One source has been posted thus far, and it contradicts what you've said. In fact, the entire first page of Google's search results for "pigs vs dogs intelligence" brings up nothing to support your point. (Low-quality sources, but again, it's currently low-quality vs no-quality.)
It's (IMO) somewhat rude to demand compliance without supporting your position.
It's (IMO) somewhat rude to demand compliance without supporting your position.