra, as would be referred to in the live album performance some three years later.
The album was the first record produced by Matthew Fisher, who quit the band soon after its release. This was also the last Procol Harum album to feature bass guitarist Dave Knights.
A Salty Dog was recorded in March 1969. The musical tensions between the group and Robin Trower were beginning to show in this album, and although his guitar sound remains integral to most of the tracks, "Crucifiction Lane" (featuring a rare Trower vocal), in retrospect, shows that Trower was already moving in a different direction from the rest of the band. Still, this album is much more musically varied than the two previous albums, with three Fisher vocals and one by Trower.
Reportedly, when Gary Brooker first played "A Salty Dog" at the piano for B.J. Wilson, a sunbeam illumined Wilson's face and he told Brooker he thought it was the most beautiful song he had ever heard.
A Salty Dog was released in June 1969 by record labels Regal Zonophone and A&M. The title track, backed with "Long Gone Geek", reached number 44 in the UK Singles Chart in 1969 and the album itself number 27 in the Albums Chart.
John Mendelson, writing for Rolling Stone, called it "a confusing album. At its best it represents the group's greatest success to date with the brand of rock for which the group is known; at its worst it is both surprisingly mediocre and trivial."Robert Christgau, on the other hand, gave it a rare 'A+' grade.
In his retrospective review, Bruce Eder of AllMusic wrote, "This album, the group's third, was where they showed just how far their talents extended across the musical landscape, from blues to R&B to classical rock. In contrast to their hastily recorded debut, or its successor, done to stretch their performance and composition range", calling the title track "one of the finest songs ever to come from Procol Harum and one of the best pieces of progressive rock ever heard".