The lowdown on arthritis

Taking a look at the causes and treatments for osteoarthritis in horses

(Image: istock)

As many of us have had the misfortune to experience, horses are commonly affected by lameness. Lameness can have many causes, including hoof abscesses, laminitis, tendon injury, fractures, muscle damage, joint injury and disease.

Of these, joint disease is the most commonly diagnosed bone and muscle condition (also known as an orthopaedic condition) that results in lameness. As it is such an important condition, we will have a look at one form of joint disease, osteoarthritis, in more detail in this article.

Types of joint disease in horses:

  • OCD – osteochondritis dissecans – a developmental disease, usually first noticed as a swollen joint in a young horse.
  • Septic arthritis – infection in the joint. Usually as a result of a wound in adults, or infection spread through the bloodstream in foals.
  • Traumatic injury
  • Osteoarthritis

Osteoarthritis is joint inflammation, and so can occur as a result of the first three conditions. It is, unfortunately, fairly common, and so an understanding of what causes it and the options for managing it are important for horse owners to know.

What causes osteoarthritis?

In the normal joint, there is bone fully covered by healthy cartilage, which is surrounded by and lubricated by synovial fluid. Trauma and/or instability of the joint results in inflammation, and lots of changes occurring in the joint.

Instability can occur as a result of damage to the supporting structures of the joint eg. the ligaments around the joint with a strain or sprain, with loss of articular cartilage (as may occur in osteochondrosis), with overuse and/or as a result of age-related changes. The trauma or instability results in inflammatory substances being produced in the joint fluid, increased amounts of joint fluid being produced, and the cartilage of the joint becoming thinner and starting to break down. The cartilage becomes thinner and thinner in places until there is no cartilage left, and the bone is then directly next to the synovial fluid in the joint. The surrounding bone then starts to react, cysts may form and new bone is produced in the joint, which can be seen on x-rays.

Signs

Early signs of osteoarthritis may be picked up as:

  • Slight change in gait
  • Slight occasional unevenness
  • Reluctance to perform certain tasks
  • Not wanting to work on the bit
  • Change in ridden behaviour

More obvious signs to look out for are lameness, stiffness, and the swelling of a joint or joints.

When osteoarthritis affects more than one joint, for example joints in either both front legs or both hind legs, then the lameness may not be as obvious as you would think. If you are concerned that your horse may be slightly lame, but you are not sure, you can do a few checks yourself. If your horse is obviously lame on one particular leg, then of course it is not advisable to do these  – call your vet.

You will need someone firstly to walk and then trot your horse in a straight line on hard ground away from you, and then towards you, with a fairly loose lead rope. You need enough distance to allow the horse to get into a steady rhythm. Hard ground (tarmac, concrete) is ideal, as you can listen as well as watch. You watch for forelimb lameness when the horse is coming towards you and hind limb as he goes away from you.

In forelimb lameness you will see a head nod at a trot if it is more than very mild. The head will rise up when the sore leg hits the ground, and go down when the sound leg contacts the ground. So if you see the head nodding down on the right fore, then the horse is lame on the left fore. It can help if you say to yourself ‘down’ on every step you see the horse nodding down on. 

With hind limb lameness it can be more tricky, but you see more movement in the gluteal (rump muscles) on the lame side (imagine they are trying to hitch the leg up).

If you are still not sure if there is a problem, then lungeing on both reins is the next step. This usually shows up a lameness on the inside leg as it takes more weight but in some injuries it will show up a lameness in the outside leg as it has to move further. Lungeing is very helpful to highlight a lameness if more than one leg is involved.

Diagnosis

If you think your horse is lame, then you need to call your vet. The vet will work through an examination to diagnose the problem, and then the best course of action for treatment and management can be decided upon. This is important as although rest is often important, unless the underlying cause is identified then the optimum treatment may not be given. The veterinarian will perform a lameness workup which includes a physical examination where all the joints will be felt, assessing for filling of the joint or swelling, heat and pain. They will then observe your horse moving as above, followed by flexion tests. Flexion tests involve holding certain joints fully flexed for a fixed length of time, followed by trotting in a straight line. This will put temporary stress on the joint and will usually show up as an increase in lameness in a problem joint.

X-rays are necessary for a proper diagnosis (Image: istock)

Nerve and/or joint blocks may follow on from flexion tests to identify more precisely where the pain is coming from. Then, if a problem with a joint is suspected, x-rays will usually be performed.

X-rays may show up early changes such as joint effusion/swelling, they can show if there is thinning of the joint cartilage, and they are very useful for showing later changes involving the bones.

Management options

Once osteoarthritis has been diagnosed, it needs to be managed. Although there is no cure for arthritis, and it will get worse over time, it can – in a lot of cases – be managed effectively. Many horses can go on performing competitively for a time, without adversely affecting their welfare. Each case is individual, however, and you will need to work with your veterinarian to develop a management plan for your horse.

There are various medications, supplements and therapy options available for the management of arthritis. Several of these are discussed below. In some cases, it can be a bit of a trial and error before finding what works for your horse, and this may need to be altered or added to as the disease progresses.

Medication

Anti-inflammatory medication for the whole horse (called systemic medication): Non-steroidal anti-inflammatory drugs (NSAIDs) such as ‘bute are given by injection or by mouth. These are commonly used to reduce inflammation in the joint and reduce pain. There is the potential for side effects when using these, and they cannot be used in a horse that is competing, but they are useful in acute injuries, for flare-ups or to keep a retired horse comfortable.

Anti-inflammatory medication into individual joints: Corticosteroids are a very strong anti-inflammatory drug that can be injected directly into affected joints. There are a few different types used, with varying length of time they are effective for, and varying side effects. Talk to your vet about the use of steroid injections if he or she feels that they are a good option for your horse.

Hyaluronic acid: This is a normal constituent of joint fluid and cartilage, which is thought to be changed or lacking in joints affected by OA. It can be supplemented by being injected directly into affected joints, given by injection into the vein or given as an oral supplement (nutraceutical). At present, there is no scientific data on the oral preparations.

Pentosan polysulphate: This is reported to limit cartilage damage and have an anti-inflammatory effect in the joint, as well as other positive effects. It is usually given as a course, either by injection into the joint or into the muscle. The course of injections into the muscle can be useful when multiple joints are affected.

Oral supplements: These include glucosamine, green-lipped mussel extract, chondroitin, and omega-3-fatty acids. These are termed ‘nutriceuticals’ and although at present, there is little scientific evidence as to their effectiveness, both owners and vets have reported an improvement when using them in certain cases. It is often case of trial and error to see if a particular supplement  will work for your horse. Talk to your veterinarian to see what they recommend. 

Joint injections are one method of treatment (istock)

Newer therapies

There are a few newer therapies being used and developed, including IRAP and stem cells. These are biological therapies which means the body’s natural substances are taken, enhanced and then injected into the joints to produce a hopefully beneficial response. 

Non-medical therapies

Ice/cold water: The use of cold therapy reduces acute inflammation. Cold therapy can be used when the trauma first happens, and also if there are any flare ups of a chronic condition. Cold therapy may reduce the amount or effectiveness of inflammatory enzymes in the joint, it also helps prevent the joint stiffening up. Movement is also important in removing inflammatory substances and, as in humans, cold therapy reduces pain.

Rest/exercise: In the acute stage of a joint injury eg. a sprain or strain, rest is important, but when joints have been affected long-term (chronic) by OA, then regular careful movement of the joint is beneficial to allow the joint fluid to circulate. A controlled exercise plan should be developed with your veterinarian. 

Weight management: As in people, if a horse is overweight this will increase the load on the joints and the pain associated with them. A controlled weight loss plan is an important part of management. 

Other therapies: There are lots of other therapies that may be worth considering including physiotherapy, hydrotherapy and acupuncture. A good farrier may also be able to help, by ensuring optimum foot balance. It is always worth talking to your farrier to see if they can do anything to help.

Conclusion

In all cases, there is an advantage in getting an early veterinary diagnosis as treatment and management therapies can be put in place early on which will improve the welfare of the horse, slow the progression of the disease, and may allow the horse to have a useful performance career for longer.

 

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  • At home with Angela Lloyd and Tich Massey
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