Donner 2023.

Knowing a variant exists is not the same as knowing how common it is.

A disease variant can be documented and still be vanishingly rare, or documented and alarmingly common in one breed and absent in another. Frequency is what turns a variant from a curiosity into a decision. Donner and colleagues set out to measure it at scale.

They screened more than a million dogs, purebred and mixed breed, from over 150 countries, for 250 disease-associated variants, and reported how often each one appears, broken out by breed. It is one of the largest pictures anyone has of how these variants are actually distributed across the dog population.

It is the carrier frequency on a breed page, and the sample size beside it.

When a Sniff breed page tells you how often a variant is carried in that breed, that number comes from Donner 2023, and it never travels without its sample size. We treat every one of these figures the way it should be treated: as a cohort, the dogs that were actually screened, and not as a pronouncement about the whole breed. Below a floor of dogs tested, the number does not soft-pedal, it disappears and says so.

That discipline is the difference between a frequency that informs a breeding decision and a frequency that misleads one. Donner 2023 gives us a real, large, breed-resolved measurement. Framing it honestly is the part we own.