Horse Joint Injections from A to VBy: Dr. Lydia Gray
Your veterinarian just recommended joint injections for your horse. What exactly IS a joint injection? Are there different kinds? And how does a joint injection fit into your horse’s overall program to help maintain soundness and prolong his athletic career? Understanding your options when it comes to treating and preventing joint disease in horses is the first step in providing optimal care for your performance horse.
What exactly IS a joint injection?The term “joint injection” can mean different things to different people. Basically there are three types of FDA-approved injectable joint therapies in horses: intra-articular (IA), intravenous (IV), and intramuscular (IM). Depending on a horse’s use, soundness problems, and which/how many joints are affected, your veterinarian may prescribe none, one, or a combination of these prescription medications for joints. Let’s dive deeper into each one for a better understanding of who, what, when, where, and why.
Are there different kinds of joint injections?
Intra-articularIntra-articular is often abbreviated “IA,” and means that a solution is injected directly into the joint itself. Clearly this must be performed by a licensed veterinarian, experienced in the technique, under sterile conditions. One advantage for choosing this administration route is maximizing the effect of the medication by putting it exactly where it is needed. Disadvantages include the expense and inconvenience of intra-articular joint injections as well as the associated risks (joint “flare,” joint infection, further damage to the joint, and even laminitis, a possibility if corticosteroids are used).
Veterinarians have several choices when it comes to delivering medication right into the joint space. FDA-approved drugs for IA injection include Legend® (hyaluronate sodium) Injectable Solution, Adequan® I.A. which is polysulfated glycosaminoglycan or PSGAG, and the corticosteroids Depo-Medrol® (methylprednisolone) and Vetalog® Parenteral Veterinary (triamcinolone), which may be administered by themselves or in conjunction with hyaluronic acid. Sometimes a small amount of antibiotic such as amikacin is added for infection control purposes.
Commonly injected joints include the hocks, stifles, and knees as well as the fetlock, pastern, and coffin joints. After ensuring adequate restraint, the joint area is cleansed for approximately 10 minutes, the soap or scrub is rinsed off with alcohol and the medication is injected using sterile gloves, needle, and syringe. Depending on the medication used and the veterinarian’s preference, the joint area may also be clipped or shaved. Usually horses are placed on stall rest for a day or two following the procedure after which they may gradually resume normal activity. In some situations one IA injection may be sufficient while in others, multiple joint injections may be necessary.
IntravenousThe shorthand for this next form of joint injection is “IV.” The most accessible vein in the horse is the large jugular vein found on both sides of the neck where blood is often drawn for Coggins and other testing. There is only one FDA-approved intravenous joint therapy, Legend, and while it does require a prescription to purchase, it does not necessarily have to be administered by a veterinarian. Owners and trainers who have been instructed in the proper IV administration of medication may prefer to inject this drug themselves, since the treatment protocol may involve weekly injections for a total of three treatments. While no local or systemic (body-wide) side effects were observed in pre-approval clinical field trials, post-approval reports do mention occasional depression, lethargy, and fever following IV use. Therefore owners and trainers should use caution when administering this product without the direct supervision of a veterinarian and observe the horse closely for side effects.
Legend is specifically indicated in the treatment of joint dysfunction of the knee and fetlock in horses due to noninfectious synovitis (inflammation of the synovial membrane) associated with equine osteoarthritis. Hyaluronic Acid, often abbreviated as HA, has a number of benefits within the joint, including stimulating the horse’s own body to make HA, providing a “protective barrier” over the synovial membrane, acting as a lubricating substance and decreasing the presence of inflammatory mediators (destructive enzymes).
IntramuscularThe final kind of joint injection is intramuscular, also known as “IM.” Again there is only one FDA-approved intramuscular joint therapy, Adequan® i.m., which is a slightly different preparation of the PSGAG approved for intra-articular use. For the treatment of non-infectious degenerative and/or traumatic joint dysfunction and associated lameness of the carpal (knee) and hock joints in horses, the optimal dosage of Adequan is 500mg (5ml) every 4 days for 7 treatments. The treatment can be repeated as needed and prescribed by a veterinarian. For example, a horse that is getting older and showing signs of stiffness might benefit from this regimen once a year before the start of riding season, while a horse competing year-round in the highest levels of his sport may respond to this regimen two or three times a year. There are no known contraindications (reasons not to use) to the use of intramuscular PSGAG in horses and many owners administer these IM injections themselves, rotating between the left and right sides of the neck.
Proven to relieve signs of non-infectious osteoarthritis, Adequan i.m. stops the destructive disease cycle, stimulates cartilage repair and reverses the joint disease process. Considered a “disease-modifying osteoarthritis drug” or DMOAD, it is a potent enzyme inhibitor that is attracted directly to traumatized knee and hock joints. There extensive studies have shown it readily passes through the synovial membrane and is taken up into cartilage where it concentrates and accumulates at the site of injury.
How does a joint injection fit into a complete soundness program?
Whether given in the joint, in the vein or in the muscle, FDA-approved injectable joint medications play an important role in managing joint health in conjunction with other therapies such as non-steroidal anti-inflammatory drugs (NSAIDs), oral joint supplements and corrective hoof care. It’s not uncommon for a veterinarian to design a treatment protocol that includes versions of both HA and PSGAG since they complement each other well, with HA targeting synovial membrane and PSGAG targeting cartilage. Often these treatment protocols include the use of a daily oral joint supplement that contains hyaluronic acid, chondroitin sulfate, glucosamine as well as other ingredients demonstrated to support healthy joints such as MSM, omega 3 fatty acids and ASU (avocado soybean unsaponifiables). Work closely with your veterinarian to develop a comprehensive joint health program that combines a variety of therapies with good horse management practices to prolong the soundness and career of your horse!
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