A dreaded, irreversible and incurable disease: a diagnosis of osteoarthritis often signals the end of a sport or leisure horse's career. Are there ways to slow the progress of osteoarthritis? Read here how you can relieve your horse's pain and stiffness from chronic joint disease and help your horse to enjoy exercise again.
What is osteoarthritis?
Osteoarthritis is a disease characterised by signs of degeneration in joint cartilage and bone structure. It is a cause of chronic lameness in horses due to the pain associated with the breakdown of articular cartilage and stiffening of the affected joint. Recent estimates suggest that 60% of all cases of lameness in horses are related to osteoarthritic processes. Osteoarthritis can affect any joints, but it is mostly seen in the hock (bone spavin), fetlock (ringbone) and knee joints.
How does a healthy equine joint function?
Our horse's joints must withstand enormous strain. Over decades they are stretched, flexed and extended, thousands of times a day. They bear the weight of both the horse and rider and absorb shocks.
A joint is a complexly constructed, movable connection between two bones that is stabilised by a joint capsule and collateral ligaments. The space between the bones is filled with synovial fluid, which is regulated by the synovial membranes and provides lubricants and nutrients to the articular cartilage that covers and cushions the bone ends. The mechanism of production and resorption of synovial fluid causes the joint to be cleansed of abrasion products.
Articular cartilage has an especially important role: It reduces rubbing in the joint, keeps it moveable and protects it from overstress and abrasion. Articular cartilage tissue consists of collagen fibres, a robust protein in the connective tissue which gives the cartilage tissue its stability. The collagens are intertwined with proteoglycans that can absorb fluid and strengthen the tissue. When the joint is flexed, the cartilage stretches and compresses, providing circulation of fluid in the spaces between the joints. Cartilage can be compared to a sponge: it absorbs liquid when the pressure to the joint subsides, and presses it out again when the pressure builds, thus acting as a shock absorber.
What happens with osteoarthritis?
Stresses from impacts or overextension often cause tiny lesions within the joint. These small injuries are "repaired" through slight inflammatory reactions in the joint. A healthy horse's own natural defences are normally able to keep these inflammatory processes under control so that the joint heals and remains mobile.
If the body is no longer able to control the inflammation, the synovial fluid is broken down and diluted by enzymes released in the inflammatory process. This results in a chain reaction: the collagen layer is not sufficiently maintained. The cartilage loses its ability to absorb and release fluid. This in turn triggers more inflammatory reactions. The joint capsule fills with fluid, leading to pressure, pain and stiffness and, most importantly, further inflammation, causing further breakdown of the synovial fluid and progressive damage to the cartilage tissue. The cartilage loses its elasticity, its surface becomes rough and frictional resistance increases. The collagen fibres can tear and the cartilage can completely disintegrate, causing the underlying bone ends to rub against each other and erode. This leads to the formation of bone spurs that stiffen the joint.
How does osteoarthritis occur?
- Osteoarthritis is often a result of joint inflammations that have not healed, such as those that occur after injuries.
- Misalignments of the limbs and/or hooves increase a horse's risk of developing osteoarthritis.
- Too early and too much strain on the horse increases the risk of chronic joint diseases.
However, wear and tear of joint cartilage is also a normal sign of ageing in many horses aged 18 and older.
What are the symptoms of equine osteoarthritis?
Osteoarthritis develops gradually and is not easy to detect in its early stages. An affected joint will sometimes be quite warm and swollen. Some horses show early signs of osteoarthritis like stiff movements or short gaits. Others may refuse to be lunged in one direction, or they don't want to trot or gallop. Others might refuse to accept the rider's aids and become resistant. It is typical for symptoms to subside as soon as the horse has warmed up a bit through movement.
If osteoarthritis is suspected, a vet should be brought in to examine the horse. A comprehensive lameness exam, flexion tests and X-rays can determine which joint is affected. Osteoarthritis cannot be reversed, but If detected early, it can at least be slowed.
Can osteoarthritis be prevented?
- A horse with musculoskeletal injuries should be thoroughly checked over by a vet, because small traumas can lead to join inflammations which in turn can lead to osteoarthritis.
- Cold starts and fast gaits on too-hard surfaces can cause microlesions in joint areas.
- Excess weight puts strain on the joints.
- Regular hoof care minimises the risk of uneven pressure on the joints.
How can I best help a horse with osteoarthritis?
Aside from pain-relieving medications which may be necessary for acute relapses, there are a number of ways to help arthritic horses to enjoy easier movement and more quality of life.
Moderate exercise helps keep joints fit. Light work – always within the horse's comfort zone – strengthens muscles and ligaments, helping to stabilise joints, and stimulates the production of synovial fluid. In addition, many horses don't take to a sudden "retirement" well, and will enjoy leisurely rides with a buddy or long walks in hand.
Caution: Avoid steep hills and surfaces that are too hard or too soft!
Some horses get all the exercise they need during turnout. The slow movement of grazing is ideal for horses with osteoarthritis, however you should keep an eye on herd dynamics. An arthritic horse will feel better with it is able to move at its own tempo in a group of calm, laid-back horses, without being chased around or enticed to run about wildly.
When a horse begins to exercise less, this reduced energy consumption should be considered when measuring its feed ration in order to avoid excess weight and associated additional stress on the joints.
If the joint is causing pain, the horse will adopt a protective posture that affects the muscles, ligaments, tendons and other joints. Manual therapy can prevent the occurrence of secondary symptoms of osteoarthritis.
Feed supplements for cartilage development
There are several feed supplements that can promote equine joint health. Most contain glucosamine, chondroitin sulphate and/or hyaluronan (hyaluronic acid) – three substances that are also found in the joints. Glucosamine promotes cartilage formation and regeneration, chondroitin sulphate keeps cartilage elastic, and hyaluronan helps lubricate the joints. Avocado-soybean extract (ASU) can also be used as an alternative or supplement to glucosamine.
Glucosamines are said to work better when they are taken in combination with omega-3 fatty acids, which are found in linseed oil and microalgae, among other products.
MSM (methylsulphonylmethane) is a white, odourless, crystalline substance which is 34% sulphur. Sulphur is a central component of the body, has anti-inflammatory and antioxidant effects and can stimulate bone metabolism. MSM can be used alone or in combination with other anti-arthritic preparations.
Herbs for horses with osteoarthritis
Conventional pain relievers like Phenylbutazone and NSAIDs provide temporary relief to the horse but should not be administered long-term, because they will impair the horse's metabolism and especially its gastric mucosa. Ginger is often recommended for reducing inflammation and cartilage deterioration, but can cause gastrointestinal ailments in high concentrations. The following medicinal herbs are good alternatives for providing subsequent relief to the organism after the use of medications.
Devil's claw contains harpagoside which has pain-relieving and anti-inflammatory effects and stimulates transmitters that protect the gastric mucosa.
Hemp-nettle contains silicic acid which protects and strengthens the joint cartilage, in addition to the anti-inflammatory substance harpagide, also found in devil's claw.
Willow contains salicylic acid which has pain-relieving and anti-inflammatory properties.
Stinging nettle likewise contains high levels of easily digestible silicic acid and has detoxifying and metabolism-stimulating properties.
Dandelion stimulates kidney function and has diuretic and blood-cleansing effects.
Rosemary promotes blood circulation and has anti-inflammatory and antioxidant effects.
Sources and further reading
- Brendieck-Worm, C., & Melzig, M. F. (2018). Phytotherapie in der Tiermedizin. Stuttgart: Georg Thieme Verlag KG.
- Meszoly, J. (Oktober 2020). Equus Magazine. Von https://equusmagazine.com/lameness/coping-with-arthritis-in-horses-8356 abgerufen
- Oke, S. (Dezember 2020). theHorse.com. Von Equine Arthritis: https://thehorse.com/wp-content/uploads/2018/04/equine-arthritis-factsheet.pdf abgerufen
- Reichling, J., Gachnian-Mirtscheva, R., Frater-Schröder, M., Di Carlo, A., & Widmaier, W. (2008). Heilpflanzenkunde für die Veterinärpraxis. Berlin-Heidelberg: Springer Medizin Verlag.
- vetepedia. (Dezember 2020). Von Gesundheitsthemen: https://www.vetepedia.de/gesundheitsthemen/pferd/bewegungsapparat/arthrose/?gclid=CjwKCAiA0IXQBRA2EiwAMODil7nqcrvimbOYSsNLhDYK-9KFdYAVAeLfcewUegzU_j83nsbbL34rYBoCqdQQAvD_BwE&cHash=d524d49bde8519fabd2276a7a4f2244f&L=0 abgerufen