It's a Ruff Life/Professor Myron Mentalapse/Dennis Race 2000
S1:E16
1985
IMDb
When Ruff upsets one of PeeBee's experiments, the dog and Joey end up with their brains switched, Ruff can speak, while Joey can only bark! PeeBee and Dennis chase them around town, trying to capture them and re-switch their brains back to their owners.