Canine Mendelian disease record

Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY)

Q: How well studied is Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY) in dogs?

OMIA curates 83 peer-reviewed references for Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY). The full, linked citation list is on this page.

Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY). Autosomal dominant. Observed in 113 of 266 breeds tested in the Sniff Atlas, with measured at-risk genotype frequencies drawn from 241,530 dogs (Donner 2023). Because this is a dominant trait, a single copy places a dog at risk rather than making it a silent carrier; whether the phenotype appears still depends on penetrance, modifier genes, and environment.

Dominant trait. A single copy of this variant places a dog at risk; it does not make the dog a silent carrier. The breed frequencies below are therefore at-risk frequencies, and penetrance plus modifier genes determine whether the phenotype actually appears.

OMIA identifier: OMIA:000157-9615
Inheritance: Autosomal dominant
Source dataset: Sniff Atlas v1.0.1 / DOI

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

"Two FGF4 retrogenes (FGF4L1 on chromosome 18 and FGF4L2 on chromosome 12) have been identified to cause dwarfism across many dog breeds. Some breeds are nearly homozygous for both retrogenes (e.g., Dachshunds) and others are homozygous for just one (e.g., Beagles and Scottish Terriers)" (Bannasch et al., 2022)

Clinical features

Batcher et al. (2019) concluded that "The FGF4 retrogene on CFA12 acts in a dominant manner to decrease the age of onset and increase the overall risk of disc disease in dogs. Other modifiers of risk may be present within certain breeds, including the FGF4 retrogene on CFA18." In Nova Scotia Duck Tolling Retrievers, Murphy et al. (2019) concluded that dogs with the retrogene variant present with clinical signs "consistent with premature chondroid degeneration of the intervertebral disc and suggest that the presence of the CFA12 FGF4 retrogene is sufficient to cause the chondrodystrophic phenotype."

Molecular genetics

Brown et al. (2017) reported that an FGF4 retrogene insertion in chromosome CFA12 (12: g.33710178_33710179insMF040221.1; CanFam3) is "responsible for type I IVDD . . . across dog breeds . . . the insertion on CFA12 is 3,209 bp long (GenBank accession no. MF040221) and includes parental FGF4 cDNA (i.e., FGF4 exons spliced without introns) . . . . The insert also contains a majority of the predicted 5′-untranslated region (UTR), which includes the transcription start site (TSS) as only PCR primers FGF4_TSS.F1 and FGF4.R1 yielded a product in RT-PCR using cDNA from neonatal beagle IVD . . . . The insertion location is intergenic between the 3′-UTR of OGFRL1 ∼9.5 kb on the proximal side and ∼350 kb to the RIMS1 gene on the distal side." Because the retrogene is not included in NCBI's Gene database, the table below lists the normal FGF4 gene.

Inheritance

Brown et al. (2017): "IVDD-affected NSDTRs were also all either homozygous or heterozygous for the CFA12 FGF4 insertion. This supports the idea that while the CFA12 FGF4 insertion is semidominant with respect to height, it is dominant for altered IVDs" Bannasch et al. (2022): "Using individual measurements of height at the shoulder, back length, head width, thorax depth and width, and thoracic limb measurements, we evaluated the combined effects of FGF4 retrogenes [FGF4L1 and FGF4L2] within" two breeds that segregate both retrogenes, namely Alpine Dachsbracke and the Schweizer Niederlaufhund. They found that "both retrogenes had significant effects reducing height at the shoulders and antebrachial length, with FGF4L1 having a much greater effect than FGF4L2. FGF4L1 alone influenced the degree of carpal valgus and FGF4L2 alone increased head width. Neither retrogene had an effect on thorax width or depth." From a detailed analysis of 569 surgical cases of IVDD, Batcher et al. (2019) concluded that "The FGF4 retrogene on CFA12 acts in a dominant manner to decrease the age of onset and increase the overall risk of disc disease in dogs. Other modifiers of risk may be present within certain breeds, including the FGF4 retrogene on CFA18."

History

As summarised by Brown et al. (2017): "Hansen [1951, 1952] described the two different types of canine IVD prolapse as type I and type II. Type I occurs exclusively in chondrodystrophic breeds [e.g. "basset hound, Pembroke Welsh corgi, and dachshund"] and is characterized by premature degeneration of all discs in young dogs. In contrast, type II occurs in older dogs and is usually limited to a single disc with only partial protrusion."

Control

Bruun et al. (2020) concluded that "Our results show that the FGF4 retrogene insertion on CFA12 is not a valid risk indicator on its own. Relying on the DNA test will have an irreversible effect on the Dachshund breed excluding almost all dogs from breeding. Thus, using calcification status remains the most reliable breeding scheme for disc herniation in Dachshunds." Bannash et al. (2022) recommend that "Selectively breeding dogs with FGF4L1 and without FGF4L2 would likely lead to a reduction in the FGF4L2-related risk of intervertebral disc herniation while maintaining the reduction in leg length resulting from FGF4L1."

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:000157-9615, 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. Showing 6 of 83.

Cervical disc disease in whippets: Results of an online survey involving Italian owners and breeders. · Res Vet Sci · 2026 · PMID 41619577
Erratum for "The relationship between radiographic disc calcification score and FGF4L2 genotype in dachshunds". · J Vet Intern Med · 2025 · PMID 40079733
Objective evaluation of gait abnormalities in dogs with a thoracolumbar myelopathy using a pressure-sensing walkway. · Front Vet Sci · 2025 · PMID 41613771
Chronic sequelae and owner burdens are common following canine intervertebral disc disease. · Vet Rec · 2025 · PMID 40207502
Paraspinal muscle fibres demonstrate a complex relationship between contractile variability and function in canines with spinal degeneration. · Sci Rep · 2025 · PMID 41330973
Prevalence and breed predisposition for spinal diseases in pugs and French bulldogs. · Vet Rec · 2025 · PMID 39853677

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 Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY) and see the odds for their puppies. Single dominant variant, exact Mendelian math.

Parent A

Parent B

NDAffected

NNUnaffected

Unaffected50%

Affected50%

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 Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY) looks like in your dog's breed.

At-risk frequency by breed

Top 25 well-sampled breeds (n ≥ 50)

Maximum at-risk 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%50%100%

Dachshund Miniature Longhaired99.5% · n 213

99.5%n 213

Cavalier King Charles Spaniel99.0% · n 2,232

99.0%n 2,232

Cocker Spaniel98.5% · n 1,870

98.5%n 1,870

Dachshund Miniature Shorthaired95.1% · n 583

95.1%n 583

English Cocker Spaniel94.0% · n 579

94.0%n 579

Cardigan Welsh Corgi93.5% · n 124

93.5%n 124

Beagle93.5% · n 5,245

93.5%n 5,245

French Bulldog87.9% · n 13,062

87.9%n 13,062

Poodle Toy81.9% · n 94

81.9%n 94

Pembroke Welsh Corgi80.4% · n 4,351

80.4%n 4,351

Spanish Water Dog71.5% · n 93

71.5%n 93

Papillon68.3% · n 197

68.3%n 197

Basset Hound67.5% · n 982

67.5%n 982

Poodle Miniature63.4% · n 3,544

63.4%n 3,544

Boykin Spaniel59.1% · n 154

59.1%n 154

n = 33,323 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 Chondrodystrophy and Intervertebral Disc Disease Risk (CDDY) is measured; phenotype outcome depends on penetrance and modifiers.

▸ Full table with Wilson 95% confidence intervals

Breed	At-risk frequency	Wilson 95% CI	n tested
Dachshund Miniature Longhaired	99.5%	[97.4%, 99.9%]	213
Cavalier King Charles Spaniel	99.0%	[98.5%, 99.3%]	2,232
Cocker Spaniel	98.5%	[97.9%, 99.0%]	1,870
Dachshund Miniature Shorthaired	95.1%	[93.0%, 96.6%]	583
English Cocker Spaniel	94.0%	[91.7%, 95.6%]	579
Cardigan Welsh Corgi	93.5%	[87.8%, 96.7%]	124
Beagle	93.5%	[92.7%, 94.1%]	5,245
French Bulldog	87.9%	[87.3%, 88.5%]	13,062
Poodle Toy	81.9%	[72.9%, 88.4%]	94
Pembroke Welsh Corgi	80.4%	[79.2%, 81.5%]	4,351
Spanish Water Dog	71.5%	[61.6%, 79.7%]	93
Papillon	68.3%	[61.5%, 74.4%]	197
Basset Hound	67.5%	[64.5%, 70.4%]	982
Poodle Miniature	63.4%	[61.8%, 65.0%]	3,544
Boykin Spaniel	59.1%	[51.2%, 66.5%]	154
Kooikerhondje	56.1%	[49.1%, 62.8%]	197
Pekingese	41.6%	[35.5%, 47.9%]	238
Chinese Crested	31.8%	[25.8%, 38.6%]	201
Nova Scotia Duck Tolling Retriever	29.4%	[19.6%, 41.5%]	63
Coton De Tulear	28.4%	[20.6%, 37.7%]	104
Chinook	24.4%	[16.3%, 34.8%]	80
English Springer Spaniel	23.6%	[20.7%, 26.7%]	749
Danish Swedish Farmdog	20.8%	[12.5%, 32.7%]	60
Bichon Frise	20.8%	[18.5%, 23.4%]	1,059
Biewer Terrier	20.1%	[15.0%, 26.5%]	184

Top 25 of 80 well-sampled breeds with at least one observed carrier shown.

▸ Also observed in 33 small-sample breeds (n < 50)

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

Breed	Estimate	Wilson 95% CI	n tested
Bavarian Mountain Hound	100.0%	[67.6%, 100.0%]	8
Clumber Spaniel	100.0%	[75.7%, 100.0%]	12
Continental Toy Spaniel	100.0%	[67.6%, 100.0%]	8
Dachshund Longhaired	100.0%	[20.7%, 100.0%]	1
Dachshund Shorthaired	100.0%	[61.0%, 100.0%]	6
Dachshund Wirehaired	100.0%	[51.0%, 100.0%]	4
Dandie Dinmont Terrier	100.0%	[20.7%, 100.0%]	1
English Toy Spaniel	100.0%	[34.2%, 100.0%]	2
Field Spaniel	100.0%	[87.9%, 100.0%]	28
Poodle Medium	100.0%	[20.7%, 100.0%]	1
Skye Terrier	100.0%	[51.0%, 100.0%]	4
Sussex Spaniel	100.0%	[43.8%, 100.0%]	3
Welsh Springer Spaniel	91.7%	[64.6%, 98.5%]	12
American Water Spaniel	83.3%	[43.6%, 97.0%]	6
Polish Lowland Sheepdog	83.3%	[31.0%, 98.2%]	3
Entlebucher Mountain Dog	77.3%	[47.8%, 92.7%]	11
Sealyham Terrier	75.0%	[30.1%, 95.4%]	4
Stabyhoun	66.7%	[47.8%, 81.4%]	27
Alpine Dachsbracke	50.0%	[5.5%, 94.5%]	1
Schapendoes	47.8%	[33.9%, 62.0%]	45
Drever	25.0%	[4.6%, 69.9%]	4
Lowchen	25.0%	[4.6%, 69.9%]	4
Puli	25.0%	[8.9%, 53.2%]	12
Bedlington Terrier	22.7%	[7.3%, 52.2%]	11
German Spitz	16.7%	[1.8%, 69.0%]	3
Pyrenean Shepherd	15.5%	[6.5%, 32.6%]	29
Tibetan Spaniel	11.5%	[4.8%, 25.2%]	39
Bolognese	10.0%	[1.1%, 53.7%]	5
Russian Toy	10.0%	[1.1%, 53.7%]	5
Russian Tsvetnaya Bolonka	10.0%	[2.3%, 34.0%]	15
Munsterlander Small	6.7%	[1.2%, 29.8%]	15
German Hunting Terrier	3.8%	[0.4%, 28.3%]	13
Silky Terrier	1.8%	[0.2%, 15.0%]	28

153 additional breeds in the Donner 2023 cohort were tested but showed no at-risk genotypes.

Scope of this record

This record carries the breed-level carrier 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 v1.0.1. 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 at-risk 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 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:000157-9615.
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.

Sniff Atlas v1.0.1, the source dataset for these frequencies.
Browse breeds, per-breed Mendelian profiles, including this disease in context.
OMIA entry OMIA:000157-9615, authoritative clinical reference.
About OMIA, the catalogue this record comes from, and how Sniff uses it.

Last updated June 20, 2026

Sources: Sniff Atlas v1.0.1 · OMIA OMIA:000157-9615 · Donner et al. 2023