covers it may be normal, denuded of hair, or covered with hard epidermal
scales, possibly half an inch in thickness, forming a hard, horny plate.
The cavity which contains the fluid may have the dimensions of a hen's egg,
an apple, or a child's head. Its walls are formed by the diseased secreting
membrane of the bursal sac, and are readily detachable from the subcutis of
the skin. Their internal surfaces are often uneven or supplied with
projections or tufted growths which support a fibrous network within the
tumor.
Tumors of the knee may also assume a granular type, as the result of
chronic inflammation or following operative or spontaneous evacuation of
pus from the part. They are either firmly connected with the skin or are
detachable from it, and when laid open disclose a whitish-red, porklike
tissue surrounding a central nucleus of pus, or a fistulous tract leading
to the outer surface. They are caused by the chronic inflammation which
follows the bruises received by cattle in lying down and in rising, or they
may be due to falls on uneven, hard ground.
_Treatment for hygromata._--When the swelling first appears cold water
should be applied, followed later by bandaging with cloths wrung out of
warm water. If the swelling is soft, it should be punctured at the lowest
point, and afterwards the cavity should be syringed with Lugol's solution.
If the tumor is hard and nonfluctuating, a mercurial blister may cause
absorption and at the same time prevent further injury to the part by
making it more painful, thus sparing it.
SEROUS CYSTS.--These swellings are another variety of extravasation cysts,
and are caused by such injuries as butting, running against hard objects,
and shipping bruises, which are followed by an outpouring of blood and
lymph into the tissue spaces. These cysts develop rapidly and may reach the
size of a man's head or even larger. They are soft, edematous, and hot at
first and contain a serous or blood-tinged fluid. Later, partially
organized clots and shreds of a fibrinous nature and of a gelatinous
consistence are formed within, and the temperature of the swelling is
reduced. They appear on the surface of the body, especially on the belly
and flank of cattle.
_Treatment of serous cysts._--Treatment consists in opening the cyst at the
most dependent point with a sharp knife. The cavity should be washed out
twice daily with a 5 per cent solution of carbolic acid, and drainage
encouraged by keeping the incision open.
DERMOID CYSTS.
These cysts have a wall which is almost an exact duplicate of the structure
of the skin, and frequently contain epidermal structures, such as hair and
teeth, which, in the development of the embryo, have been misplaced. Thus
we may find in an ovary or testicle a dermoid cyst, containing a tooth or a
ball of hair. Dental cysts are included in the class above.
DENTAL CYSTS.--It happens occasionally that the teeth of cattle, instead of
developing normally within strong supporting alveolÊ, remain inclosed
within a cystic membrane, which assumes a tumorlike character. One tooth
may be included alone in the cyst or a number may be inclosed together.
However this may be, the malformation progresses, especially if confined to
the incisor teeth, until the remaining teeth that began to develop normally
are crowded out of position and rendered useless. The tumor may reach the
size of a man's fist. It appears to be fleshy and dents upon pressure, but
it may also appear on closer examination as though it contained irregular
sections of thin bone. The outer surface is always smooth, and no
indication of purulence, softening, or scab formation is ever exhibited.
Upon being laid open with the knife the tumor is seen to be surrounded by a
firm, smooth membrane which limits it completely from the adjoining
tissues. It is filled with material which possesses partly edematous,
partly fleshy, and partly bony properties. It is supposed that this mass is
composed of rudiments of the jawbone or of the alveolar walls which,
becoming spongy, lose themselves in the soft, fleshy mass contained within
the capsule of the tumor. It occasionally happens that the tumor is hollow
and that the cavity extends back into the body of the lower jaw for a
considerable distance.
Tumors of this kind, being of congenital origin, are very naturally
observed most frequently in young cattle, but they may continue to expand
for a period of several months after the birth of the calf, even until they
become troublesome and unsightly.
_Treatment for dental cysts._--Treatment consists in the complete
extirpation of the cyst and the destruction of the lining pouch by
curetting.
RETENTION CYSTS.
Retention cysts arise from the retention of normal secretions, owing to
obstruction of a duct leading from a gland. The mucous cysts found in the
mouth, udder, and vestibule of cows are samples of this form.
MUCOUS CYSTS.--Saclike dependent tumors, caused by retention of the
secretions from the mucous glands, sometimes develop in the mouth, nose,
pharynx, and vulva of cattle. They are called "mucous cysts." These are of
sizes varying from peas to pigeon eggs, are roundish and translucent, and
surrounded by a delicate, vascular membrane. They contain a siruplike
substance more or less thick and transparent and whitish yellow in color.
Treatment consists in the puncturing of the swelling, if accessible, and
the destruction of the cyst walls by the injection of Lugol's solution.
PROLIFERATION CYSTS.
These are found especially in the ovaries of cows, called "cystic ovaries,"
and may produce nymphomania (chronic bulling).
The treatment indicated in this case is the removal of the diseased
ovaries.
FOOTNOTES:
[3] The term "tumor" literally means a swelling, and thus has been applied
to the prominence caused by an overdistended bladder, to the enlargement of
pregnancy, to the swelling produced by an abscess, to the overgrowth of
tissue (hyperplasia) associated with injury and consequent inflammation,
and to numerous other phases of tissue enlargement directly connected with
recognized disease processes. For this reason it is becoming more common
for scientists to apply the word "neoplasm" to the new growths described in
this chapter. Because of the still popular use of the word "tumor," it is
retained in this chapter for the designation of those new growths to which
the sevenfold characterization of our descriptive definition applies.
DISEASES OF THE SKIN.
By M. R. TRUMBOWER, D. V. S.
[Revised by John R. Mohler, V. M. D.]
GENERAL DISCUSSION.
The skin consists of two parts--a superficial layer, the epidermis, or
cuticle, and the deep, or true, skin, the dermis, cutis vera, or corium.
The epidermis, cuticle, or scarf skin, is an epithelial structure, forming
a protective covering to the corium. It varies in thickness, is quite
insensible and nonvascular, and consists of a sheet of cells.
The epidermis is divided into a firm and transparent superficial and a
deep, soft layer. The latter is the rete mucosum, whose cells contain the
pigment which gives color to the skin. The deep surface of the epidermis is
accurately molded on the papillary layer of the true skin, and, when
removed by maceration, presents depressions which correspond to the
elevations on the dermis. From the cuticle tubular prolongations pass into
the sebaceous and sudorific glands; thus the entire surface of the body is
inclosed by the cuticle.
The dermis, or true skin, is vascular and highly sensitive, containing the
tactile ends of the nerves of touch. It is covered by epidermis and
attached to the underlying parts by a layer of areolar tissue, which
usually contains fat. The cutis consists of a fibro-areolar tissue and
vessels of supply. It is divided into two layers, the deep, or true, corium
and the upper, or papillary. The corium consists of strong interlacing
fibrous bands, chiefly white; its meshes are larger and more open toward
the attached surface, giving lodgment to the sweat glands and fat. The
papillary, or superficial, layer is formed of a series of small conical
eminences or papillÊ, which are highly sensitive, and consists of a
homogenous, transparent tissue. The blood vessels form dense capillary
plexuses in the corium, terminating by loops in the papillÊ. The papillary
nerves run in a waving manner, usually terminating in loops.
Hair is an appendage of the skin and forms its external covering. It is a
special modification of epidermis, having the same essential structure, and
consists of a root, shaft, and point. The root has a bulbous extremity, is
lighter and softer than the stem, and is lodged in a recess or hair
follicle, which may either be in the corium or subcutaneous areolÊ. The
follicle is dilated at the bottom to correspond to the root bulb, and the
ducts of one or more sebaceous glands open into it. At the bottom of each
follicle is a conical, vascular papilla, similar in every respect to those
on the surface of the dermis; this papilla fits into a corresponding
depression in the root of the hair. The shaft consists of a center, or
medulla, a surrounding fibrous portion, and an external coating, or cortex.
The medulla consists of cells containing pigment or fat, is opaque, and
deeply colored. All kinds of hair do not have this medulla. The fibrous
portion occupies the bulk of the stem, and the cortex is merely a single
layer of thin, flat, imbricated (shinglelike) scales.
The sebaceous glands, lodged in the corium, are most abundant in parts
exposed to friction. They generally open into the hair follicles,
occasionally on the surface of the body. Each gland consists of a small
duct which terminates in a lobulated recess. These lobules vary, and are,
as is the duct, lined with epithelium. They are filled with sebaceous
matter which, as it is secreted, is detached into the sacs. They are very
plentiful between the claws of cattle.
The sudorific glands, or sweat glands, are situated in the subcutaneous
areolar tissue, surrounded by a quantity of fat. They are small, round,
reddish bodies, each of which consists of one or more fine tubes coiled
into a ball, the free end of the tube being continued up through the true
skin and cuticle, and opening on the surface. Each sweat gland is supplied
with a cluster of capillary blood vessels which vary in size, being very
large when perspiration is excessive. The contents of the smaller ones are
fluid, and of the larger, semifluid.
The skin may be regarded as an organ supplementary in its action to the
lungs and kidneys, since by its secretion it is capable of removing a
considerable quantity of water from the blood; it also removes small
quantities of carbon dioxid, salts, and in certain instances during
suppression of the renal secretions a small quantity of urea. The skin is
also the chief organ for the regulation of animal heat, by or through
conduction, radiation, and evaporation of water, permitting of loss of
heat, while it also, through other mechanisms, is able to regulate the heat
lost. The hair furnishes protection against extreme and sudden variations
of temperature by reason of the fact that hairs are poor conductors of
heat, and inclose between them a still layer of air, itself a nonconductor.
The hairs are also furnished with an apparatus by which the loss of heat
may be regulated; thus, in cold weather, through the contraction of
unstriped muscular fibers of the skin, the hairs become erect and the
external coat becomes thicker. Cold, too, acts as a stimulus to the growth
of hair, and we find, in consequence, a thicker coat in winter than in
summer. The hairs also furnish protection against wet, as they are always
more or less oily from the secretion of sebaceous glands, and thus shed
water. Through their elasticity they furnish mechanical protection, and
through the thickness of the coat, to a certain degree, resist the attacks
of insects. Finally, the hairs assist the sense of touch.
The sweat glands are constantly discharging a watery secretion in the form
of insensible perspiration, and by their influence act as regulators of the
temperature of the body; hence, in warm weather, the secretion of the skin
is increased, which tends to prevent overheating. Sweating, in addition to
regulating heat, is also an active agent in removing effete material from
the blood; therefore this secretion can not be checked without danger. If
the skin is covered with an impermeable coating of grease or tar, death
results from blood poisoning, owing to the retention of materials destined
to be excreted by the skin.
All secretion poured out by the skin is not only modified by the condition
of the atmosphere but also by the character and quantity of the food, by
the amount of exercise, and especially by the quantity of fluid taken.
The sebaceous secretion is intended to lubricate the skin and hairs. It
consists of soft, fatty material suspended in water, and is characterized
by an odor peculiar to the animal by which it is secreted.
I will not attempt to classify the various diseases of the skin, for in a
work of this kind it would serve only to confuse the reader.
We shall first consider a class of diseases which are of an inflammatory
type; next, those caused by faulty secretion and abnormal growth; then,
diseases of parasitic origin; lastly, local injuries of the skin.
PRURITIS (ITCHING).
We shall consider pruritis first as a distinct subject. It is not a
disease, only a sensation, and therefore a symptom. It is one of the
symptoms accompanying the majority of the diseases which we will consider
in this chapter. It is, then, a functional affection produced by slight
irritation from without or by an internal cause acting upon the sensory
nerves of the skin. Nothing characteristic is seen except the secondary
lesions, produced mechanically by scratching or rubbing.
There are various forms of itching, the result of specific skin diseases,
where the pruritis is a secondary symptom. In such cases it should not be
regarded as an independent affection.
_Causes._--Many causes may induce the condition which we recognize here as
pruritis. The most common one is dirt on the skin, resulting from
insufficient care. If the ceiling of the stable is open, so that dust and
straw may fall, the skin is irritated and pruritis results. It also occurs
in some forms of indigestion.
The parts of the body most exposed to this condition are the croup, the
back, the top of the neck, and the root of the tail.
Another cause is found in affections of the liver and of the kidneys, when
an increase of effete material has to be thrown off by the skin. Morbid
materials circulating in the blood may produce a tickling or smarting
sensation of the skin in their passage from the blood to the free surface
of the skin. Certain irritating substances when eaten may be excreted by
the skin, and coming thus in direct contact with the sensory nerves produce
itching, or may go further and cause distinct inflammation of the skin. In
another class of cases the pruritis may be ascribable to an atrophy,
contraction, or hardening of the skin, when the nerves become irritated by
the pressure. These conditions may be so slightly marked in a thick skin
like that of the ox that they can not be recognized. It is frequently
noticed that cattle rub themselves as soon as they pass from the stable
into the open air--changing from a warm to a cold atmosphere. Again, we may
find one that does all its rubbing in the stall. We may look for lice, but
fail to find them. These conditions are generally attributable to high
feeding and to too close confinement. They may be associated with
inflammatory irritation or not; certainly we fail to discover any morbid
changes in the skin. There is to some extent a delightful sensation
produced by rubbing, and it may partly become a habit of pleasure.
_Treatment._--We must place our chief reliance upon a change of food,
plenty of exercise, and in most cases the administration of an active
cathartic--1 to 1-1/2 pounds of Epsom salt, a handful of common salt, a
tablespoonful of ginger or pepper, mixed with 2 quarts of water, all of
which is to be given at one dose. Afterwards half an ounce of hyposulphite
of soda mixed with the feed may be given twice a day for a week. For an
external application, when the skin is abraded or thickened from rubbing, a
solution of borax, 4 ounces to the quart of water, may be used. Carbolic
acid, 1/2 ounce to a quart of water, will give relief in some cases.
INFLAMMATORY DISEASES OF THE SKIN.
ERYTHEMA.
This is the simplest form of inflammation of the skin. It consists of an
increased redness, which may occur in patches or involve considerable
surface. The red coloration disappears when pressed by the finger, but soon
returns after the pressure is removed. There is seldom much swelling of the
affected part, though often there is a glutinous discharge which dries and
mats the hair or forms a thin scale upon the skin. In simple erythema the
epidermis alone is affected; when it becomes chronic, fissures form and
extend into the corium, or true skin.
_Causes._--Simple erythema, consisting of an inflammatory irritation, is
seen in very young calves, in which the navels leak. The discharge being
urine, it causes an irritation of the surrounding skin. Chafing, which is
another form of erythema, is occasionally seen on the udders of cows from
rubbing by the legs; chafing between the legs is not uncommon among fat
steers. Chronic erythema is found in the form of chapped teats of cows and
chapped lips in sucking calves. It frequently occurs in cows when they are
turned out in winter directly after milking, and in others from chafing by
the sucking calf. Some cows are peculiarly subject to sore teats. The
fissures when neglected in the early stage of formation become deep, very
painful, often bleeding at the slightest touch, and when milked in that
condition cause the animal to become a kicker. Occasionally the lower
portions of the legs become irritated and chapped when cattle are fed in a
muddy or wet yard in winter, or if they are compelled to wade through water
in frosty weather. Another form of erythema occurs in young cattle highly
fed and closely stabled for a long winter. The erythema appears in patches,
and as it is most common near the end of the winter it is known as the
"spring eruption" or "spring itch."
_Treatment._--In ordinary cases of erythema the removal of the cause and
the application of benzoated oxid of zinc ointment, carbolized cosmoline,
or ichthyol ointment applied a few times, will restore the skin to a
healthy condition.
When there are fissures the zinc ointment is the best. If at the teats, a
milk siphon (Pl. XXIV, fig. 4) should be used instead of milking by hand,
and the calf, if one is suckled, should be taken away. The calf should be
fed by hand if its mouth is affected. When the legs are irritated or
chapped, dry stabling for a few days and the application of tar ointment
will soon heal them.
URTICARIA (NETTLE RASH, OR SURFEIT).
This is a mild, inflammatory affection of the skin, characterized by sudden
development of patches of various sizes, from that of a nickel to one as
large as the hand. The patches of raised skin are marked by an abrupt
border and are irregular in form. All the swelling may disappear in a few
hours, or it may go away in one place and reappear on another part of the
body. It is always accompanied with a great desire to rub the affected
part. In its simplest type, as just described, it is never followed by any
serous exudation or eruptions, unless the surface of the skin becomes
abraded from scratching or rubbing.
_Causes._--Digestive derangements caused by overloading the stomach when
the animal is turned out to graze in the spring, certain feed constituents,
high feeding of fattening stock, functional derangement of the kidneys,
spinal and other nervous affections, are the most common sources of nettle
rash.
The disease consists in paralysis of the nerve ends that control the volume
of the capillary vessels in certain areas of skin, thus permitting the
vessels to expand, their contents in part to exude, and thus produce a
soft, circumscribed swelling.
_Treatment._--Administer a full dose of Epsom salt. Give soft, easily
digested feed, and wash the affected parts with a solution of bicarbonate
of soda (common baking soda), 8 ounces to the gallon of water twice a day,
or diluted glycerin may be applied to the skin. If it assumes a persistent
tendency, give a tablespoonful of the following powder in the feed three
times a day: Cream of tartar, sulphur, and nitrate of potassium, equal
parts by weight; mix.
ECZEMA.
Eczema is a noncontagious inflammation of the skin, characterized by any or
all of the results of inflammation at once or in succession, such as
erythema, vesicles, or pustules, accompanied with more or less infiltration
and itching, terminating in a watery discharge, with the formation of
crusts or in scaling off. The disease may run an acute course and then
disappear, or it may become chronic; therefore two varieties are
recognized, vesicular (or pustular) and chronic eczema.
_Causes._--Eczema is not so common among cattle as in horses and in dogs,
in which it is the most common of all skin diseases. Among cattle it is
occasionally observed under systems of bad hygiene, filthiness, lousiness,
overcrowding, overfeeding, excessively damp or too warm stables. It is
found to develop now and then in cattle that are fed upon sour substances,
distillery swill, house or garden garbage, etc. Localized eczema may be
caused by irritant substances applied to the skin--turpentine, ammonia, the
essential oils, mustard, Spanish-fly ointment, etc. Occasionally an
eruption with vesiculation of the skin has been induced by the excessive
use of mercurial preparations for the destruction of lice. It is evident
that eczema may arise from local irritation to the skin or from an
autointoxication. Cattle fed on the refuse from potato-starch factories
develop a most obstinate and widespread eczema, beginning on the legs.
_Symptoms._--In accordance with the variety of symptoms during the progress
of the disease we may divide it into different stages or periods: (1)
Swelling and increased heat of the skin; the formation of vesicles, which
are circumscribed, rounded elevations of the epidermis, varying in size
from a pinhead to a split pea, containing a clear, watery fluid; (2)
exudation of a watery, glutinous fluid, formation of crusts, and sometimes
suppuration, or the formation of vesicles containing pus (pustules); (3)
scaling off (desquamation), with redness, and thickening of the skin. From
the very beginning of the disease the animal commences to rub the affected
parts; hence the various stages may not always be easily recognized, as the
rubbing produces more or less abrasion, thus leaving the skin raw--
sometimes bleeding. Neither do these symptoms always occur in regular
succession, for in some cases the exudation is most prominent, being very
profuse, and serve to spread the disorder over a large surface. In other
cases the formation of incrustations, or rawness of the skin, is the most
striking feature. The disease may be limited to certain small areas, or it
may be diffused over the greater part of the body; the vesicles, or
pustules, may be scattered in small clusters, or a large number run
together. The chronic form is really only a prolongation of the disease,
successive crops of pustules appearing on various portions of the body,
frequently invading fresh sections of the skin, while the older surfaces
form scabs, or crusts, upon the raw, indurated skin.
In old, standing cases the skin breaks, forming fissures, especially on
portions of the body that bend--the neck and limbs. Thus the disease may be
prolonged indefinitely. When eczema reaches its latest period, either acute
or chronic, desquamation of the affected parts is the most prominent
feature. The formation and shedding of these successive crops of scales
constitute the character of the disease frequently denominated psoriasis.