(153.) Causes of Foot-rot. "What do we gain," says Mr Dick, "by enticing the sheep from his native and natural haunts to the richer pasturage of our meadows or lawns? There the animal enjoys a more luxuriant repast; it fattens to a larger size, and will, in this respect, repay the increased allowance which has been made to it. But instead of moving about in small troops, with the alacrity of the wild kinds, the sheep are seen in flocks of thousands, moving slowly over their pastures, and gorging themselves to an extent which cuts short the thread of life, by the advancement of various diseases. Instead of wandering from the summit of one peak to another, in quest of a scanty subsistence, or instead of being compelled to descend from the summits of the mountain in the morning, and ascend again in the evening, they are compelled, in many cases, to remain within a few yards of a particular spot for weeks together, and there engorge themselves to satiety.
"But what, it may be asked, has this to do with the foot-rot? More, I am inclined to think, than is generally imagined. The hoofs of the sheep being intended to receive a degree of friction from hard surfaces, are not acted upon when the animal is placed under such circumstances; and the necessary consequence is an overgrowth of the hoof. The crust,—the part naturally intended to support the weight of the animal, and to endure the greatest share of fatigue,—is here allowed to grow out of all due bounds, because the softness of the pasturages, upon which it now moves, presents little, if any, of that rough friction to which the feet of the animal is naturally intended to be exposed. The crust, therefore, grows unrestrained, until it either laps over the sole, like the loose sole of an old shoe, and serves to retain and accumulate earth and filth, or is broken off in detached parts, in some cases exposing the quick, or opening new pores, into which the particles of earth or sand force their way, until reaching the quick, an inflammation is set up, which, in its progress, alters or destroys the whole foot."
"The finest and richest old pastures and lawns are particularly liable to this disease; soft, marshy, and luxuriant meadows are equally so; and it is also found in light, soft or sandy districts. In the first of these it is perhaps most prevalent in a moist season, and in the latter in a dry one; in short, it exists to a greater or less extent in every situation which has a tendency to increase the growth of the hoofs without wearing them away, and more especially where they are kept soft by moisture. It is so prevalent in fine lawns and pleasure grounds, that they are, in many instances, reduced in value to a mere trifle as a pasture for sheep; they are said to be infected with this disease, and having once become so, the vicissitudes of seven seasons are scarcely sufficient to destroy the contagion! A luxuriant herbage, on soft pastures, is equally subject to it; and, in both cases, the disease is increased in a wet season.
"The reason why, in these situations, sheep are so liable to the disease, is quite obvious. They are generally brought from lands where their range of pasturage was greater than in these situations. In their former state, from the exercise which the animal took, and the nature of the grounds on which it pastured, the hoof was worn down as it grew; but, under the state in question, the hoofs not only continue to grow, but, where the land is moist, that growth is greatly increased; and the animal does not tread upon hard ground, nor has it exercise to wear them down. Now, in the case of man himself, when the nails of his fingers or toes exceed the proper length, they break, or give him such uneasiness as to induce him to pare them. And the same takes place with the hoof of sheep. But there is this difference in the case of the latter, that when their hoof once breaks, as the animal has not the power of paring it, the part thus broken must continue a wound. Some parts grow out of their natural and proper proportions; the crust of the hoof (c.c.) grows too long; and the overgrown parts either break off in irregular rents and unnatural forms, or, by over-shooting the sole (s.), allow small particles of sand or earth to enter into the pores of the hoof. These particles reach the quick, and set up an inflammation, which is followed by the destructive effects which are too well known to require description.
"Similar effects are produced on soft, wet grounds. The feet, in such a situation, are not only not subject to a proper degree of friction to wear down the hoofs, but the growth of the hoofs is materially increased by the soft and moist state in which they are kept. And this state renders the feet the more liable to the disease, as it opens up the pores of the horn, and allows the earth or sand to penetrate, and wound the quick, in the manner I have already stated. On soft sandy ground, of a dry nature, the same circumstances may occur. The soft sand gives way by the weight of the animal, and the crust of the hoof is not worn down. The sand penetrates between the sole and the crust, as has been already explained, and produces inflammation. The disease, however, is not so common on sand as in the other situations to which I have alluded, the sand seldom being found in such a loose state."
Another variety of foot-rot is produced by the friction of long grass between the hoofs, but is mostly confined to hill sheep, when first pastured on lowland districts. These animals, from having been accustomed to collect their food on extensive ranges of bare pasture, are more exposed than heavy breeds to this frequent exciting cause of the complaint. The rubbing of the grass frets the skin in the cleft of the hoof, the gland in that situation swells, becomes enlarged, and suppurates, and in no long time the animal is compelled to rest upon its knees.[ [30] This complaint is, however, more readily remedied than the former, and does not cause nearly so much suffering to the sheep.
(154.) Treatment and Prevention of Foot-rot. As foot-rot, in nine cases out of ten, is an attempt on the part of nature to get rid of a portion of the hoof, which ought, in the proper course of things, to have been worn away as fast as it appeared, the prevention and treatment of the first stage of the complaint will naturally suggest themselves. "As this disease," says Mr Dick, at the conclusion of the aforementioned paper, "arises in consequence of the hoofs not being exposed to sufficient friction to wear them down, or keep them in their proper state, or where their natural growth is increased by the nature and moisture of the ground, the hoofs of all the flock should be regularly rasped or pared at short intervals, say from eight days to a fortnight, according to the rapidity with which a particular pasture produces the disease. In certain situations, they might be made to travel upon a hard surface, similar to natural sheep tracts, or be folded in a place purposely prepared, upon which they could move about and wear their hoofs. For that purpose, they should be placed in it every day."
When foot-rot has fairly commenced, pare the hoof from the affected part, and trim away any ragged portions, wash the foot with soap and water, and place the animal in a situation where as few irritating things as possible will be in the way of the tender surface, and give a purgative. If not properly attended to, the suppuration soon terminates in mortification. Cleanliness in every stage and variety of foot-rot, is of the first importance. Many corrosive preparations are recommended for the cure of this disease, but I have decided objections to one and all of them. When the foot is clean, endeavour, by frequent applications of soap and water, to keep and treat the ulcers as directed in paragraph 110.
(155.) Inflammation produced by Insects in the Air Passages. Much annoyance is caused to the sheep by the presence of animals in the air passages. The Œstrus ovis deposits its eggs on the margin of the nostril in autumn; these are soon hatched, and the larvæ immediately find their way up the interior of the nose, till they arrive at the frontal sinus, a cavity situated between the layers of the frontal bone, and of considerable size in the sheep. Here they remain till the following spring, when they quit their hold, become winged insects, and enter upon the career of torment so ably gone through by their predecessors.