Old English Sheepdog
Old English Sheepdogs have a cited life expectancy of 12.1 years (McMillan 2024 / VetCompass, n=1,210, 95% CI 11.9 to 12.5). The most carried tested variant is Exercise-Induced Collapse, in 13% of 423 Old English Sheepdogs tested (Donner 2023), then Acral Mutilation Syndrome (7.9%) and MDR1 (5.3%). 20 dogs stand behind the atlas figures here, so treat this page as an early sketch.
What genetic diseases do Old English Sheepdogs carry?
From a panel of 250 Mendelian-disease variants screened in 1,054,293 dogs (Donner et al. 2023), Old English Sheepdogs carry 8 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.
ABCB1what this gene does
ABCB1 is a gene that helps control how certain drugs are processed and cleared from a dog's body.
For your dog: If your dog is from a breed that carries this gene variant, ask your vet about medication sensitivities before giving any new drugs.
DNM1what this gene does
DNM1 is a gene that helps nerve cells communicate properly by managing how they send signals during muscle activity.
For your dog: If your dog belongs to one of the breeds known to carry this gene variant, it's worth discussing EIC with your vet, especially if your dog is very active or shows signs of weakness during exercise.
GDNFwhat this gene does
GDNF is a gene that helps support nerve cells, especially those involved in sensing pain and movement.
For your dog: If your dog is from a breed that can carry this gene change, it’s worth asking your vet about testing to understand any potential risks.
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.
NHEJ1what this gene does
NHEJ1 is a gene involved in repairing breaks in DNA, helping maintain the integrity of genetic information in cells.
For your dog: If your dog belongs to one of the breeds known to carry this gene variant, it's worth discussing testing with your vet to understand any potential eye health risks.
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.
What these results mean for a Old English Sheepdog
5.3% of Old English Sheepdogs in the Donner 2023 cohort carried it (n=423).
- MDR1 is a drug sensitivity, not a disease. A dog with the variant lacks a pump that keeps certain drugs out of the brain.
OMIA 001402-9615
“Multidrug resistance 1 is caused by a lack of P-glycoprotein drug transporter in the blood-brain barrier, which is characterized by neurotoxicity after administration of certain drugs.” OMIA 001402-9615
- Heartworm prevention is safe. At the dose on the label, every FDA-approved heartworm preventive sold in the United States is safe even for a dog with two copies of the variant.
Mealey 2008
“at the manufacturer's recommended dose, all FDA-approved heartworm preventive products marketed in the United States are safe, even for dogs with the ABCB1 mutant/mutant genotype” Mealey 2008
- The risk is dose. The same drug family (ivermectin, milbemycin and their relatives) causes toxicity in these dogs at doses other dogs tolerate, and some chemotherapy drugs are handled by the same pump.
Mealey 2008
“renders affected animals extremely susceptible to toxicosis induced by substrate drugs, such as the macrocyclic lactones at doses well below those tolerated by dogs with the wild-type ABCB1 gene” Mealey 2008
“Many drugs used in veterinary medicine are substrates for P-gp, including many chemotherapeutic agents and macrocyclic lactones” Mealey 2008
What to do
Keep heartworm prevention going at the label dose. Tell your veterinarian the dog's MDR1 status before any off-label parasite treatment or chemotherapy.
No test, or a mix
No test yet, or a mix that may have herding ancestry: label-dose heartworm prevention is safe either way. For any higher-dose decision, tell your veterinarian the dog is untested so it can be treated as a possible carrier.
Identified as Old English Sheepdog (VBO:0200969) in the Vertebrate Breed Ontology (Mullen et al. 2025, CC-BY 4.0) · registry IDs FCI 16 · iDog 174 · VeNom 14723.
For researchers Population genetics, disease models and every recorded condition Open the research detail for the Old English Sheepdog
In the atlas, the Old English Sheepdog clusters consistently as Old English Sheepdog (100% of the 20 dogs here). Genetic diversity is high (mean heterozygosity 0.3413), reflecting either a mixed-breed cluster or breeds with broad genetic backgrounds. Dogs here sit in a relatively sparse region of the atlas, fewer close neighbors than typical.
Ranks 83 of 107 on the bottleneck severity scale, in the upper quartile of genetic diversity. Mean heterozygosity is 0.341, notably high, indicates broad genetic background. Only 20 dogs of this breed in the atlas, modestly sampled.
What the atlas genotypes say about Old English Sheepdog
Computed from the 14,478 CanVAS dogs in the Atlas, on an imputed genotype backbone: 77,215 directly typed sites per dog, imputed to 9.67 million variants.
The confidence below counts dogs, not reads: it is the size of the sample, and it is separate from how the genotypes were measured.
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.
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.
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.
Old English Sheepdogs are a natural model for human disease
Because the same genes cause the same conditions across species, the inherited conditions documented in Old English Sheepdogs help researchers understand, and work toward treating, the human diseases they model. This is the dog advancing human medicine. The breed models the human disease; it does not have it, and this is not a prediction for your dog.
- hemophilia A, modeled by the breed's Haemophilia A via F8, the same underlying biology.
- hemophilia B, modeled by the breed's Haemophilia B via F9, the same underlying biology.
- OMIM:120080, modeled by the breed's Multidrug resistance 1, ABCB1-related via ABCB1, the same underlying biology.
- OMIM:612415, modeled by the breed's Ataxia, cerebellar, juvenile to adolescent, RAB24-related , the same underlying biology.
- OMIM:611290, modeled by the breed's Choroidal hypoplasia, NHEJ1-related , the same underlying biology.
- primary ciliary dyskinesia 14, modeled by the breed's Ciliary dyskinesia, primary, CCDC39-related , the same underlying biology.
Every condition recorded in the Old English Sheepdog
Beyond the testable carriers above, OMIA's literature catalogue records 12 genetic conditions in the Old English Sheepdog, 10 of which have a known human equivalent. This is the documented landscape across all Old English Sheepdogs ever studied, not a prediction for any one dog.
- Haemophilia A X-linked recessiveHuman equivalent: hemophilia A
- Haemophilia B X-linked recessiveHuman equivalent: hemophilia B
- Multidrug resistance 1, ABCB1-related Autosomal incomplete dominantHuman equivalent: OMIM:120080
- Ataxia, cerebellar, juvenile to adolescent, RAB24-related Autosomal recessiveHuman equivalent: OMIM:612415
- Choroidal hypoplasia, NHEJ1-related Autosomal recessiveHuman equivalent: OMIM:611290
- Ciliary dyskinesia, primary, CCDC39-related Autosomal recessiveHuman equivalent: primary ciliary dyskinesia 14
- Craniomandibular osteopathy, generic MultifactorialHuman equivalent: Caffey disease
- Hyperekplexia (Startle disease), SLC6A5-related Autosomal recessiveHuman equivalent: hyperekplexia 3
- Human equivalent: OMIM:155550
- Multiple ocular defects, COL11A1-related Autosomal dominantHuman equivalent: Stickler syndrome type 2
- Myopathy, mitochondrial Mitochondrial
- Osteochondritis dissecans Multifactorial
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 in the structured data for every variant the panel covers. Mondo, OMIM, Ensembl, and HGNC cross-references live on the gene and disease pages this page links to, rather than being repeated here. What is still absent from this breed page is anything not in the cited panel, and each such gap carries its cause where it appears.
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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- 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
- Brundage DM (2026). CanVAS: A Harmonized and Imputed Canine Variant Atlas. bioRxiv. doi:10.64898/2026.04.13.718238
- 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).