Are All Scottish Folds Affected? SFOCD and TRPV4 Studies, 1999–2025

SamSome say every Scottish Fold lives in pain, others say ours will be fine. Who’s right?

Elena MarshBoth camps can cite a study. A 1999 University of Sydney series and a 2023 review of Australian clinic records reached very different conclusions, for reasons worth knowing.

SamOur Fold is three and still jumps onto the bookcase. Does that mean we dodged it?

Elena MarshNot necessarily. Cats hide joint trouble well; a 2007 Seoul National University report noted owners often miss early signs as the cat shifts weight to its other legs.

SamWould a DNA test settle it for our cat, or just add one more number to worry about?

Elena MarshIt answers one question: how many copies of the TRPV4 variant your cat has. The 2016 study that found the variant explains why that matters; an X-ray and exam answer the rest.

Bottom line: The folded ear of the Scottish Fold and the bone and cartilage disease called Scottish Fold osteochondrodysplasia (SFOCD) come from the same single-letter change in the TRPV4 gene, identified in a 2016 study by teams in the US and Australia. It is dominant, not recessive: one copy produces the fold and can produce skeletal changes, and two copies are consistently associated with severe disease. Whether “all Folds are affected” depends on what you count. A small Sydney case series in 1999 found every fold-eared cat it examined affected to some degree; a 2021 blinded X-ray study found one-copy cats much milder than earlier reports; and a 2023 review of 1,131 Scottish Folds in Australian clinic records found a recorded clinical diagnosis in 1.1%, a figure its authors say may be an undercount. A DNA test tells you the copy number, not how your cat will fare; diagnosis is made by a veterinarian with a physical exam and X-rays, and there is no cure, only pain management.

One letter, two traits: the 2016 TRPV4 discovery

The folded ear was long known to be a dominant trait, and some fold-eared cats were known to develop thick, stiff tails and misshapen paws. The gene arrived in 2016, when Barbara Gandolfi, Bianca Haase and co-authors at the University of Missouri, the Murdoch Children’s Research Institute, the University of Melbourne, RMIT and the University of Sydney published it in Osteoarthritis and Cartilage.

The team genotyped 44 Scottish Folds and 54 control cats on a feline DNA array, ran a case-control genome-wide association study, and found a region on cat chromosome D3. Inside it sat TRPV4, a gene for a calcium-permeable ion channel involved in how cartilage and bone cells develop. Sequencing turned up a single substitution, c.1024G>T, which swaps one amino acid in the channel protein (p.V342F). The same change was absent from 648 unaffected cats of several breeds and unknown ear type.

What makes this disease unusual is that the variant does two jobs at once. It produces the ear shape that defines the breed, and it is the cause of the skeletal disorder. The abstract describes “a dominantly inherited osteochondrodysplasia involving malformation in the distal forelimbs, distal hindlimbs and tail, and progressive joint destruction.” In later genotyping studies, every fold-eared cat tested carried it: all 10 in a 2021 US study and all 85 phenotype-checked Folds in a 2022 panel survey.

Cell experiments in the same paper showed the change is not a simple loss of function: the altered channel reached the cell surface less often and gave a weaker maximum response, yet had higher background activity and reacted more strongly to hypotonic (low-salt) conditions. How that becomes a folded ear and malformed joints is still being worked out.

The variant also turns up outside the pedigree breed. A 2022 PLoS Genetics survey of more than 11,000 cats tested on a commercial panel reported it in 0.4% of 10,945 cats overall, in 72 of 76 Scottish Fold Shorthairs and 13 of 14 Scottish Fold Longhairs (also sold as Highland Folds), and in 6 of 617 non-pedigree cats, all six of them Fold mixes. Japanese screening has since found it in some Munchkins, Minuets, American Curls and one Norwegian Forest Cat, likely traces of past crossbreeding. Folds carry almost all of it, but not all.

Sydney, 1999: the study behind “every Fold is affected”

The claim that all fold-eared cats are affected traces back mainly to a 1999 paper in the Australian Veterinary Journal by Richard Malik and colleagues at the University of Sydney. They combined records from five veterinary practices with X-ray screening at one cattery.

The six clinical cases, four neutered males and two spayed females aged five months to six years, showed a recognisable picture: lameness, reluctance to jump, a stiff, stilted gait, short and misshapen lower limbs, swelling at the back of the hind feet, and short, thick tails that would not bend. Cattery screening found four more, aged 15 months to 11 years. X-rays showed irregular bones in the wrists, ankles, paws and tail, narrowed joint spaces and new bone building up around the lower limb joints; advanced cases had a bony mass on the sole behind the heel.

All nine cats with pedigree information were said to come from fold-to-straight matings, the pairing used to avoid two-copy kittens. Onset, severity and progression varied widely. The authors’ conclusion became the most quoted line on the subject: “As all Scottish Fold cats suffered from osteochondrodysplasia of some degree, the best solution would be to avoid using fold-eared cats for breeding and instead use Scottish shorthairs.”

That sentence describes the cats in the study, a group assembled partly because they had come to a vet with problems. A 2008 family study from Tochigi, Japan, pointed the same way: every fold-eared cat in a three-generation pedigree showed some lower-limb change, though mildly affected ones were clinically normal. But a case series cannot tell you what share of all Folds will ever show signs.

SamSo the 1999 paper wasn’t wrong, it just looked at cats that were already struggling?

Elena MarshThat’s the fair reading. The Sydney group described ten affected cats in useful detail, but a 2021 study listed selection bias and missing controls as weaknesses of early work.

Blind readers and 22 cats: the 2021 radiograph survey

By 2021 the variant could be tested directly. A study in Human Genetics by Chris Rorden and colleagues had authors from the Cat Fanciers’ Association, the Orthopedic Foundation for Animals, North Carolina State University, the testing company Paw Print Genetics, and Richard Malik from the 1999 paper.

They named the weaknesses of earlier work: selection bias, no controls, readers who knew which cats had folded ears, and unknown genotypes. Their design tried to fix each one. They collected DNA and side-view X-rays from 22 Scottish Folds, 10 with folded ears and 12 with straight ears. Four reviewers scored the images without being told the ear type.

Genotyping lined up neatly with ears. All 10 fold-eared cats had one copy of the variant, and all 12 straight-eared cats had none. No two-copy cats were included; the paper notes that earlier work had already shown homozygous cats have severe radiographic disease.

The result was nuanced. Each reviewer, on average, gave the fold-eared cats numerically worse severity scores than the straight-eared ones. But the images of the one-copy cats showed much milder changes than previously published reports had suggested. The authors did not declare the breed safe; they said the findings add information to a complicated debate about whether cats should be bred for the folded ear.

Twenty-two cats is a small sample, and an X-ray score is not the same as pain. Still, the study makes it hard to claim every one-copy Fold resembles the worst older cases, and equally hard to say one-copy cats show nothing.

1,131 cats in clinic records: what VetCompass Australia counted

Clinic records come closer to a population figure. In 2023 Brandon Velie, Bianca Haase and colleagues searched VetCompass Australia, a research database of electronic records from participating practices, for every Scottish Fold and Scottish Shorthair seen in New South Wales, Queensland and Victoria between 1992 and 2018. That produced 1,131 Scottish Folds and 117 Scottish Shorthairs, covering 34,926 consultation records.

Twelve Folds had a recorded clinical diagnosis of SFOCD: 1.1%. Another 64 Folds (plus 5 Shorthairs) had notes suggesting the disease without a firm diagnosis; those suspected Folds made up 5.7% of the 1,131, reported as a separate category rather than added to the 1.1%. The diagnosed cats were young, with a median age of 20 months, and 11 of the 12 were diagnosed between 3 and 29 months. The suspected cases were much older, with a median of 98 months.

The authors call this prevalence relatively low but explain why the true figure is probably higher: inconsistent records, cats moving between clinics, and practices outside VetCompass. Genotypes were unknown, so one-copy and two-copy cats cannot be separated. One author (Haase) disclosed a link to a genetic testing laboratory.

Because diagnoses clustered before 30 months, the paper suggests removing cats with signs by that age from breeding. That is a breeding point, not reassurance for an individual owner.

SamSo can I tell people only about one in a hundred Folds gets sick?

Elena MarshNo. The 1.1% counts recorded diagnoses in Australian clinic notes, and the VetCompass authors say it may undercount. It’s a floor for that sample, not your cat’s risk.

Why the numbers refuse to agree

Side by side, the four English-language studies at the centre of this debate are measuring different things in different groups of cats.

Three distinctions explain most of the gap. First, who gets into the study: a case series starts with sick cats, while a records review starts with every cat seen. Second, what counts as “affected”: a narrowed joint space on an X-ray, a limp an owner notices, and a diagnosis a vet writes down are three different thresholds. Third, copy number: older reports mixed one-copy and two-copy cats, often without knowing which was which, and two-copy cats are consistently the severe ones.

Age adds a fourth layer. A 2023 study from the University of Turin of 17 cats in two Italian catteries found the variant in one copy in all 12 Folds, and only one of them, a 6.5-year-old, had both clinical signs and X-ray changes (only 5 of the 12 Folds were X-rayed). The cats averaged 2.3 years old, and the authors concluded the variant is probably not the only cause or risk factor for SFOCD.

Breeding practice is shifting the mix too. A 2026 Japanese survey of 8,610 cats from breeders and pet shops reported that two-copy Scottish Folds fell from 14.2% of those born in 2017 to 1.9% of those born in 2024, while the one-copy share did not fall. That should reduce the most severe cases, but leaves the one-copy question open.

What can be said with confidence: two copies carry a high risk of severe disease; one copy carries a real but highly variable risk, from no visible problem to lameness; and no one has measured the lifetime rate of clinical disease in one-copy cats.

What a TRPV4 test can and can’t tell you

A cheek-swab test reports one of three results: no copies (the known SFOCD variant is absent), one copy (the usual finding in a fold-eared cat, with variable risk), or two copies (high risk of severe, early disease).

It cannot predict severity for a one-copy cat or rule out other causes of joint pain; ordinary arthritis is common in older cats of every breed. A result is risk information, not a diagnosis.

The test is most useful where the eye fails. In a 2026 Japanese study of insured Scottish Folds followed by photographs, 7 of 55 one-copy cats had kitten ears that later stood up. Crosses can even hide the fold: a 2020 Tokyo report described two cats registered as a Munchkin and an American Curl that carried two copies (the Curl cross’s ears did not look folded; the Munchkin cross’s did) and developed severe hind-limb bony growths, and the 2022 panel survey recorded a Fold–Highlander kitten whose ears curled back rather than folding forward but whose tail was short and stiff. A straight-eared cat with Fold ancestry is not proven variant-free until it is tested.

In the US, the variant is included in Wisdom Panel Complete for Cats, listed as “Earfold and Osteochondrodysplasia (Discovered in the Scottish Fold)”, at $90.99 in an October sale (regular $129.99; tax not stated; checked 8 October 2026) (results stated within three weeks). Wisdom Panel reports the variant in 1 in 140 cats in its own testing, which describes its customers’ cats, not cats in general. In the UK the same kit was listed at £94.99. For this result alone, LABOKLIN offers a single test (service 8349, sequencing, one to two weeks after the sample arrives), listed at £48.00 including VAT on LABOKLIN UK’s cat price list. Genomia in the Czech Republic lists its SFOCD test at $56.00 excluding VAT. We could not confirm an Australian-priced test for this variant, so Australian owners should ask their vet which laboratory they use.

SamIf my straight-eared Scottish Shorthair tests clear, is that the end of the worry?

Elena MarshFor this variant, yes. But the Turin study concluded TRPV4 is probably not the only factor in SFOCD, and older cats of any breed get arthritis, so new stiffness still needs a vet.

Registries, rules and the welfare case in the UK, US and Australia

In the US, the Cat Fanciers’ Association gave the shorthaired Fold championship status in 1978 and the longhair in 1992, and in 2022 accepted straight-eared cats as well, so the breed now shows in four divisions. CFA’s registration rules state that, effective 1 May 2022, “no folded ear to folded ear matings are permitted”. Its breed standard also disqualifies a tail “lacking in flexibility due to abnormally thick vertebrae” and says there must be “no hint of thickness or lack of mobility in the cat due to short, coarse legs”, which lists as faults the very signs that SFOCD produces.

In the UK, the Governing Council of the Cat Fancy lists the Scottish Fold among breeds that are ineligible for recognition because of “known serious health problems (osteochondrodysplasia)”, and suggests the British Shorthair as an alternative. A 2025 Animal Welfare review by authors from Cats Protection and the Royal Veterinary College used the Fold as a clear example of conformation-related welfare concern and called for “an immediate and complete cessation of breeding of cats with folded ears”. It notes the UK’s three registries are GCCF, Felis Britannica (FIFe) and TICA.

The British Veterinary Association’s extreme conformation policy names Scottish Fold cats and states that animals with harmful extremes of conformation should not be used for breeding. International Cat Care, which has campaigned with the BVA, calls continued breeding of the variant unethical, and the rescue charity Battersea says it examines every Scottish Fold that comes into its care.

English law is narrower than many assume. The Animal Welfare (Licensing of Activities Involving Animals) (England) Regulations 2018 bar keeping an animal for breeding when its genotype or phenotype could harm its offspring, but that rule sits in the schedule on breeding dogs; there is no cat-breeding licence. Cats are covered by the licence for selling animals as pets, under which an animal with a condition likely to affect its quality of life must not be offered for sale, and cats under eight weeks must not be sold.

In Australia, where both the 1999 and 2023 studies were carried out, the RSPCA Australia knowledgebase describes the condition as progressive, with no cure, and notes changes can be seen on X-rays from seven weeks of age. We did not find a state law specific to fold-eared cats, and none is claimed here.

Signs to watch for, and the path from GP vet to orthopaedic referral

Reported signs centre on the lower legs and tail: reluctance to jump, a stiff or stilted gait, lameness, thickened paws and ankles, and a tail that is short, thick or will not bend. International Cat Care adds the quieter clues of pain in cats, such as hiding, eating less, grooming less, not curling up to sleep, and toileting outside the litter tray when stepping in hurts.

Diagnosis rests with a veterinarian: a physical and orthopaedic examination plus X-rays of the limbs and tail, with any DNA result as background. If surgery or radiotherapy is being considered, the general-practice vet refers the cat on. In the UK, referral centres such as the Royal Veterinary College’s small animal referral service take cases through the vet’s referral form. In the US, the American College of Veterinary Surgeons keeps a public search of board-certified surgeons, and in Australia networks such as AREN list orthopaedic surgery among their referral services. Take earlier X-rays and any DNA report with you.

SamOur vet says the X-rays show early changes. Is there anything that actually fixes this?

Elena MarshNothing reverses it. A 2020 Azabu University case report put it plainly: no single treatment works for all affected cats. What exists is pain management and a few case reports.

What treatment reports describe, and how insurers handle an inherited condition

No treatment trials exist, only single-cat and small case reports showing what happened in those cats, not what will happen in yours. Doses are for the treating veterinarian and are not given here.

Surgery has been reported for cats crippled by bony growths. A 1995 University of California, Davis report described a cat whose hind-limb lameness from bony masses at the ankles resolved after staged removal of the growths on both sides and fusion of the ankle joints; 48 weeks after the second operation the lameness had not returned, although X-ray changes in the toe joints progressed.

Radiation has been used to relieve pain. A 2004 University of Zurich report described a cat whose signs eased within weeks of palliative radiotherapy. A 2015 report of three cats in Japan found pain controlled for 59 to 72 months, while the bone disease kept progressing slowly. A 2019 University of Missouri case, an eight-year-old neutered male, had external beam radiation to a mass on the hind foot that stabilised it for 14 months; after it progressed, a bone-seeking radioactive drug (samarium-153) was given three times about six months apart, and the cat’s overall mobility improved.

Medical management is what most affected cats receive. The 1999 Sydney paper reported improvement in two of three cats given injections of pentosan, and later reports mention glucosamine-type supplements, glycosaminoglycans and anti-inflammatory drugs; a 2015 Japanese report judged the effect of medical treatment limited and long-term medication impractical in such young cats. At home, International Cat Care suggests low beds or steps, raised bowls, a low-sided litter tray, ramps to favourite spots and rugs on slippery floors.

Because SFOCD is inherited and often diagnosed before 30 months, timing matters more than the brand of policy: the insurers we checked in all three markets cover hereditary conditions only if not present before cover began.

In the UK, Agria’s pre-existing conditions page says hereditary conditions are treated as pre-existing if the pet showed clinical signs or was diagnosed before cover started, and that symptoms can count even without a formal diagnosis; its cat policies are advertised with up to £20,000 a year towards vet bills. In the US, Embrace lists “hereditary and congenital conditions … when not pre-existing at the time of enrollment” in its coverage. In Australia, Pet Insurance Australia’s cat plan lists hereditary and congenital conditions as covered in all plans, excludes certain pre-existing conditions, and offers 70%, 80% or 90% back with an excess of $0 to $600 (AUD) and annual limits from $15,000.

So insure a kitten before any stiffness or tail change reaches its records. Whether a positive DNA result alone counts as pre-existing is not addressed on the pages we read; ask the insurer in writing before you buy.

Frequently asked questions

Q. Are all Scottish Folds affected by osteochondrodysplasia?
Fold-eared cats in the published studies almost all carry at least one copy of the TRPV4 variant, and two-copy cats are consistently severely affected. For one-copy cats, the answer depends on what is measured: a 1999 Sydney case series found all examined fold cats affected to some degree, while later blinded X-ray and clinic-record studies found milder or less often recorded disease. There is no reliable lifetime figure for one-copy cats.

Q. Is the 1.1% figure from Australia the chance my Fold will get sick?
No. It is the share of 1,131 Scottish Folds with a recorded clinical diagnosis in Australian clinic records, which the study’s authors say may be an undercount. A further 5.7% of the Folds had suspected but unconfirmed cases, counted separately.

Q. Is a one-copy Scottish Fold healthy?
Not necessarily. One copy can produce skeletal changes ranging from none visible to lameness. A 2021 blinded study still found one-copy cats scored worse on X-rays than straight-eared cats, though milder than earlier reports.

Q. Can a DNA test diagnose SFOCD?
No. It tells you whether your cat has zero, one or two copies of the known variant. Diagnosis is made by a veterinarian through examination and X-rays. If your cat is stiff or reluctant to jump, see your vet whatever the test says.

Q. Is a straight-eared Scottish Fold or Scottish Shorthair free of the variant?
Usually, but ear shape is not proof. A Japanese study found some one-copy kittens whose ears later stood up, and crosses with breeds such as the Highlander or American Curl can mask the fold. A DNA test is the way to check.

Q. Can SFOCD be cured?
No. Reports describe pain relief, surgery for bony growths and radiotherapy in individual cats, but none reverses the disease. Pain management is your veterinarian’s decision.

Q. Is it legal to breed Scottish Folds in the UK?
The 2018 English licensing regulations have no cat-breeding licence, and their genotype/phenotype breeding rule applies to dogs. Licensed sellers must not offer an animal with a condition likely to affect its quality of life. GCCF does not recognise the breed, and the BVA and International Cat Care oppose breeding fold-eared cats.

References

• Gandolfi B, Alamri S, Darby WG, Adhikari B, Lattimer JC, Malik R, Wade CM, Lyons LA, Cheng J, Bateman JF, McIntyre P, Lamandé SR, Haase B (2016). A dominant TRPV4 variant underlies osteochondrodysplasia in Scottish fold cats. Osteoarthritis and Cartilage 24(8):1441-1450.
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• Wisdom Panel (Mars Petcare). Earfold and Osteochondrodysplasia (Discovered in the Scottish Fold) — cat health condition page. Retrieved 2026-10-08.
• LABOKLIN. Osteochondrodysplasia (OCD) — Service ID 8349 (cat). Retrieved 2026-10-08.
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About the author

Elena Marsh

Editor & writer (not a veterinarian)

A writer with a molecular-biology background and a lifelong dog and cat owner. Not a veterinarian — she translates peer-reviewed genetics research and primary data into plain language, always as information rather than diagnosis.