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Brittany

Brittany
Photo: Pharaoh Hound / CC BY-SA 3.0 · Wikimedia

29 Brittanys in the atlas. Every number on this page has a source.

Population-genetic snapshot of Brittanys in the Sniff Atlas, source-graded Mendelian carrier frequencies from Donner 2023, and nutrition guidance tied to the genetic findings above.

Also known as Brittany Spaniel, Brittany Wiegref, Epagneul Breton, and French Brittany.

See in the atlas → From CanVAS
The plain version

Brittanys have a moderately diverse genetic background, which is a good sign for their overall health. They usually weigh around 37 lb and live about 12 years on average. This breed is related to dogs like the Weimaraner and Irish Water Spaniel. So far, no specific genetic health concerns have been found in their gene pool, but it’s always a good idea to chat with your vet or consider genetic testing for your own dog.

What the atlas says about Brittany

In the atlas, the Brittany clusters consistently as Brittany (100% of the 29 dogs here). At the trait loci, HMGA2 runs higher than the atlas average (100% here vs 56%); SMAD2 runs lower than average (31% here vs 74%). Dogs here sit in a relatively sparse region of the atlas, fewer close neighbors than typical.

Low breed predictability score (0.24), individual dogs of this breed vary widely in genetics, suggesting active substructure or sub-population diversity. Only 29 dogs of this breed in the atlas, modestly sampled.

Genetic dimensions · CanVAS atlas

What the genome says about Brittany

Computed from the 18,477 research dogs in the Atlas.

Dogs in the Atlas
29Founders
19 from Hayward2016, 10 from Spatola
Genetic diversity
0.32Moderate
Mean heterozygosity across the breed. Ranks 68th most genetically tight of 107 ranked breeds.
What does genetic diversity mean?

How varied a breed's gene pool is — the share of gene spots where a typical dog of the breed carries two different versions rather than two identical ones.

How to read it: Higher = more diverse. Among well-sampled breeds it ranges roughly 0.22 (least diverse) to 0.33 (most diverse).

Diversity is a strength, not a verdict on any individual dog. Lower diversity means it's worth paying attention to recessive-risk testing — not that a dog is doomed.

Cluster structure
Single tight cluster
Intra-breed RMS distance: 35.06
What does within-breed variation mean?

How much individual dogs within the breed differ from each other genetically.

How to read it: Higher = more internal variety among individuals of the breed.

Sensitive to how many dogs of the breed we've sampled.

Related breeds
Built from
Close cousins
In the Sporting group
Explore the full lineage map →
VBO foundation stock (breeding records) · AKC breed group
Relatedness is documented lineage + kennel family. Genetic-ancestry distance measures diversity, not kinship, so it isn't used here.
How long they live
11.1years (life expectancy)
95% CI 10.9–11.3 · VetCompass, McMillan 2024, n=991. source
What does typical lifespan mean?

The median age dogs of the breed tend to reach.

How to read it: Higher = longer-lived. Compare to longevity-for-size to see whether it's just a size effect.

Drawn from population lifespan records; individual dogs vary widely with care, genetics, and luck.

Trait genetics
Allele frequencies at named morphology loci

Frequency of the alternate allele in this breed at each locus's representative SNP.

Body size
IGF156%
HMGA2100%
SMAD231%
LCORL90%
STC252%
ADAMTS1773%
Leg length
FGF4·CFA1895%
FGF4·CFA1250%
Coat
RSPO240%
FGF541%
KRT7169%
MC1R78%
Ear set
MSRB379%
Skull shape
BMP369%
SMOC267%
n = 29 dogs · moderate confidence · CanVAS (Brundage 2026) · Sniff Atlas
Names & origins

Other names

The Brittany is also recorded as Brittany Spaniel, Brittany Wiegref, Epagneul Breton, and French Brittany.

Identified as Brittany (VBO:0200238) in the Vertebrate Breed Ontology (Mullen et al. 2025, CC-BY 4.0) · registry IDs iDog 54 · VeNom 22569.

What you see when you look at a Brittany

What does the genome say about how a Brittany looks?

Brittanys look the way they do because of a small set of fixed and near-fixed morphology genes that, taken together, define the visible breed. Each translation below pairs the gene with the trait an owner actually sees, the breed's allele frequency at that locus, and a one-clause causal phrase.

Where the breed-defining genes act, mapped on a generic dog-body key — and how fixed each marker is in the Brittany. The figure is the most-settled marker we read in that region; the full per-locus panel is below. (The silhouette is a shared anatomical guide, not this breed's outline.)

Body sizeHMGA2 · 100%Skull shapeBMP3 · 69%EarsMSRB3 · 79%Leg lengthFGF4 CFA18 · 95%Coat & colorMC1R · 78%
CanVAS trait-locus panel (Brundage 2026)
15 morphology markers read across 5 regions. Allele frequency = how fixed a marker is in this breed, not whether your dog carries it.

Size and build

IGF1 sits at 56% for the small-body allele. IGF1 is the gene that sets dog body size from Chihuahua to Great Dane. Intermediate frequencies typically keep a breed in the mid-sized range rather than tipping toward the larger working forms.

IGF1what this gene does

IGF1 is a gene that plays a key role in determining a dog's body size. It influences how much a dog grows, affecting overall stature.

For your dog: Knowing about IGF1 gives you insight into your dog's size traits, but it’s just one part of the bigger picture when it comes to their health and care.

Full IGF1 gene page →

HMGA2 is near-fixed at 100%, reinforcing the breed's size signal through a second locus on chromosome 10.

HMGA2what this gene does

HMGA2 is a gene that influences body size in dogs, helping determine how big or small a dog grows.

For your dog: Knowing about HMGA2 helps you appreciate the genetic factors behind your dog's size, but it doesn't signal any health issues.

Full HMGA2 gene page →

SMAD2 sits at 31% at the chromosome-7 height locus.

SMAD2what this gene does

SMAD2 is a gene involved in regulating body size by influencing how cells grow and develop.

For your dog: Knowing about SMAD2 helps understand your dog's size traits but isn't linked to health issues; no immediate action needed.

Full SMAD2 gene page →

LCORL is near-fixed at 90%, the NCAPG/LCORL height locus that is one of the strongest single contributors to canine body size.

LCORLwhat this gene does

LCORL is a gene that influences body size in dogs. It helps determine how big or small a dog might grow.

For your dog: Knowing about LCORL helps you appreciate the genetic factors behind your dog's size, but it’s just one piece of the bigger picture when it comes to health and care.

Full LCORL gene page →

STC2 sits at 52%.

ADAMTS17 sits at 73%. ADAMTS17 is a body-size locus also linked to lens disorders.

ADAMTS17what this gene does

ADAMTS17 is a gene that influences body size and also plays a role in certain eye conditions. It affects the structure of tissues in the eye and elsewhere in the body.

For your dog: If your dog belongs to a breed known to carry ADAMTS17 variants, it’s worth discussing genetic testing and eye exams with your vet to stay ahead of potential issues.

Full ADAMTS17 gene page →

Leg length

The FGF4 retrogene on chromosome 18 is near-fixed in this breed at 95%. This is the leg-length variant. The breed is fully committed to the long-legged form rather than the short-legged Corgi-and-Dachshund body plan.

The FGF4 retrogene on chromosome 12 sits at 50%, the chondrodystrophic variant.

Coat type, length, and color

RSPO2 sits at 40% for the furnishings variant. Furnishings (the eyebrow-and-mustache pattern seen in Schnauzers and Wheaten Terriers) vary across the population at this intermediate frequency, and visible expression depends on the specific allele combination each dog carries.

RSPO2what this gene does

RSPO2 influences the texture and appearance of a dog's coat, particularly the presence of 'furnishings' like mustaches and eyebrows. It helps determine whether a dog has that distinctive wiry or textured look.

For your dog: If your dog has those wiry eyebrows or a mustache, RSPO2 is part of the reason—no health worries, just a coat feature worth knowing about.

Full RSPO2 gene page →

FGF5 sits at 41% for the long-coat variant. Coat length is influenced by other loci as well, so intermediate FGF5 frequencies do not always correspond to intermediate visible coat lengths.

FGF5what this gene does

FGF5 is a gene that influences the length of a dog's coat. It acts like a natural switch, telling hair follicles when to stop growing longer fur.

For your dog: If your dog has a notably long or short coat, FGF5 is likely part of the reason—no action needed, but it’s a neat genetic detail to know.

Full FGF5 gene page →

KRT71 sits at 69% for the wavy/curly variant. Coat curl varies across individuals at this intermediate frequency, and visible expression is also influenced by modifier loci.

KRT71what this gene does

KRT71 is a gene that influences the curliness of a dog's coat. It helps determine whether a dog's fur is straight or has a distinctive curl.

For your dog: If your dog has a curly coat, KRT71 is likely part of the reason; it’s a natural variation, not a health concern.

Full KRT71 gene page →

MC1R sits at 78% at the representative SNP. MC1R controls the switch between red-to-gold pigment and black-to-brown pigment, with the e/e homozygous genotype producing the gold-to-red spectrum. Substrate frequencies at this SNP depend on the array's polarity, so visible coat color in the breed is a more reliable indicator than this single number.

MC1Rwhat this gene does

MC1R is a gene that influences coat color in dogs, affecting how pigments are produced in the fur.

For your dog: Knowing about MC1R gives insight into your dog's coat color but doesn't relate to health issues.

Full MC1R gene page →

Ears

MSRB3 sits at 79% for the drop-ear allele, which is why ear set varies across the breed.

MSRB3what this gene does

MSRB3 is a gene involved in the development of ear shape and structure in dogs.

For your dog: Understanding MSRB3 helps explain why your dog's ears look the way they do, but it isn't linked to any health issues.

Full MSRB3 gene page →

Skull shape

BMP3 sits at 69%, contributing to the breed's moderate, mesaticephalic head shape rather than the extreme brachycephalic form.

BMP3what this gene does

BMP3 is a gene that influences the shape of a dog's skull, particularly contributing to a shorter, broader head shape known as brachycephaly.

For your dog: If your dog has a broad, short skull, it's worth discussing with your vet how this might impact their health, even though BMP3 isn't directly tied to illness.

Full BMP3 gene page →

SMOC2 sits at 67%, contributing to the breed's moderate head shape.

SMOC2what this gene does

SMOC2 influences the shape of a dog's skull, particularly affecting how flat or short the face appears.

For your dog: If your dog has a short nose, it's worth discussing with your vet how this trait might impact their health over time.

Full SMOC2 gene page →
Mendelian-disease genetics

What genetic diseases do Brittanys carry?

From a panel of 250 Mendelian-disease variants screened in 1,054,293 dogs (Donner et al. 2023), Brittanys carry 4 of them at observable frequency. Carrier frequency is not clinical risk. Most recessive variants require two copies for disease expression; many dominant variants show incomplete penetrance. Read this as a population fingerprint of what's in the gene pool, not a per-dog prediction.

Dilated Cardiomyopathy risk factor (Discovered in the Doberman Pinscher; PDK4-related)
Autosomal dominant (Incomplete penetrance)
low 0.86%
n = 349 dogs · 2 variants tested · OMIA:000162-9615 · omia.org →
PDK4what this gene does

PDK4 helps regulate how cells use energy, especially in the heart muscle.

For your dog: If your dog is one of the breeds known to carry this gene, it’s worth discussing heart health with your vet, but being a carrier doesn’t mean your dog will develop disease.

Cone-Rod Dystrophy (cord1-PRA/crd4)
Autosomal recessive (Incomplete penetrance)
low 0.43%
n = 347 dogs · 1 variant tested · OMIA:001432-9615 · omia.org →
RPGRIP1what this gene does

RPGRIP1 is a gene involved in the function of photoreceptor cells in the eye, which help dogs see in different light conditions.

For your dog: If your dog belongs to a breed known to carry RPGRIP1 mutations, it’s worth discussing with your vet to understand the risks and monitor eye health.

Complement 3 (C3) Deficiency
Autosomal recessive
low 0.14%
n = 349 dogs · 1 variant tested · OMIA:000155-9615 · omia.org →
Degenerative Myelopathy (DM)
Autosomal recessive (Incomplete penetrance)
low 0.14%
n = 349 dogs · 1 variant tested · OMIA:000263-9615 · omia.org →
SOD1what this gene does

SOD1 is a gene that helps protect cells from damage caused by harmful molecules called free radicals.

For your dog: If your dog is a carrier of SOD1 variants, it's worth discussing with your vet, but remember carrier status doesn't mean your dog will get the disease.

Source: Donner J et al. 2023. Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLOS Genetics 19(2):e1010651 · Evidence: Limited (DTC ascertainment, tag-SNP proxy) · Confounding MEDIUM · License CC-BY-4.0 · Phene IDs from OMIA (Sydney School of Veterinary Science, The University of Sydney; DOI 10.25910/2AMR-PV70).
Sample size in this breed: 349 dogs from the Donner 2023 cohort.

Which Mendelian variants matter most for Brittanys?

The Mendelian-disease table above lists four variants screened in 349 Brittanys (Donner 2023). All four are rare in the breed. The carrier frequencies are low enough that routine screening is not a first-tier concern for most Brittany owners.

Dilated Cardiomyopathy risk factor (TTN)

Dilated cardiomyopathy in Brittanys is an autosomal-dominant condition with incomplete penetrance. The variant sits in TTN, a gene first studied in connection with Doberman Pinschers. Affected dogs develop enlarged, weakened hearts. Only 0.86% of Brittanys in the Donner cohort carry the variant (n=349). Testing exists and is available through most commercial DNA labs.

Cone-Rod Dystrophy (cord1-PRA/crd4)

Cone-Rod Dystrophy in Brittanys is an autosomal-recessive condition with incomplete penetrance. The disease causes progressive loss of sight, first in dim light, then in daylight. Carrier frequency is 0.43% (n=347). Not every carrier-by-carrier pairing produces affected puppies. Testing is available.

Degenerative Myelopathy (DM)

Degenerative myelopathy in Brittanys is an autosomal-recessive condition with incomplete penetrance. The disease causes progressive spinal-cord degeneration leading to hind-limb weakness and eventual paralysis. Carrier frequency is 0.14% (n=349). Testing exists and can guide breeding decisions.

Complement 3 (C3) Deficiency

Complement 3 deficiency in Brittanys is an autosomal-recessive condition. The disease affects the immune system, and affected dogs struggle with certain infections. Carrier frequency is 0.14% (n=349). Testing is available through specialty labs.

How should I test my Brittany?

The four variants above are rare enough in Brittanys that a breed-specific panel is not cost-effective for most owners. If you are breeding, a single-gene test for whichever condition runs in your lines is the pragmatic choice. Ask your breed-club health contact or your vet which variant, if any, has appeared in your pedigree. If you are buying a puppy, ask the breeder whether they have tested parents for the four conditions listed above. The honest answer is that most Brittany breeders do not test because the variants are so infrequent.

What should I feed a Brittany?

Brittanys were built for all-day hunting across fields and marshes. A pet Brittany eating maintenance kibble in a house is being fed for a job they are not doing. The breed’s lifespan median is 11.8 years (atlas data), which is solid for a sporting breed; the priority in feeding is sustaining the lean, athletic build the breed standard expects and protecting the joints that carry that frame through field work.

Large-breed puppy formulations are unnecessary. Brittanys weigh 30 to 40 pounds at adulthood. A standard puppy formula with a calcium-to-phosphorus ratio between 1.1:1 and 2:1 (NRC 2006) is appropriate. The growth rate is not extreme; overfeeding puppy-formulated calories is a more common mistake than underfeeding.

Activity level is the real caloric lever. A Brittany working four days a week needs more food than a Brittany sleeping on the couch. The breed’s sporting heritage means the metabolism is responsive to work. If your Brittany is active, feed to maintain visible ribs with a one-finger indent of fat over the ribcage. If your Brittany is a house dog, reduce portions accordingly to prevent creeping weight gain. The breed is prone to becoming overweight when overfed, and excess weight accelerates joint wear.

Joint support matters because Brittanys are high-impact athletes. The carrier frequency for degenerative myelopathy is low (0.14%, Donner 2023, n=349), but the breed’s field-work intensity means hip and elbow stress is real. Omega-3 supplementation from fish oil (EPA + DHA) has evidence for joint support in high-activity dogs. The NRC 2006 standard does not mandate it; breed-club experience supports it for working Brittanys. An adult maintenance kibble with joint supplementation, or a high-quality fish oil added to the regular diet, is a reasonable choice for a hunting dog.

Grain-free diets have no evidence benefit and possible cardiac risk. The FDA’s 2018 advisory flagged taurine-related dilated cardiomyopathy in dogs on certain grain-free, pulse-heavy formulations. Brittanys carry a TTN variant linked to DCM risk at 0.86% (Donner 2023, n=349), which is rare, but the breed is not immune to diet-associated cardiac disease. A grain-inclusive, taurine-adequate adult formula is the conservative default.

What we don’t know

The atlas cohort for Brittanys is small: 29 dogs. This is the honest limit of what the data can settle. The Donner 2023 screening (n=349) is larger and gives us solid carrier frequencies for the four detected variants, but 349 dogs is still a modest sample for a breed with thousands in the field.

We do not have Brittany-specific cancer prevalence data. The breed is not listed among the breeds with documented high cancer rates (like Goldens or Bernese Mountain Dogs), and no published cohort studies on Brittany mortality have been indexed. This does not mean cancer is not a concern; it means we have not systematically counted it in this breed.

Hip and elbow dysplasia are common in sporting breeds broadly. OFA does publish breed-specific hip and elbow statistics; check the OFA breed statistics page (ofa.org) for current Brittany figures. Ask your breeding prospect’s breeder for OFA or PennHIP scores on the parents; that is the actionable data point.

Frequently asked questions about Brittanys

Are Brittanys good for first-time dog owners? Brittanys are high-energy hunting dogs. They need daily exercise and do best with owners who understand the sporting-breed drive for activity and mental engagement. They are not good fits for sedentary households.

How long do Brittanys live? The atlas median lifespan for Brittanys is 11.8 years. Individual longevity varies based on genetics, health care, and lifestyle.

What is the most common health problem in Brittanys? The published data are sparse. Hip and elbow dysplasia are common in sporting breeds broadly, and joint wear from field work is the most frequent complaint among hunting Brittany owners. Ask your breeder for OFA scores on the parents.

Do Brittanys have genetic predispositions I should know about? Brittanys carry four documented Mendelian variants at low frequency (Donner 2023, n=349): a dilated cardiomyopathy risk factor (0.86%), cone-rod dystrophy (0.43%), degenerative myelopathy (0.14%), and C3 deficiency (0.14%). All are rare. Most Brittany owners will never encounter them.

Should I do a DNA test on my Brittany? If you are breeding, ask your breed-club health contact which variants, if any, run in your lines. If you are buying a puppy, ask the breeder whether parents have been tested. For pet owners, testing is not routine; the variants are too rare to justify screening cost.

What is the best diet for a Brittany? A grain-inclusive adult formula sized to maintain lean body condition is the standard. Activity level is the real dial: working Brittanys need more calories than house dogs. Omega-3 supplementation supports joints in high-activity dogs.

Are Brittanys prone to ear infections? Brittanys have pendant ears that can trap moisture, which is a general risk factor for otitis in dogs with drop ears. Regular ear cleaning after water exposure is routine preventive care. This is not genetic; it is breed anatomy.

What should I expect at the vet? Annual exams are standard. Request OFA or PennHIP hip screening before breeding. Ear checks are part of routine wellness. Heart murmurs should be evaluated; the TTN dilated cardiomyopathy risk variant is rare (0.86%), but the breed is not immune to cardiac disease.

The data behind this page

Where every number on this page came from.

This page draws on three primary data sources. Carrier frequencies for the Mendelian section come from Donner et al. 2023 (CC-BY-4.0). We grade these data at evidence Limited because the cohort is a direct-to-consumer ascertainment, which biases toward owners who chose to test their dogs. The panel also uses tag-SNP proxies for some variants rather than direct causal-variant assays. Limited is a study-design grade, not a quality grade: the Donner cohort is the largest open canine-genotype dataset in existence and we are grateful for it. We rate the confounding MEDIUM.

Population-genetic dimensions (heterozygosity, intra-breed PCA distance, nearest neighbors, trait-locus frequencies) come from CanVAS (Brundage 2026), harmonized through the Sniff Atlas. The exact release date and verification commit are pinned at the bottom of the page so a researcher can trace a number back to a specific snapshot. The disease-gene-variant graph comes from OMIA (Online Mendelian Inheritance in Animals; Nicholas, Tammen, and the Sydney Informatics Hub at the Sydney School of Veterinary Science, The University of Sydney; retrieved April 2026, DOI 10.25910/2AMR-PV70).

What this page does not yet have. Inheritance modes and per-disease penetrance evidence from Donner 2023 are now in the structured data for every variant the panel covers. Mondo, OMIM, Ensembl, and HGNC cross-references on gene pages remain pending, they arrive in December 2026 alongside the imputed 9.67M-variant CanVAS dataset via the OMIA SQL dump absorption. Until then, gene IDs carry NCBI Gene and OMIA phene URLs only; the wider human-homolog and disease-ontology cross-reference set fills in with that release.

How to cite this page. The computed dimensions on this page are derived from the open Sniff Atlas v1.0.1 (Gehring 2026, doi:10.5281/zenodo.20566358, CC-BY 4.0). Full citation formats including BibTeX, RIS, and CITATION.cff at sniff.world/cite.

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References
  1. 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. doi:10.1371/journal.pgen.1010651
  2. Brundage J, et al. (2026). CanVAS: a harmonized canine variant atlas. bioRxiv. doi:10.64898/2026.04.13.718238
  3. Nicholas, F.W., Tammen, I., & Sydney Informatics Hub. (2026). Online Mendelian Inheritance in Animals (OMIA) [dataset]. The University of Sydney. https://omia.org. doi:10.25910/2AMR-PV70 (retrieved April 2026).
Last updated
Sources: CanVAS (Brundage 2026) · Donner 2023 · OMIA