Equine Joint Injections: Case by Case
These procedures can be complicated by a horse’s age, purpose, and health; here’s how veterinarians approach various scenarios.
Joint injections are no longer novel procedures. In fact, they’ve become part of mainstream equine practice. They remain important topics of discussion, however, when it comes to keeping athletic or aging horses comfortable and staying up to date on evolving injectable options. I reached out to equine practitioners from across North America who focus primarily on sports medicine and asked them how they’d address unique lameness cases necessitating joint injections.
These cases, while fictional, are based on scenarios I’ve encountered in my own practice, and I’ve named them after some of my favorite patients.
Foxhunter With Fusing Hocks
Virgal is a 12-year-old Thoroughbred mare used as a foxhunter. She has experienced hock pain this season, and radiographs revealed the beginnings of fusion in her lower hock joints. The owner would like to try injections prior to surgical referral.
The equine hock comprises four joints, and its lowest two—the tarsometatarsal and distal intertarsal joints—are most prone to osteoarthritis (OA) and fusion. “In a horse with significant hock arthritis, I would generally recommend steroid treatment,” says Candice Crosby, DVM, senior associate at TD Veterinary Group, in Calgary, Alberta, and an official FEI veterinarian focusing.
Corticosteroid injections have been the mainstay of equine sports medicine since its inception, and they are incredibly effective at reducing inflammation of the joint itself. However, steroids aren’t always good for cartilage health. Eventually, cartilage degradation can lead to bridging and fusion of the joint.
“The selection of a steroid is less important for low-motion joints such as the distal intertarsal joint, although I often lean toward triamcinolone or betamethasone for most treatments due to reduced medication withdrawal time over methylprednisolone acetate for competition horses,” Crosby says. “For me, the timing of treatment will be important, not due to medication withdrawal times but to maximize the efficacy and duration of the treatment for the horse’s competitive season.”
She advises attending veterinarians to treat the lower hock joints with their steroid of choice, plus or minus hyaluronic acid, at least two weeks before hunt season begins, “but not too far in advance, because I would expect a reduced duration of efficacy of treatment in a horse with advanced osteoarthritis,” she adds. “I would also recommend the coupling of the targeted joint treatment with the use of a systemic anti-inflammatory, such as firocoxib (Equioxx), to help keep the horse comfortable for its job.”
Broodmare With Osteoarthritis
Topaz is an 11-year-old Quarter Horse broodmare carrying her fifth foal at three months of gestation. She has a history of fetlock osteoarthritis and was injected with triamcinolone prior to the most recent breeding. She is moderately lame and limps periodically out in the pasture. She shows pain on flexion of both front fetlocks. Firocoxib doesn’t improve her comfort.
Physiologic changes in mares during pregnancy mean they metabolize medications differently than nonpregnant mares. Further, the use of certain medications could affect fetal health. “For these reasons, I would first recommend the conservative use of a systemic anti-inflammatory and icing/supportive wraps to manage an inflamed joint,” Crosby says. “If a significant chronic lameness persisted despite conservative therapy, sometimes a targeted joint treatment ends up being the best option for the overall health and comfort of the mare during pregnancy.
“My gold standard would be the use of an orthobiologic joint treatment, such as autologous protein solution, as it would be the least invasive joint treatment for a pregnant mare as only one injection is recommended, while other regenerative products often recommend a series of treatments for best effects,” she adds.
Orthobiologic treatments are processed using the horse’s own blood, often stallside, to isolate properties beneficial to the joint. These treatments can provide targeted pain relief without the potential negative physiological and metabolic side effects (e.g., spontaneous abortion, harm to the fetus) of steroid use. The downside is these treatments are significantly more expensive than steroids.
“In most cases I would feel comfortable injecting a fetlock joint in a pregnant mare with a low dose of a steroid such as triamcinolone if I felt it was indicated for the quality of life of the mare and orthobiologic treatments were not an option financially,” Crosby says. “Treatment with polyacrylamide (hydro)gel (PAAG) could also be considered, although (manufacturers of) these formulations often recommend pretreatment with a steroid for best effects. Polyacrylamide gel works by reducing friction in a joint, which can be a very effective option for advanced arthritis.
Performance Horse With PPID
Fitz is a 14-year-old Morgan gelding with early onset pituitary pars intermedia dysfunction (PPID, formerly equine Cushing’s disease). His condition is well-controlled on 1 milligram of pergolide (Prascend) daily, and his owner shows him regularly in saddle seat shows. Earlier this year Fitz was diagnosed with coffin joint osteoarthritis. He improved on a polysulfated glycosaminoglycan (Adequan) series but is still experiencing performance issues.
Bonny Henderson, DVM, IVCA, CVA, CREP, owner of Henderson Equine Clinic, in Avon, New York, is a huge proponent of adjunct therapies. Prior to injections she recommends her clients try a variety of nutraceuticals to provide building blocks for the healing process and to decrease systemic inflammation. She says she’s had incredible results with this approach.
“I like to combine Eastern and Western medicine for my patients,” Henderson says. “I try to get people to treat the whole horse, identify what is causing the lameness and why exactly the cause occurred—in other words, the functional limitations predisposing the horse to the injury itself. Then I treat both the lameness and the underlying cause.”
This case requires careful attention because of the horse’s endocrine disease. “PPID horses can be more sensitive to steroids, and this can result in laminitis,” says Henderson. “Even if he’s well-maintained, you have to take into account his body condition score and hoof capsule. If the hoof capsule contains external growth rings wider in the heel than the toe, you’ve likely had some prior clinical or subclinical (not showing obvious signs) laminitic episodes. There is a lot of concussion going through these horses’ feet; ground force reactions are much more pronounced due to the shoeing package and actions of the horse and have a greater impact on the hoof. You have to watch out for a subclinical condition of what we used to term ‘road founder’ that would compound the metabolic issue of PPID.”
In these complex cases Henderson says she reaches for an orthobiologic. “I would first ultrasound this joint to visualize the health of the cartilage,” she says. “If there is cartilage present, I would start with an autologous protein solution. If the lameness is from an injury or if there is a lot of (inflammation in the joint fluid), I would recommend injecting α-2 macroglobulin, followed by the autologous protein solution once the inflammation is resolved.”
The α-2 macroglobulin injections are relatively novel treatments in equine practice. This orthobiologic isolates the horse’s natural α-2 macroglobulin, a potent anti-inflammatory with molecules typically too large to cross into the joint. The veterinarian can then inject the α-2 macroglobulin into the joint to reduce the synovitis (joint inflammation) without the negative effects of corticosteroids.
Senior With End-Stage Arthritis
Clover is a 22-year-old Thoroughbred mare. She is a retired racehorse-turned-jumper-turned-dressage horse. Her multitude of careers has left her with relatively severe carpal arthritis of her right forelimb, with osteochondral fragments and excessive bony changes. She has a very caring owner who has tried just about anything to keep the mare comfortable, including rounds of polysulfated glycosaminoglycan, intravenous hyaluronic acid, and systemic anti-inflammatories. Clover is still lame and resistant to flexion of the carpus. This joint is end-stage.
When osteophytes (bone spurs) are present in a joint, they are not usually the direct cause of a horse’s pain. In my experience, the greater pain comes from synovitis and the lack of cartilage. “I would talk to the owner about α-2 macroglobulin, because these cases often require a multiple-layered treatment plan,” says Henderson. “I would also recommend following the α-2 macroglobulin with a 2.5% polyacrylamide hydrogel once the severe inflammation is controlled.”
Researchers have shown that the 2.5% PAAG provides the synovial lining with structure and stability and facilitates increased production of joint fluid. The integration of the product into the membrane, thickening the structure, also provides shock absorption. It essentially increases joint lubrication and provides a cushion in these end-stage joints.
Often, horses with end-stage OA stop responding to medical management, at which point surgical fusion of the joint can offer long-term comfort.
Stallion With Cervical Osteoarthritis
Cole is an 8-year-old Warmblood stallion who competes in the hunter/jumper ring. His attending veterinarian has diagnosed him via radiographs and computed tomography with osteoarthritic changes in his distal cervical vertebrae, causing a left forelimb lameness.
“Cervical pain and dysfunction in the horse has become increasingly recognized as a cause of poor performance and can be more involved than just pain originating from the joint proper,” says Michael Caruso III, VMD, Dipl. ACVS-LA, owner of Reedsdale Equine Specialists, in Nashville, Tennessee, who specializes in equine lameness diagnosis and treatment.
While OA can affect any joint, the cervical vertebrae can be an insidious location. “Osteoarthritis of the cervical articular process joints (is) obviously a disease of the cartilage surface and bone, but other structures are involved and intimately associated with the joint, including the joint capsule, synovium, subchondral bone (beneath the cartilage), and paraspinal muscles,” Caruso explains.
Because cervical OA is so complex, vets must combine multiple methods to treat it. “I believe that many horses with cervical facet joint pain/osteoarthritis require a multimodal approach to treatment depending upon the age of the horse and severity of the dysfunction,” he says. “We know that horses with neck arthritis can present with a wide range of issues, from poor performance and intermittent forelimb lameness to ataxia (incoordination).”
Cervical joint OA can disrupt the adjacent spinal cord nerve roots, causing this neurologic manifestation.
“Injection must be performed using ultrasound guidance,” Caruso says. “I would inject the articular process joints with a corticosteroid (betamethasone or triamcinolone), plus or minus hyaluronic acid, plus or minus (the antimicrobial) amikacin and, depending on the horse’s range of motion and muscle tension, might prescribe a muscle relaxant (methocarbamol) and/or perform mesotherapy and shock wave for any muscular/fascial pain adjacent to the affected joints.”
Caruso says he would take any metabolic issues into account before injecting corticosteroids. “In horses that have some sort of metabolic dysfunction, I will routinely utilize orthobiologics in the affected joints,” he says, adding that his personal preferences are platelet-rich plasma (PRP) and autologous conditioned serum.
“All horses treated for cervical pain are prescribed therapeutic rehabilitation,” Caruso says. “Dynamic exercises of not only the cervical region but also the whole body … appear to positively affect muscle activation and strengthening. The exercise program aims to improve joint stability and range of motion by focusing on the deep paravertebral muscles.”
Sport Horse With Stifle Pain
Remington is a 6-year-old Warmblood gelding who competes in the jumpers. He becomes lame in the right hind, and his veterinarian isolates the lameness to the stifle. On imaging, the medial (toward the midline) meniscus looks enlarged and mottled. He is referred for an arthroscopy of his medial femorotibial joint. The surgeon suggests injecting it six weeks following the procedure.
With this case, Caruso says he’d first recommend injecting mesenchymal stem cells (MSCs) into the medial femorotibial joint. “While we have lots to learn about stem cells, in the stifle—especially postoperatively with meniscal damage—stem cells have been shown to improve the long-term outcome for return to work in the horse,” he says.
He cites one study (Ferris et al., 2014) on the outcome of horses undergoing stifle surgery plus bone-marrow-derived mesenchymal stem cell injections. The researchers found that of the horses treated for stifle injury with surgery and stem cells, 75% returned to some level of work postoperatively, which compares to previous reports of 60-63% with surgery alone.
“The stifle is one joint that I will recommend injection with bone-marrow-derived MSCs following arthroscopic surgery as a first-line treatment,” Caruso says. “This is one joint that I believe stem cells have an advantage if finances allow.”
Veterinarians typically harvest stem cells from the horse at the time of surgery, usually from the sternum, pelvis, or tibia. While they have potent healing factors, they are generally more expensive than the other orthobiologics mentioned. If an owner can’t afford that price tag following stifle surgery, Caruso recommends PRP.
“Clinically, I see a great response (from PRP) both in soft tissues and in joints,” he says. “I feel that MSC injection in stifle cases with proper rehabilitation following meniscal injury are more successful with less convalescent time.”
While joint injection techniques are well-documented, the tricky part is what goes into the syringe. Gone are the days of simple corticosteroid injections as our only option—though they’re still used and have a place in equine medicine. The insights from these veterinarians show we have several ways to approach a lameness, especially a complicated joint case.
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