The Lame Horse

hosted by
James Rooney, D.V.M.

Experiment and Observation and Horse Science
Apologia pro vita sua

Some recent, and not so recent, conversations and readings prompt me to this essay which is, in a way, an unapologetic apology for my life and work; thus, the subtitle: a defense or explanation of his life.

To the point here, oversimplifying considerably, there are two kinds of science: experimental and observational. In the first things are manipulated under reasonably well controlled, usually laboratory, conditions, and the results of the manipulation are observed, recorded, and often subjected to statistical analysis.

In the second, observational approach, such manipulation is impossible for any of a number of reasons. In paleontology, for example, experiments are hardly possible since the material has already been dead and fossilized for millions of years. Large scale, statistically verifiable studies are very difficult with many animals such as horses, elephants, or gnus, often for financial reasons but also because of tactical and/or humane considerations.

Specific to my thesis here, however, are the methods of pathology. Experimental pathology is a valid and contributory field. Observational pathology is equally valid and contributory and, often, the only feasible approach. If one starts out to study the causes of lameness in horses, for example, it is essential to examine as many animals as possible at postmortem in order to discover, define, and describe the tissue changes – lesions – associated with the many different clinical manifestations of lameness. Once having such information, the next step is to formulate reasonable, logical hypotheses as to the pathogenesis of these lesions.

Pathogenesis, briefly, is the study of the cause and development, the natural history, of a disease process. Once an hypothesis has been developed from a series of observations, it may be tested by further observation and by experimental methods if applicable.

“If applicable” is most important. Once having determined that spavin is an arthrosis of small joints of the hock, and observation further suggests that arthrosis to be more common in sickle hocked horses or horses that work that way (jumping, pulling loads), what does one do to test the hypothesis experimentally? Frankly, I do not know. Anything I have thought of and had suggested to me would be horribly mutilating and require that mutilation to be practiced on a large number of horses.

Some years ago experimenters were interested in producing lameness lesions in horses in order to test the efficacy of some drug or other. I suggested, based on pathology and a mechanical hypothesis, how they could regularly cause arthrosis of the pastern joint. That hypothesis had been verified by the nonexperimental observations of Lars Haakenstad in Norway as well as by my own ongoing observations. The experimenters were horrified and said they would never do such a thing to a horse! No, and neither would I; I just told them how it could be done. Do the authors of, for example, Equine Locomotion, know that? Do the authors of Equine Lameness know that? No, neither do because, I suppose, they do not consult with or read what pathologists have to say. Are pathologists god-like about this? No, they are not, because it is a sad fact that the majority of veterinary pathologists have no interest in the locomotor system. When someone does look, clinicians, usually, interested in specific problems, the results are often poor if not catastrophic because of lack of experience with “the blooding of the postmortem room.”

People who, in recent years, have been interested in the study of normal equine locomotion have contributed a great deal of useful information using the experimental approach. At the same time – in fact, earlier – the observational pathology approach has contributed to greater understanding of both normal and abnormal locomotion. These two approaches are not contradictory and should be complementary. It is, however, a simple, easily verifiable fact, that most students of normal equine movement know little or nothing of the pathology of the locomotor system of the horse and seem to make it a point of honor not to learn.

In my specific case I found basic mechanics to be a helpful tool for developing hypotheses for the pathogenesis of the lesions which have been observed. There have been and are well-trained engineers who have contributed to understanding the mechanics of equine locomotion. In all instances of which I am aware, however, those engineers know little or nothing of pathology and do not want to know about abnormal locomotion. Their training, after all, is in how to build things that do not fail and not to create or study failures.

When possible, the mechanical hypotheses have been tested experimentally. Specifically in the case of navicular disease a concept of pathogenesis was developed in the postmortem room and tested in vitro in a testing machine. The hypothesis was verified as far as in vitro testing could do so. From that work it was abundantly clear that experimental production of navicular disease in live horses (with attendant large numbers and statistics) was completely out of the question.

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