Alvin and the Chipmunks - Season 7 - Eps 1: Cookie Chomper III
Theodore encounters a stray kitten that entered through an open window in the house. He and the boys take an instant liking to the kitten, and after some compromising, they name the kitten Cookie Chomper III, and after Dave is cured of his allergy to cats, he comes to like the kitten as well. After Cookie Chomper gets run over, the boys have a hard time dealing with it. Eventually, they get a new pet, a puppy they name Lilly.
About Alvin and the Chipmunks

Title: Alvin and the Chipmunks
First Air Date: 1983-09-17
Last Air Date: 1990-12-01
Status: Ended
Rating: 6.8/10 (from 74 votes)
Language: EN
Seasons: 9
Total Episodes: 172
Network: NBC
Genres: Animation, Comedy, Family
Production Companies: DiC Entertainment, Bagdasarian Productions, Ruby-Spears Productions, Murakami Wolf Swenson, A-1 Productions
Synopsis
Three chipmunk brothers, Alvin, Simon, and Theodore are adopted by human, Dave.
Cast

Ross Bagdasarian, Jr.
Alvin / Simon / Dave Seville (voice)

Janice Karman
Theodore / Brittany / Jeanette / Eleanor (voice)

Dody Goodman

Nancy Cartwright

Frank Welker

Tress MacNeille

Ross Bagdasarian