BLOOMFIELD -- Police have arrested a Belleville man who they say beat up his ex's new boyfriend with a baseball bat after the two got into an argument about the man's dog.

According to Bloomfield police, Willie Brooks, 32, was visiting his son at his ex partners's house on Dec. 29 when he heard the woman's 33-year-old boyfriend make "derogatory" comments about Brooks' dog.

Brooks admitted to hitting the man in the arm and head with a baseball bat after hearing the comments, authorities said.

The man suffered bruising and swelling from the beating, police said.

Brooks was arrested on aggravated assault and unlawful possession of a weapon charges, and was released after posting bail, police said.

Jessica Mazzola may be reached at jmazzola@njadvancemedia.com. Follow her on Twitter @JessMazzola. Find NJ.com on Facebook.