Degenerative joint disease (also called arthritis) refers to degeneration and loss of the articular cartilage in a horse’s joints.

Common triggers for arthritis include aging, traumatic injuries, and excessive use. Horses may develop symptoms such as joint swelling, reduced range of motion in the joint, and lameness.

There is no definitive treatment for arthritis, and the disease is progressive. Treatment primarily focuses on pain control and slowing the progression of disease. Common treatments include joint injections, anti-inflammatory medications, and rest from exercise.

The prognosis for degenerative joint disease varies depending on the severity of cartilage degeneration and the joint affected. Horses with equine arthritis require ongoing management and adjustment of treatment protocols for the remainder of life.

By working closely with veterinarians and other qualified bodywork practitioners, owners can ensure the best quality of life possible for their arthritic horses.

Degenerative Joint Disease in Horses

In horses, degenerative joint disease or osteoarthritis can develop in any joint, however it is most common in weight-bearing joints found in the limbs.

Normally, articular cartilage protects the bones on either side of a joint from rubbing against each other. [1] In horses with arthritis, the cartilage degenerates and the bones contact each other, resulting in grinding of the bone surfaces and pain. [1]

Arthritis in horses usually occurs from one of two scenarios: abnormal cartilage experiencing normal stresses, or normal cartilage experiencing abnormal stresses. [1]

Abnormal Cartilage

Abnormal joint cartilage is any cartilage unable to withstand a normal workload. In affected horses, the joint cartilage sustains damage when even mild forces are applied during use of the joint. [2]

This damage activates enzymes (proteins that break down tissue) within the joint, resulting in further cartilage damage. [2]

Common examples of abnormal joint cartilage include osteochondrosis, a developmental defect of joint cartilage, and aging.

Osteochondrosis

In osteochondrosis, the joint cartilage fails to completely cover the bony surfaces within the joint or produces wavy or indented cartilage that does not glide smoothly. [1]

Interaction of these defects during movement of the joint can damage the cartilage, triggering inflammation and arthritis. [2]

Aging

With aging, several changes occur that compromise the function of joint cartilage. Major changes include: [3]

  • Thin cartilage unable to withstand extreme forces
  • Increased activity of enzymes that break down cartilage
  • Reduced activity of healing and repair products in the joint fluid
  • Poor synthesis of new cartilage to replace damaged tissue

The combination of these factors results in weak cartilage that is unable to repair small injuries, making the joint more likely to develop arthritis even under normal use. [2]

Abnormal Stresses

Abnormal stresses on joint cartilage can result from injuries to the joint and its surrounding structures, or from excessive use of the joint. [2]

Injuries

Injuries, such as bone fractures, ligament tears, or tendon damage, can affect the stability of nearby joints, causing irregular or erratic movement (joint laxity). [2]

When unstable joints are used, there is a risk of the cartilage surfaces contacting each other, causing abrasions or irritation. [2]

Abrasions from joint laxity can damage chondrocytes, the cells that make up cartilage. [2] Chondrocyte damage activates enzymes that break down tissues and results in loss of key structural components of the cartilage. [2]

Loss of cartilage tissue resulting from chondrocyte damage eventually leads to arthritis. [2]

Excessive Use

Excessive use of a joint can also result in chondrocyte damage and loss of cartilage structure. [2] Exercise can produce microtrauma within cartilage, microscopic injuries that must be repaired by the joint’s repair mechanisms. [2]

Under most circumstances, microtraumas are quickly repaired and the joint continues normal function. [2] With excessive joint use, microtraumas accumulate faster than the cartilage is able to repair them. [2] Eventually, continued chondrocyte injury activates degrading enzymes, which initiates inflammation and arthritis. [2]

Horses with the highest risk of excessive joint use are those used for disciplines with frequent high-impact weight bearing events. [2] Example disciplines include racing, jumping, and barrel racing, where the joints experience a large amount of concussive force as the horse performs. [2]

Effects of Cartilage Degeneration

Once joint cartilage is damaged, it activates inflammation, which leads to further damage within the joint. [2]

The cycle of cartilage damage triggering inflammation leading to further cartilage damage results in progressive destruction until there is no joint cartilage remaining. [2]

Inflammation can also cause secondary effects in the joint itself and the tissues surrounding it. [1] The main outcomes of degenerative joint disease are: [1]

  • Pain
  • Joint swelling
  • Reduced range of motion
  • Changes in joint fluid consistency
  • Alterations in bone composition within the joint

Pain

Cartilage does not have nerve endings, however the bones and soft tissues surrounding the joint do. [1] The inflammatory response associated with arthritis produces proteins that activate these pain-sensing nerves. [1] As a result, horses with cartilage degeneration feel pain from flexing the joint or during movement. [1]

An additional contributor to pain from arthritis is disruption of the periosteum, the connective tissue that covers bones. [1] The periosteum contains a large network of nerve endings that can be disrupted by bony proliferations associated with advanced arthritis. [1]

Affected horses can develop high levels of pain from osteophyte (new bone tissue) development for this reason. [1]

Joint Swelling

Inflammation makes blood vessels in the affected area leaky, causing increased fluid accumulation in the joint. Leakage into the joint also increases the concentration of anti-inflammatory proteins in the affected joint. [1] These factors combined result in joint swelling. [1]

Although the delivery of anti-inflammatory proteins can be beneficial, severe joint swelling increases pressure within the joint capsule, limiting range of motion and preventing normal function. [1] Swelling can also trigger pain by stretching the joint capsule and activating its nerve endings. [1]

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Reduced Range of Motion

As arthritis develops, the maximum range of motion of the joint reduces significantly. [1] In developing cases of arthritis, a combination of pain and joint swelling are the main reasons for reduced joint mobility. [1]

Horses with chronic, long-term arthritis often develop periarticular fibrosis, scarring of the soft tissues surrounding a joint. [1] Scarring occurs due to inflammation activating fibroblasts, the cells that produce connective tissue. [1]

Affected horses may have permanent reductions in joint mobility if fibrosis develops. [1]

Joint Fluid Changes

Inflammation can reduce the viscosity (fluid thickness) of the joint fluid, which can further aggravate cartilage damage. [1]

Joint fluid normally contains high levels of hyaluronan, a compound that acts as a lubricant to ensure smooth motion of the joint. [1] Hyaluronan also contributes to the viscous nature of joint fluid, which is the body’s natural shock absorption for joints. [1]

Horses with arthritis have significantly lower levels of hyaluronan in their joint fluid, likely due to inflammatory products breaking down the compound. [1] With inadequate hyaluronan, the cartilage is more likely to grind against itself due to lack of lubrication, increasing the risk of damage from concussive forces during exercise. [1]

Bony Changes

Without adequate protective cartilage, the bones making up the joint become damaged as arthritis progresses. Common bony changes include: [1]

  • Formation of osteophytes, bony proliferations that attempt to stabilize the joint
  • Thickening of the bone surfaces in response to microfractures or increased concussive forces
  • Fragments of bone or cartilage within the joint space
  • Complete fusion of the bone surfaces together, obliterating the joint space

These changes are the hallmarks of arthritis that veterinarians look for to make a diagnosis on X-ray or other diagnostic imaging techniques. [1]

Diagnosis of Arthritis

The main symptom of degenerative joint disease is lameness. [1] Other symptoms may include: [1]

  • Swelling over or around a joint
  • Reduced range of motion in a joint
  • Pain or stiffness when moving a particular joint

Veterinarians presented with a lame horse perform a lameness examination, which consists of a physical examination, gait evaluation, flexion tests, and nerve blocks. [1]

The goal of the lameness examination is to identify the source of lameness, including which joints or areas of the affected limb are most painful. [1] Using this information, the veterinarian can perform additional diagnostic tests to determine the underlying cause of lameness. [1]

Diagnostic Tests

Additional diagnostic tests that can identify degenerative joint disease include: [1]

  • X-rays
  • Nuclear scintigraphy (“bone scan“)
  • Magnetic resonance imaging (MRI)
  • Ultrasound

Treatment Methods

Degenerative joint disease is a manageable condition that does not have a definitive cure. [4] Goals of arthritis treatment include reducing pain, facilitating the body’s repair processes, and slowing the progression of arthritis. [4]

Pain Control

Most veterinarians recommend nonsteroidal anti-inflammatory drugs (NSAIDs) as the primary means for pain control in arthritic horses. [4] These medications interrupt the release of prostaglandin, one of the main triggers of pain sensation. [4]

The most common NSAIDs used in horses are: [2]

Alternative Treatments

There are also several alternative therapies that may reduce pain in arthritic horses. [4] Modalities include: [4]

Each case of arthritis is nuanced and unique. Work with your veterinarian to develop a management plan for your horse’s needs. If seeking alternative therapies, always work with a qualified practitioner. Do not make changes to your horse’s medications without medical guidance.

 

Supporting Repair Processes

Some treatments for degenerative joint disease are designed to target the body’s natural repair functions, introducing high levels of proteins that stimulate growth and healing directly into the joint space. [5]

Treatments that target improved repair of damaged cartilage include: [5]

  • Platelet-rich plasma (PRP)
  • Autologous conditioned serum (IRAP®)
  • Autologous protein solution (Prostride®)
  • Autologous conditioned plasma (Alpha-2 EQ®)
  • Stem cell therapy

These technologies require more research to confirm their efficacy in treating arthritis, but current investigations show promising results. [5]

Nutritional Supplements

Some dietary supplements also support normal repair functions to maintain healthy joints and connective tissue. Supplements that help to support joint health and normal maintenance of cartilage include: [4]

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  • Cartilage & connective tissue
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Slowing Disease Progression

Degenerative joint disease is an inflammatory condition, so many of the treatments targeted at slowing disease progression work by combating inflammation. [4] Some medications are chondroprotectants, meaning they support cartilage health to slow the rate of damage. [4]

Depending on the type of medication, these treatments can be either intra-articular (into the joint) or systemic (whole body). [4]

Common intra-articular treatments include: [4][6]

Common systemic treatments include: [4][7]

  • Hyaluronic acid (Legend®)
  • Polysulfated glycosaminoglycans (Adequan®)
  • Pentosan polysulfate (Zycosan®)

Lower Limb Arthritis

Although the general approach to treatment for arthritis is the same for most joints, specific forms of arthritis related to the lower limbs have their own treatment protocols and management considerations.

Low Ringbone

Low ringbone refers to arthritis of the distal interphalangeal joint, the joint between the coffin bone and the short pastern. [8]

Risk Factors

Common risk factors for developing low ringbone include: [8]

  • Horses with hoof imbalances that alter the axis between the hoof and the pastern
  • Navicular syndrome
  • Fractures of the coffin bone
  • Bone cysts in the coffin bone
  • Bone chips within the distal interphalangeal joint

Symptoms

Low ringbone characteristically causes a firm or bony swelling surrounding the short pastern (hence the term “ringbone”). [8] These bony swellings begin as soft swellings of the joint capsule and become firm as arthritis progresses. [8]

Affected horses typically show the most severe lameness when circling or trotting on hard ground. [8] During a lameness examination, lameness usually resolves after a palmar/plantar digital nerve block, which primarily blocks feeling in the hoof. [8]

Treatment

The most common treatments for low ringbone are intra-articular medications and corrective shoeing. [8] Some horses may also benefit from 6-9 months of rest from performance activities. [9]

In particular, changing the horse’s shoeing and trimming to favor shortening the toe helps reduce mechanical forces on the distal interphalangeal joint. [8] This practice stabilizes the joint during motion, reducing the pain associated with excessive joint movement and grinding of bony surfaces against each other. [8]

Some farriers and veterinarians may also recommend shoe pads to absorb some of the impact of hoof to ground contact. [8]

Prognosis

Studies suggest that around 30% of horses respond to a combination of joint injections, NSAIDs, and shoeing protocols. [9] These horses may successfully return to low level performance work. [9] Many horses require repeated joint injections every 3-10 months to maintain soundness. [9]

High Ringbone

High ringbone is arthritis of the proximal interphalangeal joint, the joint between the short and long pastern bones. [8] This condition is most common in older horses, and primarily affects the front limbs. [8]

Risk Factors

The most common cause of high ringbone is overuse of the joint or repetitive concussive trauma. [8] Risk factors associated with the development of high ringbone include: [2][8]

  • Upright pastern conformation
  • Performance horses required to stop and start suddenly or twist/turn abruptly
  • Previous fractures or joint luxation (dislocation)
  • Osteochondrosis of the proximal interphalangeal joint

Symptoms

Similar to low ringbone, high ringbone begins as a soft swelling of the pastern region that progresses to a firm, bony swelling. [8] Some horses with mild arthritis may show no visible abnormalities. [8]

Lameness from high ringbone is typically worse when the horse is circling with the affected limb on the inside of the circle. [8] On a lameness exam, most horses do not completely respond to a palmar/plantar digital nerve block but will show complete resolution of lameness with an abaxial sesamoid nerve block. [8]

This nerve block numbs everything below the fetlock, including the proximal interphalangeal joint. [8]

Treatment

There are several treatment options available for high ringbone, and the choice of treatment depends on the severity of arthritis and the horse’s response to previous treatments. [8] Most treatment protocols involve a combination of the following: [8]

  • Joint injections
  • Stall rest
  • NSAIDs
  • Systemic medications such as polysulfated glycosaminoglycans and hyaluronan
  • Nutritional supplements
  • Corrective shoeing to adjust the conformation of the hoof and pastern

Surgery

When these treatments fail to resolve lameness, surgical treatment is also an option. [8] The surgery performed for high ringbone is called arthrodesis, the process of joining two bones together so that a joint no longer moves. [8]

By preventing all motion within the proximal interphalangeal joint, the horse no longer experiences pain from the bones grinding against each other. [8]

In most cases, arthrodesis involves placing a metal plate across the proximal interphalangeal joint and screwing the plate into the pastern bones. [1][8] After surgery, horses require 2-3 weeks of limb casting to ensure complete healing of the surgical site. [1]

Prognosis

Most horses with mild to moderate high ringbone are manageable using medical treatments alone. [8] Surgical arthrodesis has the best prognosis, with around 85% of horses returning to athletic performance after the procedure. [8]

Some horses may develop implant infections which can cause further lameness and worsen the arthritis. [8]

Osselets

“Osselets” refers to arthritis of the fetlock joint, and typically results from a traumatic injury affecting the fetlock. [8]

Risk Factors

Any source of trauma to the fetlock can potentially progress to arthritis. [2][8] Common risk factors for developing arthritis include: [2][8]

  • Soft tissue injuries from overuse of the joint, including ligament sprains
  • Joint injuries or bone fatigue due to overextension of the fetlock in racehorses
  • Abnormal limb conformation causing increased strain on the fetlock

Symptoms

Many horses with osselets show no signs of lameness but may show evidence of swelling and heat around the fetlock joint. [8] With more severe cases of arthritis, the fetlock joint becomes stiff and obviously enlarged. [8]

Horses with osselets do not respond to a palmar/plantar digital nerve block or an abaxial sesamoid block, but typically show reduced lameness with a low four-point block. [2]

This nerve block numbs the entire fetlock joint. [2] Injecting local anesthetics, such as lidocaine, into the fetlock joint can also resolve lameness in most horses, however significant bone pain may not resolve completely in some horses. [1]

Treatment

Treatment protocols for fetlock arthritis primarily rely on medical treatment and rehabilitation practices. [2] Protocols may include: [2]

  • Physical therapy
  • Stall rest, often up to 30 days
  • Systemic and intra-articular joint medications
  • Corrective shoeing, including placing shoe pads to reduce concussive forces
  • Icing and bandaging the fetlocks after exercise
  • Biologic therapies, such as IRAP or stem cells

Horses with bone damage or fragmentation may benefit from arthroscopic surgery, where a surgeon introduces a camera into the joint space and removes any damaged tissues. [2]

Prognosis

The overall prognosis for osselets is good to excellent, as many horses can continue their performance careers with proper management. [2][8] Horses that no longer respond to medical treatment may be able to return to a lower level of performance after an extended period of rest. [2]

Front Limb Arthritis

Some cases of equine arthritis are isolated to the front limbs, which may require specialized medical intervention.

Knee Arthritis

The equine knee has three joints: the radiocarpal joint (between the knee and the upper limb), the middle carpal joint, and the carpometacarpal joint (between the knee and the lower limb). [8]

Horses most commonly develop arthritis in the radiocarpal and middle carpal joints (“carpal arthritis”) after a traumatic injury affecting the knee. [8]

Risk Factors

There are two major types of carpal arthritis: a type affecting young athletic horses and a type affecting older horses. [2]

Young horses typically develop carpal arthritis after a traumatic injury to the joint, usually due to excessive force or strain on the joint during performance. [8] Horses with osteochondrosis of the knee are much more likely to develop carpal arthritis. [1]

Older horses can develop a slowly progressive form of carpal arthritis that is not associated with previous injury to the knee. [2] Horses with abnormal knee conformation, such as back at the knee or bench knee, may be predisposed, however the condition can occur in any mature horse. [1]

Carpometacarpal arthritis commonly occurs in mature Arabian horses and Quarter horses. [2] The precise cause of this type of arthritis is unknown, however it may be related to an abnormality in the connection between the bones in the knee joint. [2]

Symptoms

Many horses with knee arthritis show swelling of the knee joints and are often painful when handlers pick up the limb and flex the knee. [8] Swelling of the joints is usually most obvious on the inside of the leg. [8]

Young performance horses tend to show few obvious symptoms of carpal arthritis, and many are not lame during lameness examination. [1] Reported symptoms include pulling to one side during racing, swelling of the joints after exercise, and generally poor performance. [1]

Lameness from carpal arthritis typically resolves with intra-articular anesthetic to numb the joint spaces. [1] Some horses with severe arthritis may require nerve blocks of the median nerve and the ulnar nerve, which numbs feeling to the entire lower limb. [1]

Treatment

Treatment for most horses with carpal arthritis involves a combination of NSAIDs and intra-articular medications. [8] These horses also benefit from controlled exercise to strengthen the tissues surrounding the knee joint to improve joint stability and reduce the pain associated with joint motion. [8]

Surgeons may recommend partial or complete arthrodesis for horses with severe carpal arthritis. [8] This procedure is typically a salvage procedure to provide comfort for horses no longer required for performance, such as broodmares or breeding stallions. [1]

For carpometacarpal arthritis, the efficacy of intra-articular medication is poor. [1] Horses can benefit from partial arthrodesis, with 83% of horses in one study reported as sound 2 years after surgery. [1]

Prognosis

Carpal arthritis is progressive, making the prognosis for long-term athletic performance poor. [8] Management through NSAIDs and intra-articular medications may slow disease progression, but as the condition worsens, horses become increasingly uncomfortable and may not respond to treatment. [8] Owners must consider the welfare of the horse in cases where pain becomes unmanageable. [8]

Elbow Arthritis

Arthritis of the elbow is rare in horses and tends to occur after a traumatic injury. [1] Horses with elbow arthritis are usually most lame when circling and when trotting on a hard surface. [1]

Most horses respond well to intra-articular polysulfated glycosaminoglycan treatments. [1] However, it is rare for horses with elbow arthritis to return to previous levels of athletic performance. [1]

Shoulder Arthritis

Shoulder joint arthritis is uncommon in horses. [1] Most cases of shoulder arthritis occur due to osteochondrosis or traumatic injuries to the joint capsule. [1]

Affected horses usually show mild to moderate lameness that may improve with injection of anesthetic into the joint space. [1]

Treatment typically involves intra-articular medications; however treatment success is usually poor. [1] The long-term prognosis for athletic performance is poor. [1]

Miniature Breeds

Miniature horses, Falabella ponies, and Shetland ponies can develop a specific form of shoulder osteoarthritis. [1] In these breeds, poor formation of the shoulder joint from birth may lead to instability of the joint, triggering arthritis. [1]

Affected horses develop severe, sudden onset lameness with no history of traumatic injury. [1] Treatment typically involves surgical arthrodesis of the shoulder joint with a poor prognosis for future athletic performance. [1]

Hind Limb Arthritis

The horse’s hind limbs are as susceptible to joint degeneration as the front limbs. Management options vary depending on which joints are affected.

Hock Arthritis

The hock is a complex joint composed of five major joints: [8]

  • Tibiotarsal joint: between the hock and the upper leg
  • Proximal intertarsal joint: between the talus, the bone in the center of the hock, and the upper cuboidal hock bones
  • Distal intertarsal joint: between the upper and lower cuboidal hock bones
  • Tarsometatarsal joint: between the hock and the lower leg
  • Talocalcaneal joint: between the talus and the calcaneus, the point of the hock

Bone spavin is the most common form of arthritis in the hock, referring to arthritis of the distal intertarsal and tarsometatarsal joints. [8]

Risk Factors

There are several potential risk factors predisposing to development of bone spavin. Common risk factors include: [8]

  • Repetitive compression or rotation of the hock joint during exercise
  • Sickle or cow-hocked conformation
  • Traumatic injuries to the lower hock
  • Malformation of the cuboidal bones due to poor development at birth

Performance disciplines known to cause repetitive injury to the hocks include jumping, dressage, driving, reining, roping, and cutting. [8] Icelandic horses appear to have a breed predisposition to bone spavin that may be hereditary. [8]

Symptoms

Common symptoms of bone spavin include: [8]

  • Mild lameness that disappears with exercising/warming up
  • Poor performance
  • Reduced flexion of the hock during movement
  • Enlargement of the inner aspect of the hock that may be painful when touched

Most horses with bone spavin show complete resolution of lameness from intra-articular anesthetic. [8] Many horses have arthritis in both hocks, so performing a full examination on both limbs is recommended. [8]

Treatment

Most horses respond to a short period of rest, NSAIDs, and intra-articular medications. [8] Adding systemic joint treatments or nutraceuticals may extend the time between intra-articular medications. [8]

In severe cases, arthrodesis to prevent motion of the lower hock joints can help reduce pain. [8] Most arthrodesis methods used in the hocks aim to damage the joint cartilage, which promotes the body’s natural bone fusion response. [8] Methods include: [8]

  • Laser abrasion
  • Surgically drilling out the cartilage
  • Injecting a noxious substance, such as ethanol, that damages cartilage

Some surgeons use one of the above strategies combined with placing a metal plate to ensure stability. [8]

Prognosis

Horses with mild arthritis have a good prognosis for athletic performance, particularly if they receive routine intra-articular medications. [8]

As the arthritis worsens, many horses cannot continue athletic careers or must move to lower levels of performance. [8] Studies show that horses receiving arthrodesis have around a 50% chance of returning to an athletic career. [8]

Stifle Arthritis

The stifle contains two joints: the femoropatellar joint between the femur and the patella, and the femorotibial joint, between the femur and the tibia. [1] Both locations can develop arthritis, often due to traumatic injury or osteochondrosis. [1]

Horses with stifle arthritis often show chronic swelling of the joint, particularly on the inner aspect of the limb. [1] Many horses are unwilling to lift their limb for farriery, as flexion of the joint is painful. [1]

Treatment for stifle arthritis typically involves intra-articular medications, systemic joint medications, and controlled exercise. [1] Mildly affected horses may continue athletic careers with routine treatment, but as the disease progresses, they may have to step down performance levels or retire completely. [1]

Hip Joint Arthritis

Hip joint arthritis is rare in horses but can occur after a traumatic injury or ligament damage. [1] Some horses may have a congenital (present at birth) abnormality of the hip socket that predisposes them to developing arthritis in this location. [1]

Many horses with hip joint arthritis resist flexion and refuse to stand on the limb for long periods. [1] Some horses with hip joint arthritis develop atrophy of the muscles in the hindlimbs due to disuse from pain. [1]

There are few treatment protocols available for hip joint arthritis, and existing protocols using intra-articular medications have poor efficacy. [1] Affected horses have a poor prognosis for athletic performance. [1]

Sacroiliac Joint Arthritis

The sacroiliac joint is the joint between the sacrum of the spine and the ilium of the pelvis. [1] Injury to this joint can occur from a traumatic event, such as getting “cast” in a stall, or repetitive injury due to excessive use during exercise. [8]

Symptoms

Horses with sacroiliac arthritis typically show mild symptoms without obvious lameness, such as: [8]

  • Reduced stride length in the hind limbs
  • Reduced engagement during collection
  • Refusing jumps
  • Difficulty walking downhill
  • “Bunny hopping” in the canter
  • Cross-firing in the canter

Some horses display behavioral issues such as bucking or rearing, particularly when asked to canter. [8]

Treatment

Treatment involves a combination of intra-articular medications and rehabilitation therapy to regain normal muscle function. [8] Biologic treatments such as platelet-rich plasma can also be beneficial. [8]

Prognosis

The prognosis for sacroiliac arthritis is typically poor to guarded for continued athletic performance. [8] Some horses respond well to six-month (or longer) rehabilitation programs aimed at returning function to the sacroiliac area. [7]

Other Types of Arthritis

Even the spine and minor joints uninvolved in sports and work can develop arthritis under certain conditions.

Vertebral Facet Joint Arthritis

The vertebral facet joints are the spaces between the vertebrae of the thoracic (chest) and lumbar (lower back) spine. [8] Horses can develop arthritis of these joints after a traumatic event such as falling, slipping, flipping over backward, or getting cast. [8]

Symptoms

Horses with facet joint arthritis typically show symptoms of back pain. [2] Symptoms include: [2]

  • Reduced motion of the front and hind limbs producing a stiff or shortened gait
  • Reluctance to go downhill
  • Refusing jumps
  • Preference to approach jumps from one direction over the other
  • Resistance when doing exercises requiring lateral bend through the spine, such as shoulder-in or travers
  • Resistance in tight turns

Many owners and riders describe affected horses as having a “tight back,” as the muscles surrounding the spine reflexively contract to reduce the pain associated with facet joint arthritis. [2]

Treatment

Initial treatment of vertebral facet joint arthritis involves reducing inflammation and pain so rehabilitation therapies to loosen the back muscles are effective. [2] Veterinarians often use a combination of NSAIDs, muscle relaxants, and intra-articular injections for these initial treatments. [2]

Once the initial muscle spasm resolves, rehabilitation therapies aim to further loosen the back muscles and restore mobility to the spine. [2] Most horses require 4-6 weeks of rest to begin, ideally on pasture turnout, to encourage the horse to stretch their back based on their own comfort level. [2]

The horse can then gradually return to work, with an emphasis on circling and lateral flexion at the walk and trot to stretch each side of the spine separately. [2]

Over a 4 – 6-month rehabilitation protocol, additional terrain challenges and more strenuous exercise are added until the horse returns to their previous level of work. [2]

Prognosis

The prognosis of vertebral facet joint arthritis for future performance varies depending on the location affected and the performance discipline. [2] In general, horses that are required to perform tight turns or jump have a poorer prognosis, due to the additional demands on the spinal column. [2]

Cervical Facet Joint Arthritis

The cervical facet joints are the spaces between the vertebrae of the neck. [2] Horses commonly develop arthritis of these joints, however symptoms do not always develop. [2]

Risk Factors

The risk factors for cervical facet joint arthritis include: [2]

  • Osteochondrosis
  • Traumatic injuries from falling, running into objects, flipping over backward, etc.
  • Malformation of the cervical vertebrae from birth

Symptoms

The range of symptoms displayed by horses with cervical arthritis is wide, with some horses displaying no symptoms at all. [2] Reported symptoms include: [2]

  • Reluctance to bend the neck from side to side
  • Reluctance to stretch the neck down
  • Difficulty with tight turns
  • Shortened, stiff gait

The bony proliferation associated with arthritis can occasionally compress the spinal cord or major nerves leaving the spinal cord. [2] Associated symptoms include: [2]

  • Uncoordinated movement, particularly affecting the hindlimbs
  • Front limb lameness with no identifiable source
  • Patchy sweating on one or both sides of the neck

Treatment

Treatment for cervical facet joint arthritis is similar to other types of arthritis and includes intra-articular medications and NSAIDs. [2]

Some horses with malformed cervical vertebrae benefit from surgical fusion, where a surgical implant is placed across the affected joint space to stabilize the area and prevent spinal cord compression. [2]

Prognosis

Horses with mild arthritis and few symptoms have a good prognosis for continued performance and can often be managed with routine arthritis treatments. [8] Horses that develop spinal cord compression or have severe symptoms have a poor prognosis for performance, with many horses requiring retirement. [8]

Temporomandibular Arthritis

There are occasional reports of arthritis affecting the temporomandibular joints, the joints between the jaw and the skull. [10] Studies suggest that many of these cases result from traumatic injury to the joint or potentially dental malocclusion (poor alignment of the teeth). [10]

Reported symptoms include: [10]

  • Dropping feed while eating (quidding)
  • Fighting the bit when bridled
  • Head shaking
  • Clicking noise when chewing

Treatment protocols are not well-researched, however there is a report of intra-articular medications reducing symptoms in an affected horse. [10] The prognosis for this condition long-term is unknown. [10]

Summary

Degenerative joint disease, also known as osteoarthritis, in horses describes the loss of cartilage within joints, causing pain.

  • Arthritis can develop in any joint in horses, but is most common in the limbs.
  • Aging, traumatic injuries, and excessive use of the joint can cause arthritis.
  • The main symptoms of arthritis in horses are joint swelling, reduced range of motion, and lameness.
  • Arthritis is progressive and has no definitive cure, requiring lifelong management changes to keep the horse comfortable and sound.
  • The prognosis for arthritis depends on the severity of disease and the joint(s) affected.

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References

  1. Ross, M. W. & Dyson, S. J. Diagnosis and Management of Lameness in the Horse. St. Louis, UNITED STATES: Elsevier, 2010. Accessed: Mar. 09, 2024.
  2. Baxter, G. M. (Ed.). Adams and Stashak’s Lameness in Horses, Seventh edition. Hoboken, NJ: Wiley-Blackwell, 2020.
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