!l6 



SHEEP— DISEASES AND REMEDIES. 



SHEEP, Scab.— The general preva- 

 lence of scab in this country gives im- 

 portance to a brief examination of this 

 subject. 



The scab of sheep, like scabies, the 

 itch of man, is caused by an insect. The 

 mange affecting the horse, ox, dog, and 

 cat, also depends upon the presence of 

 insects. There are different insects, 

 known as acari, infesting different ani- 

 mals, having destructive characteristics 

 in each, and generally confined to that 

 species of animals, yet the mange from a 

 dog is said to have been communicated 

 to man, and a horse has been infested 

 with mange by means of the skin of a 

 mangy cat. 



The sheep acarus does not bore gal- 

 leries in the skin, but remains on the sur- 

 face, clinging to the wool, and finding 

 shelter among the masses of scab pro- 

 duced by the drying of exudations from 

 the wounds inflicted by these parasites. 

 Experiment has shown that increase of 

 temperature hastens the hatching of their 

 ova; fourteen days, according to Profes- 

 sor Brown, of England, sufficed to hatch 

 a lot in a bottle " carried in the trowsers 

 pocket," while two months' time was re- 

 quired with some kept under glass in a 

 room. The young have six legs; the 

 fully grown, after several changes of skin, 

 have eight. The microscope reveals 

 sucking-caps or disks in the legs, ena- 

 bling the parasite to cling to the wool 

 and skin of the sheep ; and renders beau- 

 tifully apparent the action of these struc- 

 tures, showing, as the feet advance, how 

 the disks are expanded to grasp the sur- 

 face of the substance over which the 

 acarus is moving, apparently retaining 

 their hold in obedience to the volition of 

 the animal. Thus its structure adapts it 

 for crawling over and adhering to the 

 skin, instead of burrowing beneath it. 

 Burrowing acari, like the itch insect in 

 man, are always armed with cutting 

 teeth, set in ] strong jaws, and their legs 

 are very short. The body of the female 

 of the sheep acarus is larger than that of 

 the male, rounder in form, the fourth pair 

 of legs are developed nearly as well as 

 the third, and are supplied with terminal 

 sucking disks. Mature mites are visible 

 to the naked eye as pellucid points of the 

 size of a pin's head. 



Various experiments have been made 



to ascertain the rapidity of the growth, 

 and reproduction of these parasites. 

 The young acari have been detected in 

 fourteen days from the direct transference 

 of the acarus to the skin of the sheep. 

 In a month the disease had spread over 

 a space of five inches ; in ten to twelve 

 weeks pretty nearly over the whole body. 

 A greater or less amount of time may be 

 required under different circumstances of 

 temperature, and other modifying in- 

 fluences. 



Symptoms. — The first sign of the exist- 

 ence of scab is rubbing against any pro- 

 jecting body within reach; as it extends, 

 sheep bite themselves, kick with their 

 hind feet at their sides and shoulders. If 

 one is caught and the hand placed on the 

 mouth, while infected parts are scratched, 

 gratification is evinced by nibbling at the 

 hand, and when the infection is severe or 

 general this nibbling movement is re- 

 garded as an infallible sign. Examina- 

 tion will disclose spots on the skin, white 

 and hard, the center marked with yellow 

 points of exudation, which adheres to the 

 wool, matting the fibers together. The 

 wool may be firm on these spots, and no 

 scabs are seen at this stage. Then the 

 yellow moisture, evaporating, gives place 

 to a yellow scab, which adheres firmly to 

 the skin and wool. Raw places appear 

 at points which the animal can reach with 

 his teeth and hind feet. The disease is 

 complicated in summer by the presence 

 of the larvae of the blow-fly, the mag- 

 gots burrowing under the scab. The ani- 

 mal becomes nervous, excited to wildness, 

 and cannot obtain properly either food or 

 rest, thus losing flesh and becoming re- 

 duced to a skeleton, from constant irrita- 

 tion and lack of nutrition, only the 

 strongest animals recovering, if left with- 

 out treatment. 



Remedies. — Destruction of the parasite 

 and its eggs is the only object of reme- 

 dial treatment. Arsenic and mercury are 

 often employed very effectually, but they 

 are poisonous, and therefore injurious and 

 dangerous to the sheep. These and 

 other solutions are used both as washes 

 and dips. Sudden changes of weather 

 and locality, or a deficiency of food after 

 such treatment, often induce serious or 

 fatal results, which cannot be guarded 

 against. Whole flocks have thus been 

 lost. Mercurial ointment, with olive oil 



