Jennifer L. Wright, DVM
A: For those not familiar with this sport, barrel racing is a speed event in which a horse and rider attempt to complete a specific cloverleaf pattern around barrels placed in a triangular pattern in the fastest time. Quarterhorse, Appendix Quarterhorse and Thoroughbreds are the predominate breed(s) used, and their ages range from the young 3 year old to the mid to late teens. Barrel racing horses need not only to be fast, but also strong, agile and intelligent. In general, repetitive movements of horses performing certain sports may cause predictable injuries, such as heel pain and distal hock lameness in cutting and reining horses, or suspensory ligament inflammation, distal hock lameness and back pain in dressage horses. In any sport, early detection of musculoskeletal disease is a key factor for prevention of further injuries and increases the likelihood of successful treatment. Therefore, determination of the prevalence of injuries causing lameness associated with a specific sport is useful because such injuries can greatly affect the intended use of the horse.
According to researchers at Texas A&M University (TAMU), changes in performance are often more obvious in barrel racing than in other disciplines because the horses compete in timed events on an identical cloverleaf pattern, and times generally remain consistent (taking into account variables such as footing and a slightly different sized course). An increased time to complete the pattern may indicate a physical ailment, and the most common performance-related complaint by riders was that their horse refused or failed to turn around the first barrel. Riders also complained that their horses experienced a decrease in speed, made wide turns around the second or third barrel, ran past the barrel, ran with their tails in the air, would not enter the arena, would not turn to the left and/or would not take the correct lead.
Barrel horses are subjected to sharp turns at high speeds. The researchers at TAMU found that these conditions placed heavy loading and torque on the horse’s forelimbs. The majority of horses in their study (118 horses) exhibited forelimb lameness (48% right, 43% left), while 47% showed only a hindlimb lameness. Front foot pain was the most common and accounted for 33% of the lameness, followed by osteoarthritis in the distal hock joints (14%) and suspensory ligament desmitis (13%). A different study performed by researchers at the College of Veterinary Sciences, Austral University of Chile (63 horses) determined that the front fetlock joint was the most frequent site of injury, with the right fore fetlock being more commonly affected that the left fore fetlock. The disproportion between right fore and left fore lameness likely stems from the fact that the right fore bears a greater load (assuming that the horse turns the first barrel tracking right, as most do)…it is theorized to occur because the first barrel is positioned on the horse’s right side, and the horse travels at maximum speed to this barrel before rapidly decelerating to turn around the barrel.
Interestingly, this data differs from reports of injuries in flat racehorses from the United Kingdom in which left and right limbs were equally affected by lameness in both forelimbs and hindlimbs (clearly the biomechanics of barrel racing is different than just flat racing).
Common sense would dictate that there are many variables that contribute to where each individual barrel horse is going to develop the most “wear and tear,” such as differences in shoeing, physical conditioning, footing, tack, rider technique, etc. Additionally, soft tissue injuries may also occur either separately or concurrently with joint injury or inflammation. The focus of this Ask The Vet answer, however, specifically addresses the question about how to determine when intra-articular injections (“joint injections”) are necessary and when they are contraindicated. The answer is long, as there is a lot of thought that should accompany this decision. An ethical veterinarian will deliberate, as described below, before injecting your horse’s joints.
First, a little about joint anatomy as discussed in my last newsletter article about systemic joint care…your horse’s joints are designed to flex, compress and extend hundreds of times per day while carrying his weight for years on end. Add a rider’s weight and increase athletic demand, and some level of joint inflammation will result due to repeated trauma or stress to the joint. The definition of a joint is “the junction between two or more bones.” Joints have several components, including: collateral ligaments (which prevent the lateral or side to side movements of bones), synovial fluid (the fluid which fills the space between the bones and provides lubrication and nourishment to the cartilage), joint capsule (which stabilizes the joint and contains all the structures of the joint), synovial membrane (the inner lining of the joint capsule which produces and regulates the synovial fluid), and articular cartilage (the soft structural tissue that covers and cushions the ends of the bones where they meet to make up the joint). The cartilage is a framework of tissue composed of collagen fibers, which give the structure its strength. The collagen is interlaced with proteoglycans, which are long, protein-based molecules with multiple attached glycosaminoglycan (GAG) chains that trap water within its matrix. As a joint flexes, the cartilage compresses and expands, forcing water in and out of its collagen matrix to provide a shock absorbing effect.
The term “arthritis,” or inflammation of a joint, can be used to describe any spectrum of joint disease ranging from early, mild, barely detectable soft tissue inflammation within the joint to chronic, severe, crippling cartilage degeneration and bone spurring. Traumatic joint disease in horses includes synovitis (inflammation of the fluid producing synovial membrane), capsulitis (inflammation of the fibrous joint capsule) and osteoarthritis (degeneration of the articular cartilage and underlying subchondral bone). In many cases, every day repetitive microtrauma produces minute damage within the joint structures that triggers mild inflammatory responses to make repairs. Normally, the body’s own defenses control inflammation and the joint remains healthy and sound.
Sometimes, however, the rate of degeneration exceeds the rate of regeneration and arthritis begins to develop. If the inflammatory process overwhelms the body’s ability to contain it, either from a single acute injury or from many years of use, a cascade of events ensues: inflammatory enzymes break down the thick, slippery lubricating synovial fluid, which becomes thin and watery. Proteoglycans are lost and collagen fibers lose structure, diminishing the cartilage’s ability to retain lubricating water. The cartilage becomes eroded or cracked, and this damage stimulates even more inflammation. The joint capsule fills with more watery fluid, leading to pressure, pain and stiffness. The cascade of inflammation leads to a buildup of more inflammatory enzymes that further degrade the synovial fluid and cartilage. Left un-checked, this inflammatory cycle can continue until eventually the cartilage tears or erodes away entirely, leaving the exposed ends of the bones to rub against each other.
It is not possible to cure arthritis at this time, but appropriate treatment can halt or slow the inflammatory cycle that results in permanent or progressive joint damage. The key is early identification of joint inflammation, ideally before any cartilage damage has occurred. Truthfully, most joint supplements do far more to prevent inflammation and joint damage than they do to treat it once it has started. Once marked inflammation has taken hold within a joint (resulting in radiographic changes and the clinical signs of lameness, stiffness, joint swelling, poor performance, etc.) direct treatment of the joint with intra-articular injections (“joint injections”) is often indicated.
If you are unsure if your horse is performing at their peak, or especially if you suspect a problem, arrange for your veterinarian to perform a soundness evaluation (sometimes called a lameness or performance evaluation) to evaluate your horse for lameness or gait abnormalities. For my clients, a soundness evaluation is a very comprehensive examination of your horse both in and out of tack. To begin, I collect as much information about your horse’s history as possible…such as how long have you owned him, what medical and/or lameness history accompanied him, what treatments/therapies/medications/supplements have been administered, what is his conditioning schedule, when is he due to be shod next, what does he eat, what is his preventive health care program, what performance issues is he currently having? While we’re talking about his history, I am evaluating his posture and conformation, reactions and attitude or frame of mind, hair coat, body condition, the manure in his stall, cleanliness of his water buckets, where he eats his hay…then I put my hands on him. I perform an acupuncture point scan, palpate the muscles in his neck, shoulders, chest, back and hindquarters, motion his spine and all the joints in his limbs, palpate the tendons, ligaments, joints and tendon sheaths in all his limbs, hoof test all four feet and evaluate foot balance, and briefly check his teeth and eyes. Next I evaluate saddle fit. By now, I have a very good impression of your horse’s general state of health, areas of discomfort, any other directions that his health care may need to take (i.e. screening for gastric ulcers, foot rebalancing, chiropractic and/or acupuncture, dental care, nutrition counseling, etc.) and (very importantly) whether or not there is any reason why a treatment, such as joint injections, would be contraindicated or deemed unsafe for your horse.
The actual soundness examination, or the evaluation of your horse in motion, comes in a variety of different “flavors.” I invariably prefer to see your horse ridden and performing their job as is expected of them. However sometimes I will evaluate them in hand or on the longe line, without the rider’s weight on their back, first. Under saddle, I will ask to see your horse at the walk and then at the jog/trot on a straight line and in a circle both directions (often on a figure 8). The trot is the easiest gait in which to identify lameness, as it is the most symmetrical gait. Circles or turns often accentuate lameness, particularly if the lame limb is on the inside of the circle, and straightaways accentuate asymmetry. Next I will ask to see your horse accept and maintain the correct canter/lope lead tracking both directions. I may also ask the rider to perform upward or downward transitions, to ride a certain pattern, ride on a harder or softer surface, or ride either collected or on a loose rein in order to further evaluate the way in which the horse travels. Any observed lameness is graded on a scale of Grade 1-5 (1: Lameness is difficult to observe and is not consistently apparent, regardless of circumstance; 2: Lameness is difficult to observe at the walk, or when trotting in a straight line, but consistently apparent under certain circumstances; 3: Lameness is consistently observable at the trot under all circumstances; 4: Lameness is obvious at the walk; 5: Lameness produces minimal weight bearing in motion and/or at rest or a complete inability to move).
Flexion tests are performed after the evaluation under saddle, often with the rider still “up” (some horses do not tolerate flexion tests well and are handled in hand for the rider’s safety). The purpose of this test is to simulate stress on a particular region of the limb, and is accomplished by holding a joint or joints tightly flexed for a predetermined amount of time then immediately evaluating the horse’s gait at the trot. A “positive” flexion test indicates that the horse appeared lame when asked to trot off. The positive flexion test may be further defined by a “rating,” commonly on a scale of 1 (very mild or transient lameness) to 5 (severe lameness). The results are subjective and depend on the veterinarian’s strength and method of holding the limb flexed. It is crucial to have “flexed” several, ideally hundreds, of joints to draw a conclusion regarding the significance of a particular result… I have developed an extensive personal “database” of flexions over the years from which I draw upon to determine whether each individual horse’s flexion is within normal limits or abnormal. Each limb may be divided into “upper limb” and “lower limb” for initial flexion tests, and a particular joint specifically re-flexed to further narrow down the affected region of the limb. The horse’s balance and the range of motion of all the joints are also concurrently evaluated during the flexion tests.
If lameness (pain, shifting of weight, shortened stride, alteration in limb movement or foot fall, lack of fluidity through transitions, asymmetry of gait, inability to maintain the correct canter lead, reluctance to travel a certain direction or at a certain gait, etc.) and/or a significantly positive flexion test is observed, or if abnormal findings upon palpation of your horse’s limbs are noted, further evaluation of your horse is warranted. This may include regional diagnostic anesthesia (“nerve blocks”) to further pinpoint the location of the lameness and/or imaging modalities such as radiography (“x-rays”) and ultrasound. In cases of obscure lameness, lameness occurring in multiple limbs, or lameness localized to the foot/extremity, advanced diagnostics such as nuclear scintigraphy (“bone scan”) or MRI may be recommended.
The importance of performing additional diagnostics to pinpoint the location and positively identify the cause of lameness is paramount to your horse’s long term athleticism. If the cause of the lameness or poor performance is an injured tendon or ligament, the course of action should be the appropriate treatment and rehabilitation of that particular soft tissue structure, not joint injections. If the lameness is localized to a joint BUT there is a bone chip, fracture, cartilage or meniscus tear, joint capsule or collateral ligament tear, surgery or other therapies are recommended, not joint injections (medications may be deposited within the joint, but not with the intention of keeping the horse in work or competing at the same time). Joint injections may be appropriately administered if the lameness is due to arthritis or synovitis, the typical end result of daily “wear and tear.”
A common misconception surrounding joint injections is that “you can just tell” when the horse needs them. After years of treating the same horse, performing the same job, with the same rider, with the same soundness examination findings documented in the medical record numerous times and multiple sequential positive responses to the same joint therapy, I have found that while an examination is always necessary, repeating diagnostics such as radiographs and/or nerve blocks may not be necessary and that one can proceed directly with a joint injection. However, if I am examining a horse that I have not cared for through multiple show seasons OR if my examination findings are not similar to previous findings that responded well to joint injections, it is prudent to perform a thorough evaluation to confirm that joint injections are the treatment that is best for your horse. A few other misconceptions are that joint injections need to be placed on a “maintenance schedule” or that once a joint is injected, it will need to be continually injected in the future. The decision to inject your horse’s joints is based on a tremendous amount of information gathered by your veterinarian, as damage may occur to the joint if not performed appropriately. In my mind, it needs to be “the right joint, at the right time, with the right medication.” I will only inject a joint when it appears that the joint needs medicating, not based on the calendar, and only if the horse can safely continue in work following the brief aftercare period. I only inject the joint(s) that need it. I always use the medication that is the safest and most effective for that particular joint and horse. I will not inject joints in a horse that has an injury that requires rest and rehabilitation. So, let’s look at a few case examples:
Case Example #1: A 9 year old QH barrel racing gelding is presented for a performance evaluation. His owner is concerned about the fact that he has become fractious in the holding area and is running past the third barrel. He has not had any medical or lameness issues in the past, except for a foot abscess in the LF a few years ago. His physical examination is unremarkable, but he demonstrates a Grade 1/5 LF lameness under saddle at the trot tracking right on a hard surface. He is positive 3/5 to flexion of the LF lower limb, and all other flexions are <1/5. He trots sound under saddle both directions on a hard surface following two “nerve blocks” in the LF which numb his entire digit (pastern and foot). Radiographs obtained of his LF foot indicate mild to moderate osteoarthritis of the pastern joint and no other significant findings. After determining that there are no concurrent soft tissue injuries or medical conditions that would render the use of steroids unsafe, I inject his LF pastern joint.
Case Example #2: Consider the same horse in scenario #1 EXCEPT that his radiographs are normal. Further examination of his digit with ultrasound demonstrates a small core lesion in his lateral straight distal sesamoidean ligament in the back of his pastern. I then discuss treatment and rehab options with his owner…
The joints that are most commonly injected are the front coffin joint, front fetlock joints, distal hock joints and stifles. However, pastern joints, carpal (knee) joints, cervical (neck) and back joints and sacroiliac joints may also need treatment. One or more joints may be injected at the same time, as long as a safe total amount of medication is used. Because hock arthritis is typically a bilateral issue (occurring in both the right and left sides), it is most common to inject both the right and left hocks at the same time….there are four joints in each hock, and it is most common to only inject the bottom two “flat” joints of each hindlimb. The other joints in the body are injected as dictated by the lameness evaluation.
The medications used are often delivered into the joint as a “cocktail” preparation, and typically include some type of steroidal anti-inflammatory, hyaluronic acid and antibiotic. There are many different types of steroids differing in their rate of onset and duration of action, but typically a quick acting and short lasting steroid is safest for the joint. Steroids are invaluable for their anti-inflammatory and pain killing effects BUT it is wise to use them judiciously because steroids may actually degrade and damage cartilage if used too often or at the wrong dose. Hyaluronic acid, a naturally occurring thick liquid that surrounds and lubricates joints, is often either thinner or decreased in inflamed joints. Similar to steroids, there are many different types of hyaluronic acid available for the use in joint injections. It is key to select the hyaluronic acid with the most appropriate “molecular weight” for the intended joint. Finally, a “joint friendly” antibiotic is also delivered into the joint to help prevent post injection infection. Less commonly, a substance called Interleukin Receptor Antagonist Protein (IRAP) is injected into the joint instead of the “cocktail” preparation. IRAP is a very effective anti-inflammatory substance derived from the horse’s own blood, and is typically used when the use of steroids are contraindicated (i.e. horses with Cushing’s disease, history of laminitis, or history of immunosuppressive illness such as EPM or Lyme disease, etc.).
The purpose of the injected medications is to decrease inflammation within the joint and to help restore the normal joint physiology. This in turn decreases pain and either halts or slows the progression of joint damage. Occasionally a joint will “flare” after an injection, meaning that it will become more inflamed, swollen and painful than before the injection. This is typically due to an adverse reaction to either one of the medications or the physical trauma of the needle penetrating the joint capsule. These “flares” are typically transient and respond well to the appropriate treatment. The greatest risk of joint injections is a post injection joint infection. I have never had a post injection joint infection in any of my patients, but I take serious precautions to prevent them from occurring.
Because the barn or stable environment will never be able to be turned into a sterile environment, it is very important to prepare for the joint injection procedure. The typical joint injection procedure goes like this: Your clean and groomed horse is brought into an area that is swept clean and free of a breeze. He is administered sedation and the joint to be injected is scrubbed with a surgical soap twice and rinsed twice, the last rinse consisting of alcohol. Using sterile gloves, the medications are drawn into a sterile syringe with a sterile needle. A different sterile needle is placed into the joint, the syringe is attached to the needle and the medication is deposited into the joint. It is very important for the horse to be adequately restrained during the injection for safety reasons and to prevent the bending or breaking of needles. Some of the joints have large entry sites and some joints have an entry site the size of the tip of a ballpoint pen! The veterinarian must be extremely familiar with anatomy to accurately deposit the medication in the correct location. The joint’s synovial fluid may leak from the needle during the injection procedure, allowing the veterinarian a “sneak peek” into the health of the joint. Normal joint fluid is clear or slightly yellow (termed “straw colored”) and should have a viscous string-like quality (similar to stringing egg whites between your fingers). Joint fluid from inflamed joints is often clear or slightly blood tinged and watery. Some joints are “dry” with very little fluid, and other joints are swollen with excessive fluid. Sometimes the joint capsule feels “crunchy” when the needle penetrates it…another indication of chronic joint inflammation. It is easy to inject the entire dose of medication in some joints, while other joints will not accept the entire dose (indicating a “narrowed joint space”). All of these observations should be recorded in your horse’s medical history for future reference by your veterinarian.
Typical aftercare instructions include stall rest for 24 hours, followed by normal turnout with no riding for 2 more days. If a bandage was applied after the injection, it may be removed after 24 hours. If a bandage was not applied, grooming or bathing of the injected area is not allowed for 24 hours. A 5-7 day course of non-steroidal anti-inflammatories is often also prescribed. Additional adjunctive recommendations may include oral joint supplements, systemic joint supplements (such as Adequan or Legend/NexHA), shoeing changes, conditioning recommendations, etc. I like to see improvement in the horse’s comfort level under saddle within 2 weeks, and I prefer that the positive effects of the joint injection last for at least 6 months. I will not routinely inject a joint more often than every 6 months, preferably not more often than yearly, and definitely only when the horse shows signs that it may be needed again. If a horse “needs” joint injections more often than every 6 months, it is time to review their activity level and care to determine if a drop in competition level or change in conditioning method is necessary OR if a different injury or source of soreness is plaguing them.
It is a must to work closely with your veterinarian to determine if joint injections are appropriate for your horse, as unnecessary or inappropriate joint injections may cause irreversible joint damage or other illnesses and health issues. A thorough soundness evaluation and the appropriate diagnostics are key in the decision making process. When administered “in the right joint, at the right time, with the right medication,” and when combined with an optimal conditioning/rest balance and a comprehensive health care program, joint injections can work wonders to improve and prolong the career of your barrel horse…1D sounds good to me!