Manassas, Va. ? Scene: the Mattaponi Kennel Club dog show.

Enter the purebreds: the buttery yellow Labradors and the lusciously springy Spaniels, and the sly Border Collies, whose owners plaster their cars with bumper stickers reading “My Border Collie is smarter than your honor student.” Enter the sleek Viszlas and the aloof Belgian Malinois, a whole team of them, with show names like Tri Sort’s Closer to the Heart.

Enter Otis.

Otis is eating a cow hoof. When he is finished, he might beg his owner, with low gentle moans, for a piece of string cheese — Otis will do anything for string cheese — or he might lick his rear end. Otis is brown(ish) and fluffy(ish)and weighs about 65 pounds. Otis is the result of an illicit tryst between a purebred Husky and a rakish Lab/Chow neighbor dog.

Mutt lovers, rise. It is a historic spring for all of your shelter dogs, mixes, halfsies and whatsits.

For the first time in the 125-year history of the AKC — the venerable organization whose mission is to “advance the study, breeding, exhibiting, running and maintenance of purebred dogs” — mutts are being allowed to compete alongside the champion bloodlines.

Not in the “beauty contests,” says Mattaponi Kennel Club show chair Katie Knepley, as she briskly walks around the grassy competition rings, partitioned off by white fences. In those “conformation” events, judges evaluate how precisely a dog conforms to its breed’s standards, which mutts do not have.

But the skill-based contests — Agility, Rally and Obedience — were officially opened to mixed breeds last month. This weekend, Mattaponi held its first event in which mixed breeds, euphemistically referred to at the show as “All Americans,” have been allowed. Otis is one of two competing, in an event that includes around 40 entries.

The question of whether to allow the mixed breeds in competitions has been a huge consideration, dating back seven or eight years, according to an AKC spokesman. One proposal involved mixed breeds competing in separate categories rather than directly against the purebreds. Mutt owners cried foul, and the division was reconsidered.

“This is a strong indication that the AKC is trying to be more inclusive in the dog world,” says Ernie Slone, editor in chief of Dog Fancy magazine. Still, there are those purebred devotees who are dubious about the whole integration. One mutt owner reports that her purebred-loving friends were concerned that mutts had special mixed-trait advantages. Greyhound + Border Collie = Superdog!