The dog will now be put to death after languishing in an overcrowded animal shelter in Jackson city, the Daily Mail reported.
According to the owner of the shelter, the dog's master noticed him "hunched over" another male dog, which led him to assume it was gay.
While dogs are known to occasionally display homosexual behaviour, animal experts say a male dog mounting another male dog is not a sign of sexual orientation but rather a sign of dominance.
A Facebook page has been set up with the message: "Don't let this gorgeous dog die because his owner is ignorant of normal dog behaviour!"
Biologists have recorded same-sex activity in more than 450 species including flamingos, bison, beetles and warthogs.
A 2010 study of Alaskan Albatrosses found that a third of the pairs actually consisted of two females.
Research also shows around one-fifth of all king penguin couples kept in captivity are gay.
In his book "Biological Exuberance: Animal Homosexuality And Natural Diversity", Bruce Bagemihl argues against "heterosexist bias", where researchers presume animals are heterosexual.
He claims homosexual behaviour has been observed in 1,500 species, and well-documented in 500 of these.
He said species like giraffe, butterfly and manatee - large marine mammals - engage in a huge, excitable, and same sex frenzy.