Written by: Becky James BSc MSc

What is arthritis?

Arthritis is chronic inflammation which has led to permanent degradation of the cartilage in a horse's joints. It is an undesirable diagnosis for any horse, regardless of their occupation. The condition can appear suddenly after trauma or gradually with worsening stiffness. Once a horse has arthritis, the damage is irreversible, the goal of treatment is to reduce the inflammation, pain and try to prevent further damage.

A normal response

Horse's joints are designed to flex, compress and extend repetitively every day, while supporting their body weight and enduring concussion from the surface they are moving on. The natural action of flexing and compression can produce minute damage within the joint structures that triggers mild inflammatory responses to make the repairs. Normally, the body's own defenses control inflammation and the joint remains healthy and sound.

How arthritis develops

Sometimes, the ‘normal’ inflammatory process overwhelms the body's ability to contain it, either from a single acute injury or from many years of use. The inflammatory enzymes break down the lubricating synovial fluid, which gets thinner. Proteoglycans are lost and the collagen fibers lose integrity. This damage stimulates even more inflammation, which fills the joint capsule with fluids, leading to pressure, pain and stiffness. The build-up of inflammatory enzymes further break down the synovial fluid, which leads to more damage to the cartilage and so on.

If this goes unnoticed, a lot more degeneration can occur because the inflammatory response keeps triggering a loss of proteoglycans and collagen. This is how an acute injury can cause progressive damage. If the cartilage erodes away entirely, the exposed ends of hardened bone rub against each other resulting in a painful, advanced case of osteoarthritis, also known as degenerative joint disease (DJD).

Arthritis can occur in horses of any age but is more commonly found in older horses following years of wear and tear on the joints. Older horses tend to lose some of the elasticity in their tendons and ligaments, and aging leads to increased cell death in fibrous tissues, causing a thinning of the joint cartilage. Such changes reduce the natural shock absorbing capabilities and result in increased trauma to the joint.

Conformation of the horse, the correctness of a horse's bone structure, musculature, and its body proportions in relation to each other, its daily routine as well as the discipline it takes part in all play a role in changing the shape of the joint. The development of uneven joint surfaces in older joints leads to misalignments and pressure points within the joint where inflammation is amplified. Past joint injuries and infections can also predispose a horse to developing arthritis.

How to prevent and manage arthritis…the earlier the better!

It’s important to investigate even minor discomfort because if you can start managing arthritis from the start and reduce the inflammation before the cascade of events described above gets into full swing. In most cases, by the time a horse is lame, the arthritis is already advanced.

Some horses show early signs of arthritis in their way of going: They'll move stiffly until they've warmed up, or they may take short strides. Others may be reluctant to move only on one lead, or in one direction, or at a certain gait--signs that are especially significant if these movements were previously performed with ease. Sometimes developing arthritis causes a sour attitude or resistance to rider aids.

Veterinary Diagnosis

The diagnostic process would start with a hands-on examination to look for heat and swelling in a horse's joints, followed by a full lameness exam, including flexion tests. Nuclear scintigraphy can detect subtle early changes that indicate injury within the bones; X rays will show the more significant changes associated with more advanced arthritis. Arthroscopy--the insertion of a fiber-optic "camera" directly into the interior of the joint--is the best way to diagnose lesions in the cartilage.

Treatment Options
It's not possible to cure arthritis at this time, but treatments can halt or slow the cycle of inflammation that brings further damage, ease pain and stiffness, and/or support the regeneration of cartilage as much as is possible.

The right treatments for an individual case of arthritis depend in part on the causes as well as severity of the problem but there are several options available via your vet.

Oral non-steroidal anti-inflammatories — the use of oral pain killers/anti-inflammatories in the management of any chronic condition is always a realistic option.

• Steroids— There are several types of steroid available to inject into joints to reduce the ongoing inflammation, ranging from basic steroids to anabolic products such as Stanozolol. The individual advantages/disadvantages of all of these need to be discussed with your vet.
• Polysulphated Glycosaminoglycans— these products can help to prevent cartilage degeneration. Most people have heard of the principle component “Chrondroitin Sulphate”. This is a massive topic well beyond the scope of this article.
• Pentosan Polysulpahte— these products have been shown to help stimulate hyaluronic acid production within joints, which is essential for good joint function. These products include Cartrophen.
• Bisphosphonates— these products are designed to affect the “turn over” of bone, which can be excessive during the arthritic process. Once again, these products have many advantages and disadvantages which need to be individually discussed and evaluated with your vet.
• Autologous products— these are products derived from the patient, quite often by extracting blood/bone marrow or fat and processing it prior to re-implantation back into the patient. This is a very specialized therapeutic avenue, but has very promising results.

In severe cases, where there is no other way to alleviate pain, a surgeon may want to fuse a joint. The remaining cartilage is removed, enabling the two exposed bone ends to grow together into a single, immobile structure. With the source of friction removed, the pain diminishes. In some cases, depending on which joints are affected, the horse may be sound enough for riding.

What else can I do for my horse?
With careful management, many horses can live comfortably with arthritis for years. The goals are to keep them as active as possible, in order to stimulate circulation, while minimizing the risks of overuse and the inflammation it brings.

Keep moving!

If appropriate, moderate ridden exercise helps keep joints healthy by stimulating the production of synovial fluid and by strengthening the muscles that help stabilize the joints. Regular turnout is important as moving around the field provides gentle exercise that reduces stiffness and allows the horse to move at his own pace.

Consider the footing

Whether for riding or for turnout, choose footing that provides some cushioning without being too soft. Hard surfaces subject the joints to pounding, concussive forces, while ground that is deep can cause strains. Also avoid steep hillsides, rocky or uneven terrain, or other areas that invite overwork or missteps.

When in the stall, horses are more comfortable standing on a padded floor and this may also encourage them to lie down and take the weight off their joints for a while.

Warm-up, Cool-down

An active warm up including dynamic stretching exercises before working a horse will warm up muscles and tendons, breaks down adhesions, and increase circulation. This has been shown to greatly reduce the incidence of injury and joint trauma.

It is equally important to allow time for the horse to cool-down after exercise. A proper cool down can range from five to 15 minutes or more depending on the horse’s general physical condition, fitness level and how hard the horse has worked. The external temperature and humidity will also be a factor to consider. This allows the pulse rate, respiration rate and body temperature to return to normal, improve blood circulation reducing the chance of inflammation, remove lactate from the muscles and allowing dilated blood vessels to slowly return to normal while relaxing and lengthening muscles.

Hoof care

Timely hoof care is important for all horses but especially so for those with arthritis, because regular trimming minimizes joint strain.

Weight watchers

As a horse's activity levels reduce, his weight is likely to go up, which puts more stress on its joints. Evaluate your horse's diet to ensure the nutritional and energy needs are met but not exceeded. A forage only diet in most cases can supply adequate calories, keep in mind that depending on the origin of the forage, additional minerals and vitamins may be necessary to balance out the deficiencies, via an equine vitamin and mineral supplement or ration balancer. More information on how to regularly assess your horses weight and weight control through feeding available via the links.

As all of this shows, degenerative condition management is multi factorial and should be tailored to every individual patient with you vet, farrier, physiotherapist, nutritionist and trainer.

The good news is ongoing research around the world is yielding new treatments and investigating management techniques that can help horses work longer and live more comfortably with arthritis.