Metro police reported Joshua Dyer, 36, was taken into custody late Thursday night.
Three other suspects have already been arrested in the case; John Gooch, James Burgess and Shawn Massey.
The discovery of the alleged dog fighting operation came as officers executed a heroin-related search warrant at the home in the 600 block of Rowan Drive.
Twenty-one pit bulls were seized, 10 of them puppies.
According to Dyer’s arrest warrants, they had scarring and injuries to their faces and bodies.
Police said the dogs were found either chained or in cages behind the home, along with a treadmill believed to have been used to train the dogs and syringes allegedly used to administer chemicals to them.
Dyer was booked into the Metro jail and faces nine counts of animal fighting and five counts of aggravated animal cruelty. His bond is set at $490,000 and he is due in court March 28.
(WKRN - March 25, 2016)