Arthritis is both overdiagnosed and underdiagnosed in horses today. It's overdiagnosed when a cause of pain other than joint disease is making your horse move stiffly or be sore. And it's underdiagnosed in the sense that early signs of arthritis often can be missed, leading to a delay in treatment at a stage when action is most likely to be helpful to your horse.
Horses are masters at compensating for relatively mild joint pain by redistributing their weight. The end result of this method is that your horse with early arthritis will often not be noticeably lame.
Signs of Arthritis
There will always be increased temperature/heat over early joint inflammation, but unless it's more than a five-degree rise you won't be able to feel it with your hand. Thickening of the synovium-the lining of the joint-is always present and fluid within the joint will be increased to varying degrees, but these changes may only be detectable by an experienced veterinarian. Nevertheless, heat and joint swelling/puffiness are things you should train yourself to check for on your horse regularly. If you're familiar with how your horse normally feels, you will be much more sensitive to any changes.
More subtle signs that something is bothering your horse include:
• shortened stride front or hind
• "stiff," rigid feeling through the back
• change in head carriage (up or down)
• more rigid head carriage (less up and down movement)
• decreased willingness to trot or canter
• preferring one diagonal or lead over another
• reluctance to turn to one side
• difficulty with circling/lunging
• difficulty going up or down hills
• development of vices or spookiness under saddle or laziness/sluggishness and unwillingness to work
• resistance to being tacked up
• flinching or moving away if you touch or brush over a joint (very common with stifles especially)
• uneven hoof or shoe wear
• preferentially resting a leg when standing or standing with the leg in an abnormal position. This includes pointing or standing with leg too far under in front legs, resting or rotating leg to the outside in hind legs.
More accurately, these are all signs that your horse has pain. If you notice any of these symptoms, get your veterinarian involved sooner rather than later. The more quickly you identify the problem, the sooner you can deal with it.
As the arthritis progresses, the symptoms listed above increase in severity and other changes commonly occur. The size of the hoof on the involved leg will often become smaller over time. As a result of uneven loading of the limbs in an attempt to unload the sore one(s), muscle bulk in a sore leg will become less developed over time, while the legs that are compensating for this by taking more of the load develop more pronounced muscles. Back muscle stiffness and even pain to the touch is also very common in horses with arthritis, both front and hind legs.
A hallmark of chronic arthritis is stiffness when your horse first starts to work, which gets better after a warm up. The amount of time it takes to warm up your horse also commonly increases. This stiffness has several causes. One is a stiffening of muscles, causing shortening of tendons, in the leg. Another is that soft tissues around the joint lose some of their flexibility over time when your horse has not been loading them normally.
