THE ROT IN SHEEP.

Southland Times, Volume I, Issue 5, 25 November 1862, Page 3

THE ROT IN SHEEP.

(From the Medical Times and Gazette.)

\i\ izotic diseases are only of less interest to the practitioner of medicine than epidemic. Especially is this true of diseases affecting those of the domesticated animals which furnish human food. The terrible pievalence of " lot 1 ' amongst sheep in 1860, which swept off whole flocks in the western and southern counties nf E> gland, and extended to several of the eastern and midland, has been the immediate occasion of the publication by Profissor J. li. Simonds of an able pamphlet on thr .sulijfCt, which embodies tlie ?esults of an investigation originally made at ihe Koval Agricultural Society. The cause of' rot" is now generally admitted to be the pre sence of the •* liver fluke " (Disloma hepalicuin) wiiliin the biliary tluets. Th- na tional hibtory of the disloma is not yet entirely made out. The following facts, however, seem tolerably certain Each of ihe innumerable ova of the fluke gives origin lo a certain number of ciliated circular embryo.".. The mmuration of the embryos, and their escape from the ova, appear from some experiments of Mr. Simonds to take place more rapidly when the ova are kt-p damp only, with free exposure to air — the ci:cumstances aHoy ed by location in a wet pasture — than when they are allowed to remain covered with

water. No change seems to lake place in the embryos until they becoue parasitic Ito water snails, slu^s, &c. Located in these cr-atuies, they become converted into a peculiar organism called a eeicaiiasac. Front the nucleus of ihe distoniaembryo within the cercaria-sac a brood of young cercat'iss — little tailed worms, si> called from their caudate form — are formed by a process of successive budding-, each one in turn becoming parent. From the first, second, or third of these offspring h return to the original form of the distoina takes place. The cercaiis resembles the distoina, except thai it has no sexual organs, in order that the higher degree of development indicated by the presence of ovaries and lestes should take place, it i* n<ce»saiy that the cercaise, after being tet from the cercaria- sac, should become entozoic. Some varieties of cercaria have been observed by Nitz.iuh, and others, to bore their wa> into water-snails, to cast off iheir tai.s, and develope into flukes with perfect sexual organs, iimbedHed in the body of the snail, before the change imo the fluke, the cercaria parsed into ilic papa slaie. by rolling itself up into a ball, and emitting from the surface of its body a quantity of mucus which hardens into a shell like covering. The p.ipa state has been observed by isteenstrup to continue in some instances for many months ; it is the penultimate stage in the series of transformations which lesult in the development of the perfact fluke, and it appears probable that it is only when entering the organism of vertebrate animals in the pupa stage of the cercaria that the entozoon will be further developed. Ten yeais ago, Mr. Siinouds administered a large quantity of the ova of the distoma to a sheep, but on killing the animal six months afterwards, and examim* the liver and other organs, not a single fluke was found. Similar experiments have been made by Gerlach and with a similar re.sult. Tl.e tailed free liv.njr forui of cercaria has also been administered by De la Valette, but no subsequent metamorphosis into the distoma took place. On the other hand, when given in the pupa state they quickly become provided wiih germ-stock, testes, and ovaries ; in fact, become converted into flukes The reason ot the great liability of Ihe ruminant animals to become the residence of distomata, Mr. himonds attributes to the fact that the encysted ceveanre are not at once liable to be' destioyea by 4fea action of the gastric juice, but are deuoed for an indefinite length of time wit Kin the rumen aud the

other preparatory stomachs. That sheep are especially the subjpets of the disease is piobably explained by their feeding dose to the ground, cropping the short where the penultimate forms of the dia<oma abound. A curio.us fact confirmatory of this view is related by Cleeve, in an essay on "Hi c s^s on Sheep" In a j Devonshire parish all the sheep depastured in the mashes « ere attacked with "rot" and died, with the exception of four. These four we«e all " hog-jawed." that \s, the lower jaw w ' .-horter than the upper; they consequently could not l>ite near the t round. The prevention of "'rot" appears to resolve itself into complete underdraining — !l>at is, getting rid of water necess.iry to the development of ihe cercarice. Mr. Simonds instances the grass land of Middlesex in ihe so-c.illpd Harrow district, wheie the Mirface-soil rests im mediately on the London clay, and where there is a great want of under-draining, as enormously lessened in value by the pvesi teiice of the " rol '' Large and profitable sheep cannot be fed there ; the Mradous are stocked w'nh Welsh and other mountain breeds of little value. Grazing in salt water marshes is likewise a pipveniive, but not a cure, when perfected disfomata are present in the biliary ducts. Saltwater i- destructive of the cevcarse, but diet will exercise but little influem eon the perfected entozea. It is a fart worth noticing that persons are sometimes seriously affected by the effluvium rising from the carcases of rotten sheep Mr. Simonds mentions the case of a butcher of intemperate habits who whs seized with c!i"lt-i"tic symptoms and died, apparemlj T in consequence of skinning and dressing a number of sheep affected with the disea-e. The sheep were open and warm, an 1 while engaged in preparing them he complained greatly °f 'he sickening smell. The post-mortem appearances present in a sheep which hd« died of "rot " are great emaciation and general pallor of the ii>sues, a haisbness and dry ness of the wool, which |>ulls casih from its follicles ; a soft, flabby state of the muscles ; infiltration of the areola tissue with watery fluid, which is apt to accumulate about ihe front and lower parts of the neck and around the lower jaw ; a.*cite« ; elusions of scum tnking the place of the omental and snpra-rnal fat ; condensation of the st uctuie of the livt-r, which assume* a pale or dirty tellow colour, not nnfrequently speckled or mottled with red ; thickening arid calcareous disposition in the coats of the biliary ducts, which are commonly dilated ; distomala in varying numbers, and ova within the ducts ; and lastly, general anaemia of ihe vi al organs. We have only space to notice two other curious points with regard to the distomnta. There seems reason to believe that, like some other internal parasites, on the death of the animal in whos: 1 body thry are located, they quit their position. as if attempting to escape. Another fact, is 'h't dead flukes sometimes form the nuclei <-f biliary calculi. We may reler such of our readers who wish for information on the stiucture of the-e entozoa, and their distribution in the anima! kingdom, to an fxcell'-nt paper "On Flukes," by Dr. T Sp- ncer Coin. old, published in the first number of the Intellectual observer. The whole subject, of the genetic cycle of the parasite's existence, together with the common and destructive epizootic disease which il originates, presents so many poi..ts of interest to the pathologist, no less than to the soinparative i hysiologNt and naturalist, that we think no apo'ojiy necessary for having thus submitted it io our readers" attention.