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Canine Mendelian disease record

Skeletal Dysplasia 2 (SD2)

Skeletal Dysplasia 2 (SD2). Autosomal recessive. Observed in 12 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,665 dogs (Donner 2023). Per-dog phenotype outcome depends on penetrance, modifiers, and environment; the carrier frequencies below describe variant prevalence, not disease incidence.

OMIA identifier
OMIA:001772-9615
Autosomal recessive
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human otospondylomegaepiphyseal dysplasia, autosomal recessive

This is the canine counterpart of otospondylomegaepiphyseal dysplasia, autosomal recessive in people. That makes affected dogs a naturally-occurring model of the human disease, and it is part of why studying dogs moves medicine forward for everyone. It does not mean your dog has the human disease. It means the two share an underlying biology.

In humans it is also called: OSMED, OSMEDB, Weissenbacher-Zweymuller syndrome.

MONDO:0044206 OMIM 184840OMIM 215150

Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Closely related human conditions exist for this gene. Sniff renders this as a model-of link; the canine disease remains the subject of this page.

About this disease

From OMIA's curated record

Documented in OMIA (Online Mendelian Inheritance in Animals). This describes the disease as recorded in the published literature, not a prediction for any individual dog. As of 2026-06-03.

Summary

Skeletal dysplasia 2 (SD2) is a mild form of disproportionate dwarfism in Labrador Retrievers. Affected dogs have short legs and their shoulder height is reduced by ~6 cm compared to non-affected dogs.

Clinical features

The SD2 phenotype is characterized by short legs with normal body length and width. In most cases the forelegs are slightly more affected than the hind legs. The international breed standard calls for shoulder heights of 56 cm–57 cm in male and 54 cm–56 cm in female Labrador Retrievers, respectively. The shoulder height in affected animals is reduced by ~6 cm on average. However, it must be noted that shoulder height is only an imperfect proxy for the SD2 phenotype as shoulder height is a complex trait with significant variance due to genetic and environmental factors. According to breeders' reports SD2-affected dogs are not particurlarly prone to secondary joint degeneration or any other health problems apart from the disproportionate dwarfism.

Molecular genetics

By whole-genome resequencing one of the affected dogs at 30X coverage, Frischknecht et al. (2013) identified 92 non-synonymous variants in the 4.44 Mb region mentioned in the Mapping section above. Two non-synonymous variants in the critical interval were perfectly associated with SD2 in larger cohorts of dogs. Of the two that were perfectly associated with the trait the most likely causative variant is COL11A2:c.143G>C, which is predicted to result in p.R48P on the protein level. This amino acid exchange is at an evolutionary conserved position at the N-terminus of the collagen molecule, before the beginning of the triple-helical domain. It is assumed to have only a minor impact on COL11A2 function as Col11a2 knock out mice and human patients with other COL11A2 mutations show more severe phenotypes.

Prevalence

SD2 occurs predominantly in so called working lines of Labrador Retrievers. Frischknecht et al (2013) reported a carrier frequency of 12% in the European Labrador Retriever population at the time of mutation discovery.

Inheritance

SD2 is inherited as a monogenic autosomal recessive trait. However, as this mild form of disproportionate dwarfism is superimposed on the normal variation in height, it is sometimes very difficult to unambiguously determine the phenotype.

History

Skeletal dysplasia 2 was characterized by Frischknecht et al. (2013). Other genetically distinct forms of inherited skeletal dysplasias in Labrador Retrievers have been described by Goldstein et al. (2010; Mamm Genome 21:398-408) [OMIA 001522-9615; OMIA 001523-9615] and Smit et al. (2011; Vet J 187:269-71) [OMIA 001790-9615].

Genetic testing

There is a test available to detect the causative mutation. Affected dogs are not reliably identified by their body proportions alone and genetic heterogeneity exists. Therefore, the genetic test can help to confirm a diagnosis. Breeding animals should be tested to avoid the non-intended production of affected puppies.

Human analog

OMIA links this condition to its human counterpart in OMIM (Mendelian Inheritance in Man), the place to read across to the deeper human literature for the same biology.

Disease · OMIM 184840 Disease · OMIM 215150 Disease · OMIM 614524 Gene · OMIM 120290

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001772-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).

The evidence

Published references

The peer-reviewed papers behind this disease, curated by OMIA. Starred entries are OMIA-designated landmark papers.

References curated by OMIA (Nicholas, Tammen & the Sydney Informatics Hub), doi:10.25910/2AMR-PV70 (CC-BY 4.0). Full list at the OMIA entry.

Predict a litter

Set each parent's status for Skeletal Dysplasia 2 (SD2) and see the odds for their puppies. Single recessive variant, exact Mendelian math.

Parent A
Parent B
NNClear
NmCarrier
NmCarrier
mmAffected
Clear25%
Carrier50%
Affected25%

These are the genetic odds for one known variant, not a promise: a real litter varies around them, and penetrance or other genes can change whether the condition ever appears. Use it to avoid pairing two carriers and to keep a line healthy, not to engineer a dog. Inheritance mode per OMIA.
Your breed

See what Skeletal Dysplasia 2 (SD2) looks like in your dog's breed.
Carrier frequency by breed

Top 11 well-sampled breeds (n ≥ 50)

Maximum per breed across variants in the Donner 2023 cohort, with . The list below is split into well-sampled breeds (n ≥ 50 tested) and small-sample breeds (n < 50, where the Wilson CI typically spans more than 20 percentage points and frequencies should not be compared directly to the well-sampled entries). Frequencies are population-level, not per-litter or per-line.

0%3%5%
Cavalier King Charles Spaniel1.5% · n 2,243
Cocker Spaniel1.0% · n 1,881
Labrador Retriever0.85% · n 16,856
Chihuahua<0.1% · n 4,273
Miniature Pinscher<0.1% · n 658
Beagle<0.1% · n 5,292
Pomeranian<0.1% · n 5,294
Poodle Miniature<0.1% · n 3,555
Poodle Standard<0.1% · n 4,203
American Staffordshire Terrier<0.1% · n 42,793
Siberian Husky<0.1% · n 9,035
n = 96,083 dogs · Donner et al. 2023 carrier-screening cohort · Sniff Atlas
Each bar is one well-sampled breed; the whisker is its Wilson 95% CI, and fainter bars have wider intervals. Frequencies are population-level, not per-litter. Carrier status for Skeletal Dysplasia 2 (SD2) is measured; phenotype outcome depends on penetrance and modifiers.
▸ Full table with Wilson 95% confidence intervals
Breed Carrier frequency n tested
Cavalier King Charles Spaniel 1.5% 2,243
Cocker Spaniel 1.0% 1,881
Labrador Retriever 0.85% 16,856
Chihuahua <0.1% 4,273
Miniature Pinscher <0.1% 658
Beagle <0.1% 5,292
Pomeranian <0.1% 5,294
Poodle Miniature <0.1% 3,555
Poodle Standard <0.1% 4,203
American Staffordshire Terrier <0.1% 42,793
Siberian Husky <0.1% 9,035
▸ Also observed in 1 small-sample breed (n < 50)

Frequencies in this section are statistical estimates with wide Wilson 95% confidence intervals (typically >20 percentage points). Treat these as "carriers observed but the true population frequency is not yet measurable" rather than as comparable to the well-sampled entries above.

Breed Estimate n tested
Sussex Spaniel 100.0% 3

254 additional breeds in the Donner 2023 cohort were tested but showed no carriers.

Penetrance

From genotype to phenotype

Carrier status is not the same as disease status. Penetrance is the fraction of at-risk dogs that develop the phenotype. The Donner 2023 S4 table tracks this for 1 variant(s) underlying this disease in the cohort.

At-risk dogs evaluated
3
Phenotype confirmed
3
Penetrance range
not yet quantifiable

Fewer than 20 at-risk dogs evaluated; too few to state a penetrance figure.

Predicted disease relevance at the per-dog level is UNPROVEN. The carrier frequency is measured; phenotype outcome is governed by penetrance, environment, and modifier loci. Consult a veterinarian for clinical interpretation.

How to cite this record

Citations

If you use this record in published work, cite the Sniff Atlas (the published dataset that carries the breed-level carrier frequencies) and the upstream sources:

  • Sniff Atlas v1.0.1 for the per-breed carrier frequencies:

    Gehring, M. (2026). Sniff Atlas v1.0.1. Zenodo. https://doi.org/10.5281/zenodo.20566358. CC-BY 4.0.

  • OMIA for the disease definition, inheritance, and gene assignment:

    Nicholas, F. W., & Tammen, I. (2024). OMIA. Sydney Informatics Hub, The University of Sydney. https://doi.org/10.25910/2AMR-PV70. Entry: OMIA:001772-9615.

  • Donner et al. 2023 for the breed × variant carrier-frequency cohort:

    Donner, J., Freyer, J., Davison, S., Anderson, H., Blades, M., Honkanen, L., et al. (2023). Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLOS Genetics, 19(2), e1010651. https://doi.org/10.1371/journal.pgen.1010651.

Full citation formats (BibTeX, RIS, CITATION.cff) at sniff.world/cite.

Related

Related

Last updated
Sources: Sniff Atlas v1.0.1 · OMIA OMIA:001772-9615 · Donner et al. 2023