We probably know what's going on in this picture. Both the cat and dog survived through the odds, looking after each other and protecting their guard. They probably saw something approaching and assume a natural, calm demeanor to ooze an aura of confidence. This is their means of self defense which keeps natural predators at bay.
The next level of defense is for them to both display their sharp jaws at once and roar in unison. But when push comes to shove, both the dog lunges at the predator while the cat tries to provide 'cover fire', flanking the enemy from the sides and rear. This method of self defense works against opponents who are much larger than them both. It doesn't work when they are outnumbered, the two of them know when to retreat.