SCAB IN SHEEP.

Patea Mail, Volume V, Issue 463, 1 October 1879, Page 2

SCAB IN SHEEP.

We take the following interesting article from the New Zealand Country Journal , which has been compiled from a pamphlet Written by the Chief Inspector of Sheep for New South Wales, by Mr P. B. Boulton, Chief Inspector of Sheep, Christchurch :• CAtfSE, The Scab in sheep is commonly known as an eruptive affection of the skin, very highly contagious, and accompanied with an almost inccssantitching. It is caused by a minute insect like the horse mite, but smaller, and known as the Scab acarus ( Sarcaptes ovis). It may be conveyed from one sheep to another : either by actual contact, or indirectly, by being left in old yards, or camping grounds where diseased sheep have been folded, or in wool hanging to trees or fences against which these sheep have rubbed, and with which the clean sheep afterwards come in contact. In Australia scab has been caused solely by contagion. It is true, that at first, some cases were attributed to spontaneous generation, consequent on ill treatment, or the poverty of the sheep but fuller inquiry showed they wore due to contagion. And sheep have, thousands of times, been subjected to all sorts of bad treatment and privation without originating this disease in a single instance. SYMPTOMS. The symptoms of scab are generally to be looked for, in the first instance, on the sides of the shoulders, or along the the back, or on the rump and near the tail, and they may bo one or more of the following, namely Biting, Scratching, or Rubbing. On watching sheep for a short time in which scab has existed for a few days, if the weather be at all favourable, some of them will bo observed to bite, rub, or scratch themselves very suddenly and keenly, much more so than when they are affected with grass seeds, which cause them to exhibit the same symptoms; but when they are affected with grass seeds “the sheep bite, rub, and scratch in a comparatively slow and lazy manner. The signs of biting may be a break, a light colored spot, or a dirty looking, wet, knotty, and matted patch in the fleece, caused by gnawing, or there may be merely a moist spot or patch. Sheep scratch themselves with their horns their hind feet, and they rub themselves on fences, trees, or stumps. The signs of scratching and rubbing are abrasions or breaks in the fleece, and discloration of it through scratching with their hind feet or rubbing. GRANGE IN COLOR OF FLEECE. Besides the changes in the natural and healthy appearance of the fleeco from biting* rubbing, or scratching, just noted, patches, of a small size at first, but which gradually enlarge, till they are in some cases larger than a man’s hand, of an unhealthy, whitish, harsh, yokeless appearance, sometimes indicate the presence of scab. If arising from this disease (smatf patches of the same appearance are sometimes caused by grass seeds) a dry thin scab, will be found at the root of the wool, on the patch thus indicated, the skin will be thick and discolored, and if the disease be not checked by . dressing, the wool would in course of time fall or be rubbed off; but in this description of scab (which may be termed the dry form), the wool adheres longef

■and more firmly than where the patch is green and moist. The dry form of the disease is generally met with on f heep in good Condition, and at a season of the year, the height of Summer, when the insect is comparatively inert. BROKEN FLEECE AND BARE PATCHES. In an early stage of the disease there will be locks or pencils of wool sticking out from the fleece, and as it advances these pencils will spread into bare patches of different sizes, according to the length of time the disease has existed. These signs are caused by the wool (which loses its holding power though tne insect destroying tbe vitality of the skin) being pulled, rubbed, or scratched off by the sheep ; and they vary in size, from a spot no larger than a shilling, T»nd only noticeable from the loose pencil, to a patch extending over half the sheep. If the disease be long neglected the sheep will present a miserable ragged appearand in some instances they will be T\ll but naked. This pencilly appearance is always to •be met with more or less in every outbreak of the disease, bat the attack is at times much more pencilly than patchy. This is especially the case in re-out-’breaks of the disease in flocks which •have been dressed for scab; and is dne probably to insects—which have remained nndestroy.ed on the run for a longer period than the dressing protected the sheep—again settling on them, separately, though often in considerable numbers. CHANGES IN THE SKIN. The skin of the aflccted part, in the early stage of the disease, say the third or fourth day after the infection is conveyed, will have lost its beautifully delicate pink color, and will be of a pale bluish green tint, and somewhat thick in texture j while a small clear white scab (a small patch or spot of dried lymph), will have gathered round the point whore the insect entered' the skin. In the course of five or six days more this spot, or pustule, as it is sometimes termed—although it seldom or never assumes the shape of a pustule as generally understood—exhibits the appearance of a small patch of decided scab; and the exudation becomes thicker and of a greenish tinge. As the disease advances the patches affected, which vary in size according to the duration of the •disease, are gradually denuded of wool, and the skin, where the disease is active, becomes thick, and assumes a decidedly unhealthy green and watery appearance (an unmistakable symptom of Scab). This discharge—the amount of which •©(•course depends upon the number of -insects—with the dust and dirt, forms •an incrustation or scab sonetimes oneeight of an inch in thickness. In any •case, there will be considerable' scab on •the patch; but as it increases in size With : the progress of the disease, the 'sbab gets generally dry and comparatively ’3ead towards the centre of the Ipatch, : and ! is only green ,wet, and active •round the outer edges, where the insect is still at work.

As the disease progresses, and the increase in size, the skin on them will feel thick, harsh, and boardy ; and ; if, at this stage of the disease, or even earlier, the skin of the affected parts be ■either scratched or pinched, the sheep will sidle up to and rub against the person scratching or pinching it; sometimes turning its head as if it would bite, and all the while moving its lips and tongue, as indicating its enjoyment ; this is also an unmistakable symptom of scab. These symptoms follow each other, and increase in fullness till the disease gradually spreads over the greater part of the sheep, and if not checked would eventually cause its death, the sheep Wasting away and dying through the torture inflicted on it by the existence of thoacari. Except in a very early stage, scab is •easily distinguished from all other cutaneous ailments and diseases to which sheep are subject—on the one hand by tlfe symptoms described above, which are peculiar to scab, and on the other by contrast with the distinctive appearances so well known to persons of ordinary experience among sheep, which denote grass seeds, wounds, fever spots, prickly heat, and rubbers—the only ailments for which scab is at all likely to be mistaken. (To he continued.)