Uveitis is essentially inflammation of the internal components of the eye, which has been posed to be a result of a breakdown in the blood vessels around and in the eye. This breakdown of blood vessels (vasculitis) is then thought to allow the exposure of the immune system to the internal components of the eye, in which they then mount an immune response. There is no doubt that this disease has a strongly inflammatory and immune component, but the question is what potentially triggers this vasculitis that is thought to head the syndrome?
There have been proposed many 'triggers' to the condition and include bacterial infections such as Leptospirosis, viral infections, parasitic infections as well as systemic inflammatory conditions related to other diseases such as colic or even pneumonia. Another thought is that it is strictly an 'immune mediated' type of condition in which the immune system misfires and become hyperactive.
In early stages with uveitis, most horses in my experience, present with mild to moderate levels of eye pain which is indicated by increased squinting as well as ocular drainage or tearing. Sometimes these horses are perceived as being off personality wise, secluded, not eating well or head shy at times. Often times, these horses are very resentful to having their eye examined and require sedation as well as peripheral nerve blocks to remove pain sensation. In some horses, the condition affects only one eye, while in others it will present in both eyes. It is common to have a horse affected in one eye soon present for the same condition developing in the opposite globe. Once the horse is sedated and nerve blocks performed, the eye can then be further evaluated. For starters, the eye is evaluated extensively, looking for damage to the cornea, cloudiness or what is termed neovascularization. The cornea may be stained to evaluate for scratches or ulcers. Ocular pressures may be measured as well looking for glaucoma. If possible, the anterior and posterior chamber are evaluated for debris and other findings such as a cataract, flare or even blood accumulation. In some horses with extensive disease, there may be cataract formation or even severe scarring of the cornea, which can lead to a blueish type of look with craters, which gives rise to the term "moonblindness".
As we can see, there are a variety of presentations for this disease from the clinically normal eye with evident pain to a horse with glaucoma, cataracts and visual blindness. The difference between these levels of disease is dependent on the level of inflammation that has been ongoing as well as time. The longer this condition goes undiagnosed and treated, the more damage that occurs. In the long term, one has to understand that this condition is best 'managed' and not likely to be cured. ERU is the most common cause of blindness in the horse and it has been noted that around 50% of ERU horses will lose vision in one or both eyes at some time. The question comes as to how to best manage these cases?
Current therapeutics include the use of injectable or oral NSAIDs, of which Banamine is most often chosen. Banamine helps to reduce pain and modulates the inflammatory response to a degree. In cases of suspected infection, antibiotics may also be chosen. Other options include the use of topical atropine, which dilates the pupil, reducing pain and helping to reduce adhesions within the eye. Corticosteroids are often utilized in a topical or injectable fashion, which again help to modulate the inflammatory and immune response. Cyclosporine is a medication that modulates the immune response and is often used topically, but can also be implanted into the conjunctiva around the eye, which allows for a low level release of medication over time. I feel that the cyclosporine implants are best for early cases of ERU and do not yield very good results in chronic cases, not to mention that they are expensive and involve general anesthesia, which carries its own risks. In the long term, a high percentage of ERU horses are often times on daily doses of medications to control the condition, but even in these instances, many of the horses continue to have flare ups with more damage occurring to the eyes.
The inflammatory response is the key area of my research and considering the pathophysiology of ERU, it is quite possible that this condition can be better managed by implementing herbal therapy along side of traditional therapeutics. In our patients, I will use our EQ Green or EQ Plus products with great success. The determinant in which product is chosen is dependent on how severe the pain is in the patient. I will dose the products twice daily for 14 days, then re-evaluate the patient. In many cases, I will use injectable or topical medications as well, but for the short term which is usually just 5-7 days, after which I will have the owners discontinue, as this is ample time for the herbal formulas to begin to work. At the recheck evaluation, about 80% of our patients are markedly improved with much less pain and less ocular reactivity. In the other 20%, I may have to restart some medications or I will add in one of our Immune Formulas to help modulate the immune response. ERU has a strong immune component, characterized by lymphocyte involvement. The mushroom polysaccharides in our Immune Formulas have been shown to modulate the lymphocyte reaction and have proven to be very valuable in our ERU patients.
Equine Recurrent Uveitis is a complex condition and one that we still have many questions about. We do know that there is a strong inflammatory component, which is readily evident, but there is also a strong immune component. It is possible that an underlying inflammatory or immune component is leading to the vasculitis, which then snowballs into the ERU syndrome. As a veterinarian, I have found tremendous value for our patients through utilizing our formulas, but keep in mind that not all horses respond, despite the therapy route chosen. Many horses end up having to have an eye surgically removed for the best outcome, while others are so severe that euthanasia is the only option. I do feel that if we approach this condition in a more thorough manner, that it is possible to at least reduce the dependence on various medications, if not eliminate them while reducing the number of flare ups that occur.
I hope this information helps those affected by this horrible condition.
Tom Schell, D.V.M.
www.curost.com
No comments:
Post a Comment