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![6 Developmental Orthopedic Diseases in Horses – [Causes, Signs & Treatment]](/wp-content/uploads/2022/08/Developmental-Orthopedic-Disorders-in-Horses.jpg)
Developmental orthopedic diseases (DODs) refer to a range of non-infectious conditions that affect the musculoskeletal system of growing horses.
These conditions arise from an interruption in the normal development of cartilage, bone, or soft tissue (joint capsule, tendon, or ligament).
Genetics, growth rate, nutrition, and exercise conditions can influence the onset of DODs in growing foals. [1][2]
While some developmental issues are apparent at birth, others occur later as the horse grows. Conditions such as osteochondrosis and physitis can affect any breed of horses and are a common cause of pain and lameness. [2]
Some developmental orthopedic diseases influence future performance, depending on what part of the horse’s joint is affected. [3]
Developmental Orthopedic Diseases
The exact percentage of horses affected by DODs is unknown, however, prevalence is known to be high in certain breeds.
In a study of 392 Warmbloods, Standardbreds, and Thoroughbreds, 66.3% of foals were affected by developmental orthopedic diseases. [4]
Causes
Key factors in the development of equine orthopedic disorders likely involve a combination of the following causes: [2]
- Genetics: Some breeds may be genetically predisposed to DODs
- Nutrition: Lack of complete or imbalanced nutrients provided in the diet of pregnant or lactating mares and foals
- Rapid growth rate in foals and obesity due to excess dietary energy provided in their feeding program
- Trauma or stress exerted on developing cartilage and bones
- Excessive exercise at a young age or a lack of activity
Diagnosis
A thorough physical evaluation by a veterinarian is necessary to identify abnormalities of the developing skeletal system in young horses. [5]
If your veterinarian suspects your horse has a developmental orthopedic disease, diagnostic radiographic or nuclear imaging and blood tests may be required to make an accurate diagnosis.
6 Common Developmental Orthopedic Diseases in Horses
1) Equine Osteochondrosis
A common developmental disorder, osteochondrosis primarily affects cartilage, the soft tissue covering the ends of long bones at the joints. [6][7]
Osteochondrosis describes abnormalities in the differentiation and maturation of cartilage. The condition impairs the normal bone formation process in which cartilage is gradually replaced by bone (endochondral ossification). [6][7]
If cartilage doesn’t receive adequate blood flow and fractures due to osteochondrosis, it can result in cartilage fragments in the joints. This condition is referred to as osteochondrosis dissecans (OCD). [6][7]
Osteochondrosis commonly affects the fetlock, hock, shoulder, and stifle joints. [6][7]
Cause
The development of osteochondrosis is believed to be influenced by rapid growth, a high energy diet, mineral imbalances, trauma to cartilage, and genetics. [6][7][8]
Signs
Physical signs of osteochondrosis vary according to the joint(s) affected. Common signs include non-painful joint swelling and stiffness and an upright limb conformation.
If the condition affects the joints of the shoulders or stifles, severe lameness may occur. [6][7]
Foals under six months of age with osteochondrosis may spend more time lying down and have difficulty moving normally. Increased joint stiffness and lameness may become apparent with the start of training.
Diagnosis
While osteochondrosis and OCD usually devleops in the first year of life, it may not be diagnosed until the horse is 2 – 3 years old and starting into training.
Physical examination, X-rays, ultrasonography, arthroscopy, scintigraphy, or magnetic resonance imaging (MRI) are often used to diagnose osteochondrosis.
Diagnostic imaging often indicates abnormal cartilage growth and the presence of cartilage fragments in the joints when osteochondrosis is present.
Treatment
Treatment of osteochondrosis depends on the severity of the condition and the specific joints affected. Horses with mild cases of osteochondrosis may recover without intervention.
If rapid growth is occurring in horses with osteochondrosis, restricted exercise and dietary modifications that reduce energy intake can help address the condition. Appropriate mineral supplementation is also required to address deficiencies in the diet. [2]
Medicating affected joints with hyaluronic acid injections has been used to reduce swelling. [9]
In some cases, surgery may be necessary to restore joint health. Surgical intervention via joint arthroscopy may be necessary to remove damaged cartilage, osteochondral fragments, and compromised bone present beneath the affected cartilage. [2]
Prognosis is poor for horses affected by joint surface loss or in which advanced osteoarthritis (degenerative joint disease) is present in combination with osteochondrosis. [2]
2) Equine Physitis (Physeal Dysplasia)
Previously referred to as epiphysitis, physitis is a DOD that describes swelling around the cartilaginous growth plates (areas within the bones from which growth or lengthening occurs) of specific long bones. One or multiple growth plates may be affected. [10][11]
The condition typically affects the distal radius (above the knee), distal cannon (above the fetlock), and distal tibia (above the hock). [10][11]
Physitis is most prevalent in foals 4 – 8 months of age that are growing rapidly and carrying excess weight. If a foal grows faster than its growth plates can develop bone (ossify), the bones can sustain structural d