What is osteochondrodysplasia and what does it mean for Scottish Folds?
Osteochondroysplasia (OCD) is a universally used term for a variety of bone and cartilage abnormalities seen in the Scottish Fold cat. The most noticeable trait of OCD is, of course, the folded ear. OCD is not limited to Scottish Folds - it is found in Bassett Hounds, Dachshunds, many other dog breeds, and in humans as well – but Scottish Folds seem to be particularly affected by this disease.
To understand how a Scottish Fold gets their signature ears (and consequently, OCD), let’s start with a little basic genetics (simplified here for our purposes): Every cat has 19 pairs of genes with each parent contributing one gene to each pair. The fold gene is a dominant gene, and if the cat inherits that gene from one of its parents, then it will have folded ears. It is impossible to “carry” the fold gene and not express it; only recessive genes can be carried in this way. Some folded ear cats, however, have very low expression of the fold gene or their ears loosen over time and can look similar to a straight ear, but such cats are still genetically folded ear cats. A straight eared Scottish cat – or “Scottish Straight” - does not have the OCD causing gene.
Most folded ear cats that are bred today are heterozygous folds, meaning they only have one copy of the fold gene. Homozygous folds have two copies of the fold gene, which likely results in very severe and painful OCD. Folds that are heterozygous will have a lesser degree of OCD than a homozygous fold. When the breed was young in its development this was not known, and many homozygous folds were bred.
By virtue of having at least one copy of the fold gene, every Scottish Fold has OCD, but how the gene expresses itself in any individual cat varies significantly. It is the goal of all ethical Scottish Fold breeders to breed a Scottish Fold cat where the only expression of OCD is in the ears and the cat is free of any other issues that result from OCD. Other expressions of this disease include shortened misshapen limbs, short thick inflexible tails, boney growths, and early onset of arthritis. Exactly how the fold gene expresses itself in individual cats is still unknown. Some folds will develop symptoms such as stiff tails or lameness as early as kitten hood while many remain asymptomatic well into adult hood and a few their entire lives.
All of this seems to paint a dire picture for the Scottish Fold breed, however there is a hope. Some breeders are heeding the warning and are doing their part to only breed structurally sound folds. Our breed is under intense scrutiny, it is banned in three European countries. It’s extremely important that people only buy from a breeder that recognizes that OCD is a problem in the breed and are actively screening cats. Even if this means a LONG wait.
There are things we can do both as breeders and owners to promote healthy bones and joints in Scottish Folds. Breeders should screen for OCD via x-rays as well as keeping a watchful eye for abnormal gait and posture and any reluctance to play or jump. It is important that folds have good nutrition to promote healthy growth of bones and supporting tissues. I recommend all folds be on a glucosamine supplement as early as 6 months old. Also green lipped mussel, fish oils and other omega 3’s and type 2 collagen help in supporting and maintaining healthy bones and cartilage. Regular low impact exercising routines help to keep your cat’s muscles in good condition supporting the bones and joints. Maintaining a healthy weight is crucial, extra weight increases the toll on the body.
Any pet can develop health issues at any point in their life whether that pet is purposely bred or bred without human intervention. It is breeders’ responsibility to recognize problems and breed away from these problems and it is our responsibility as breeders to educate buyers.