You can get Garfield cartoons with Garfield speaking on YouTube, I have embedded one here for you.
You can feed the URL of a YouTube video into the YouTube-mp3 site and it will create an mp3 version of the audio that you can download to your computer. http://funadvice.com/r/bf1ego4pemd
I have seen hundreds of Pink Panther Cartoons and as far as I can recall he only ever spoke in one of them, where he said something like "Why can't humans be more like animals?" Can't remember what the title of it was though. In the classic Pink Panther cartoons that I remember, it is close to the truth to say he does not have a voice.
-- Best wishes - Majikthise.