Kenneth Kellmer was allegedly found on the floor of his girlfriend’s sister’s home.
He is reported to have been on his hands and knees, with his pants pulled down, and the husky dog on top of him.
The woman who walked in on the shocking sexual act told police that the 3-year-old dog had been “hunting” him.
Court documents read: "On or about the 21st day of February, 2015, Missoula City Police Officer Campbell spoke with a woman (complainant) about a report she wanted to make regarding her sister’s boyfriend, Kenneth Kellmer.
"Complainant stated earlier today she returned to her home in Missoula County to find Kellmer insider her home.
"Kellmer was on the floor, on his hands and knees, with his pants down. She saw her dog, a 3.5 year old husky, ‘humping’ Kellmer."
Kellmer, who was arrested shortly after the incident, faces one felony count of deviate sexual conduct.
The 41-year-old appeared in court earlier this week and was released without bail, and ordered not to have contact with any dogs or cats – including his own six pets.
According to Missoulian.com, the owner of the husky allegedly assaulted by Kellmer, told the court: "They have a house full of animals, ma'am.
"They have umpteen amount of dogs, cats (and) rats."
He is due to appear in court again in several weeks.
If found guilty, Kellmer faces a hefty prison sentence and a possible fine.