Answer by taking a quote from the following article:

"Hound Dog" is a twelve-bar blues song written by Jerry Leiber and Mike Stoller. Recorded originally by Willie Mae "Big Mama" Thornton on August 13, 1952, in Los Angeles and released by Peacock Records in late February 1953, "Hound Dog" was Thornton's only hit record, selling over 500,000 copies, spending 14 weeks in the R&B charts, including seven weeks at number one. Thornton's recording of "Hound Dog" is listed as one of the Rock and Roll Hall of Fame's "500 Songs That Shaped Rock and Roll", and was inducted into the Grammy Hall of Fame in February 2013. "Hound Dog" has been recorded more than 250 times. The best-known version is the July 1956 recording by Elvis Presley, which is ranked number 19 on Rolling Stone magazine's list of the 500 Greatest Songs of All Time; it is also one of the best-selling singles of all time.

Two records were released that were neither cover versions of nor answers to Thornton's release, yet used a similar melody without any attribution to Leiber and Stoller. The first was Smiley Lewis's "Play Girl", credited to D. Bartholomew and released by the Imperial Records label (Imperial 45-5234) by the end of March 1953. Described as a "stomping uptempo boogie rocker", it began: "You ain't nothin' but a Play Girl / Staying out all night long". In April 1955, female impersonator Jesse "Big 'Tiny'" Kennedy recorded "Country Boy" accompanied by His Orchestra that was released by RCA's Groove Records (Groove 4G-0106) by May 21. While credited solely to Kennedy, this song has a similar melody to "Hound Dog": "'Country Boy' has a deceptively slouching flip on the 'Hound Dog' motif - this time with Tiny proclaiming proudly that he 'ain't nothing but a country boy'".  In the early 1970s Robert Loers, owner of Dutch label Redita Records, found a song with the same melody as "Hound Dog" called "(You Ain't Nuttin' But a) Juicehead" on an anonymous acetate at Select-o-Hits, the Memphis distributorship owned by Sam Phillips' brother, Tom, where Sun artifacts were stored.  When Juice Head first appeared on a Redita Records LP [in 1974], it was credited to Rosco Gordon. But it's not Rosco. It simply is not him. Really. Even Rosco confirmed that. It might not even be a Memphis Recording Service demo. Just substitute the words "Hound Dog" for "Juice Head" and what have you got? Of course the inspiration for this song came from Big Mama Thornton's "Hound Dog" or perhaps even from Rufus Thomas' "Bear Cat". But the song's other parent is Eddie Vinson's slowed down "Juicehead Blues" which harks to the previous decade...If indeed this originated from Sam Phillips' studio, it was nothing that Phillips needed to touch because it was another lawsuit waiting to happen."  Philip H. Ennis sees "Two Hound Dogs", which was recorded on May 10, 1955, by Bill Haley & His Comets (Decca 29552), as a response to Thornton's recording. While not an answer record in the traditional sense, the lyric characterized "Rhythm" and "Blues" as the titular "Two Hound Dogs," an apparent testament to the stature of "Hound Dog."

How many different versions of this song were recorded?
Two records were released that were neither cover versions of nor answers to Thornton's release,