Sergeant Michael Smith was also found guilty of dereliction of duty and conspiracy to mistreat prisoners and could now face a jail term of up to eight years and nine months as well as a dishonourable discharge.
Smith, 24 was accused of using his Belgian shepherd dog to threaten prisoners in January 2004 at the Baghdad jail which earned worldwide notoriety because of previous abuse cases involving US soldiers.
Prosecutors said he set the dog on prisoners for his own amusement.
He was found guilty of two counts of maltreatment involving three detainees, one count of conspiring to make detainees soil themselves, one of dereliction of duty, one of assault and one of committing an indecent act. Smith was acquitted on seven other charges.
One of the incidents involved two juvenile detainees at the jail who were threatened and harassed by growling dogs.
He was found guilty of assaulting an inmate named as Ashraf Al-Juhayshi by threatening that his dog, Marco, would kill or cause bodily harm.
Prosecutors said that in November, 2003 and again in January 2004, Smith had his dog lick peanut butter off the breasts and genitals of Specialist Jennifer Scala while the act was filmed by another sergeant, Jay Burr. For this Smith was found guilty of committing an indecent act.
Smith's defence said that he was following orders from his superiors and that the use of dogs was authorised.
Photos of abuse by guards at Abu Ghraib were shown in 2004 and recently by SBS television that led to widespread condemnation of US tactics in Iraq.