Understanding Your Horse's Pain Lecture by Tracy Turner, Notes Courtesy of German Dressage

Understanding Your Horse’s Pain
Tracy Turner, DVM
USDF Convention
Saturday, December 14, 2002

Before we can discuss lameness, we need to first understand the horse’s development and the issues that occur through the phases of development in the made horse and how to prevent them.

From birth to 2 years, the single biggest problem that we face is Developmental Orthopedic Diseases (DOD).

Angular Limb Deformity applies to crooked legs that result from a disturbance in growth in the long bones. It typically affects weanlings and yearlings. All bones come from cartilage, which is soft. That’s why kids bounce. Damage anywhere along the growth plate causes crooked growth. Angular limb deformity can be treated, but it must be treated early because it relies on taking advantage of the ongoing growth.
Flexural Limb Deformity applies to abnormal flexion of the joints.
1. Club foot is the most common example of this one. It is a coffin joint deformity and is most common in the first year. The treatment is to correct nutritional problems. There is very little room for error, especially with regard to energy. DO NOT overfeed the dam. It is OK for the dam to get skinny. Feeding too much pushes the baby and contributes to growth-related problems. The mare’s feed must be balanced with respect to Ca+, Phosphorous, Selenium, Zinc, etc. The breeder must understand what they have in their feed and what they are feeding. More severe deformities may require surgery to lengthen or relax the deep flexor tendon (Stage 1). Stage 2 absolutely requires surgery.
2. Fetlock flexural deformities are also seen, more often in the yearling to 2 year old group. This is a suspensory and/or superficial flexor and/or deep flexor tendon problem. At this age, the suspensory is really still a muscle and hasn’t become a ligament. All the involved elements are still suspending and supporting the fetlock, and no longer function properly, allowing the fetlock to come forward. The treatment is correction of nutritional problems, therapeutic shoeing, and surgery (though none of the surgeries work universally). Pain is a contributing factor, therefore, it is important to rule-out osteochondrosis as a contributing factor.
3. Osteochondrosis is developmental diseases of the joints. All joints form from cartilage. There are two forms: Osteochondrosis dessicans and cyst-like lesions.
  1. Osteochondrosis dessicans presents as swelling in the joints, and may not show any symptoms in the youngster. On xray, you may see that bone under the articular cartilage cartilage fails to form properly and fails to calcify at the rate it was supposed to—these uncalcified areas within the bone leave a flap of cartilage and bone that is weak and a potential problem., It is most common in yearlings, and typically presents with a markedly swollen joint IF/WHEN a piece breaks off. The treatment is surgical, and the prognosis is excellent. These lesions typically travel in pairs, so it is wise to look on the opposite side and remove the “twin” at the same time.
  2. Cyst-like lesions are pieces of bone that never calcified and are unable to provide supportive strength to the articular surface. They typically manifest themselves when the horse goes into training because they provide an uneven joint surface. They can also be treated surgically if they are caught before a lot of damage is done. They are more difficult to deal with than osteochondritis dessicans.

From training to third level, the horse is gaining strength and developing muscles to perform. This is a critical stage in the horse’s development. Bones are remodeling in order to accept the stress of performance, and problems associated with weak conformation begin to show up.

Splints, which are an injury to the ligament between the splint bone and the cannon bone, are first seen at this stage. The first symptom is often a reluctance to go forward, as there is often no swelling initially (swelling may not occur for 2 – 6 weeks). The horse is often tender over the splint bone, and adjacent to the suspensory ligament. Radiographs will show callous formation. Horses that “cheat” and recruit their adductors (hamstring) muscles to propel themselves forward are more prone to splint formation.

Hock pain can also be seen at this level, and is usually bilateral. The horse will move with a shortened stride behind, “stabbing” at the ground. The back is often sore, and the rear limb flexions are positive. Radiographs will show remodeling of the lower joints to functionally fuse, and the formation of bone spurs. The bone spurs themselves are not painful, but a sign of the process. Horses that are overusing their adductors and going base narrow as a result will predispose themselves to flares as they go through these changes.

The horses are developing their toplines in response to the work performed, and in response to HOW the work is performed. It is critical that the work be performed correctly. Muscle problems are COMMON and must be addressed or they will lead to bigger problems. Abnormal loading of the legs, such as getting too heavy on the forehand, can lead to navicular problems, sacroiliac problems or even “kissing spines” later on. (As an aside, jumper horses that are allowed to go around hollow and inverted to fences and that are described as “cold-backed” later in life are now often found to have “kissing spines” and it appears that their earlier way of going and later arthritic problems are related.)

***Muscle pain is a given in any developing athlete, human or equine.*** The key is recognizing it, limiting its severity, and working through it.

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Gluteal muscle pain manifests itself as mild lameness. It involves the croup muscles. When severe, owners describe problems as “losing the hind end” or “no flexion in the stifles” or “?stifle problems.” The gluteals are the muscles of forward propulsion, and provide support during collection. Horses cheat and will shift to use the hamstrings when their glutes are not strong enough. This is a sign that they need a slower, more gradual strengthening program.

Quadriceps Muscle Problems are usually not painful, but they are frequent. The quadriceps are needed to extend the stifle, otherwise the horse has a “locking stifle.” These muscles can be developed through ground pole work, cavaletti and hill work. Recommended work for young horses and rehab/strengthening includes up and down hills, over poles and cavalettis, walk and trot (not canter), lots of straight lines with only a few circles, transitions for balance, changes of direction. Focus on balance, muscle and building strength while working in a non-hollow (long and low) frame. These should be your ONLY goals for young horses.

Adductor Muscles (inner thigh muscles) keep the limbs from slipping away from the horse’s body. These muscles allow engagement, collection and lateral work. These can get very painful (just think of a human groin injury!), and can come back to haunt you. Be careful not to repeat too much and overdo it, and give the horse frequent rests when schooling the lateral work. A horse that is having trouble here will show abnormal outward rotation of the limb. This twisting puts tremendous strain on the hocks.

Shoulder muscle pain can be a real problem. The shoulder muscles extend the shoulder as well as support the torso. The horse typically shows reluctance to extend the shoulder, especially at the walk, and will also tend to be girthy and reluctant to go forward/move out—often described as “pony-gaited.”

When horses develop muscle problems, the solution is to:

reduce schooling exercises (Don’t drill!)

increase warm-up

increase stretching

increase conditioning

Schooling teaches skills. Conditioning teaches fitness and strength. Conditioning is a form of schooling, but schooling is not necessarily conditioning. Schooling can actually bite you. Think about strengthening without injury.

From Fourth Level to Grand Prix, we begin to struggle with the effects of wear and tear, foot and hoof problems, flexor tendon injuries, suspensory problems and arthritis.

Palmar Hoof Pain can be a major issue, and can be due to a number of causes including navicular disease, hoof capsule heel pain, pedal osteitis, insertional deep flexor tendonitis, coffin joint pain. Diagnosis involves the use of hoof testers, xrays, and, more recently, ultrasound, which allows the application of specific therapies and rehabilitation programs. Generally, hoof pain is the result of long-term micro-trauma, which may eventually result in failure. Rest is NOT the ally of the older dressage horse.
Back problems are difficult to diagnosis, and are the result of chronic stress secondary to guarding. Thermography is excellent for diagnosis, and allows for specific diagnsosi and formulation of a treatment plan.
Arthritis is inflammation of a joint. Joints are made of friction reducing cartilage surrounded by a fluid filled capsule that functions to
1. Distribute nutrient rich fluid by movement
2. Adapt to pressure to provide shock absorption
3. Lubricate for movement
In arthritis/injury, the cartilage is damaged (loses its friction reducing capacity to varying degrees) and inflammatory cells enter to clean up the debris. Enzymes are released which change the joint fluid so that it becomes less lubricating, and cause further collateral damage to the cartilage. A synnovitis/capsulitis occurs due to working trauma which is enhanced by poor conformation. There is no cure for wear and tear.

PREVENTION

?”Maintenance” Injections:
Corticosteroids: NO! Chronic usage damages cartilage. Occasional judicious usage extremely helpful, however.
Hyaluronic Acid: Natural substance in joint fluid that gives it its stickiness. Lubricates the joint and is anti-inflammatory.
Adequan: Similar. It is chondroprotective and binds to damaged cartilage. It inactivates enzymes and restricts enzymes.
Oral GAGs. Provides substrates to build cartilage. Only Cosequin has the clinical studies. Glucosamine appears to be the most important ingredient.

It was our misfortune that the room was reserved for another meeting, because Dr. Turner could have gone for another hour or two. He was a wealth of knowledge, and we would have liked to pick his brain much much longer. If you ever get the chance to hear him speak, I would highly recommend it.

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