Cow and Chicken (1997)

S3E7 Cow Fly

Cow feels lonely and sad about her lack of friends until she discovers a fly buzzing around her room. They quickly form an unbreakable bond and spend all their time together. However, their happiness is threatened when Chicken, Mom, and Dad decide to hire a fly exterminator to get rid of the unwanted pest. As the threat looms, Cow must confront her feelings about friendship and what it means to protect those she cares about.