British Shorthair Cat Breeding

The disease in question is hypertrophic cardiomyopathy (HCM, a thickening of the heart muscle). Thickened muscle makes the heart stiff, so it fills badly and moves less blood with each beat.

The numbers for this breed come from a Danish screening study of 329 British Shorthairs. Heart scans found HCM in 8.5% of them. The split by sex is the part to remember: 20.4% of males against 2.1% of females, an odds ratio of 7.89. The median age at diagnosis was 2.7 years, so the disease often arrives before a cat has finished breeding. The authors wrote that they "strongly recommend echocardiographic screening in this breed, especially cats used for breeding".[5]

Why the DNA test on sale does not apply here

The American College of Veterinary Internal Medicine writes the feline heart guidelines. Its 2020 consensus statement puts it plainly: "Genetic testing for the A31P and R820W MYBPC3 mutations in non-Maine Coon or non-Ragdoll cats is not recommended, because these 2 mutations are almost completely specific to Maine Coon and Ragdoll cats."[6]

A 2024 review went back over every feline heart variant on sale and landed in the same place. It sampled five breeds, British Short- and Longhair among them, and still advised routine testing only for A31P in the Maine Coon and R818W in the Ragdoll.[6] A separate panel of 395 British Shorthairs turned up neither variant.[2] The Ragdoll has a validated gene test of its own. This breed does not.

The scan schedule that does apply

Two honest notes on that table. An echocardiogram is an ultrasound scan of the heart, and it needs a vet who scans hearts regularly. PawPeds also wrote this schedule for the Maine Coon and says other breeds "might be better off with slightly different recommendations".[7] It is still the closest thing to a published schedule, and with a median diagnosis age of 2.7 years in this breed, yearly scanning to three fits well.[5]

Two good datasets disagree about this breed and birth, so here are both.

• Swedish insurance records, 1999 to 2006. The British Shorthair had the highest rate of dystocia (a birth that stalls and needs veterinary help) of any breed studied, at 2.5 times the rate of other pedigree cats. Purebred cats ran 67 cases per 10,000 cat-years against 7 for domestic shorthairs.[10]
• A 2024 questionnaire covering 853 litters. British Shorthair and Longhair caesareans came in at 13.1% against a 10.19% average. The same study found the breed differences were not statistically significant, and named the Cornish Rex as the most common caesarean breed.[11]
• What is statistically solid. Kitten deaths up to 12 weeks ran 18.1% against a 13.81% average, and that difference held at P<0.001.[11]

Nobody knows why. Resist the popular explanation that a cobby build or a broad head causes it. The Swedish authors ruled that out in writing: "No common factor among the high-risk breeds explained their high risk for dystocia."[10] Their own data points the other way. The flat-faced Persian and Exotic group ran at less than half the risk of other pedigree cats. In the 2024 survey the same group came in at 2.3%, which the authors called one of the lowest rates in the study. Korats and Neva Masquerades needed no caesareans at all, and the breed differences did not reach significance.[11]

The 2024 survey did turn up two findings worth printing, because both run against instinct. Queens over five years old had a lower risk of a difficult birth, and so did litters of more than six kittens. A longer pregnancy raised the risk.[11]

One thing a breeder can actually measure. A radiograph study compared 30 British Shorthair queens, half of whom had a difficult birth. The dystocia group had a significantly smaller pelvic inlet, 22.89 cm2 against 27.16 cm2.[12] A narrow pelvis shows on an X-ray before you ever mate her.

Those thresholds come from the Merck Veterinary Manual, which gives them for dogs and cats together. Its rectal temperature rule is stated for dogs only, so do not apply it to your queen.[12]

Why they ask you

The CFA lists the allowable outcross breeds for the Scottish Fold as the British Shorthair and the American Shorthair.[16] A large share of the world’s Folds carry British Shorthair blood by design, which is why the request lands in your inbox rather than someone else’s.

What the gene does

A dominant variant in the TRPV4 gene folds the ear by disrupting cartilage.[17] The same cartilage sits in every joint, so the effect does not stop at the ear. The condition that follows is osteochondrodysplasia, a disease of bone and cartilage.

Where the evidence genuinely conflicts

Registries take the strong line. The GCCF lists the Scottish Fold as ineligible for recognition, citing "known serious health problems (osteochondrodysplasia)". It tells owners to expect "a pet who suffers with joint pain in mid-old age".[16] FIFe goes further still. A cat with osteochondrodysplasia, or with such a cat in its ancestry, cannot be bred, registered, exhibited or advertised under its rules.[15]

Two careful studies read differently. The best-controlled one took X-rays and DNA from 22 cats. Ten had folded ears and all ten carried one copy of the variant. Twelve had straight ears and none carried it. Four reviewers scored the images without knowing which cat was which. They rated the folded cats worse on average, but the authors reported "much milder radiological signs than previously published".[17] A second team genotyped 17 cats and found the variant in every folded-ear cat. Even so, only 1 of the 12 folded cats showed clinical signs, and none had developed skeletal changes 18 months later.[22] Separately, Australian veterinary records covering 26 years and 1,131 Scottish Folds recorded a clinical diagnosis of osteochondrodysplasia in 12 cats, which is 1.1%. A further 64 cats, 5.7%, were logged as suspected.[17]

Here is the honest position. The variant sits in every folded-ear cat, so the risk is real and you cannot breed around it. How often it turns into a painful joint disease is genuinely disputed, and the best-controlled study to date found milder signs than the older literature. Anyone who tells you the question is settled, in either direction, is ahead of the evidence.

Ear shape will not tell you what a kitten carries

Researchers photographed 114 cats as they grew, then genotyped them. Seven moved from folded ears to straight ears while maturing, and all seven carried the variant.[18] Those cats looked like safe straight-eared cats and were not. Picking by appearance does not work, which is the whole argument for testing.

What the kittens can be registered as

This is the practical part for a British Shorthair owner. Straight-eared kittens from a Fold mating are Scottish Straights, not British Shorthairs. Neither the GCCF nor FIFe recognises the Scottish Fold, so in their territory those kittens can never be registered as British Shorthairs.[16][15] The GCCF is explicit about the Scottish Straight too. It would need DNA screening to prove the cats do not carry the Fold gene.[16]

Where it is now restricted

The Netherlands banned keeping folded-ear cats from 1 January 2026. Cats born and microchipped before that date are exempt.[19] That is a keeping ban rather than a breeding ban, and it is the furthest any national rule has gone so far.