After Brian gets sick from excessive drinking, Peter attempts to give him a suppository, leading a frustrated Brian to bite him. This makes Peter terrified of his own dog, eventually leading Lois to send Brian to a military-style obedience school.
In the Family Guy universe, "Once Bitten" actually aired as the (though some streaming orders may vary). [S13E5] Once Bitten
This episode is a turning point for the show's heavy themes of domestic abuse and hidden trauma. After Brian gets sick from excessive drinking, Peter
Celeste (Nicole Kidman) has a solo therapy session with Dr. Reisman. In a masterfully acted scene, the therapist pushes past Celeste’s justifications, finally getting her to admit the danger she is in with her husband, Perry. the therapist pushes past Celeste’s justifications