Long story short, Rutmutts are a species of sexually predatory wild dogs that can't reproduce internally. Females are so rare that they're practically a birth defect and are basically unilaterally infertile; Rutmutts are instead sexual predators, they reproduce by virtue of the fact that they're able to insemnitate almost any other species on two legs.

Operating on their sense of smell like other breeds of wild dog, Rutmutts have the unique ability to smell heat and estrus at a much larger range than normal scent - if a potential mother enters their domain in heat, she may as well be screaming at the top of her lungs for all the attention it'll draw. However, if their sense of smell is confused or otherwise snubbed, they've known to accidentally prey on males as well, particularly if they have a feminine figure - a good ass IS a good ass, after all, and doggos this needy tend to feel draught come on faster than most.

At an incredibly old age, Rutmutts can grow into alphas called Poundhounds, standing around 9 feet tall on average. However, there tends to only one per pack as they don't get along, instinctively incentivizing them to spread out over larger regions.

Poundhounds are incredibly virile, packing tools anywhere between a foot and a half and three feet long when engorged, and regularly leak spurts of pre just as powerfully and voluminously as a normal person's orgasm when they're feeling raucous. Poundhound pre is actually an incredibly powerful aphrodisiac, dulling the senses and compelling their prey to submit themselves, inducing heat and even ovulation with enough exposure.

When out on a hunt, the Poundhound has first dibs on the prey, as having the first go naturally gives him the best odds of fathering a child, keeping the bloodline strong. After this, he tends to pass them to the rest of the pack; if his copious job doesn't take, 10-12 hours of being passed around by the uncanny hours-long stamina and virility of a pack of wild Ruts almost certainly will.

Rutmutts, however, are not an inherently violent species, being less powerful than a wolf in a straight fight, lacking the overt brutality of their cousins - their aim isn't to wound their prey, it's to subdue it, as an injured mother is a miscarrying one. Given this plus the fact that sex is their MO, they tend to be very socially attuned to sexual concepts like mood and consent, never being more forceful than they need to: if their prey is nice to them they'll be nice right back. Basically, once they've marked their prey, it's an unwritten rule that they'll be leaving with a belly full of Rutpups, and if they're pleasant about it, all the better, but if not, they do what's gotta be done.

After a mother-to-be is taken and stuffed, she's brought back to the den, where she's treated with all the prestige and respect of a lord, basically becoming an itinerant pack mother with a contingent of big fluffy puppies all to eager to wait on her, hand and foot. It's actually an oddly matriarchal society, Poundhounds aside.

Rutmutts have incredibly dominant genes, and coupled with the fact that their pool of potential mates is so vast, they tend to stick to their normal doggish look, never skewing too far towards any one species (hence their Mutt moniker). You could absolutely see the effects of breeding into a single species with enough time in a controlled environment, but that's unnatural and doesn't tend to occur unless forced.

Understandably, Rutmutts are treated like pests and hunted by more civilized species out of security and prosperity, harvesting pelts and ensuring none of their women come to a sweaty, crusty hot fate. Because of this, wild Ruts tend to stay secluded to their natural environs, preying on other wild animals and only becoming bold enough to go after larger, more civilized species when imbued with the reckless bravery of the threat of extinction.