In the Golarion setting, the cayhound (statted up for the Inner Sea Bestiary by Jim Groves) is an outsider descendant of Cayden Cailean’s loyal divine hound Thunder. If your setting has a similar deity of freedom, spirits, revelry, and/or bravery, then you’re good to go. If not, your local azatas (eladrin to you 3.5 fans) will be happy for the cayhounds’ company instead. The god of thieves and other trickster deities can always find a use for servants who ignore locked doors. Cayhound stats also work well for representing coin-sith and other fey dogs, particularly those that accompany the goodly trooping faeries.
Be careful, though—these are dogs that crave adventure, battle, and alcohol. These dogs might get you out of trouble, Lassie-style…but they’re far more likely to get you into it.
Fearing betrayal from within their household, the local monarchs ask adventurers to spirit their child out of the palace to safety. There is only one problem: They never cleared this plan with the dog. A gift from the child’s (very real) faerie godmother, the great mastiff is actually a cayhound charged to guard the prince with his life. Before they depart the adventurers will have to overcome the suspicions (not to mention the thunderous bark) of this dog who only speaks Celestial. If it comes to combat, the sound of the dog’s thunderous bark will alert both the family guard and the would-be usurpers. And if the adventurers end up slaying the cayhound, they will have an outraged fey lady to deal with down the road.
Man’s Grace Isle is, ironically, uninhabited by men. It is tended instead by roving dogs that effortlessly resist any attempt to collar, cage, or otherwise round them up. The dogs seem to have a playful sense of humor, and those who speak Celestial can confirm their good natures. But they allow no one to travel the island unaccompanied. Persistent treasure hunters and those who try to stay past sundown are unceremoniously herded to the beach to board their boats or suffer the less-than-tender mercies of the Isle’s selkies. Devoted to freedom they may be, but these mastiffs clearly wish to keep at least one secret locked up.
Coerced into joining a celestial hunt, a party of adventurers is paired with a hound archon and a cayhound. Both canines love the hunt but bicker constantly about almost everything else, from where to set up camp to what that smell is to whose translation of St. Xiophenes’s Last Tract is better. But both are happy to have the adventurers help them bring down the hunt’s quarry: fiendish gargoyles. The cayhound is particularly good at savaging the monstrous humanoids with its bark and its righteous bite, but will need help against a foe the hunt is unaware of: roaming packs of caltrop-hurling schirs.
—Inner Sea Bestiary 8
This isn’t the first time I’ve suggested using another monster to represent the dogs of Faerie. The “Hell Hound & Nessian Hell Hound” entry offers another approach.
Note also that, for IP reasons, the OGC’s cayhound entry linked above has been shortened. The Inner Sea Bestiary has the full ecology.
That noise you’re hearing while reading this is the Blue Angels flying over my head as I type. Spoiler alert: They are loud.
Also, I am going to a sportsball match of some sort tonight. Athletic contests are not my forte, but I’m wearing a shirt with a bird from an Edgar Allan Poe poem in defiance of a bunch of louts known as “the Stealers,” so I’ve at least got that part down. The rest I’ll fake when I get to the coliseum.