PG . 36
HORSE HEALTH
FIGURE 1 . OCD LESION
FIGURE 2 . PHYSITIS
( insulin and thyroid ), body weight , inappropriate or no exercise and growth rate . DOD is a complex , multifactorial disease . ‘… genetics loads the gun and the environment pulls the trigger …’. Nutrition and exercise management determine whether the normal variations in cartilage thickness resolve spontaneously – or progress to DOD . Because the window of opportunity for sound bone and joint development is open for a short time , correct nutrition of the pregnant mare and young horse is essential for soundness . Prevention should be sought before and after birth and must be the priority for the foal , weanling and yearling .
Although osteochondrosis lesions are likely to happen during the first few months of life , there is thought to be a ‘ window of repair ’ between six months and one year of age during which diet and feeding changes that encourage consistent , steady growth result in spontaneous healing and resolution . This provides us with a second opportunity to guide and regulate growth to protect the future soundness of the young horse .
FIGURE 3 . ANGULAR LIMB DEFORMITY
The period from 3 months before birth to 5 months of age is one of turbulent change for the musculo-skeletal system . In the foetal foal , bone begins as cartilage , gradually converting to mature bone during the first 18 months of life . Anything that disrupts or disturbs these dynamic processes affects the final constitution of joint cartilage . Because these processes are only active during the first year of life , DOD lesions only develop during this period – even they may not show up for months or years .
Specific joints have precise ‘ windows of vulnerability ’. Hock DOD is usually present at 1 month of age , even though signs may not show until the horse is a 3 year old . Stifle lesions develop between 3 and 8 months of age but may not be apparent until 2 years of age and shoulder OCD or bone cysts may not become evident until 12-18 months of age .
During periods of vulnerability the joint is susceptible to the combined effects of nutritional imbalances , hormones
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DOD lesions are formed in a very limited window of time and the pathologic insult to a susceptible joint is short ( weeks ), occurring randomly during the period of joint vulnerability . The age at which periods of irregularity occur varies for each joint . During periods of irregularity the joint is susceptible to the combined effects of nutritional imbalances , body weight and growth rate . Management determines whether the normal variations in cartilage thickness resolve spontaneously – or progress to DOD . This provides us with an opportunity to guide and regulate growth and to protect soundness .
RISK FACTORS FOR DOD : 1 . Body weight and growth rate : With the exception of early fetlock lesions , DOD is linked to higher bodyweights and faster growth . The concussive trauma of high bodyweight increases the compressive load on the immature , growing skeleton and disrupts the blood supply to the cartilage - hindering its conversion to bone . Hock DOD occurs more frequently in taller and heavier-born
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