SCAB ON SHEEP.

Waikato Times, Volume X, Issue 707, 28 December 1876, Page 3

SCAB ON SHEEP.

The following is the essay read by Major Wislon at the last meetms of the Cambridge Farmers Club :— Mr President, taking into consideration the absence of ' scab' in this district, it may at fir.t light, be deemed inopportune to discsus the question at present to the exclusion, perhaps, of more immediately inportaut matteia But one » never oertamof immunity from mfection, and the recent aotion of the GoTernmenfc in bringmg forward an Act m the last Aasembly to destroy the natif c flocks on tbe East Ccast, on account of that disease evinces the necessity of careful watching. It bss only been by the most strenous exertions on the part of the flock owners of Mew Zealand, supported by the most striDpeut laws, directed against even the appearance of the disease that we may Sjoice in that Immunity, which we now ijoy, and which makes it almost appear a work of supererogation to notice an iniiotion apparently never likely to oocur. fccnb has been observed as a scourge to tbe flock owner in all ages, and was trsphically and minutely d< scribed by Virgil in his Georges, Livy, too, four hundred and twetityfonr years before the Christian Era writes of a cutaneous disease obtair ing in sheep and cattle, which communicated iteeif even to men, and which might or might not hare been tht diseate under diamssion. Although, now the human ■object is not so infected by contact with the nhe«p, we know that at difltreat epochs, certain "well known due*»es j h»ve marfuVsted virulent phases, and that their development m the 1 modern stages of the >arne illness are altogether so much milder, that they are looked npon|bymaey ns being quio dfferenfciu character. Even, in our own days we have malignant scarlet- fever, and its milder tyre, hut still tbe same disease, commonly known «s scarlatina, and possibly the irfectiuua disease of Livy might have be"en an inveterate c*»e of so* bits. lhi« disease is caused by an acarun jomrwhat analatto»s to that of the itch in the humsn subject ; and is, from its very nature, ' highly contagtous ; tbe»e minute insects or animalcnke breeding rapidly, snd extending themselves in all directions. M VV»tz, a' German vet*renari»n, as quoted by Yoo&tt, has bestowed much care and attention to iher observation Df the acari, and has discovered that if female ncari are placed on tbe wool of a found *heep, they quickly travel to the root, and bury themselves into the skin, the p)sce at which they penetrated being scarcely risible, or only distinguished by a mmnte red point. On the tvnth or twelth day a slight swelling may be detected between the flnger and thumb, the skin changes its color and has a greenish upptarance, the pustule is now rapidly formed, aDd breaks about the sixteenth day, when the mother again appears with her little oae» attached to her feet, a\|d covered by a portion of the rhell of the egg from which they have just escaped. These little onfl immediately penetrate the nei){hbouiint» skin, and bury them* selves bmeath it, finding their proper nouiisbment, and grow and propagate ai those before thsm. M Watz placed some of the small acari on tbe sound skin of a cheep, and they, too, turrowed their way. and disappeared for a while, and the pustule in due time aroae l^ but the itching and the scab soon disappeared without the employment of any remedy. According to this author, every litter of thue parasites comprises from eight to fifteen, the females became in a very short time four times their original' size. Th» acai us newly hatched placed in a dry place, diet in a few days and crumbles into dust. The more adult insects become dry, and perish more or less slowly, according to the state of the atmosphere, whether dry or moist ; but -swhen the summer has passed, and the Mnsectbasbecouieold, it retains its life from the Autumnal to the Spring equinox, or dmirg the whole of tbe winter— A very important fact — illustrating the difficulty of netting rid of scab when it once spreads in a flack. In size, these acari •re very minute,' which might be represented by the puncture tbat a small needle would -mate in a piece of writing ' apt r. 'VV here one of thete insects to be placed on such paper it could readily be distinguished by the naked eye, but on their natural habit can only be recognisrd by t) c use of the microscope. Tb» existence l>f this pamtite points to the phi)osr|iliy of (he cutaneous eruption, and its distraction it tbe only mean* of performing a cure. To tht uninitiated in the mysteries of the microscope, the disease is simply observable as a cutaneous eruption ; he notices that an animal has some loose wool about the shoulder, that it frequently bites the spot, or running to some post or projection, rubs itself violently, and in its uneasiness cannot rest long in ono position withont reverting to the biting and rubbing to which the itching impells it The aonte farmer, albeit he is not learned in the nses of scientific instruments, is so novice as to the meaning of these symptoms in his sheep, and cannot rest satisfied until the patient is examined, to see whether it be the veritable scab h* so much dreadi, or only some 'prickly heat,' or may be grass seed which has entered the skin, and which in many oases simulates incipent scabs : uo much ■o, that even upon examination it is very difficult to come to a conclusion withont the aid of the microscope. Tbe symptoms of grass seed puncture begins oftsn, rising the wool on tbe part, and a smsll greenish pimple, easily felt with the finper and thumb, and which, when cut with a knife, like tbe true scabiss, divides with a olean cut, showing a sharp edge on the lips of the in* cisioft. » If, however, it proves to be the veritable dieesse of which we write, the small apot enlarges, as we have seen, and rapidly tpreade over all parts likely to be affected by the insect, i.e., on the •boulder, more especially, and the tides and back of the animal to the tail. The breast being not •often effected, the belly acaroely •ver, and the head, we msy uy, not at

all, a rath»r curious circumstai'Cf, ae-iog that, from the animal's continuous bi iug, the no*e and head cornea ii* auoh closo contact with the affected ptrti. I have seen a flock of over throe thousand dipped for very severe scab, and their heada carefully guarded, from an ignorant fear of their eyes being iujured, and yet, that one dressing effected a radical cure, and that, too, after the flock had been bad for three years. When once scab infects a flock for the first time, it makes its way quickly through it, and in a very short time the fluck presf nta » moat deplorable appearance, the fleece hanging in great patches, and, after tome time, those tint taken have managed to rub the wool on the shoulderi quite short— tke skw, to the touch, feeling like strong felt, and as thick ai pasteboard — and in otni r places is completely denuded of wool, and either raw, or covered with bard crust, the effect of confluent pustules. We have it from Youatt, that the poet mortem appearances exhibit geteral y chronic luflamation of the intestines, with the presence of a great number of worms. The liver is occasionally scirrous, and the spleen enlarged, and there are frequent serous effusions in the belly, and sometimes in the chest there has been evident sympathy between the digestive and the cutaneous systems. After the flock has been cured of the disease, if it re appear, it is much slower in it its progress, only taking a speedy hold of the lambs not previously affected.