It is estimated that close to 90% of horses will develop joint related lameness conditions and arthritis over their lifespan. The frequency rate obviously climbs as the horse ages, but those younger competitive horses are also at an increased risk of joint disease. A joint allows for motion in the body, but as the joint begins to deteriorate, not only is that motion impaired, but with it there is often a high level of discomfort. This can then create a limiting factor impairing performance for the equine athlete and a decreased quality of life for the aging horse. Are there better options for managing joint disease and arthritis in the horse than what we are currently doing?
A joint is the junction of two bones present within the body, which allows for movement to various degrees. There are numerous joints present in the horse, but often horse owners just associate readily with the joints present in the legs including the carpus, hock, fetlock, pastern, and coffin joints. Although these are the most commonly affected and recognized by horse owners, there are in fact numerous other joints, including those higher in the limbs and along the vertebral column of the back, not to mention those involving the head and jaw region.
There are many terms used to related to joint degeneration, including arthritis, osteoarthritis, or degenerative joint disease. There are other conditions, including osteochondrosis dissecans, which are not arthritic conditions, but can contribute to arthritis over time.
What Happens When a Horse Joint Degenerates?
A joint is the junction between two bones, which is outlined in the image below, enclosed by a layer of tissue called the joint capsule. The space between the two bones, where they meet, is referred to as the joint space. The two bone ends should essentially glide across one another to facilitate movement. To do this, the ends of the bones are covered in articular cartilage, which facilitates the movement and protects the ends of the bone, almost like an eraser over the end of a pencil. To further facilitate smooth movement, the cells within the joint capsule secrete a sticky fluid called joint fluid, which helps to lubricate the joint and provide friction-less movement.
The joint is considered a ‘sacred’ place due to it being separated off and secluded by the joint capsule. The joint itself is sterile and sealed off from the surrounding tissues. Joint degeneration occurs slowly over time, unless some acute traumatic situation arises or there is a localized infection in the joint to speed up the process. The process of arthritis or degeneration actually starts in the soft tissue layers around the joint and the end result over time is the destruction of the bone and joint. We often tend to think that we must see obvious changes on the radiograph within a joint to indicate that there is joint degeneration. By the time we see these changes the process has been well underway.
As the joint degenerates or is impacted, there are stages of progression that take place.
First, the condition usually starts in the soft tissue around the joint, which includes the joint capsule and the joint itself. These tissues become stressed, inflamed, and begins to respond by becoming thicker and often secreting more joint fluid to lubricate an irritated joint. This is commonly seen as joint thickening, or fluid accumulation within a joint or joint space, which is referred to as an effusion. In those cases, there is often lameness in the horse and pain on flexion of the joint, but when radiographs are taken there is little to no evident bone degeneration present.
Second, the condition starts to progress inward, impacting the joint on a deeper level. The already irritated joint capsule that was secreting excess joint fluid now becomes compromised, and produces a lower level of fluid. This is due to tissue changes in the joint capsule related to inflammation, which impacts cellular function. The lowered joint fluid production results in less lubrication to the articular cartilage, and then friction becomes a factor. As this friction becomes more of a factor, the internal structures of the joint now become compromised. This decrease in joint fluid can be seen in any stage of arthritis but is noted when a veterinarian injects a joint but is only able to retrieve a small amount of joint fluid, which is commonly referred to as a ‘dry joint’.
Third, the internal structures of the joint begin to breakdown as a result of the decreased fluid production. This fluid not only lubricates the structures, but also helps to provide nourishment to the cartilage and other components. When there is less fluid, there is less lubrication but also a lower nutrient provision. A result is degradation of the internal structures, beginning with the joint cartilage. Over time, the cartilage begins to erode, or wear away. As this happens, we begin to see changes in the joint space on x-rays and additionally, a fuzzy type of look to the region. Over time, as the cartilage erodes, the underlying bone becomes exposed and begins to take on more stress.
Fourth, the joint begins to demonstrate bone type changes, further erosion of the cartilage and subchondral bone. In addition, we may also see new bone formation in the shape of bone spurs or exostosis, which are a means of the body to try to stabilize the failing joint. These changes are generally pretty obvious and prominent on radiographs.
Here are some comparison radiographs to demonstrate normal and degenerative:
What Causes A Horse Joint to Develop Arthritis?
A joint will degenerate due to many factors, but the common line denominator is joint stress which then creates inflammation within that structure. This joint stress can occur due to a variety of factors and is dependent on the horse and their usage.
An older horse will experience natural joint degeneration over time due to the aging process, which is directly related to oxidative stress damage and inflammation. Over time, the tissues within the body, including the muscles, tendons, bones and cartilage will all experience wear and tear. As this process begins, it can become like a viscous cycle of events with one event leading to another.
The competitive equine athlete is obviously at a much higher risk of degenerative joint disease due to increased wear and tear upon the joints. Whether if the horse is a hunter, a jumper, dressage, barrel racer, or competes in roping events, the joints are often taking a much higher level of abuse than they were originally intended. This increased stress upon the joint initiates the inflammatory process, which then creates the degenerative changes within the joint space.
Foals and younger horses are often at risk of degenerative joint disease secondary to infections within the joint space. This can also occur secondary to a traumatic event or joint injection. The bacteria present within the joint initiate an immune response, which then leads to inflammation and in most, degenerative changes.
The presence of conformational issues in the horse can dramatically impact joint degeneration. If a horse is toed-in or out, as an example, it will lead to increased stress upon the joint. The same will happen if a horse is ‘camped under’ or ‘camped out’, regarding the carpus or the hock. Other joint related conditions, including O.C.D, are physical defects in normal cartilage development. They are really a weak spot in the cartilage and can signify improper cellular signaling at the time of development. Given the weakness that they indicate, this may mean an increased risk of joint instability and degeneration in some patients. Even with surgery, many of these patients suffer the ill effects of joint degeneration down the road in their life. Whether if this is directly due to the presence of an O.C.D. lesion or an effect of the surgery is debatable.
Joint Therapy Options for Prevention and Treatment of Arthritis
As in the case of most disease conditions, it is far better to intervene on a level of prevention than it is to pursue a situation after disease has taken place. As the saying goes, “an ounce of prevention is worth a pound of cure.”
In order to understand treatment or therapy options, we must first understand the workings of the joint.
The process of joint degeneration involves one main cellular signaling event, which is inflammation. The process of inflammation is at the root of everything negative that occurs within the joint. As the process of inflammation grabs hold, degenerative changes occur. One of the first, as mentioned, is a reduction in joint fluid production or a reduction in the quality of that joint fluid. This is due to inflammatory changes within the joint capsule, impairing the production of fluid. Then, as the condition progresses inward, cellular changes develop within the cartilage resulting in a breakdown of this tissue. That may mean that there is less glycosaminoglycans present with hyaluronic acid to maintain cartilage health and bind water for a cushion effect. Then, as the condition further progresses, cellular changes occur within the bone, altering bone production and bone loss pathways.
The ultimate question is where do you choose to intervene and how?
Many horse owners elect to use typical joint supplements including glucosamine, chondroitin, and maybe hyaluronic acid. Although these supplements can provide benefits and are supported by research, there are a few things to consider. The first main concern is the dose that is utilized in the supplement that is chosen. Most research studies in horses are using upwards of 10-20 grams of each ingredient. Many supplements on the market are only providing a fraction of this level, so their effects are not well noticed in patients. The second thing to consider is the time frame to see clinical improvement. In most research studies, in horses and humans, clinical benefits were seen generally after 6 months of daily usage, resulting in an improved range of motion and comfort, but not all patients benefited.
Another option is through an injection in the muscle of glycosaminoglycans (Adequan®). These injections are commonly performed by the owner or veterinarian, usually completed as a course of several injections in a series. These injections, of which there are generics on the market, work very similar to the oral use of glucosamine and chondroitin. The whole purpose is to provide a framework for the cartilage and attempt to rebuild the structure. The injectable form is perceived to provide a higher level of these nutrients as opposed to the oral route. Do they work? Yes, they can provide benefits to many horses but ideally are utilized in the early stages of joint disease. The further the condition is progressed, the less likely they are to help. They can also be fairly expensive, and not every horse will respond or benefit from their usage.
By far the most common approach to joint disease is through the utilization of joint injections. This is a common practice for veterinarians and can make up a large portion of their practice income, especially if involved in the sport horse industry. Joint injections can be very effective, in the short term, for most equine patients. In most cases of an injection, there are several medications that can be used. In most, a corticosteroid is chosen to aid in reduction of inflammation, which is then usually added to a hyaluronic acid to increase lubrication effect to the joint. While these injections can provide quick improvement for many horses, they are not without their side effects. Most injections go smoothly, but in some cases, infection can occur which can be disastrous and career ending. In other cases, sometimes the needle breaks off during the injection which can warrant surgery and also create major joint damage. In all cases, one must realize that joint injections are not curing any condition, and the more often they are utilized, the more the horse becomes dependent upon them. While they do help to slow down the inflammatory process, they are limited in that respect, only tackling a small piece of the puzzle. Some studies have indicated that long term corticosteroid use in the joint can hasten or speed the degenerative process, leaving the patient worse over time than they were originally.
Are There Other Options to Protect the Joint?
To be honest, yes, but most other options are not well received or given enough credit. Two things are important when it comes to joint health. First, intervene early or ideally on a prevention level. Second, keep in mind that the process of inflammation is at the root of it.
A horse owner can intervene using glucosamine, chondroitin, or hyaluronic acid, in an attempt to support and rebuild joint cartilage, but these ingredients are often doing very little to impact the inflammatory process. Research does indicate that they do aid in modulating inflammation, but if inflammation is our target…you can do much better.
In most cases when utilizing these supplements or ingredients, we are often left fighting an uphill battle. The horses do respond and improve, but not as much as we desire. In most cases, this is because that inflammatory response is still ongoing. The question is why and what more can you do?
First, realize that inflammation is often instigated by other factors present in that horse or even their diet. If a horse is not properly trimmed and balanced in the feet, this will lead to increased stress upon the joints, not to mention tendons and ligaments. So, in a case of arthritis, it is imperative to evaluate the feet and not just rely on a farrier to make those decisions. Get involved, understand the feet, and make observations and judgement calls based on what you see.
Second, the diet and other factors such as stress are also co-contributors to the inflammatory process. Foods that are given to your horse can either create more inflammation or stifle it. Excess grains, as an example, can dramatically raise levels of inflammation in the body, which can then contribute to more joint problems. Feeding the wrong foods period can create more issues, even if those foods are perceived as being healthy. An example would be using excess oils or even Flax seed in an already overweight horse. Although those foods are potentially healthy, they are also a source of high calories which can add to the weight problem and therefore contribute to more inflammation.
Third is conformation. No horse is perfect, mind you, but you need to realize that if there are conformational issues going on, they may be creating hurdles that can’t be overcome. In many of those cases of conformational issues, it is even more important to make sure the feet are being addressed properly and kept balanced. Most of these horses will wear improperly over time and require more frequent trimming and balancing to keep the structures supported.
What else can be done? Target the inflammatory process specifically!! Ideally, this is done through the proper use of herbs and foods.
There are many foods out there that impact the inflammatory process on a positive note, but most of these foods are whole-foods, not processed foods. If your horse is on a processed food diet or grain, or even if you are using a commercial vitamin-mineral supplement, it may be time to consider a move. Going with whole foods, such as whole grains, vegetables, and a high-quality forage can provide numerous benefits not just in inflammation reduction but also cellular health.
There are many whole food herbs that are available that can pack of punch in regard to nutrition and inflammation. Several examples include:
- Alfalfa herb
- Barley grass
Then there is the topic of herb usage to combat inflammation. Again, here we likely have hundreds if not thousands of herbs that demonstrate anti-inflammatory properties, but not all are backed by research. For some people, they like to see clinical research to support an herb before they use it, while others know the history of the herb and rather go with that.
In terms of herbs to directly impact inflammation, again there are numerous including:
- Turmeric (curcumin)
- Devil’s claw
- Red clover
The list goes on and on, and most of these are supported by research. However, again, one needs to keep in mind the dosage utilized in most studies, relating that to horse. On average, if a person is using Turmeric in their horse, as the whole root powder, the dose can range from 20-30 grams. If one is using one of the active ingredients, Curcumin, then the dose is much lower but still high at 5-15 grams. Boswellia and many other herbs tend to have lower doses, but often still much higher than most traditional supplements utilize.
The benefit to using herbs, ideally in combination to gain synergistic benefits, is that they can impact the inflammatory process more completely, than even a corticosteroid medication. By impacting the process on a higher level, it is not uncommon to see not just a reduction in pain or discomfort, but on a cellular level there is often an alteration of the negative pathways. This may mean that it is possible to slow the bone or cartilage degeneration through the use of herbs. It may also be possible with long term usage to rebuild that bone or cartilage. In our practice, we mainly rely on herbs to promote joint health in our patients and personally, I feel that in the long and short term, they provide a higher level of benefit to the patient.
Joint Function and Protection is in Your Hands
Ultimately, all horses will likely experience joint dysfunction and degeneration. The question is whether if you as an owner choose to recognize the problem early and intervene, or if you wait until the problem has clearly developed? The longer one waits, the more difficult it is to control and manage no matter which route is taken.
There are many options to promote healthy joints and you likely don’t need a specialized ‘joint’ product or supplement. You can make dietary modifications and include specific herbs into your horse’s program to help encourage health joints and cartilage, keeping in mind that inflammation modulation is your end goal.
Author: Tom Schell, D.V.M., CVCH, CHN