I'm sure that Donkey in Shrek had an American accent ;)

I don't expect Wikipedia to be good source of information.

According to Wikipedia, animals do have regional variations which could be classed as accents, for example: It has been noted that cows moo at different pitches depending on the location and size of their herding group.

i agree on thank you answer. well it is impossible. cowboy...

Yes, they do. I have seen articles on scientific studies on the differences in whale songs depending on where they come from. I also remember there was a study on bird songs that showed regional differences as well. Ah, quick search came up with the following: http://www.fishersci.com/wps/portal/CMSTATIC?LBCID=00&href=ScienceEducation/scienceEduStandard/Support/Literature/se_std_AnimalswithAccents_022707_1306.jsp&store=ScienceEducation&segment=elementary