The Scottish Fold breed of cat is a very popular pet in the USA, due to its affectionate and gentle nature and distinctive appearance. These cats have flattened ears that fold forward and downward, sitting like a cap and giving the quaint look of an owl. This ear fold is the result of a natural genetic mutation first observed in a farm kitten in Scotland in 1961. The tightly folded ears do not appear to be any more prone to infections than those of cats with upright ears. However, this unique ear shape is caused by an underlying defect in the formation of cartilage, which would normally retain the ears in a normal shape.
This inherited cartilage defect (also known as Scottish Fold disease, or Osteochondrodysplasia) causes other deformities throughout the body and is a dominant trait, meaning all kittens in the litter will be affected. The disease is evident on x-rays of cats from as young as 7 weeks of age. Serious abnormalities in joints and bone growth lead to arthritis (painful, swollen joints), short, abnormally thick and inflexible tails, spinal abnormalities and short, stiff legs. The welfare impacts are severe in terms of pain and inability to perform natural behaviours, as these cats can be lame, walk with an abnormal gait, can be reluctant to engage in normal movements such as walking or jumping, and can even become completely crippled.
There is no cure for this progressive condition. Cats who develop arthritis need long term pain relief, which can have undesirable side effects, and dietary supplements to slow its development. In a small number of cases, surgery or radiotherapy has been effective in slowing the progression of the disease. Those with severe disease are often suffering immensely and require euthanasia, sometimes early in life.
Due to the crippling deformities evident in this breed, it was excluded from the Cat Fancy of Great Britain as a recognised breed in 1974 and was also banned by the Fédération Internationale Féline. Breeders in the USA persisted, however, and have attempted to improve the health of the breed by never breeding Scottish Folds together but instead, crossing them with either American Shorthairs or British Shorthairs. Half of the kittens born from these matings still have the folded ears however, which means they will develop the painful disease.
It was once thought that the ear fold was the only impact on cross-bred Scottish Folds but in the early 1990s, Australian veterinary researchers proved that all cats with the ear fold will develop the painful effects of osteochondrodysplasia to varying degrees. The visual deformities are less severe in cross-bred cats and the resulting arthritis may be milder or slower to progress in some, but others still suffer from significant disease from as early as 6 months of age. Euthanasia on welfare grounds may be required.
This condition is preventable by not breeding from any cats with folded ears. All Scottish Fold cats with folded ears are affected by this disease. Scottish Fold cats continue to be bred in the USA, Australia and Asia, with marketing focusing on the quality of the ear fold. RSPCA Australia believes it is unethical to breed from animals with a genetic mutation that is known to cause painful deformities and disease. It is important to realise that the folded ears many find ‘cute’ in Scottish Fold cats, are highly unnatural for the animals themselves (the result of a random and unfortunate mutation) and that the underlying condition responsible for this appearance has profound detrimental effects on their welfare.
Further reading
https://www.ufaw.org.uk/cats/scottish-fold-osteochondrodysplasia
Malik R Allan GS Howlett CR Thompson DE James G McWhirter C and Kendall K (1999) Osteochondrodysplasia in Scottish fold cats. Australian Veterinary Journal 77: 85–92
