Many of the diseases to which sheep are subject can be traced to want of
due care in their management. The common practice of letting them range
in marshy lands is one of the principal causes of disease.
The feet of sheep are organized in such a manner as to be capable, when
in a healthy state, of eliminating from the system a large amount of
worn-out materials--excrementitious matter, which, if retained in the
system, would be injurious. The direct application of cold tends to
contract the mouths of excrementitious vessels, and the morbid matter
accumulates. This is not all. There are in the system numerous
outlets,--for example, the kidneys, lungs, surface, feet, &c. The health
of the animal depends on all these functions being duly performed. If a
certain function be interrupted for any length of time, it is sure to
derange the system. Diseases of the feet are very common in wet
situations, and are a source of great loss to the farming community.
Hence it becomes a matter of great importance to know how to manage them
so as to prevent diseases of the feet.
Professor Simonds says, "No malady was probably so much feared by the
agriculturist as the rot; and with reason, for it was most destructive
to his hopes. It was commonly believed to be incurable, and therefore it
was all important to inquire into the causes which gave rise to it.
Some pastures were notorious for rotting sheep; on other lands, sheep,
under all ordinary circumstances, were pastured with impunity; but, as a
broad principle, it might be laid down that an excess of moisture is
prejudicial to the health of the animal. Sheep, by nature, are not only
erratic animals, wandering over a large space of ground, but are also
inhabitants of arid districts. The skill of man has increased and
improved the breed, and has naturalized the animal in moist and
temperate climates. But, nevertheless, circumstances now and then take
place which show that its nature is not entirely changed; thus, a wet
season occurs, the animals are exposed to the debilitating effects of
moisture, and the rot spreads among them to a fearful extent. The malady
is not confined to England or to Europe; it is found in Asia and Africa,
and occurs also in Egypt on the receding of the waters of the Nile.
"These facts are valuable, because they show that the cause of the
disease is not local--that it is not produced by climate or temperature;
for it is found that animals in any temperature become affected, and on
any soil in certain seasons. A great deal had been written on rot in
sheep, which it were to be wished had not been. Many talented
individuals had devoted their time to its investigation, endeavoring to
trace out a cause for it, as if it originated from one cause alone. But
the facts here alluded to would show that it arose from more causes than
one. He had mentioned the circumstance with regard to land sometimes
producing rot, and sometimes not; but he would go a step further, and
ask, Was there any particular period of the year when animals were
subject to the attack? Undoubtedly there was. In the rainy season, the
heat and moisture combined would produce a most luxuriant herbage; but
that herbage would be deficient in nutriment, and danger would be run;
the large quantity of watery matter in the food acting as a direct
excitement to the abnormal functions of the digestive organs. Early
disturbance of the liver led to the accumulation of fat, (state of
plethora;) consequently, an animal being 'touched with the rot' thrived
much more than usual. This reminded him that the celebrated Bakewell was
said to be in the habit of placing his sheep on land notorious for
rotting them, in order to prevent other people from getting his stock,
and likewise to bring them earlier to market for the butcher."
Referring to diseases of the liver, Professor S. remarked, that "the
bile in rot, in consequence of the derangement of the liver being
continued, lost the property of converting the chymous mass into
nutritious matter, and the animal fell away in condition. Every part of
the system was now supplied with impure blood, for we might as well
expect pure water from a poisoned fountain as pure blood when the
secretion of bile was unhealthy. This state of the liver and the system
was associated with the existence of parasites in the liver.
"Some persons suppose that these parasites, which, from their particular
form, were called flukes, were the cause of the rot. They are only the
effect; yet it is to be remembered that they multiply so rapidly that
they become the cause of further diseased action. Sheep, in the earlier
stages of the affection, before their biliary ducts become filled with
flukes, may be restored; but, when the parasites existed in abundance,
there was no chance of the animal's recovery. Those persons who supposed
flukes to be the cause of rot had, perhaps, some reason for that
opinion. Flukes are oviparous; their ova mingle with the biliary
secretion, and thus find their way out of the intestinal canal into the
soil; as in the feculent matter of rotten sheep may be found millions of
flukes. A Mr. King, of Bath, (England,) had unhesitatingly given it as
his opinion that flukes were the cause of rot; believing that, if sheep
were pastured on land where the ova existed, they would be taken up with
the food, enter into the ramifications of the biliary ducts, and thus
contaminate the whole liver. There appeared some ground for this
assertion, because very little indeed was known with reference to the
duration of life in its latent form in the egg. How long the eggs of
birds would remain without undergoing change, if not placed under
circumstances favorable to the development of life in a more active
form, was undecided. It was the same with the ova of these parasites; so
long as they remained on the pasture they underwent no change; but place
them in the body of the animal, and subject them to the influence of
heat, &c., then those changes would commence which ended in the
production of perfect flukes. Take another illustration of the long
duration of latent life: Wheat had been locked up for hundreds of
years--nay, for thousands--in Egyptian mummies, without undergoing any
change, and yet, when planted, had been found prolific.
... He was not, then, to say that rot was in all cases a curable
affection; but at the same time he was fully aware that many animals,
that are now considered incurable, might be restored, if sufficient
attention was given to them. About two years ago, he purchased seven or
eight sheep, all of them giving indisputable proof of rot in its
advanced stage. He intended them for experiment and dissection; but as
he did not require all of them, and during the winter season only he
could dissect, he kept some till summer. They were supplied with food of
nutritious quality, free from moisture; they were also protected from
all storms and changes of weather, being placed in a shed. The result
was, that without any medicine, two of these rotten sheep quite
recovered; and when he killed them, although he found that the liver had
undergone some change, still the animals would have lived on for years.
Rot, in its advanced stage, was a disease which might be considered as
analogous to dropsy. A serous fluid accumulates in various parts of the
body, chiefly beneath the cellular tissue; consequently, some called it
the _water_ rot, others the _fluke_ rot; but these were merely
indications of the same disease in different stages. If flukes were
present, it was evident that, in order to strike at the root of the
malady, they must get rid of these _entozoa_, and that could only be
effected by bringing about a healthy condition of the system. Nothing
that could be done by the application of medicine would act on them to
affect their vitality. It was only by strengthening their animal powers
that they were enabled to give sufficient tone to the system to throw
off the flukes; for this purpose many advocated salt. Salt was an
excellent stimulative to the digestive organs, and might also be of
service in restoring the biliary secretion, from the soda which it
contained. So well is its stimulative action known, that some
individuals always keep salt in the troughs containing the animal's
food. This was a preventive, they had good proof, seeing that it
mattered not how moist the soil might be in salt marshes; no sheep were
ever attacked by rot in them, whilst those sent there infected very
often came back free. Salt, therefore, must not be neglected; but then
came the question, Could they not do something more? He believed they
could give tonics with advantage....
"The principles he wished to lay down were, to husband the animals'
powers by placing them in a situation where they should not be exposed
to the debilitating effects of cold storms; to supply them with
nutritious food, and such as contained but a small quantity of water;
and, as a stimulant to the digestive organs, to mix it with salt."
The remarks of Professor S. are valuable to the American farmer. First,
because they throw some light on the character of a disease but
imperfectly understood; secondly, they recommend a safe, efficient, and
common-sense method of treating it; and lastly, they recommend such
preventive measures as, in this enlightened age, every farmer must
acknowledge to be the better part of sheep doctoring. The reader will
easily perceive the reason why the food of sheep is injurious when wet
or saturated with its own natural juices, when he learns that the
digestive process is greatly retarded, unless the masticated food be
well saturated with the gastric fluid. If the gastric fluid cannot
pervade it, then fermentation takes place; by which process the
nutritive properties of the food are partly destroyed, and what remains
cannot be taken up before it passes from the vinous into the acetous or
putrefactive fermentation; the natural consequence is, that internal
disease ensues, which often gravitates to the feet, thereby producing
rot. This is not all. Such food does not furnish sufficient material to
replenish the daily waste and promote the living integrity. In short, it
produces debility, and debility includes one half the causes of disease.
It must be a matter of deep interest to the farmer to know how to
prevent disease in his flock, and improve their condition, &c.; for if
he possessed the requisite knowledge, he would not be compelled to offer
mutton at so low a rate as from three to four cents a pound, at which
price it is often sold in the Boston market. We have already alluded to
the fact that neat cattle can, with the requisite knowledge, be improved
at least twenty-five per cent.; and we may add, without fear of
contradiction, that the same applies to sheep. If, then, their value can
be increased in the same ratio as that of other classes of live stock,
how much will the proprietors of sheep gain by the operation? Suppose we
set down the number of sheep in the United States at twenty-seven
millions,--which will not fall far short of the mark,--and value them at
the low price of one dollar per head: we get a clear gain, in the
carcasses alone, of six millions seven hundred and fifty thousand
dollars. The increase in the quantity, and of course in the value, of
wool would pay the additional expenses incurred. It is a well-known fact
that, when General Washington left his estate to engage in the councils
of his country, his sheep then yielded five pounds of wool. At the time
of his return, the animals had so degenerated as to yield but two and a
half pounds per fleece. This was not altogether owing to the quality of
their food, but in part to want of due care in breeding.
It is well known that many diseases are propagated and aggravated
through the sexual congress; and no matter how healthy the dam is, or
how much vital resistance she possesses,--if the male be weak and
diseased, the offspring will be more or less diseased at birth. (See
article _Breeding_.)
Dr. Whitlaw observes, "The Deity has given power to man to ameliorate
his condition, as may be truly seen by strict attention to the laws of
nature. An attentive observer may soon perceive, that milk, butter, and
meat, of animals that feed on good herbage, in high and dry soils, are
the best; and that strong nourishment is the produce of those animals
that feed on bottom land; but those that feed on a marshy, wet soil
produce more acrid food, even admitting that the herbage be of the bland
and nutritious kind; but if it be composed in part of poisonous plants,
the sheep become diseased and rotten, much more so than cattle, for they
do not drink to the same degree, and therefore (particularly those that
chew the cud) are not likely to throw off the poison. Horses would be
more liable to disease than cattle were it not for their sagacity in
selecting the wholesome from the poisonous herbage.
"A great portion of the mutton slaughtered is unfit for food, from the
fact that their lungs are often in a state of decomposition, their
livers much injured by insects, and their intestines in a state of
ulceration, from eating poisonous herbs."
Linnaeus says, "A dry place renders plants sapid; a succulent place,
insipid; and a watery place, corrosive."
One farmer, in the vicinity of Sherburne, (England,) had, during the
space of a few weeks, lost nearly nine hundred sheep by the rot. The
fear of purchasing diseased mutton is so prevalent in families, that the
demand for mutton has become extremely limited.
In the December number of the London Veterinarian we find an interesting
communication from the pen of Mr. Tavistock, V. S., which will throw
some light on the causes of disease in sheep. The substance of these
remarks is as follows: "On a large farm, situated in the fertile valley
of the Tavey, is kept a large flock of sheep, choice and well bred. It
is deemed an excellent sheep farm, and for some years no sheep could be
healthier than were his flock. About eighteen months ago, however, some
ewes were now and then found dead. This was attributed to some of the
many maladies sheep-flesh is 'heir to,' and thought no more about. Still
it did not cease; another and another died, from time to time, until at
length, it becoming a question of serious consequence, my attention was
called to them. I made, as opportunities occurred, minute post mortem
examinations. The sheep did not die rapidly, but one a week, and
sometimes one a fortnight, or even three weeks. No previous illness
whatever was manifested. They were always found dead in the attitude of
sleep; the countenance being tranquil and composed, not a blade of grass
disturbed by struggling; nor did any circumstance evidence that pain or
suffering was endured. It was evident that the death was sudden. We
fancied the ewes must obtain something poisonous from the herbage, and
the only place they could get any thing different from the other sheep
was in the orchards, since there the ewes went at the lambing time, and
occasionally through the summer. But so they had done for years before,
and yet contracted no disease. Well, then, the orchards were the
suspected spots, and it was deemed expedient to request Mr. Bartlett, a
botanist, to make a careful examination of the orchards, and give us his
opinion thereon. The following is the substance of his report:--
"The part of the estate to which the sheep unfortunately had access,
where the predisposing causes of disease prevailed, was an orchard,
having a gradual slope of about three quarters of a mile in extent, from
the high ground to the bed of the river, ranging about east and west;
the hills on each side being constituted of argillaceous strata of
laminated slate, which, although having an angle of inclination favoring
drainage on the slopes, yet in the valleys often became flat or
horizontal, and on which also accumulated the clays, and masses of rock,
in detached blocks, often to the depth of twenty feet--a state of things
which gives the valley surface and soil a very rugged and unequal
outline; the whole, at the same time, offering the greatest obstruction
to regular drainage.
"These are spots selected for orchard draining in England; the truth
being lost sight of, that surfaces and soil for apple-tree growth
require the most perfect admixture with atmospheric elements, and the
freest outlet for the otherwise accumulating moisture, to prevent
dampness and acidity, the result of the shade of the tree itself,
produced by the fall of the leaf.
"On this estate these things had never been dreamt of before planting
the orchards. The apple-tree, in short, as soon as its branches and
leaves spread with the morbid growth of a dozen years, aids itself in
the destructive process; the soil becomes yearly more poisonous, the
roots soon decay, and the tree falls to one side, as we witness daily,
while the herbage beneath and around becomes daily more unfit to sustain
animal life. Numerous forms of poisonous fungi, microscopic and
otherwise, are here at home, and nourished by the carburetted and other
forms of hydrogen gas hourly engendered and saturating the soil; while
on the dampest spots the less noxious portions of such hydrates are
assimilated by the mint plant in the shape of oil; and which disputes
with sour, poisonous, and blossomless grasses for the occupancy of the
surface, mingled with the still more noxious straggling forms of the
ethusa, occasionally the angelica, vison, conium, &c.
"This state of things, brought into existence by this wretched and
barbarous mode of planting orchard valleys, usually reaches its
consummation in about thirty years, and sometimes much less, as in the
valley under notice. Thus it is that such spots, often the richest in
capabilities on the estate, (the deep soil being the waste and spoil of
the higher ground and slopes,) become a bane to every form of useful
vegetation; and, at the same time, are a hotbed of luxuriance to every
thing that is poisonous, destructive, and deleterious to almost every
form of animal life. And such an animal as the sheep, while feeding
among such herbage, would inhale a sufficiency of noxious gases,
especially in summer, through the nostrils alone, to produce disease
even in a few hours, though the herbage devoured should lie harmless in
the stomach. But with regard to the sheep in the present case, we fear
they had no choice in the matter, and were driven by hunger to feed,
being shut into these orchards; and thus not only ate the poisoned
grasses, but with every mouthful swallowed a portion of the
water-engendering mint, the acrid crowfoot, ranunculus leaves, &c.,
surrounding every blade of grass; while the other essential elements of
vegetable poison, the most virulent forms of agarici and their spawn,
with other destructive fungi, were swallowed as a sauce to the whole.
This fearful state of things, to which sheep had access, soon manifested
its results; for although a hog or a badger might here fatten, yet to an
animal so susceptible to atmospheric influences, unwholesome, undrained
land, &c., as the sheep, the organization forbids the assimilation of
such food; and although a process of digestion goes on, yet its hydrous
results (if we may use such a term) not only overcharge the blood with
serum, but, through unnatural channels, cause effusion into the chest,
heart, veins, &c., when its effects are soon manifested in sudden and
quick dissolution, being found dead in the attitude of sleep."
It is probable that the gases which arose from this imperfectly drained
estate played their part in the work of destruction; not only by coming
in immediate contact with the blood through the medium of the air-cells
in the lungs, but by mixing with the food in the process of digestion.
This may appear a new idea to those who have never given the subject a
thought; yet it is no less true. During the mastication of food, the
saliva possesses the remarkable property of enclosing air within its
globules. Professor Liebig tells us that "the saliva encloses air in the
shape of froth, in a far higher degree than even soap-suds. This air, by
means of the saliva, reaches the stomach with the food, and there its
oxygen enters into combination, while its nitrogen is given out through
the skin and lungs." This applies to pure air. Now, suppose the sheep
are feeding in pastures notorious for giving out noxious gases, and at
the same time the function of the skin or lungs is impaired; instead of
the "nitrogen" or noxious gases being set free, they will accumulate in
the alimentary canal and cellular tissues, to the certain destruction of
the living integrity. Prof. L. further informs us that "the longer
digestion continues,--that is, the greater resistance offered to the
solvent action by the food,--the more saliva, and consequently the more
air, enter the stomach."