Califa de Perro wears leather arm bracers with fur tufts near the elbows, a canine mask that canines the upper half of his face and extends forward and a mount at his waist of a canine's face. He oils his body, and has perfect teeth.
While his name is said by Taylor to mean "King of Dogs", it's important to note that its actual translation would be "Caliph of Dog". It is unknown why Califa decided to go with the singular form of perros, or whether the choice of 'caliph' points toward anything about the Dog King's background.
↑ 1.01.11.2Califa de Perro used his massive spear to sweep a squadron out of the way before striking the ground, using the impact to throw himself back out of the way. He landed and straightened. He was shirtless, and had no doubt oiled his skin, though dust had collected on it, turning him a gray-bronze. He had bracers with fur tufts near the elbows, and a dog mask that covered the upper half of his face, extending a distance forward. The only other affectation he wore that made his outfit resemble a costume was the mount at his waist, too large to be a belt buckle, with a molded dog’s face jutting a rather generous handspan in front of him. He smiled, his teeth white and perfect, as the capes he’d batted aside climbed to their feet. [...] Califa de Perro, King of Dogs, howled and joined the fight, ready to capitalize on the success. In the same instant, I sensed my bugs being eliminated. Not dying, per se, but being eradicated from existence. The ones who’d been following after the column had been caught inside.
It hadn’t changed direction. It had stopped, in preparation for a change in direction. I didn’t even have to look to see Khonsu’s target. I caught an earring of the King of Dogs with my silk, tugged. - Excerpt from Scarab 25.6
↑ 1. Leet Quest - Post Brockton Bay, Pre-Death, South America - Reddit
↑I recognized Adalid, a South American cape, hero to the people, alongside Califa de Perro, who had one foot propped up on the desk, an elbow resting on his knee. There was a man I assumed to be an interpreter beside them. - Excerpt from Extinction 27.2