Breed cat and dog?..

If inter-racial exists so does inter-species. But, its usually very rare. They usually breed the same species to gether but different species all together may cause some genetic defects. I heard, though I'm not sure if its true, that some scientist did try breeding different species. They were trying to produce an animal that had certain genes that could benefits as man. However, it usually didn't last long because of too many complications.