day, besides the continuance at his ordinary work, it would prove the worst event for veterinary surgeons that has ever yet happened in the horse world; because it would tend more to cut off our supply of groggy lameness, and its attendants, than any circumstance, or single cause, that has ever yet been published, or even named.

considered.

3dly, The absence of frog pressure is another cause. The frog is doubtless an important organ in preserving the natural form of the hoof; but I differ from those eminent veterinary authors who have urged, in opposition to our distinguished President, Professor Coleman, that the frog cannot bear pressure, my experience having shewn me Frog pressure that it can; and I have convinced myself, by repeated experiments, that it can endure an extraordinary degree of protected pressure without injury to itself or other parts of the foot. I use the words protected or secondary pressure as a distinguishing mark from the frog pressure, which has been so long insisted on by Professor Coleman; and, if I mistake not, this gentleman inculcates the necessity of the foot being shod with the frog exposed, at least, on a level with the heels of the shoe.

Experience has convinced me, as well as Mr. Coleman, that frog pressure is both natural and beneficial; but I must admit, with many other practitioners, that, in the present improved state of our roads, the sensitive foot cannot sustain the shock

Pointing of the feet-the

or that marked symptom of the disease, pointing of weight convey- the feet. If such a horse be carefully watched in

ed or directed

extensors-in

chiefly on the his stall, without being disturbed, he will be found dicative of ap- inclining his weight as much as possible on his exproaching distensor tendons, and thereby relaxing the limb.

ease.

moisture to the

hoof.

Allowing the hoof to become hard, dry, and inelastic, particularly the sole and frog, from the want of stoppings or emollients, a serious evil ensues; but I think the degree of evaporation of the moisImportance of ture of the hoof, arising from the heat of litter, has been much over-rated by Mr. Coleman and others; and I coincide with Mr. Percivall, sen., that the clean straw beds usually given at the present day are perfectly harmless, rather suspecting, that the evaporation is occasioned by heat generated within the foot than applied from without.

nefit and a bane

With regard to shoeing, as one of the causes, I believe all writers, ancient and modern (except the renowned Nimrod), are agreed by having desigShoeing, a be-nated it "a necessary evil." An evil undoubtedly it is of great magnitude, but it is also an inestimable benefit; as, without this art, horses would be comparatively useless in proportion to the excellence of our roads.

The first pernicious consequence of contraction I have invariably observed to be a very gradual displacement of the navicular and coffin bones: they ascend within the hoof; but more particularly the navicular bone and heels of the coffin bone. This

of the navicular

deviation from the natural position is not only obser- Displacement vable on dissection, but is quite as apparent in the and coffin bones living foot, by paring down to the quick those commissures or channels between the bars and frog which will be found so morbidly deep, and take so much time for the knife to reach the quick, that a by-stander, ignorant of the nature of it, would be induced to remark that such a horse was devoid of blood in his foot. Exactly in proportion to this morbid concavity externally is the morbid convexity internally, and thus, with a fixed ascent of the frog, an unnatural arch is formed: the soft elastic parts Unnatural arch and protrusion of the frog being absorbed, it becomes a rigid pro- the foot. of frog within tuberance, and is the rock of danger, on which I am daring enough to assert that the most valuable horses have struck. This protrusion of frog within the foot is accompanied by an undue concavity of A highly elastic sole and rigidity of the bars. The navicular bone nerated into a lies transversely across this projecting part of the rance. frog, with the long flexor or perforans tendon passing under, and, by articulating with the bone, The navicular forms the navicular joint. The joint receives its tuate. share of the superincumbent weight from the small pastern bone, and with violence, in the ratio of rapidity with which the animal moves, and is required to yield and descend in proportion to the impetus. It should also be remembered, that it is placed immediately under the centre of weight, which is conveyed in a perpendicular direction.

cushion dege

rigid protube

joint, where si

Its lining membrane crushed,

essence of na

The occult or partial contraction abruptly opconstituting the poses the navicular bone in its descent, and thereby vicular disease. crushes or bruises the delicate synovial membrane lining the joint, which suffers a mechanical injury from the very material which Nature bestowed as a defence, and which has degenerated into a hard, rigid, inelastic protuberance, no longer capable of yielding and expanding under the superincumbent weight. Nature has made ample provision to ward off concussion from these parts in the colt or unshod foot; for not only are the posterior parts much more elastic, as compared with the toe and sides of the foot, but she has also bolstered the navicular joint with two elastic cushions placed one on the other, and which, united, form such a hard and soft medium, as no human ingenuity could imitate; the tough, though highly elastic, horny frog being opposed to the ground, and the fatty frog encompassing the navicular bone and flexor tendon, which are further shielded by elastic cartilages. Now, as all these parts, in a state of nature, preserve their elastic properties, they yield and give room for the navicular joint to play like a pulley, without compression or restraint, in the most violent exertions of the animal.

I am thoroughly satisfied, that, when contraction is accompanied with chronic lameness, disease exists in the navicular joint, either structural or functional; and that this complaint, at its com

mencement, is neither more nor less than a bruise of the synovial membrane lining the joint.

so much from

as from rest.

Although it appears that some degree of violence is essential to the completion of this formidable disease, yet I am convinced that it does not originate in wear and tear, from contact with either the roads Originates not of the former or present day: it has, in reality, its wear and tear origin in rest. It is certainly engendered in the stable, but becomes permanently established by sudden violence out of the stable and I have frequently observed, that, under peculiar pre-existent circumstances, a very moderate proportion of exertion on a hard road or stones has been quite sufficient. Two or three severe days' work in succession, immediately after long continued confinement in a stall, and the hurried pace and distance united, would compel the animal eventually (though perhaps reluctantly) to convey his weight abruptly, and with considerable force, on this obstructing body formed by a fixed elevation of the frog in conjunction with a morbidly thick sole.

I believe Mr. Coleman is of opinion, that a defective secretion of synovia is the first derangement of the navicular joint: this I take to be merely secondary, and for this reason, that I have uniformly found the navicular joint sound, and containing the due proportion of synovia in feet, however much contracted, which had always been known to have been free from lameness. The bruise and conse