Addressing the issue of eye disease in working and performance horses

Human and to a somewhat lesser extent small animals ophthalmology has developed dramatically over the last 30-50 years but equine ophthalmology continues to rely on relatively few specialists and specialist centers. However, the horse donkey, and mule are badly neglected in this respect, and it is unfortunate therefore that amongst working populations of horses, eye disease is very prevalent. Even in leisure and performance horses eye disease is often overlooked as being trivial. The range of pathology is extremely wide but on presentation, it is almost invariably in an advanced state and therefore usually in a state where repair or resolution, or even some element of visual restoration, is out of the question. This is particularly regrettable since the e eye does have remarkable powers of healing in spite of its incredible complexity and delicacy.

A number of studies have culminated in at least a recognition that there is a problem that needs to be addressed on a global basis rather than just a local basis. A study carried out in several different countries by Pritchard et al. (2005) showed that 66% of horses and 86% of donkeys had an ocular abnormality. These included discharges, ocular pain, keratitis, uveitis, and blindness. Individual measures may have been taken to try to prevent disease and of course, as always, prevention is better than cure. For example, the simple expedient of developing a “steering head collar” in Mauritania and Mali resulted in a dramatic reduction in the number of cases of ophthalmic disease suggesting that there was a strong management role in the instigation and maintenance of pathology of the eyes (Scantlebury et al., (2019); (Doumbia A and Reed K, personal communications). It is however very true to say that the circumstances under which working animals are forced to endure their existence are very often conducive to the development of serious eye pathology ranging from physical insult, infection, and neoplasia via almost every other potential class of etiology. A study carried out by Scantlebury et al. (2019) in Ethiopia identified that eye disease was extremely prevalent and that there were some interesting potential factors involved. For example, right eye pathology seemed more common than left eye pathology and this was then ascribed to the potential at least of a right-handed driver holding a whip in the right hand implying that there was a physical trauma involved in the instigation of some of the eye pathology. Anecdotal reports from Central America also identify interesting potential etiological, aspects that could be extrapolated from data derived from surveys of horses presented for other reasons as well as for ophthalmic disease. All these reports show a remarkable similarity in identifying the presence of advanced pathology on initial presentation and very little recognition that there was a problem at all by the owner/user. Of course, so long as the working horse works, there is probably little effort to seek professional guidance on the potential presence of pathology. Of course, again, there are few facilities for either diagnosis or treatment in any event and that is a matter of considerable concern.

The veterinary profession for the most part in such circumstances tends to have a rather more ambivalent attitude toward ophthalmic disease than we would like to see. There is little doubt at all that a little effort and a lot of publicity coupled with extra training in ophthalmic medicine and surgery would have a profound influence on the betterment of the welfare of working horses and donkeys. There are countless other diseases of course that are not necessarily easily managed, and, in this respect, infections are a major player. Infections such as viral or bacterial diseases or even fungal or parasitic diseases are very common n various parts of the world. For example, in Ethiopia, ophthalmic forms of epizootic lymphangitis are relatively common and are extremely difficult to manage. Indeed, there is very little that can be done to help affected animals when the infection gets into the circumstance. On the other hand, Setaria digitata is a very common intraocular parasite in parts of India and Pakistan, and the veterinarians there are extremely adept at managing it by removing the parasites surgically – often without any need for general anesthesia. Once owners/users recognize the benefit of presenting their horses for early treatment, progress can be made and significant benefits in welfare can be accrued. Common things occur commonly in individual areas of the world and have significant differences in the implication and the ability of the veterinary profession to both recognize and manage ophthalmic disease in working animals. There is a massive demand for further information, expertise, and publicity amongst users and owners alike. When presented with an ophthalmic condition, the clinician needs a really logical thorough, and practical examination method that provides useful diagnostic and therapeutic information. It is of course far better to prevent ophthalmic disease than it is to cure it but until we take a very much more proactive stance, we will continue to encounter serious /advanced ophthalmic pathology – usually in a situation where the animal is already blind and where any prospects of site restoration have already been lost. The eye does not tolerate chronic insult or disease even though it has amazing powers of repair. Simple measures to prevent eye disease include proper fitment of harnesses around the head, the education of drivers/users of working horses in terms of cal solutions that can improve the short medium and long-term welfare of these valuable working animals as well as the more expensive sport horses can be devised and applied. It is remarkable how simple treatments can be if the conditions are dealt with early enough – and how complex and disappointing they can be in advanced, neglected or mistreated cases. The role of the horse in global society is immeasurable and their ability to see is a precious sense that we have no right to remove from any animal

The prevention of physical injury, and the early detection of infection of a relevant nature in the environment concerned, all help.

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