2. The Rev. Dr Singer, to whom Scotland at large, and Dumfries-shire in particular, is much indebted for numerous and valuable papers on agricultural subjects, states, in the third volume of the _Highland Society's Transactions_, page 478, that "The sp.a.w.n or eggs of the liver fluke are most probably _conveyed upon the gra.s.s_ by summer watering, and afterwards taken into the stomach with it." A few lines further on, he speaks of the eggs being "wafted thither by harvest waterings." Now, as the fluke is only produced within the sheep, I need only put the unanswerable questions--How are they conveyed to the gra.s.s? and from whence are they wafted? to refute at once this hasty notion.

3. The eggs may be voided by the sheep, may fall upon the herbage, and there remain till they are eaten. Such is the supposition published by Mr King of Hammersmith, in the _Quarterly Journal of Agriculture_, No. x.x.xI. p. 331, in which, after showing the vast number of eggs which must fall upon the gra.s.s, he says, "We must cease to wonder that so many sheep die of rot; the miracle is, that every sheep does not die of it."! I cannot, however, for my part, see a miracle in the matter, for the simple reason, that the eggs of the entozoa are not capable of retaining their vitality when absent even for a very short time from the place of their nativity, and therefore may be eaten with impunity.

II. Supposing the eggs to have reached the sheep's stomach in a condition to allow of their being hatched, they, according to popular voice, find their way into the gall bladder by one of two routes.

1. Mr King, the gentleman above spoken of, conjectures, in the same paper, that the fluke, after leaving the egg in the stomach of the sheep, _makes its way up the gall vessels_. This is, I am sorry to say, a very idle conjecture, as, from the valvular nature of the opening of the gall duct into the duodenum, an entrance from that intestine to the gall bladder is perfectly impracticable to any of the entozoa.[36]

[36] The notion that rot is occasioned by animalcules getting into the liver is not confined to this country. Leake, in his travels in the Morea, alludes to an opinion prevalent there, that the _vidhela_ (rot) is caused by the sheep feeding in marshy places in August and September, when it is imagined that an insect from the plants finds its way into the biliary vessels.

2. The eggs are believed by a writer in the _Letters of the Bath Society of Agriculture_, for 1781, to be taken into the blood along with the chyle from the small intestines, and to be arrested in the liver by the secretory ducts. This, it must be clear to every one, is the most absurd of all the notions; for if a globule of blood, which we must suppose to be the largest body capable of being absorbed from the intestine, is only about 1/3000 of an inch in diameter, how can the egg of a fluke worm pa.s.s through the same channel, when Mr King has, by careful observation, shown it to be 1/300 an inch in its shortest measurement. Again, allowing that they are taken into the blood, would they not frequently be hatched there, and would they not also be found in other quarters besides the liver. But do we ever find them in the blood? Do we ever see them in other organs?

Certainly not.

Not one of these theories would ever have been broached had their authors been aware of two important circ.u.mstances. 1. That M.

Schreiber, the director of the Museum at Vienna, has proved that worms and their ova are not capable, under ordinary circ.u.mstances, of resisting the action of the digestive organs, and, therefore, that they cannot be introduced into the body by this channel. "During six months, he fed a pole-cat almost exclusively on various kinds of intestinal worms, and their eggs mixed up with milk; and on killing and examining it, at the end of this period, not a single worm of any kind was found in it."[37] The reader may perhaps object to this ill.u.s.tration, on the ground that there is so vast a difference between a sheep and a pole-cat, that a comparison in regard to their digestive habits cannot possibly hold good, but if he will turn to paragraph (96), he will see that the stomach of a sheep is as well fitted as that of a carnivorous quadruped for the digestion of animal matters.

2dly, the fluke worm has been found by Frommen in the foetus of the sheep, into which it could not have been conveyed by transmission from the mother, as there is no direct vascular communication between the foetal and maternal side.

[37] Cyclopedia of Practical Medicine, Vol. iv. p. 524.

From a consideration of all these data, the conclusion must at once be drawn, that as living flukes cannot reach the liver from without, they must of a necessity be produced only in particular states of the animal they inhabit. How they originate we cannot of course determine, and this is not the place to hazard physiological conjectures; but it will be found that their appearance in the bile is always preceded by tuberculous deposits in the lungs or liver. This I have proved by numerous dissections, in which I have occasionally found tubercles without flukes, but never met with flukes where I did not at the same time discover tubercles. Fluke worms, therefore, can never be regarded as a cause of rot, they must be looked upon merely as a symptom. We cannot, however, say that tubercles give rise to the liver-fluke, for tubercles are often present in cases where flukes are absent; and if the latter were the effect of the former, their presence under such circ.u.mstances would in all probability be constant.

III. Particular plants have been said to cause rot, but the proofs of their evil tendencies being in every instance about as logically supported as the fluke theories already mentioned, I need not trouble myself or the reader by proceeding to details.

_Real Causes of Rot._ Everything that has a tendency to weaken the animal, will be more or less liable to lead to rot. Exposure to cold and wet, mishaps at lambing time, food bad in quality or deficient in quant.i.ty, and over-driving, will all predispose the const.i.tution to the deposition of tubercles. It is from the causes being in this way common to the whole flock, that contagious properties have been ascribed to rot, it having been observed, from the time of Virgil, to break out in many animals at once.[38]

[38]

"Nor oftener are the floods disturb'd with wind Than sheep with rots; nor doth the sickness find One to destroy, but suddenly doth fall On root and branch, stock and original."

_Virgil's Georgics_, Lib. III.

The reason of so many different things having, from first to last, been reckoned capable of producing this disease, appears to lie in the known fact, that if a sheep be exposed to any of the above depressing agents, rot, if the animal be as yet untainted, will not, at the moment, shew itself; but a chain of morbid actions will in all probability then commence, and, being beyond the ken of ordinary observers, will pa.s.s unheeded, till some slight mismanagement in food or shelter, hastens their progress, and renders them apparent to the plainest understanding. The final symptoms of rot may thus occur on any kind of pasture, and the scene of the catastrophe will incur a stigma which ought to be attached to herbage which the sheep have consumed at some distant place or date.

Bad food is justly regarded as one of the most common causes of rot, and ranks, in my estimation, next to cold and wet, in its power of producing it. I shall only remark, on this point, that of all the food on which sheep can possibly be kept, none is known to act so deleteriously as gra.s.s which has sprouted quickly. Rot is well known to occur most frequently on land which has been irrigated during summer, for at this season any excess of moisture is peculiarly injurious to the economy of a plant.

When plants by heat and moisture are stimulated to increased exertion on a poor soil, they acquire bulk without having it in their power to obtain at the same time those saline matters which const.i.tute a healthy plant, becoming in fact, to the eye of an inexperienced person, thriving vegetables, while to the palate they prove wersh and watery.

The same result may follow from a different process. The saline matter may not be taken up, even when the soil is rich in such ingredients, from the functional derangement into which the roots or digestive organs have been thrown by the unnatural circ.u.mstances in which it has been placed. A plant is composed, like all organized bodies, of a certain number of proximate principles, which are more or less numerous in different kinds. These are combined with varying quant.i.ties of pota.s.s, soda, lime, magnesia, and iron, which, though formerly supposed to be too trifling in quant.i.ty materially to affect the quality of the plant, have yet been recently and satisfactorily proved completely to change the character of the compound, even when the excess or deficiency amounts only to a 1/10000th part so that, supposing an animal to thrive on plants which contain salts of any or all of the above bodies, it will soon fall off if these plants are in any way deprived of a single adjunct; for by the removal of that one salt, their nature has been entirely altered.

The certainty and rapidity with which Bakewell could rot his sheep, by pasturing them, in Autumn, on land over which water had been allowed to flow during the previous summer, may seem to controvert what I have above stated, as to time and frequent change of pasture often intervening between the origin of the disease, and its termination; but when it is recollected that he pursued the destructive system of breeding _in_ and _in_, of itself sufficient to induce a tuberculous predisposition, the reader will perceive that his sheep were, in all likelihood, more or less tainted, and therefore, sure to fall victims to the disease the moment they were subjected to the deleterious influence of an unwholesome pasture.[39]

[39] When parcels of Mr Bakewell's best sheep became, from any defect, unserviceable to him, he used to fatten them for the butcher. But as there was a _probability_ of their becoming valuable in other hands, he always gave them the rot before he sold them! An example, which, I hope, for the sake both of man and sheep, never to see followed.

Over-driving and hurrying of every kind, is, in my opinion, a fruitful source of rot, not only from the fatigue it causes, or the risk it leads to of taking cold, but also from the injury, which in many cases results, to the delicate texture of the lungs. As shown in the note to paragraph (157), no animal is more easily put out of breath by running, than the sheep. Whenever the breathing is hurried, the circulation through the lungs is quickened also. If the tissue of the lungs be in any way delicate, the force with which the blood is propelled is sure to make it yield, and in this manner the animal is often suffocated by the large quant.i.ty of blood, which issues into the air tubes at once from many points. Fig. 1, Plate VI. exhibits a good ill.u.s.tration of this taken from a sheep. Numerous red points are seen sprinkled over the surface of the section, indicating that blood has been effused from many minute torn vessels. Now, if this animal had survived, each speck of blood would have formed a centre, round which tuberculous matter, as in Fig. 2, Plate VI. would have been secreted, and death from rot, at some ulterior period, would, in all probability, have been the result.[40]

[40] Pathologists differ as to whether tubercle is the cause or consequence of _hemoptysis_, as this effusion of blood into the tissue of the lungs is termed. Andral, however, is decidedly of opinion that hemoptysis is one of the exciting causes, and, in domestic animals, I believe it to precede tubercle more frequently than is generally imagined.

(165.) _Treatment of Rot._ As reason and experience have taught us that tathy herbage is a common cause of this complaint, we should, when it shows itself, at once remove the animals to a better pasture, where they should be exempted from teazing of every kind.

Salt appears, after every trial, to be the best medicine, and to this they should have, at all times, ready access. Should the disease be rather far advanced, the breathing hurried, and the cough annoying, occasional doses of the following infusion will be of service, in enabling the farmer to keep down the disease, till such time as he can conveniently dispose of the animal.

Take of Leaves of Foxglove two ounces, Boiling water two English pints:

pour the water on the leaves, cover up the vessel, and keep it in a warm place for six or eight hours, then strain.

Two tea-spoonfuls morning and evening may be given to a sheep, but as the plant is an active poison, and the strength of its infusion liable to vary, a couple of days should always intervene between every six doses.

About the year 1800, a notion prevailed in this country, that an effectual remedy for rot had been discovered by the Dutch, but this was quite unfounded, no _cure_ ever having been hit upon for this sweeping malady; indeed, a cure is fairly out of the question: its prevention and palliation, but not its eradication, being all that we can hope for. Sundry plausible plans of treatment have, however, at one time or another been contrived, some of them, in all conscience, harmless enough, but others again as well adapted for the destruction of the animal, as the removal of the disease.

As fluke worms have usually been reckoned the cause of rot, so the treatment has princ.i.p.ally consisted in attempts to effect their extermination. With this view, Sir George Steuart Mackenzie of Coule, in defiance of all preconceived medical opinion, advocated, in his work on _Sheep_, published in 1809, the employment of mercury to stay the progress of rot, and in the same work, _or one very like it_, as lately published anonymously by the Society for the Diffusion of Useful Knowledge, under the t.i.tle of the _Mountain Shepherd's Manual_, the utility of this dangerous procedure is as firmly maintained. At the same time Sir George, though rather in the dark as to the real nature of the disease, admits, in both editions, that tubercles exist in rot, especially in the lungs. Now, if he had inquired of any medical person what drug ought, when tubercles are present, of all others to be avoided, he would have found that medicine to be mercury. The administration of it therefore in rot, no matter what may be the form or mode in which it is exhibited, will to a certainty aggravate the symptoms, and shorten life. If, for the sake of doing something, you will _endeavour_ to remove the worms, Chabert's animal oil will be found a safe and efficacious remedy; but, if my opinion can have any weight, I would recommend the farmer to allow them to remain.

Sheep, when displaying symptoms of rot, should always be kept dry and warm. If they must be retained throughout the winter, good sound solid food, such as well made hay or oats, should be afforded them, and the shelter of a straw yard should if possible be obtained. A liberal supply of salt should be given with all their provender; and if they do not seem to relish it, give them occasionally a small quant.i.ty in water as a drench.

(166.) _Prevention of Rot._ On this head I need do little more than remark that attention to the causes will go a great way to point out the necessary means for its prevention. Admission of the sheep to rank soft gra.s.s, heavy stocking, short allowance of food during winter, every thing in fact which leads to the exposure of the animal should be scrupulously avoided. The strongest const.i.tution cannot with impunity be tampered with, and the soundest habit will fall before the mining attacks of want and weather. Keep your stock always in as high health as possible, for such is the surest prevention of tuberculous disease.

As rot is hereditary,[41] the importance of weeding out ewes from the flock on their first exhibiting appearances of unsoundness, is acknowledged by all. Many ways have been pointed out for detecting the incipient symptoms, but none plainer and better than those written by the late Mr Beattie of Muckledale, and published in the 3d vol. of the _Highland Society's Transactions_. "The first thing to be observed,"

says Mr Beattie, "is in the spring, when they are dropping their lambs.

A sound ewe, in good order, drops a lamb covered with a thick and yellow slime, which the ewe licks off it, and the rule is, the sounder and the higher the condition the ewe is in, the darker and thicker will be the slime; but when they observe a ewe drop a lamb covered with thin watery bubbles, and very white, they note her down as unsound."

[41] MM. Dupuy and Andral have seen tubercles in the foetus of the sheep.

"About the month of September, when they intend to dispose of their draught ewes, they put all their sheep into a fold, and draw them by the hand, that is, they catch them all, viz. the ewes they design to sell any of, and clapping their hand upon the small of the back, they rub the flesh backwards and forwards between their fingers and thumb and the ends of the short ribs: if the flesh be solid and firm, they consider her as sound; if they find it soft and flabby, and if, when they rub it against the short ribs, it ripples, as we term it, that is, a sort of crackling is perceived, as if there were water or blubber in it, they are certain she is unsound. This is the most certain of all symptoms, but is not to be discerned with any degree of certainty but by an experienced hand; for although, as I have here related it, it seems a very simple affair, and easily acquired, yet it is well known that many shepherds, who have followed sheep all their lives, never arrived at any thing like certainty in judging by the hand, whilst men of superior skill will seldom be mistaken, and will draw by no other rule. Yet still it must be acknowledged that the seeds of this disease will sometimes lie so occult, as to baffle all skill, and that no man can with absolute certainty draw a stock tainted with the rot. There is another method, to which men of inferior skill resort, which is more easily acquired. They take a sheep's head between their hands, and press down the eyelids, they thereby make the sheep turn its eyeball so that they get a view of the vessels in which the eyeball rolls: if these are thin, red, and free of matter, they consider the sheep as sound; but if they are thick, of a dead white colour, and seem as if there was some white matter in them, they are confident she is rotten.

This is a pretty general rule, and easily discerned; but I think it is not so certain as when they are judged by the back; for in firm healthy lands the eye of a sheep is far redder than it is in sheep upon gra.s.sy lands. And in some boggy lands the eye is never very red, be the sheep ever so sound, so that there you cannot so well judge by the eye; but when you see the eye of a sheep a good deal whiter and thicker, and more matter in it (I mean the vessels in which the eyeball rolls) than the run of the flock amongst which it feeds, you have reason to suspect it is not sound.

"There is another method by which I have seen some men attempt to judge of the soundness of sheep. It is a well known fact, that when sheep are rotten the lungs swell to a greater size; they therefore lay the sheep down upon its broad side, and pressing the skin in at the flank, up below the ribs, _pretend_ to feel the lungs. But if there is anything to be learned by this I could never perceive it, and have seen some men, who pretended to know most by it, very often mistaken.

"These are the princ.i.p.al rules by which the Highland farmers draw their stocks; and they relate all to ewe stocks; for as to wedders, they are generally all sold off when they are three years old, and those that buy them for feeding mostly buy them by the condition they appear outwardly to be in at the time, and the character of the ground upon which they were bred."

(167.) _Jaundice._ I have never seen this disease in the sheep, and have heard almost nothing of it; indeed it is very rare, few having ever witnessed cases of it. It is consequently very imperfectly understood, every one who has written about it a.s.signing for its occurrence a different cause. The princ.i.p.al symptoms to be depended on, according to those who have treated it, are a yellowness of the eyes, and an obstinate sluggishness of the animal, almost amounting to sleep.

Copious bleeding and two ounce doses of Glauber salts have been recommended for the treatment, which must be gone about promptly, as the disease is said to be quickly fatal. Reasoning from what is known about jaundice in man, I would, were a case to occur to me in the sheep, give a good dose of calomel, say 15 grains, in conjunction with the salts, unless the disease had supervened on rot, when I would subst.i.tute ten grains of ipecacuanha for the mercury.

(168.) _Dropsy._ When it is the concluding symptom of a disease, it may be reckoned part of the complaint itself, and treated accordingly.

Often, however, it is the first thing which attracts the attention of the shepherd, and when such is the case it will usually be traced to long exposure to cold and wet. In this event the best plan is to bleed largely, and give two or three smart doses of Epsom salts. When it occurs in young lambs, sweet spirit of nitre, given in the quant.i.ty of a tea-spoonful twice a-day, is found to be attended with the happiest effects. Tapping, or, as it is popularly termed, _stabbing_, or _sticking_, to permit the escape of the water, is the cure resorted to in South Africa, when it appears in old sheep, after exposure to rain; but this ought never to be resorted to unless under the guidance of a medical person. It would be much better at once to kill the sheep.

(169.) _St.u.r.dy._ As shown in the tabular view of the diseases, in foot-note to paragraph (121), this affection may be the result either of pressure on the brain from an animal growth, or from the acc.u.mulation of a fluid. Serum is in both cases the mechanical cause of the symptoms, but in the former it is eliminated from neighbouring parts by a hydatid, while in the latter it is merely deposited in some of the natural cavities (the ventricles) of the brain, owing to a congested state of the spinal marrow, the result of continued cold upon the back.

Figure 2, Plate VII., taken from Rudolphi, exhibits a view of the animal which gives rise to the first variety of st.u.r.dy. It is the many-headed hydatid of the brain, _Coenurus Cerebralis_ of naturalists.

Like the _Cysticercus tenuicollis_, already described under the head of Rot, it consists of a thin membranous cyst, full or otherwise of serous fluid; but, unlike the aforementioned animal is studded over with groups of little velvety appendages or heads, each of which has a series of barbs projecting round the mouth. Figure 2, _a_, Plate VII., is a highly magnified representation of two of these heads.

A good idea of the hydatid, as it exists in the sheep, may be derived from an inspection of Fig 1. Pl. VIII., which has been engraved from a sketch kindly furnished to me by my friend Dr Kirk of Deal. Fig. 1 represents the brain of a sheep two years old, which has been affected with st.u.r.dy. The right lobe, _a_, of the cerebellum or lesser brain, is much distended with fluid, which is enclosed in a membraneous bag, as shown at _b_, where an incision has been made to expose it, and at _c_, where it is shining through one of the coverings of the brain, the pia mater.

The hydatid is found of all sizes, from that of a pea to that of Fig.

2, Plate VII. Large ones are far from rare, and the ventricle is frequently enormously distended. The hydatid in the brain from which Fig. 2, Plate VIII. was taken, though not filled to repletion, contained ten drachms of serum. The ventricle was consequently much dilated, as shown at _a_ in that figure, and the usual course and size of the convolutions completely altered. Instead of being folded, like the intestines, upon themselves, they proceeded, as seen at _b b_, from back to front of the brain; while the furrows between them, which are, in the healthy animal, usually too shallow to be measured, were in several places as deep as the length of the lines at _c d_.

This excessive acc.u.mulation of fluid within the brain leads, as might be expected, to the dilatation of the skull, and to the absorption of its walls, when the bones, young though the animal be when affected with st.u.r.dy, can no longer be made to yield. For this reason the skull, towards the termination of the disease, generally becomes thin and soft in front of the root of the horn, and in this way offers a spot which, from its being easily pierced, is frequently made the seat of surgical operations. Other parts of the skull also undergo considerable thinning, more so indeed than in front of the horn. The attention of the farmer has hardly, if ever, been called to this fact, though I believe that, for one instance in which perforation occurs in the frontal bone, it will be noticed a score of times on the sides of the head. In a head with which I was favoured by Mr Grieve, Branxholm braes, each temple, exactly beneath the superior extremity of the upright branch of the lower jaw, displayed a circular opening entirely through the bone, wide enough to permit the pa.s.sage of an ounce bullet.