Equine joint injections – a helpful guide for horse owners

Are you searching for a complete guide to joint injections in horses? Equine surgeon Thijs de Bont MRCVS demystifies their contents, application and use in pain and performance management

Most horse owners are familiar with equine joint injections. “I get his hocks done every year,” is a phrase we’ve all heard, accepted, and just moved on. But what does this really mean? Is it right, or even necessary?

Joint injections are technically known as intra-articular injections and are often referred to as intrasynovial injections. Intrasynovial injections also include injections into other synovial structures that are not joints specifically but are closed synovial compartments, such as tendon sheaths or bursae.

Joint injections allow for localised, targeted treatment of a specific area, maximising the dose of medication at the target site and minimising any potential systemic effects. They are used to reduce inflammation and therefore pain, which results in an improvement and often resolution of lameness. They improve flexibility and the horse’s ability to train key muscle groups. In some cases they can even be disease-modifying.

Equine joint injections can be used both to improve comfort and consequently welfare, and to ultimately enhance performance levels in our equine athletes.

Equine joint essentials

Joints in horses are made up of cartilage, bone and soft tissue, all of which have injury potential. The different types of joint include:

• High-motion, such as the fetlock or stifle joints
• Low-motion, such as the lower hock (tarsometatarsal and centrodistal) joints
• Fibrocartilaginous, for example the sacroiliac joint

Injuries to any of these structures cause inflammation. Joints may appear puffy (joint effusion) due to increased production of joint (synovial) fluid. Further clinical signs may include heat, pain on flexion with a reduced range of motion and, of course, lameness.

Typically, there are two main scenarios where joint injections are used in horses:

Targeted treatment for a recognised lameness originating from a joint. This is when a horse presents with a pain-related gait asymmetry and has undergone a full orthopaedic evaluation. This typically includes diagnostic nerve and joint blocks in combination with imaging such as radiography, ultrasonography,  CT or MRI, which in turn have provided a specific diagnosis.

A drop in performance with no obvious lameness detectable, but rather a number of more subtle symptoms including changes in rideability, resistance to performing certain movements or consistently landing to one side over a fence. In these cases, your vet will recognise certain patterns that can be associated with certain types of injury. Targeted joint treatments can then be used in the first instance both as a treatment and for diagnostic purposes.

Which medications are used in equine joint injections?

Medications used for joint injections in horses primarily have anti-inflammatory properties. None can repair cartilage, but by providing a healthier joint they can slow the progression of degenerative joint disease.

The main medications used by vets to reduce joint inflammation are corticosteroids. They are a very effective, consistent and relatively cheap medication. Many products are available, but triamcinolone and betamethasone are the two most commonly used, due to their consistent effects and relatively short detection times – the approximate period of time for which a drug (or its metabolite) remains in the horse’s system.

In general, corticosteroids will be used alone or in combination with hyaluronic acid, which can contribute to pain relief via a variety of mechanisms.

Biologicals are a group of treatments whereby the animal’s own cells are collected, processed and injected back into a specific region, such as a joint or soft tissue structure. These include products such as platelet-rich plasma and a variety of autologous-conditioned serum products that essentially concentrate a variety of the animal’s own natural anti-inflammatories and growth factors at various volumes, with or without incubation. One major advantage of biologics is that they have no detection times and certain types provide enough volume that they can be frozen and stored for multiple future use.

Mesenchymal stem cells have anti-inflammatory effects and the potential to promote healing. They can either be autologous cells, which are processed from the patient itself either from bone marrow or fat tissue, or allogeneic, meaning that the cells are processed and are available as an off-the-shelf product following collection from a donor animal.

Polyacramide hydrogels reportedly integrate into the lining of the joint capsule, improving elasticity and therefore joint flexibility. They also supplement the synovial fluid, which in turn protects the joint surface.

Management of joint problems in horses

In principle a joint should be injected as infrequently as possible, and there is little truth in the theory that once you start you can’t stop. Joint disease is often progressive and intra-articular medication can slow the progression of cartilage degeneration.

Repeated injection of the correct dosage does not make the injections less effective, nor do horses become immune. Rather the level of damage within the joint becomes progressively worse over time, necessitating more frequent injections to maintain the same level of soundness.

Incorrect use of medications can directly contribute to the process of cartilage degradation, by injecting too frequently at too high a dose for example. However, even when used correctly, by increasing comfort and therefore your horse’s exercise levels, the medication can indirectly contribute to further exercise-induced wear and tear of the joint surface.

Your vet will always discuss the options available and the reasoning behind using a particular medication type based on your horse’s needs. However, injections are only truly beneficial if all other parts of the horse’s management are optimised.

It is essential to use a team approach, whereby the rider, vet, farrier, equine nutritionist and physiotherapist work together to optimise every controllable factor. This includes clearly defining both long- and short-term goals and making the right decisions at the appropriate time.

Working to this level of detail allows the horse to train both more consistently and in a correct way, which in turn maximises performance.

Day-to-day considerations

● Tailor your exercise plan to your horse’s individual needs and give your horse the time to strengthen and increase fitness levels.
● Don’t expect your horse to jump higher or perform more complicated movements if not physically ready.
● Prioritise a good warm-up and warm-down.
● Make sure your horse is not standing still in a stable for long periods of time throughout the day.
● Make sure to have your tack fitted by a professional at regular intervals.
● Diversify your rides and the type of work you do, and exercise on multiple different surfaces.
● Work on your own fitness and arrange for a rider biomechanics assessment to optimise your positioning, to prevent asymmetry.
● Get to know the normal appearance of your horse’s joints. Be aware of how the joints look, how they feel and how flexible they are.
● If you feel your horse is lame, stop and first consult your vet, prior to continuing ridden exercise.

Equine joint injections can contribute to a horse’s soundness in a hugely positive way, but should not be used to try and mask a significant injury. The welfare of our animals should never be compromised, and the horse’s best interests must always remain at the forefront of our decision making process.