Developmental orthopaedic disease (DOD) in horses is a syndrome, an umbrella term if you will.
When referenced by vets, it could include a range of musculoskeletal disorders that begin before or after birth during a rapid growth phase. It can also mean disorders that manifest as disease sometime later in young foals (often as weanlings).
In more mature horses, it usually only appears when exercise loads increase.
These diseases are a significant cause of lameness and poor performance as well as poor welfare, and ‘wastage’ – not a word I particularly like but readers, and especially breeders, know what it means.
The term DOD includes conditions affecting bones, joints and soft tissues at a time when ‘soft’ early structures are maturing into final, finished form where they are hardened and capable of withstanding wear.
Disease processes and terms include:
OCD – Osteochondritis Dissecans: dissecting flaps of cartilage/bone, typically affecting hock, stifle and shoulder joints. OC – Osteochondrosis: lesions where cartilage and bone meet, including ‘chips’ in fetlocks and knees and mal-shaped surfaces in hocks and stifles.Physitis: inflammation of growth plates, at the ends of bones – mostly in limbs but also the spinal column.Subchondral bone cysts: defects (‘holes’) in bones close to growth plates, most commonly where they are immediately above the stifle joint.Angular limb deformities: deviations outward (valgus) or inward (varus) in limbs secondary to the above processes.Flexural limb deformities: similar to angular but in the forward-backward plane, leading to clubfoot or collapsed fetlocks, knees or hocks.Wobbler Syndrome: the result of DOD affecting neck vertebrae causing abnormal pressure on the spinal cord.
A good house is built on solid foundations: sire, dam and ancestor selection are the foundation of breeding sound stock.
Some 40 years since we started talking about DOD, the exact causes are still subject to debate, but suffice to say they are complex, multifactorial and interrelated. These include factors that breeders can do something about – nature (genetics) and nurture (nutrition and biomechanics).
Genetics
Inherited genetic factors mean that some breeds, such as warmbloods and thoroughbreds, and some studbooks within such a breed, have been found to have a higher incidence of DOD.
If you drill down again, some breeding lines within a studbook might be predisposed, particularly if selectively bred for traits like size and speed – which means rapid growth phases at some stages in the foal’s development.
Outbreeding confers hybrid vigour to a blood line, the greatest example being the mule which (when properly conformed) can carry more weight and do more work per kg body weight than the parent horse or donkey.
Developmental orthopaedic disease in horses is a syndrome which includes a range of musculoskeletal disorders that begin before or after birth during a rapid growth phase; \ Louise O'Brien Photography
Inbreeding concentrates bad traits like osteochondrosis as well as desirable ones such as speed or jumping ability. A good house is built on solid foundations: sire, dam and ancestor selection are the foundation of breeding sound stock.
Nutrition
There are general and specific dietary components, both excess and deficiency, that should also be considered.
Excessive intake of certain nutrients, particularly calories in the form of dietary carbohydrates found in cereal feeds, can drive growth spurts that outrun the supply of essential vitamins and minerals and exceed the structural capabilities of the skeleton.
On the other hand, a fundamental deficiency in quality protein, in elements such as calcium, magnesium or copper, or imbalances between essential elements, adversely affect development of a good musculoskeletal system.
It’s hard to beat grass grown over limestone land; equally be wary of molybdenum-rich soil – it counteracts copper.
It would be like pouring foundations using concrete with the wrong ratio of cement, water, sand and aggregate. How can your house possibly stand? Or for how long?
Biomechanics
Immature ‘soft’ cartilage, bones and joints, especially if not maturing properly, do not withstand stress well. Deformation ensues. Overexercising, for example trying to keep up with a dam in a large paddock, or inadequate opportunity to rest lying down in comfort, can exacerbate the problem.
Similarly, if young horses are pushed too hard too early in their training without allowing their maturing skeleton time to adjust to the demands, they fail in a structural way. And a traumatic incident such as being kicked can be the trigger.
Imagine putting up walls, floors or a roof too heavy for the foundations you have laid – defects, deformities and stress fractures will soon be seen.
Early detection and timely intervention are critical to preventing long-term damage – growth plates do not remain open ad infinitum, soft structures harden and a lot of cartilage matures into bone. It is far more difficult, if not sometimes impossible to correct later in the building process – a foal’s foundations can hardly be dug up to allow you to start again.
Diagnosing DOD requires a combination of clinical evaluation, diagnostic imaging and sometimes arthroscopic examination. The clinical exam may reveal signs of inflammation; heat or pain on palpation; swelling of joints or at growth plates; lameness, or abnormal posture including limb deviations.
Diagnosis
Radiography (X-rays): these have been the staple of DOD diagnosis for decades revealing cysts and chips, the source of a limb deviation or the site of pressure, eg on the spinal cord.
Radiography (x-rays) can reveal cysts and chips, the source of a limb deviation or the site of pressure.
Its forte, like CT a 3-D type of radiography, is the imaging of bone. However, it is not an exact science – some of the changes seen in DOD mimic those seen as ‘normal variants’ including smooth, rounded bone fragments of no clinical significance.
Ultrasound (U/S): ultrasound is very good for evaluating soft tissue including the cartilage found in joints and at growth plates. And MRI is a 3-D imaging modality capable of delivering detailed images of all tissue types.
Sometimes however, it is best and indeed necessary to have a direct look, during surgery most typically by ‘scoping’ a joint (arthroscopy). This assists with diagnosis but sometimes, it is also an essential step in case management, eg of dissecting cartilage lesions or subchondral bone cysts.
The management of DOD varies depending on the specific condition within the umbrella, its severity, the owner’s budget, the age of the animal and the purpose for which it is intended.
In many cases, early and relatively cheap interventions such as a change in diet or exercise regime, or good farriery can prevent long-term damage and allow the foal to mature properly and develop into a horse with normal function.
The next steps
Nutrition: where necessary, adjustments in diet are crucial in managing DOD and the science behind young horse dietary formulation was radically altered many years ago as these conditions became better understood.
A balanced diet that ensures proper vitamin (vitamin D) and mineral (calcium and copper) intake supports optimal bone development.
Reduce excessive calorie intake (dietary carbohydrates) especially in top-heavy foals, weanlings or yearlings with rapid growth rates.
Farriery: a skilled farrier is an essential team member, particularly in the management of limb deviations.
Timely foot trimming and glue-on hoof extensions guide the direction of growth of a foal’s limbs.
As a mild degree of valgus is normal and growth plates close earlier in lower limbs compared to the upper limbs, early identification and intervention is particularly important where varus limb deviations of the fetlock are suspected.
Medication: anti-inflammatory medications and joint supplements (neutraceuticals) are commonly employed to reduce inflammation and pain, and to support cartilage health and joint function. In some cases local injections, eg corticosteroids, into a joint are used.
Exercise: excessive stress on immature limbs should generally be avoided but moderate, controlled levels are essential to promote normal bone development. Box rest, large stall confinement, hand walking and small paddock turn-out all feature at different stages for DOD conditions.
The advice can be very different for a case of flexural limb deformity compared to OC – so take expert advice.
Physical therapy and rehabilitation: similarly, passive movement of limbs, massage and controlled exercise programmes need skilled oversight to ensure these contribute to case management.
Surgery: case selection is key to success here. If breeding-to-sell in times when X-ray screening has become the norm, there is a temptation to intervene.
But surgery can be nothing other than cosmetic – tidying up chips of no clinical significance, for example.
In genuine cases of DOD involving OCD flaps, subchondral bone cysts or clinically significant joint chips, arthroscopy is an essential tool to achieve a sound future athlete. And surgery is sometimes essential to achieve straightening of limb deviations, for example surgical staples/screws/wire for valgus/varus deformities or the cutting of ligaments/tendons in flexural deformities.
Conclusion
When it comes to DOD, prevention is always better than treatment and the first step here for breeders is careful selection of dam and sire.
Next comes nutritional management of the pregnant mare and a proper diet and exercise programme with careful monitoring of the growing foal. DOD is a complex and multifactorial condition that requires early intervention and careful management. While genetics play a role and can’t be undone, proper nutrition, exercise management, good farriery and timely veterinary interventions can ensure that many foal sufferers go on to live full, productive horse lives.
Developmental orthopaedic disease (DOD) in horses is a syndrome, an umbrella term if you will.
When referenced by vets, it could include a range of musculoskeletal disorders that begin before or after birth during a rapid growth phase. It can also mean disorders that manifest as disease sometime later in young foals (often as weanlings).
In more mature horses, it usually only appears when exercise loads increase.
These diseases are a significant cause of lameness and poor performance as well as poor welfare, and ‘wastage’ – not a word I particularly like but readers, and especially breeders, know what it means.
The term DOD includes conditions affecting bones, joints and soft tissues at a time when ‘soft’ early structures are maturing into final, finished form where they are hardened and capable of withstanding wear.
Disease processes and terms include:
OCD – Osteochondritis Dissecans: dissecting flaps of cartilage/bone, typically affecting hock, stifle and shoulder joints. OC – Osteochondrosis: lesions where cartilage and bone meet, including ‘chips’ in fetlocks and knees and mal-shaped surfaces in hocks and stifles.Physitis: inflammation of growth plates, at the ends of bones – mostly in limbs but also the spinal column.Subchondral bone cysts: defects (‘holes’) in bones close to growth plates, most commonly where they are immediately above the stifle joint.Angular limb deformities: deviations outward (valgus) or inward (varus) in limbs secondary to the above processes.Flexural limb deformities: similar to angular but in the forward-backward plane, leading to clubfoot or collapsed fetlocks, knees or hocks.Wobbler Syndrome: the result of DOD affecting neck vertebrae causing abnormal pressure on the spinal cord.
A good house is built on solid foundations: sire, dam and ancestor selection are the foundation of breeding sound stock.
Some 40 years since we started talking about DOD, the exact causes are still subject to debate, but suffice to say they are complex, multifactorial and interrelated. These include factors that breeders can do something about – nature (genetics) and nurture (nutrition and biomechanics).
Genetics
Inherited genetic factors mean that some breeds, such as warmbloods and thoroughbreds, and some studbooks within such a breed, have been found to have a higher incidence of DOD.
If you drill down again, some breeding lines within a studbook might be predisposed, particularly if selectively bred for traits like size and speed – which means rapid growth phases at some stages in the foal’s development.
Outbreeding confers hybrid vigour to a blood line, the greatest example being the mule which (when properly conformed) can carry more weight and do more work per kg body weight than the parent horse or donkey.
Developmental orthopaedic disease in horses is a syndrome which includes a range of musculoskeletal disorders that begin before or after birth during a rapid growth phase; \ Louise O'Brien Photography
Inbreeding concentrates bad traits like osteochondrosis as well as desirable ones such as speed or jumping ability. A good house is built on solid foundations: sire, dam and ancestor selection are the foundation of breeding sound stock.
Nutrition
There are general and specific dietary components, both excess and deficiency, that should also be considered.
Excessive intake of certain nutrients, particularly calories in the form of dietary carbohydrates found in cereal feeds, can drive growth spurts that outrun the supply of essential vitamins and minerals and exceed the structural capabilities of the skeleton.
On the other hand, a fundamental deficiency in quality protein, in elements such as calcium, magnesium or copper, or imbalances between essential elements, adversely affect development of a good musculoskeletal system.
It’s hard to beat grass grown over limestone land; equally be wary of molybdenum-rich soil – it counteracts copper.
It would be like pouring foundations using concrete with the wrong ratio of cement, water, sand and aggregate. How can your house possibly stand? Or for how long?
Biomechanics
Immature ‘soft’ cartilage, bones and joints, especially if not maturing properly, do not withstand stress well. Deformation ensues. Overexercising, for example trying to keep up with a dam in a large paddock, or inadequate opportunity to rest lying down in comfort, can exacerbate the problem.
Similarly, if young horses are pushed too hard too early in their training without allowing their maturing skeleton time to adjust to the demands, they fail in a structural way. And a traumatic incident such as being kicked can be the trigger.
Imagine putting up walls, floors or a roof too heavy for the foundations you have laid – defects, deformities and stress fractures will soon be seen.
Early detection and timely intervention are critical to preventing long-term damage – growth plates do not remain open ad infinitum, soft structures harden and a lot of cartilage matures into bone. It is far more difficult, if not sometimes impossible to correct later in the building process – a foal’s foundations can hardly be dug up to allow you to start again.
Diagnosing DOD requires a combination of clinical evaluation, diagnostic imaging and sometimes arthroscopic examination. The clinical exam may reveal signs of inflammation; heat or pain on palpation; swelling of joints or at growth plates; lameness, or abnormal posture including limb deviations.
Diagnosis
Radiography (X-rays): these have been the staple of DOD diagnosis for decades revealing cysts and chips, the source of a limb deviation or the site of pressure, eg on the spinal cord.
Radiography (x-rays) can reveal cysts and chips, the source of a limb deviation or the site of pressure.
Its forte, like CT a 3-D type of radiography, is the imaging of bone. However, it is not an exact science – some of the changes seen in DOD mimic those seen as ‘normal variants’ including smooth, rounded bone fragments of no clinical significance.
Ultrasound (U/S): ultrasound is very good for evaluating soft tissue including the cartilage found in joints and at growth plates. And MRI is a 3-D imaging modality capable of delivering detailed images of all tissue types.
Sometimes however, it is best and indeed necessary to have a direct look, during surgery most typically by ‘scoping’ a joint (arthroscopy). This assists with diagnosis but sometimes, it is also an essential step in case management, eg of dissecting cartilage lesions or subchondral bone cysts.
The management of DOD varies depending on the specific condition within the umbrella, its severity, the owner’s budget, the age of the animal and the purpose for which it is intended.
In many cases, early and relatively cheap interventions such as a change in diet or exercise regime, or good farriery can prevent long-term damage and allow the foal to mature properly and develop into a horse with normal function.
The next steps
Nutrition: where necessary, adjustments in diet are crucial in managing DOD and the science behind young horse dietary formulation was radically altered many years ago as these conditions became better understood.
A balanced diet that ensures proper vitamin (vitamin D) and mineral (calcium and copper) intake supports optimal bone development.
Reduce excessive calorie intake (dietary carbohydrates) especially in top-heavy foals, weanlings or yearlings with rapid growth rates.
Farriery: a skilled farrier is an essential team member, particularly in the management of limb deviations.
Timely foot trimming and glue-on hoof extensions guide the direction of growth of a foal’s limbs.
As a mild degree of valgus is normal and growth plates close earlier in lower limbs compared to the upper limbs, early identification and intervention is particularly important where varus limb deviations of the fetlock are suspected.
Medication: anti-inflammatory medications and joint supplements (neutraceuticals) are commonly employed to reduce inflammation and pain, and to support cartilage health and joint function. In some cases local injections, eg corticosteroids, into a joint are used.
Exercise: excessive stress on immature limbs should generally be avoided but moderate, controlled levels are essential to promote normal bone development. Box rest, large stall confinement, hand walking and small paddock turn-out all feature at different stages for DOD conditions.
The advice can be very different for a case of flexural limb deformity compared to OC – so take expert advice.
Physical therapy and rehabilitation: similarly, passive movement of limbs, massage and controlled exercise programmes need skilled oversight to ensure these contribute to case management.
Surgery: case selection is key to success here. If breeding-to-sell in times when X-ray screening has become the norm, there is a temptation to intervene.
But surgery can be nothing other than cosmetic – tidying up chips of no clinical significance, for example.
In genuine cases of DOD involving OCD flaps, subchondral bone cysts or clinically significant joint chips, arthroscopy is an essential tool to achieve a sound future athlete. And surgery is sometimes essential to achieve straightening of limb deviations, for example surgical staples/screws/wire for valgus/varus deformities or the cutting of ligaments/tendons in flexural deformities.
Conclusion
When it comes to DOD, prevention is always better than treatment and the first step here for breeders is careful selection of dam and sire.
Next comes nutritional management of the pregnant mare and a proper diet and exercise programme with careful monitoring of the growing foal. DOD is a complex and multifactorial condition that requires early intervention and careful management. While genetics play a role and can’t be undone, proper nutrition, exercise management, good farriery and timely veterinary interventions can ensure that many foal sufferers go on to live full, productive horse lives.
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