OMIA.
5,967 inherited traits. 755 species. Curated by hand for 31 years.
The reference for inherited disease in animals.
Why OMIA exists
Human medicine has OMIM. For most of the last century, animals had nothing like it.
OMIM, the Online Mendelian Inheritance in Man, is the catalogue that lets a human geneticist look up a gene and find every disorder linked to it, with the evidence. It is one of the quiet pieces of infrastructure that modern medicine is built on. Animals had no equivalent. Inherited disorders in dogs, cattle, horses, cats, and hundreds of other species were scattered across decades of papers in dozens of journals, described in a dozen vocabularies, impossible to search as one body of knowledge.
Frank Nicholas, a geneticist at the University of Sydney, set out to build the animal counterpart. It began as a book and became a free internet resource in 1995. It has been curated by hand ever since, today by Associate Professor Imke Tammen and a team of specialists at Sydney. OMIA turned 31 in 2026.
Thirty-one years of one team reading the literature and writing down, carefully, what is actually known about inherited disease in animals.
What OMIA catalogues
OMIA records inherited disorders and single-locus traits across 755 mostly-vertebrate species, along with the genes and variants underneath them and how each trait is inherited. The five species with their own dedicated resources, including human and mouse, are deliberately left out. Everything else, from the well-studied to the barely-studied, lives in one place.
For the dog: 1,010 traits.
Of those, 448 are single-gene traits, and 370 have a known likely causal variant. Each entry carries an OMIA number, the species (the dog is NCBI taxon 9615), the gene where known, the mode of inheritance, and the references behind it. When the same disorder is known in humans, the entry links to the human equivalent in OMIM. That cross-link is the bridge between a dog's genetics and a century of human medical genetics.
And a grade for how sure we are.
Not every reported variant is proven to cause disease. For some, OMIA records a pathogenicity classification on the same five-tier scale human medicine uses: pathogenic, likely pathogenic, variant of uncertain significance, likely benign, benign. Animal genetics now has its own published criteria for making that call objectively, the Animal Variant Classification Guidelines (Boeykens et al. 2024), with the resulting classifications published on OMIA. The grades are deliberately sparse. Only a couple of dozen documented canine variants carry one, because a real classification takes evidence that often does not exist yet. That sparseness is the honesty of it. A blank is not a verdict of safe. It means the work has not been done.
What OMIA contributes to Sniff
OMIA is how Sniff knows what is documented, and how sure the field is.
When a breed page lists the conditions documented in that breed, those are OMIA records. When Sniff shows the human equivalent of a canine disease, that is the OMIA-to-OMIM bridge. When the answer engine grounds a disease question and cites an OMIA number rather than guessing, that is OMIA doing the work. When a variant carries a causality grade, that grade is OMIA's pathogenicity classification.
OMIA is also the ground truth Sniff's AI is measured against. The protein-language-model pathogenicity scores in the Sniff Atlas were calibrated against OMIA's pathogenic variants and reached an AUC of 0.935. Without a hand-curated set of known-pathogenic variants to test against, there would be no way to say whether the model's predictions mean anything. OMIA is the answer key.
It is the difference between a site that tells you what is documented and cited, and a site that makes things up. We chose the first kind, and OMIA is a large part of why we can.
OMIA was founded by Professor Frank Nicholas and is curated by Associate Professor Imke Tammen with a team of specialists, supported by the Sydney Informatics Hub at the Sydney School of Veterinary Science, The University of Sydney. It has been a free resource for the world for over three decades, sustained largely by careful, unglamorous, continuous work.
Sniff is not affiliated with OMIA. We credit it here, cite it on every disease surface, and link back to the entry. The catalogue belongs to the field. We are grateful for it, and we are doing our best to send people to the source.
Citation: Nicholas, F.W., Tammen, I., & Sydney Informatics Hub. Online Mendelian Inheritance in Animals (OMIA) [dataset]. doi:10.25910/2AMR-PV70. Individual entries are cited as OMIA:NNNNNN-9615 (the six-digit trait number; 9615 is the NCBI taxon id for dog).