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David Rutherford BVM&S CertES(Orth) DipECVS MRCVS

Fellowes Farm Equine Clinic Ltd


Veterinary surgeon

David Rutherford

XLEquine practice

Fellowes Farm

Equine Clinic Ltd

Osteochondritis dissecans

in horses

OCD is caused by a combination of factors:

Genetics - OCD is at least partially


Rapid growth and large body size

Nutrition - diets high in energy or with

a mineral imbalance (usually low copper)

Hormonal imbalances - insulin and

thyroid hormones

Trauma - possibly a specific injury or

just during 'normal' exercise

Osteochondritis dissecans (OCD) affects 5-25% of all horses, but it is most common in

Thoroughbreds and Warmbloods and rare in ponies. It occurs when the joint surface of

young growing horses does not form properly, causing the cartilage and bone underneath

it to be irregular and weak. This can lead to the development of cartilage and bone flaps,

which either remain partially attached to the bone or break off and float around the joint.

These loose fragments irritate the inside of the joint causing joint swelling and moderate

lameness. Age at the development of signs can vary but 18 months to 4 years is most

common – often joint swelling and lameness initially occurs when a young horse begins work

for the first time. OCD can occur in all joints, but is most common in the stifle and hock.

OCD might be suspected when a large

young horse develops lameness and a

swollen joint, and is easily confirmed with

x-rays. Often loose bone fragments can be

seen, or if just the cartilage is involved, we

just see a flattened area on the joint surface.

OCD is commonly present within the same

joint in the other leg even if there are no

signs, so x-rays of the other leg should

always be taken.

Occasionally, OCD might be treated by joint

medication alone, but the optimum treatment

is the removal of loose bone fragments and

diseased cartilage by keyhole surgery

(arthroscopy). A camera the size of a pencil

is inserted into the affected joint through a

1cm incision. The joint is distended with

sterile saline solution or carbon dioxide gas,

and the joint surface can be examined using

the image projected onto a television monitor.

The loose fragments and soft diseased

cartilage are located and removed using

grasping instruments placed through a second

small incision. Any soft bone under the

fragments can then be scraped away before

the joint is flushed clean and the skin sutured

closed. Arthroscopy is usually performed by

specialist equine surgeons under general

anaesthetic in an equine operating theatre,

but it is occasionally possible for surgery to

be undertaken in the standing sedated horse.

It is not a cheap undertaking with the cost of

investigations, surgery and immediate

aftercare being approximately £2500-3500.

After surgery horses will typically be stable

rested for about 3 weeks and then undertake

a steady return to exercise over the next few

months. Often the affected joint(s) will be

injected with cortisone and lubricants 4-6

weeks after surgery to remove any residual

inflammation. Alternatively biologic therapies

such as platelet rich plasma (PRP) or stem

cells can be injected to help stimulate healthy

cartilage to cover the exposed bone surface.

The prognosis for a full athletic career

following OCD surgery is good to excellent

in most cases with the best results achieved

with smaller injuries and when horses are

treated at a young age.

Stifle effusion associated with an

OCD lesion

X-rays of a horse’s stifle show an OCD

fragment at the front of the joint before

(left) and after (right) surgery to remove it