Joint Injections and Soft Tissue Injury Treatments
Answers by Amy Poulin-Braim, VMD, DACVS-LA, Neshanic Station, NJ, AAEP member.
Question: I believe that there is a pro and con for everything. With injections, the pros are obvious but what are the cons with injections without any complications?
Answer: Thank you for your question about the pros/cons of joint injections! You are right, there are always two sides to one stone and joint injections can be very valuable in certain circumstances.
Lameness is the #1 performance limiting factor that we face as owners, riders and veterinarians. Ideally, lameness should be localized by your veterinarian after performing a complete lameness evaluation. Once the lame limb is identified by watching your horse go at the walk and trot on a straight line and circle, along with completion of flexion examination and hoof tester evaluation, diagnostic anaglesia (“Nerve Blocks”) should be performed to localize the region that is causing the source of pain that is creating the lameness.
Once the area of lameness is identified, other diagnostics may be indicated that may include: Radiographs, Ultrasound, MRI and/or CT scan and Nuclear Scintigraphy. Lameness can be caused by a multitude of factors, not limited to: Bone bruising, arthritis, soft tissue injury, trauma causing noninfectious synovitis (inflammation of the lining of the joint capsule, causing increased production of fluid).
Joint injections can be performed with multiple products depending on the situation, site and need (ex: corticosteroids +/- hyaluronic acid, platelet rich plasma, IRAP, legend, adequan) help to relieve inflammation, provide pain relief as well as help the joint capsule lining start to produce more normal joint fluid to lubricate the joint gliding surface.
Joint injections should be used to treat a known, diagnosed issue within the joint. They should be performed judiciously and only when needed (ie: not for ‘routine maintenance’ like an oil change for your car). Inflamed joints respond differently to corticosteroids as compared to normal or non-inflamed joints. When normal joints are injected with corticosteroids, there is a risk of increased cartilage damage within the joint. So while you may think you are doing something to help your horse, long term, you may in fact be speeding up internal damage to the joint and therefore, speeding up the progression of arthritis within the joint.
Any time a needle is inserted into a joint, after thorough aseptic preparation of the area, there is always a slight (albeit low) risk of possible joint flair (acute onset of lameness that is caused by an inflammatory response) or infection (acute onset of lameness that is caused by infectious process), even with the absolute perfect preparation and post injection site care.
Bottom line is to always involve your veterinarian in the evaluation and decision making process when it comes to joint injections. After evaluating your horse, they will complete a risk assessment to determine if joint injections my help or hinder your horse.
Question: How real is the chance injections cause infection?
Answer: You ask a very important question regarding joint injections. Current literature suggests that the incidence of infection post joint injection is extremely low as long as the appropriate precautions are taken prior to injection.
Your veterinarian likely has a very strict protocol for joint injections to do as much as possible to mitigate this risk. This may include: injecting your horse in a clean, quiet environment with the barn doors closed to reduce air turbulence and possible dirt contamination of the injection site. Aseptic preparation of the injection site with a surgical scrub and alcohol wipe down. Use of sterile gloves, needles and syringes with a new bottle of medication and antibiotic used in the joint. Applying a sterile wrap over the site post injection. Reduced exercise and bathing/hosing for a few days post injection and a gradual reintroduction to exercise under saddle.
If joint infection were to occur, generally speaking it is most common to see clinical signs of non-weight bearing lameness, heat, pain and swelling associated with the joint within 3-5 days post injection. However, it has been seen as far out at 14 days.
Joint injections certainly have their place in helping our horse’s comfort level when an appropriate and complete lameness examination has been performed and other diagnostics (nerve blocks, radiographs, ultrasound, nuclear scintigraphy, MRI, CT etc.) are used to determine the specific site of pain causing the lameness. Injections should be used when needed, and not prophylactically as ‘routine maintenance’, as this could be detrimental to the joint cartilage if injected without a need into a normal joint.
Anytime a needle enters into a synovial space, there is always that slight risk of flare (inflammation without infection) or infection. So the fewer times the synovial space is entered with a needle, the less chance there is of that occurrence.
Question: Why do some horses experience laminitis after joint injections?
Answer: Thank you for your question regarding joint injections. To date, there have been no definitive published research studies establishing a connection or cause and effect between joint injections and laminitis in the veterinary literature.
That being said, there may be certain horses that veterinarians may be more wary of injecting corticosteroids. Those would include horses with a previous history of laminitis and those horses that are obese and/or have been diagnosed with insulin resistance or Equine Metabolic Syndrome. Corticosteroids are potent anti-inflammatory and analgesic (pain relieving) drugs and may affect certain metabolic pathways depending on type of steroid and dose used.
While joint injections are very helpful to those horses where the lameness has been localized to a certain area and there is concurrent intra-articular arthritis or synovitis (inflammation of the joint capsule), it is not an innocuous procedure and could be detrimental to a normal healthy joint with no indication of inflammation. There is always a risk, albeit low, of joint flare or infection post injection even when all appropriate steps to aseptic preparation and post injection care are instituted. Therefore, joint injections should be carefully considered and risk analysis performed by your veterinarian. Generally speaking, the universal rule of thumb is that the lowest level/dose of corticosteroid should be injected that will elicit a response regardless of horse age, breed, use or history.
If your horse is considered to be in the possible higher risk categories described above, alternatives to corticosteroids for joint injections could also be considered if joint injections are considered to be necessary. That could included: platelet rich plasma, IRAP, mesenchymal stem cells, Legend or Adequan. It is always best to have your veterinarian evaluate your horse for lameness and identify the source of lameness with appropriate diagnostic tests prior to just simply injecting a joint based on a hunch. Your veterinarian will take into consideration the age, breed, use and prior history coming up with a plan for an appropriate injection protocol. They can explain to you the pros and cons of each option.
The American Association of Equine Practitioners, headquartered in Lexington, Ky., was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse. Currently, AAEP reaches more than 5 million horse owners through its over 9,000 members worldwide and is actively involved in ethics issues, practice management, research and continuing education in the equine veterinary profession and horse industry.
This article was printed in Performance Horse Digest, Volume 9, Issue 4