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Joint wear and tear is a part of every equine athlete’s life. As your horse ages, joints naturally become stiff and sore – a process that is accelerated with heavy exercise.
Intra-articular injections deliver medication directly to the affected joints. These injections are a reliable way to reduce pain and inflammation, supporting mobility and comfort in your horse.
Injections may be used to administer corticosteroids, hyaluronic acid, anti-inflammatory compounds, or platelet rich plasma. These treatments are most commonly used in horses with osteoarthritis, but may also be used to treat infections and other joint diseases.
While generally safe, there are some risks associated with intra-articular injections. These treatments can also be expensive and need to be repeated regularly to continue to work.
In addition to injectable therapies, there are many options to maintain joint health. Supplements, oral medications, exercise modifications, dietary strategies, topical treatments and bodywork are some of the modalities used to address joint issues in horses.
Consult with your veterinarian to determine whether joint injections are appropriate for your horse. Also, consider diet and management strategies to support your horse’s joint health and reduce reliance on pharmaceutical drugs.
Joint Injections for Horses
Joint injections are administered intra-articularly, directly into the free space between the bones within the joint capsule.
There are three main reasons to perform intra-articular joint injections:
- To block or anesthetize the joint in order to determine if a specific joint is the cause of your horse’s lameness
- To sample fluid (or synovial fluid) in the joint and determine whether there is infection present
- To introduce medications, such as anti-inflammatories, antibiotics, or other specific compounds
You and your veterinarian must take into account many considerations before deciding if joint injections are necessary for your horse. The type of injection used will depend on the intended purpose.
Joint Blocking
Anesthetizing or “blocking” the joint is a diagnostic tool used to identify where your horse’s pain originates from.
For example, let’s say you and your vet determine that your horse is lame in the hind end, but it is unclear whether the hock or the fetlock is the issue.
Your vet blocks the fetlock and asks to see your horse move again. If your horse is still lame, the source of the pain is not the fetlock. If your horse is now sound, the source of the pain is identified as the fetlock.
Synovial Fluid Sample
Synovial fluid is a clear, viscous liquid that provides lubrication and reduces friction in the joint.
If your horse is suffering from joint issues, your veterinarian may take a sample of the synovial fluid to determine the overall health of the joint. Your vet will examine: [1][2]
- Overall appearance of the fluid – the colour and thickness of the fluid can indicate infection or inflammation
- Protein concentration – too much protein can indicate infection or blood in the joint
- Nucleated cell count – an increase of immune or white blood cells
Medicating the Joint
If your horse is experiencing soreness, intermittent lameness, or stiffness in a joint, your vet will likely suggest medicating their joint.
Before thaking this step, your vet will want to perform a full lameness exam to determine which joint(s) are the source of lameness. A lameness exam can involve many steps, including a motion exam, flexion tests, “nerve blocks“, and diagnostic imaging.
In many cases, joint injections are recommended for horses suffering from osteoarthritis (OA). OA is a type of arthritis that involves progressive joint cartilage degradation. This results in inflammation, which leads to further degenerative change throughout the joint. OA ultimately results in pain, which can affect the horse’s performance and quality of life.
Depending on how your horse reacts to treatment, your vet may suggest routine injections yearly, bi-yearly, or on an as-needed basis. It is not recommended to inject the same joint more than twice in one year. [3]
Joint Injection Treatment Options
Intra-articular joint injections are primarily used to:
- Reduce inflammation, thus slowing disease progression and relieving pain
- Facilitate the body’s natural repair processes
The most common medications that your vet will inject into the joint are hyaluronic acid and corticosteroids.
Regenerative therapies, such as Interleukin-1 Receptor Antagonist Protein (IRAP(r)), platelet rich plasma (PRP), and Autologous Protein Solution (Pro-Stride®) are becoming more accessible and popular with owners and ambulatory veterinarians. [4]
Hyaluronic Acid and Corticosteroids
Hyaluronic acid is a natural component of healthy joints, making up part of the cartilage and connective tissues.
Corticosteroids are a class of synthetic steroid drugs used primarily for their anti-inflammatory properties.
Whenever there is damage to the cartilage of a joint, the body responds by sending inflammatory mediators to that site. This inflammatory process can become detrimental to the joint, ultimately causing more degenerative change and pain.
A combination of hyaluronic acid and corticosteroids are used in some joint injections to reduce inflammation and ease your horse’s pain. [5][6] Research by Dr. Auer first established the efficacy of medicating joints with HLA.
In a 1980 study, Dr. Auer treated horses with chip fractures of the radial carpal bones of both front legs with a hyaluronic acid injection into one leg.
These horses showed a significant increase in weight-bearing on the injected leg, to the point where there was no observable lameness on that leg. This study led to the development of HLA and corticosteroid solutions used today.
Compared to other joint medications, hyaluronic acid and corticosteroid injections are less expensive. However, they do not influence the body’s ability to regenerate joint tissue. They are a temporary solution to provide pain relief and must be re-injected on an ongoing basis to maintain efficacy. [5][6]
Interleukin-1 Receptor Antagonist Protein (IRAP)
Interleukin-1 Receptor Antagonist Protein is a protein that your horse’s body naturally produces to combat interleukin-1 (IL-1), one of the principle pro-inflammatory mediators in joint inflammation.
IRAP is collected by drawing blood from your horse, incubating the blood over specialized glass beads to isolate the target protein, and injecting the solution directly into the joint. [7]
IRAP may stop the inflammatory process and trigger regeneration of the cartilage within the joint. Cartilage is a protective tissue that sits over the end of the bones where they connect to form a joint.
Cartilage is extremely smooth and allows the joint to move fluidly without friction or pain. If this cartilage is damaged or inflamed, your horse can experience pain. [7]
IRAP therapy promotes the healing of damaged cartilage. A recent study examined the effects of IRAP in joints that underwent arthroscopy.
Not only was there a significant increase in anti-inflammatory biomarkers, but also there was a reduction in the breakdown of hyaluronic acid in synovial fluid. [7]
Regenerative therapies like IRAP injections are more expensive than traditional corticosteroids. However, they are becoming more accessible and affordable for owners and veterinarians to perform.
Platelet Rich Plasma (PRP)
Similar to IRAP, Platelet Rich Plasma injections also use a solution derived from your horse’s own blood. Your vet will draw a volume of blood from your horse and process it in a centrifuge – a device that spins fluids at high speeds to separate out components.
The centrifuge separates platelets from the rest of the blood. Your veterinarian will then inject that platelet-rich solution back into the joint. [8]
Platelets contain growth factors that stimulate tissue regeneration and cell reproduction. Injecting these platelets directly into the intra-articular space assists in healing cartilage and reducing joint pain.
PRP injections are not only used for osteoarthritis, This therapy is also beneficial for tendon or ligament tears because it stimulates regenerative effects. [8]
Although studies are limited, promising early evidence indicates that PRP promotes tissue regeneration and reduces inflammatory markers in the synovial fluid. [8]
Autologous Protein Solution (Pro-Stride®)
Pro-Stride® therapy is also made using a derivative of your horse’s blood. This orthobiologic medication is made by processing your horse’s blood into a concentrated solution of platelets, growth factors, and anti-inflammatory cytokines. [9]
This autologous protein solution is then injected directly into the joint to address soft tissue injuries, reduce inflammation, and slow cartilage degradation. Pro-Stride® protects the joint from damage and alleviates pain. [9]
In addition to osteoarthritis, Pro-Stride® has been used to treat bursitis, tendinitis, partial ligament ruptures, bowed tendons, lumbosacral stenosis, patellar luxation, joint laxity, osteochondral dissecans. [9]
Most research into the efficacy of Pro-Stride® has been conducted on dogs with ligament ruptures. Based on these promising results, researchers intend to further study the use of Pro-Stride® in equine osteoarthritis. [9]
The two-step process to make Pro-Stride® is proprietary and is more costly than traditional corticosteroid injections. However, it is becoming a more popular option compared to IRAP because it can be processed in 20 minutes and does not require overnight incubation.
Administering Joint Injections
The process of administering joint injections to your horse is the same regardless of the medication chosen. Injections should only be administered by a trained equine veterinarian.
For easily accessible joints, such as the hocks, knees, and stifles, injections are generally performed at your farm. To prepare for the procedure, make sure that the treatment area is cleaned in advance and minimize the number of people or horses walking around.
Choose a location that is clean, but with minimal airflow and away from activity. Fans, wind, or activity within the barn stirs up dust. This can contaminate the injection site and increase the risk of infection.
Procedure
Your veterinarian will clip the hair around the area they intend to inject. The veterinarian or an assistant will then scrub the injection site thoroughly with an antiseptic solution, working from the centre of the area outwards. They will repeat this process for approximately 10 minutes.
Prior to injection, your vet will sedate the horse and may also ask that the horse is twitched for their safety. Twitching the upper lip is a humane way to release endorphins and distract the horse from the unpleasant poke of the needle. Even with heavy sedation, horses can still react by kicking or stomping, which is dangerous for the vet.
Once the joint is prepared, your vet will don sterile gloves and handle all supplies as aseptically as possible to minimize contamination. The needle will be inserted into the joint, and the medication injected.
Don’t be alarmed if clear fluid leaks out of the needle. This is the synovial fluid that naturally occurs in the joint. [3]
Aftercare
After the injection, your veterinarian may place a bandage on the site or spray the area with liquid bandage. Your horse will need to remain on stall rest for the next 24 hours with no turnout or exercise.
Some veterinarians recommend you hand-walk your horse periodically the following day. In most cases, your vet will recommend a period of rest following injection, with a slow return to full work over 1-2 weeks.
Your veterinarian may suggest you administer NSAID medications such as flunixin meglumine (Banamine®) or phenylbutazone (Bute) to control any pain and inflammation post-injection. [4]
If your horse exhibits any heat or lameness of the area, let your veterinarian know as soon as possible. Heat and lameness could indicate serious infection that needs to be addressed immediately.
Risks of Joint Injections
Although rare, infection is a major concern with joint injections and synovial sampling. Inserting a needle into the joint space could introduce bacteria that can multiply quickly and cause serious issues.
Symptoms of joint infection include:
- Extreme lameness of the injected limb
- Heat and swelling of the joint
- Fever
These symptoms are usually observed 7-10 days after the injection. Call your vet at the first sign of anything, as joint infections can be career-ending and even life-threatening.
It’s important to remember that the risk of infection small and veterinarians take upmost caution in maintaining a sterile injection site. Some vets choose to inject antibiotics along with medication in order to reduce the likelihood of infection. [4]
Adjunct Therapies
To optimize the effectiveness of joint injections, it is important to make sure your horse has the proper nutrition to keep joints healthy.
Ensure that your horse is maintained at a healthy body condition. Carrying excess bodyweight puts added strain on the joints.
Always feed your horse a balanced vitamin and mineral supplement to avoid common deficiencies in the diet. Key nutrients for collagen synthesis and joint health include copper, zinc, Vitamin D, selenium, iodine and Vitamin C.
Methylsulfonylmethane (MSM)
MSM is a very well-researched and well-tolerated joint supplement that can be added to most feeding programs.
MSM is a source of the mineral sulfur, which is an important component of glucosamine and collagen. These are two proteins that make up connective tissue.
Research shows that MSM supports joint health by:
- Acting as an antioxidant to reduce cell-damaging free radicals
- Inhibiting cholinesterase, an enzyme that promotes muscle spasms and joint pain
- Decreasing the level of inflammatory compounds in the body [10]
In a study of horses involved in jumping competitions, feeding MSM reduced oxidative stress and exercise-indu