How is Muscular Hypertrophy (Double Muscling) inherited in dogs?

Muscular Hypertrophy (Double Muscling) follows a Autosomal recessive inheritance pattern, associated with the MSTN gene. It has been observed in 1 of 266 breeds screened in the Sniff Atlas.

Is there a genetic test for Muscular Hypertrophy (Double Muscling)?

Muscular Hypertrophy (Double Muscling) is associated with the MSTN gene. Where a validated DNA test for the causal variant is available, it can identify carriers before breeding. Per-breed allele frequency figures are published in the Sniff Atlas (242,664 dogs screened).

What is the human equivalent of Muscular Hypertrophy (Double Muscling)?

OMIA links Muscular Hypertrophy (Double Muscling) to its human counterpart in OMIM (OMIM 614160), the bridge to the deeper human-medicine literature for the same underlying biology.

How well studied is Muscular Hypertrophy (Double Muscling) in dogs?

OMIA curates 8 peer-reviewed references for Muscular Hypertrophy (Double Muscling). The full, linked citation list is on this page.

Canine Mendelian disease record

Muscular Hypertrophy (Double Muscling)

Muscular Hypertrophy (Double Muscling). Autosomal recessive. Observed in 1 of 266 breeds tested in the Sniff Atlas, with measured allele frequencies drawn from 242,664 dogs (Donner 2023). Per-dog phenotype outcome depends on penetrance, modifiers, and environment. The allele frequencies below count tested gene copies, not dogs, and describe how common the variant is, not disease incidence.

OMIA identifier: OMIA:000683-9615
Inheritance: Autosomal recessive
Linked gene: MSTN
Human counterpart: In humans, this gene is MSTN. OMIM 601788 In people, MSTN rarely tolerates loss-of-function variation (gnomAD v4.1 constraint, LOEUF 0.57), a sign it does important, dosage-sensitive work. In people, variants in the MSTN gene have conflicting classifications in ClinVar, and none is expert-reviewed. The evidence is unsettled, not that variants here are benign.
Source dataset: Sniff Atlas v1.0.2 / DOI

The human connection

A model of human myostatin-related muscle hypertrophy

Dogs with this condition carry a change in MSTN. In people, changes in the same gene cause myostatin-related muscle hypertrophy. This canine condition is studied as a natural model of myostatin-related muscle hypertrophy in people; it is not the same as that human diagnosis. Studying dogs can move medicine forward for everyone; the canine disease remains the subject.

In people, the disease is described as: Myostatin-related muscle hypertrophy is a rare condition characterized by reduced body fat and increased muscle size. Affected individuals have up to twice the usual amount of muscle mass in their bodies. They also tend to have increased muscle strength. This condition is not known to cause any medical problems, and affected individuals are intellectually normal. Myostatin-related muscle hypertrophy is caused by mutations in the MSTN gene. It follows an incomplete autosomal dominant pattern of inheritance.

In humans it is also called: MSLHP, muscle hypertrophy.

MONDO:0013598 OMIM 614160

Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). 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 2026-08-27.

Summary

In addition to the occurrence of natural variants for this trait, variants have been created artificially (e.g. Zou et al., 2015): Genetically-modifed organism; GMO.

Clinical features

Affected dogs show an unusual amount of muscularity, especially in the neck and legs. They are broad chested and typically don’t conform to the breed standard (slim, long neck, pointed snout) (Mosher et al., 2007). Dogs with a single copy of the mutation show a smaller degree of hypermuscularity are significantly faster than homozygous wild-type whippets (Mosher et al., 2007). Hence, being heterozygous for the mutation is considered performance enhancing. For whippets with a double copy of the mutation, there is little evidence about potential associated health risks. It has been anecdotally reported amongst breeders that affected whippets are otherwise generally healthy and only suffer from occasional muscle cramps and a distinctive overbite (Mosher et al., 2007). IT thanks DVM student Lucas Anderson, who provided the basis of this contribution in May 2023.

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 614160 Gene · OMIM 601788

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:000683-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).

OMIA curates the disease definition, the clinical description and the reference list. The cross-species disease identity is Monarch's. Sniff renders these and adds the breed-level frequencies, the plain-language summary, and a stated reason wherever a number is missing.

Signs & cross-references

How it presents

Catalogued in the Mondo disease ontology (the cross-species disease identity used by the Monarch Initiative) as myostatin-related muscle hypertrophy (MONDO:0013598).

Phenotype terms: Human Phenotype Ontology + Mammalian Phenotype Ontology; disease terms: Mondo (Monarch Initiative). Cross-references curated by OMIA (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. Showing 6 of 8.

Evolutionary characteristics, biochemical structure, and function impact of MSTN gene. · Genes Dis · 2025 · PMID 40727588
Deciphering myostatin's regulatory, metabolic, and developmental influence in skeletal diseases. · Front Genet · 2021 · PMID 33854530
The myostatin gene: an overview of mechanisms of action and its relevance to livestock animals. · Anim Genet · 2018 · PMID 30125951
Generation of gene-target dogs using CRISPR/Cas9 system. · J Mol Cell Biol · 2015 · PMID 26459633
Mutations in the myostatin gene leading to hypermuscularity in mammals: indications for a similar mechanism in fish? · Anim Genet · 2011 · PMID 21175702
Sprinting without myostatin: a genetic determinant of athletic prowess. · Trends Genet · 2007 · PMID 17884234

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 Muscular Hypertrophy (Double Muscling) and see the odds for their puppies. Single recessive variant, exact Mendelian math.

Parent A

Parent B

NNClear

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 Muscular Hypertrophy (Double Muscling) looks like in your dog's breed.

Allele frequency by breed

Top 1 well-sampled breeds (n ≥ 50)

Maximum allele frequency per breed across variants in the Donner 2023 cohort, with Wilson 95% confidence intervals. 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%

Greyhound0.48% · n 105

0.48%n 105

n = 105 dogs · Donner et al. 2023 carrier-screening cohort · Sniff Atlas

n counts the dogs in the breeds charted here; the page total above counts every breed screened. 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 Muscular Hypertrophy (Double Muscling) is measured; phenotype outcome depends on penetrance and modifiers.

▸ Full table with Wilson 95% confidence intervals

Breed	Allele frequency	Wilson 95% CI	n tested
Greyhound	0.48%	[0.0%, 4.4%]	105

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

Scope of this record

This record carries the breed-level allele frequencies from the Donner 2023 cohort. Penetrance data (the fraction of at-risk dogs that develop the phenotype) is not yet quantified for this disease in the Sniff Atlas v1.0.2. The OMIA entry is the authoritative reference for the clinical phenotype, inheritance pattern, and gene assignment.

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

How to cite this record

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

Sniff Atlas v1.0.2 for the per-breed allele frequencies:
Gehring, M. (2026). Sniff Atlas v1.0.2. 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:000683-9615.
Donner et al. 2023 for the breed × variant allele-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.

Gene page: MSTN, cited identity, disease associations, and the human-gene bridge.
Sniff Atlas v1.0.2, the source dataset for these frequencies.
Browse breeds, per-breed Mendelian profiles, including this disease in context.
OMIA entry OMIA:000683-9615, authoritative clinical reference.
About OMIA, the catalogue this record comes from, and how Sniff uses it.

Last updated August 27, 2026

Sources: Sniff Atlas v1.0.2 · OMIA OMIA:000683-9615 · Donner et al. 2023 · gnomAD v4.1 (Karczewski 2020) · ClinVar (Landrum 2018)