Scottish Fold Australia Original Cats

Scottish Fold (osteochondrodysplasia)

The Scottish Fold is one of the rarest purebred cats in Australia. The defining feature of the breed is its ears, which fold forward. The ear fold is not present at birth but develops at 3 to 4 weeks of age. The breed was developed in Scotland by mating a queen, affected by a natural mutation, to local farm cats and British Shorthairs. Preliminary genetic analyses suggested that the defining genetic abnormality, which causes the auricular cartilage to fold, is inherited as a simple autosomal dominant trait, and the foldear allele is designated Fd.


Although fold-eared cats were first bred in 1961 and registered in 1966, there was no mention of any skeletal
deformities until 1971 when progressive bony abnormalities and a crippling lameness were recognised.1,4 Inheritance studies were based on three different types of matings: skeletally normal Folds to skeletally normal Folds, affected Folds to skeletally normal Folds, and affected Folds to normal cats. Kittens with radiological lesions were only produced from Fold-to-Fold matings.

It was inferred that affected kittens are homozygous for the Fd gene: thus normal cats are fdfd, skeletally normal Scottish Folds are Fdfd, and Scottish Folds with osteodystrophy are FdFd. It has been suggested that breeding of fold-eared cats should be limited, and if used at all, they should be mated only to normal-eared cats.

The breed was banned in England in 1974, but continued to evolve in the USA where initial imports from the UK were outcrossed to numerous other breeds.1,4,5 Fold-to-Fold matings were avoided, so only about 50% of offspring had folded ears. Kittens with normal (prick, pert or upright) ears from this type of mating are known as ‘Scottish shorthairs’ in North America and Australia (synonym: Scottish Fold S/E [straight ear], Scottish Fold variant; J Sternbeck personal communication).

A limited description of SFOCD was given initially by Jackson,5 and more details for a single case were reported recently. The earliest and most consistent finding is a tail with an abnormally thick and inflexible base. The feet are short, and the underlying skeletal changes result in reduced ability to support weight, an abnormal gait and ultimately lameness. In affected homozygous individuals, joint lesions progress until the cats are unable to walk. Lesions are evident radiographically in kittens aged 7 weeks.5 The metaphyses of metatarsal and metacarpal bones are distorted with widened physes, and similar but less marked changes are evident in phalanges.

Results Six Scottish Fold cats (four castrated males, two spayed females) aged between 5 months and 6 years were presented for signs of skeletal disease including lameness, reluctance to jump, a stiff stilted gait, short misshapen distal limbs, swelling of plantar tarsometatarsal regions and short thick inflexible tails. A further four cases (one male, three females, 15 months to 11 years) were identified by radiographic screening of a cattery.

A diagnosis of osteochondrodysplasia was based on characteristic radiological findings including irregularity in the size and shape of tarsal, carpal, metatarsal and metacarpal bones, phalanges and caudal vertebrae, narrowed joint spaces, and progressive new bone formation around joints of distal limbs with diffuse osteopenia of adjacent bone. A plantar exostosis caudal to the calcaneus was present in advanced cases. In all nine cases where pedigree information was available, affected cats allegedly originated from the mating of a Scottish Fold to a cat with normal ears.

The severity and time of onset of physical signs, and rate of progression and extent of radiographic abnormalities, varied from case to case. Limited histological observations suggested the underlying problem may be an osteochondrodysplasia, related to inadequate cartilage maturation. Clinical signs were ameliorated by administration of pentosan subcutaneously in two of three cats in which it was trialled, and one of these also benefited from an oral glycosaminoglycan preparation.

Scottish Fold (osteochondrodysplasia)