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This affection generally accompanies the same disease in other portions of the body, but may occasionally make its appearance independent of this cause. The edges of the flap become rough, thickened, and furrowed, the itching intolerable; and the dog perpetually shaking and scratching the head, occasions a constant oozing of blood from the wound. Smooth-haired dogs are most subject to this disease, such as pointers, hounds, and terriers.Treatment— Slightly stimulating washes, such as castile soap, alum-water, or infusion of oak-bark, will, in the majority of cases, induce these sores to heal up. If these do not answer, it will be necessary to use the mange ointment, keeping the animal hobbled to prevent him from scratching. Old inveterate cases are best cured by trimming off the affected parts. — L.
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There is some difficulty in describing the ethmoid bones; but we shall not, however, deviate far from the truth if we give the following account:
A great number of small hollow pedicles proceed from and form around the cribriform plate; as they move downwards, they project into distinct vesicles or cavities, smaller and more numerous behind, fewer in number and larger in front; and each of them not a simple cavity, but more or less convoluted, while the long walls of those cells are of gossamer thinness, and as porous as gauze. They even communicate, and are lined, and externally wrapped together, by the same membrane; the whole assuming a pear-like form, attached by its base or greater extremity, and decreasing in size as it proceeds downwards; the cells becoming fewer, and terminating at length in a kind of apex, which passes under the superior turbinated bone, and forms a valve between the nasal cavity and the maxillary sinuses.
If
to this is added, that the olfactory or first pair of nerves abut on these cribriform plates, and pass through their minute openings, and spread themselves over every one of these cells, we have a tolerably correct picture of this portion of the ethmoid bones. This nerve has different degrees of development in different animals, in proportion to their acuteness of smell. There is comparatively but little necessity for acuteness in the horse. The ox has occasion for somewhat more, especially in the early part of the spring, when the plants are young, and have not acquired their peculiar scent. In the sheep it is larger, and fills the superior portion of the nasal cavity; but in the dog it seems to occupy that cavity almost to the exclusion of the turbinated bones. It is also much more fragile in the dog than in the ox, and the plates have a considerably thinner structure.
The ethmoid bone of the horse or the ox may be removed from its situation with little injury; but that of the dog can scarcely be meddled with without fracture. Below it are the two turbinated bones; but they are reduced to insignificance by the bulk of the ethmoid bone. The inferior turbinated bone in the dog is very small, but it is curiously complicated.
The
meatus
contains three distinct channels; and the air, loitering, as it were, in it, and being longer in contact with the sensitive membrane by which it is lined, contributes to the acuter sense of smell. The larger cavity is along the floor of the nasal duct. It is the proper air-passage; and because it has this important function to discharge, it is out of the way of violence or injury.
The
lachrymal duct
is the channel through which the superfluous tears are conveyed to the lower parts of the nostril. A long canal here commences, and runs down and along the maxillary bone. It is very small, and terminates in the cuticle, in order that the highly sensitive membrane of the nose may not be excoriated by the tears occasionally rendered acrimonious in inflammation of the eye. The oval termination of this duct is easily brought into view by lifting the nostril.
From some occasional acrimony of the tears, the lining of this duct may be inflamed and thickened, or some foreign body, or some unctuous matter from the ciliary glands, may insinuate itself into the duct, and the fluid accumulates in the sac and distends it, and it bursts; or the ulcer eats through the integument, and there is a small fistulous opening beneath the inner canthus of the eye, or there is a constant discharge from it. It is this constant discharge that prevents the wound from healing. In some cases the lachrymal bone is involved in the ulcerative process and becomes carious. In the dog, and particularly in the smaller spaniel, the watery eye,
fistula lachrymalis
, is of no unusual occurrence. The fistula will be recognised by a constant, although perhaps slight, discharge of pus.
The
structure and office of the
velum palati
, or veil of the palate, is in the horse a perfect interposed section between the cavity of the mouth and the nose, and cutting off all communication between them. In the dog, who breathes almost entirely through the mouth, the
velum palati
is smaller; the tensor muscle, so beautifully described by Mr. Percivall, is weak, but the circumflex one is stronger and more developed. When
coryza
in the dog runs on to catarrh, and the membrane of the pharynx partakes of the inflammation, the
velum palati
becomes inflamed and thickened, but will not act as a perfect communication between the mouth and the nose. When there is a defluxion from the nose, tinged by the colour of the food, and particles of food mingle with it, we have one of the worst symptoms that can present itself, because it proves the extent and violence of the inflammation.
In inflammatory affections of the membrane of the nose in the dog, we often observe him snorting in a very peculiar way, with his head protruding, and the inspiration as forcible as the expiration. An emetic will usually afford relief, or grain doses of the sulphate of copper.
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The
superior maxillaries
here swell into importance, and constitute the whole of the outer wall, and, sometimes, a part of the roof. The jaws are the weapons of offence and defence; and as much space as possible is devoted to the insertion of those muscles that will enable the animal to seize and to hold his prey. One of the most powerful of them, the
masseter
, rises from the superior maxillary bone, and spreads over its whole extent: therefore, that bone is developed, while the nasal bone is compressed into a very small space. The substitution of a portion of cartilage, instead of bone, at the posterior part of the orbital ring, in order to give more play for the coracoid process of the posterior maxillary, round which the temporal bone is wrapped, is a contrivance of the same nature.
The scent of the dog is not sacrificed or impaired by the apparent diminution of the nasals; for the cavity enlarges considerably upward, and is occupied chiefly by the
ethmoid bone
, which, having the greater portion of nervous pulp spread on it, seems to have most to do with the sense of smell.
The nasal bones of the dog are essentially different from those of the horse, cattle, and sheep. They commence, indeed, as high up in the face as those of the horse, their superior extremities being opposite to the lachrymal gland; but that commencement is an apex or point varying materially in different breeds. They form, altogether, one sharp projection, and are received within breeds these processes extend nearly one-third of the length of the nasals.
The superior maxillary (3.3.) takes the situation of the nasal (2.), pushes the lachrymal bone (4.) out of its place, and almost annihilates it, reaches the frontal bone (7.) and expands upon it, and forms with it the same denticulated suture which is to be seen in the nasal. The action of the muscle between these bones, and for the development of which all this sacrifice is made, is exceedingly powerful. The strength of this muscle in a large dog is almost incredible: the sutures between these bones must possess corresponding strength; and so strong is the union between them, that, in many old dogs, the suture between the superior maxillary and frontal bones is nearly obliterated, and that between the nasal and frontal maxillary quite effaced.
As the nasal bones proceed downward they become somewhat wider. They unite with a long process of the anterior maxillary for the purpose of strength, and then terminate in a singular way. They have their apexes or points on the outer edge of the bone; and these apexes or points are so contrived, that, lying upon, and seemingly losing themselves, on the processes of the anterior maxillary, they complete, superiorly and posteriorly, that elliptical bony opening into the nose which was commenced by the maxillary anteriorly and inferiorly. The nasal cavity of the dog, therefore, and of all carnivorous animals, terminates by a somewhat circular opening, more or less in the form of an ellipse. This bony aperture varies in size in different dogs, and, as we should expect from what we have seen of the adaptation of structure to the situation and wants of the animal, it is largest in those on whom we are most dependent for speed and stoutness.
The
olfactory
, or first pair of nerves, have a double origin, namely, from the
corpus striatum
and the base of the
corpus callosum
. They are prolongations of the medullary substance of the central portion of the brain. They are the largest of the cerebral nerves. Their course is exceedingly short; and they have not a single anastomosis, in order that the impression made on them may be conveyed undisturbed and perfect to the brain.
The olfactory nerve is a prolongation of the substance of the brain, and it abuts upon the cribriform bone, of which mention has been made. I will not speak of the singular cavities which it contains, nor of their function; this belongs to the sensorial system: but its pulpy matter has already been traced to the base of the ethmoid bone, and the under part of the septum, and the superior turbinated bone. Although we soon lose it in the mucous membrane of the nose, there is little doubt that in a more filmy form it is spread over the whole of the cavity, and probably over all the sinuses of the face and head. It is, however, so mingled with the mucous membrane, that no power of the lens has enabled us to follow it so far. It is like the
portio mollis
of the seventh pair, eluding the eye, but existing in sufficient substances for the performance of its important functions.
We have frequent cases of
ozæna
in old dogs, and sometimes in those that are younger. The discharge from the nostril is abundant and constant, and sometimes fetid. The Schneiderian membrane, of more than usual sensibility in this animal, is exposed to many causes of irritation, and debilitated and worn out before its time. Pugs are particularly subject to ozæna. I scarcely ever knew a very old pug that had it not to a greater or less degree. The peculiar depression between the nasal and frontal bones in this breed of dogs, while it almost totally obliterates the frontal sinuses, may narrow the air-passage at that spot, and cause greater irritation there from the unusual rush of the air, and especially if the membrane becomes inflamed or any foreign body insinuates itself.
Little can be done in these cases, except to encourage cleanliness about the face and nostrils. It is, in the majority of these cases, a disease of old age, and must take its course.
A terrier uttered a continual loud stertorous sound in breathing, which could be plainly heard in our parlour when the dog was in the hospital. The animal was evidently much oppressed and in considerable pain. He made continual, and generally ineffectual, efforts to sneeze. When he did succeed, a very small quantity of pus-like fluid was discharged; the dog was then considerably relieved, but a quarter of an hour afterwards he was as bad as ever. I ordered a slight emetic every third day. There was some relief for seven or eight hours, and then he was as bad as ever. I could neither feel nor see any cause of obstruction. The owner became tired, and the dog was taken away; but we could not learn what became of it.
Another terrier was occasionally brought for consultation. The dog breathed with considerable difficulty, and occasionally snorted with the greatest violence, and bloody purulent matter was discharged; after which he was somewhat relieved; but, in the course of a few days, the obstruction was as great as ever. I am not aware of a single instances of this affection of the pug being completely removed. The discharge from the nostrils of the bull-dog is often considerable, and, once being thoroughly established, is almost as obstinate as in the pug.
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Ozæna, or fetid discharge from the nose, is, perhaps, the most troublesome and frequent affection that this organ is subject to; it is attended, at first, with slight fever, swelling of the parts, and a fetid discharge from the nostrils, which, if not corrected in the early stage of the disease, subsides into a chronic purulent secretion, that not only weakens the dog, but renders him peculiarly offensive. Caries and destruction of the bones of the nose will ultimately take place.
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In the dog we trace the triumph of
olfactory power
. How indistinct must be that scent which is communicated to, and lingers on, the ground by the momentary contact of the foot of the hare, the fox, or the deer; yet the hound, of various breeds, recognises it for hours, and some sportsmen have said for more than a day. He also can not only distinguish the scent of one species of animal from another, but that of different animals of the same species. The fox-hound, well broken-in, will rarely challenge at the scent of the hare, nor will he be imposed upon when the crafty animal that he pursues has taken refuge in the earth, and thrusts out a new victim before the pack.
The sense of smelling is, to a certain degree, acute in all dogs. It is a provision wisely and kindly made, in order to guide them to their proper food, or to fit them for our service. It may possibly be the medium through which much evil is communicated. Certain particles of a deleterious nature may be, and doubtless are, arrested by the mucous membrane of the nose, and there absorbed, and the constitution, to a considerable degree, becomes affected. Hence appears the necessity for attention to ventilation, and especially to prevent the membrane of the nose from being habitually stimulated and debilitated by the effluvia generated in a close and hot kennel.
M.
Majendie
instituted some curious experiments on the sense of smelling, and he was led to believe that it depended more on the fifth pair of nerves than on the olfactory nerve. He divided the fifth pair, and from that moment no odour, no puncture, produced the slightest apparent impression on the membrane of the nose. In another dog he destroyed the two olfactory nerves, and placed some strong odours beneath the nostrils of the animal. The dog conducted himself as he would have done in his ordinary state. Hence he concluded it probable that the olfactory nerve was not that of smelling.
The simple fact, however, is, that there are two species of nerves here concerned — those of common and of peculiar sensation. The olfactory nerve is the nerve of smelling, the fifth pair is that of common sensation. They are to a certain degree necessary to each other.
Scent
. — This leads us to the consideration of the term "scent." It expresses the odour or effluvium which is constantly issuing from every animal, and especially when that animal is in more than usual exercise. In a state of heat or excitement, the pores of the skin appear relaxed, and a fluid or aqueous vapour is secreted, which escapes in small or large quantities, adheres to the persona or substances on which it falls, and is, particularly, received on the olfactory organs. The hound, at almost the earliest period, begins to comprehend the work which he has to perform. The peculiar scent which his nostrils imbibe urges him eagerly to pursue but the moment he ceases to be conscious of the presence of the effluvium, he is at a perfect loss.
Mr.
Daniel
, in his work on the
Chase
, very properly observes, that
"the scent most favourable to the hound is when the effluvium, constantly perspired from the game as it runs, is kept by the gravity of the air at the height of his breast. It is then neither above his reach nor does he need to stoop for it. This is what is meant when the scent is said to be breast-high."
When the leaves begin to fall, the scent does not lie well in the cover. It frequently alters materially in the same day. This depends principally on the condition of the ground and the temperature of the air, which should be moist but not wet. When the ground is hard and the air dry, there will seldom be much scent. The scent rarely lies with a north or east wind. A southerly wind without rain is the best. Sudden storms are sure to destroy the scent. A fine sunshiny day is not good; but a warm day without sun is always a good one. If, as the morning advances, the drops begin to hang on the bushes, the scent will not lie. During a white frost the scent lies high, and also when the frost is quite gone; but at the time of its going off the scent never lies. In a hard rain, if the air is mild, the scent will sometimes be very good. A wet night often produces the best chases. In heathy countries, where the game brushes the grass or the boughs as it goes along, the scent seldom fails. It lies best on the richest soils; but the countries that are favourable to horses are not always so to hounds. The morning usually affords the best scent, and the game is then least able to escape. The want of rest, added perhaps to a full belly, gives the hounds a decided superiority over an early-found fox; and the condition of the ground and the temperature of the air are circumstances of much importance.
Such are the results of the best observations on scent; but, after all, we have much to learn concerning it. Many a day that predicated to be a good one for scent has turned out a very bad one, and
vice versa
. An old or experienced sportsman, knowing this, will never presume o make sure of his scent.
We shall be forgiven if we pursue this subject a little at length.
There is not only a constant appropriation of new matter to repair the losses that animals are continually sustaining, but there is a constant elaboration of gaseous or fluid matter maintaining the balance of the different systems, and essential to the continuance of life. This effluvium, as the animal moves from place to place, is attracted and detained for a while by the substances with which it comes into contact, or it remains floating in the atmosphere.
There is a peculiar smell or scent belonging to each individual, either generally or under peculiar circumstances.
The sportsman takes advantage of this; and, as most species of dogs possess great acuteness of olfactory power, they can distinguish, or are readily taught to distinguish, not only the scent of the hare from that of the fox, but that of the hare or fox which they are pursuing from that of half a dozen others that may be started during the chase.
The dogs that are selected for this purpose are those the conformation of whose face and head gives ample room for the development of the olfactory apparatus, and these are the different species of hounds; but a systematic education, and too often a great deal of unnecessary cruelty, is resorted to, in order to make them perfect in their work. The distinction between the scent of the fox and that of the hare is soon learned by the respective packs; and, when it is considered that the hunted hare is perspiring at every pore, and her strength being almost exhausted, she is straining every limb to escape from her pursuers, the increasing quantity of vapour which exudes from her will prevent every other newly started animal from being mistaken for her.
It has been well observed that when the atmosphere is loaded with moisture, and rain is at hand, the gas is speedily dissolved and mingles with the surrounding air. A storm dissipates it at once, while the cessation of the rain is preceded by the return and increased power of scent. A cold, dry easterly wind condenses and absorbs it, and this is even more speedily and irretrievably done by superabundant moisture. On fallows and beaten roads the scent rarely lies well, for there is nothing to detain it, and it is swept away in a moment; while over a luxuriant pasture, or by the hedge-row, or on the coppice, it lingers, clinging to the grass or the bushes. In a sunshiny day the scent is seldom strong; for too much of it is evaporated by the heat. The most favourable period is a soft southerly wind without rain, the scent being of the same temperature and gravity with the atmosphere. Although it spreads over the level, it rises not far above the ground, and, being 'breast high', enables the hound, keeping his muzzle in the midst of it, to run at his greatest speed. The different manners or attitudes in which the dog runs afford pleasing and satisfactory illustrations of the nature of the scent. Sometimes they will be seen galloping with their noses in the air, as if their game had flown away, and, an hour or two afterwards, every one of them will have his muzzle on the ground. The specific gravity of the atmosphere has changed, and the scent has risen of fallen in proportion.
A westerly wind stands next to a southerly one, for a hunting morning. This is all simple enough, and needs not the mystification with which it has been surrounded. A valuable account of this may be found in Johnson's
Shooting Companion
, a work that is justly and highly approved.
Mr.
Delmé
Radcliffe has also, in his splendid work on "the noble science," some interesting remarks on the scent of hounds. He says that there ia an idiosyncracy, a peculiarity, in their several dispositions. Some young hounds seem to enter on their work instinctively. From their first to their last appearance in the field they do no wrong. Others, equally good, will take no notice of anything; they will not stoop to any scent during the first season, and are still slack at entering even at the second; but are ultimately distinguished at the head of the pack; and such usually last some seasons longer than the more precocious of the same litter.
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The manner of drinking is different in the different animals. The horse, the ox, and the sheep do not plunge their muzzles into the water, but bring their lips into contact with it and sip it gradually. The dog, whose tongue is longer, plunges it a little way into the fluid, and, curving its tip and its edges, laps, in the language of Johnson, with a "quick reciprocation of the tongue." The horse sucks the water that is placed before him, the dog laps it; and both of them are subject to inflammation of the tongue, to enlargement of that organ, and to a considerable or constant flow of saliva over it.
Extending from the base to the tip of the tongue there is on either side a succession of tendons, which help to retain the tongue in the mouth, and to curve the edge of it, so as to convey the food or the water to the posterior part of the mouth. These all spring from one central cord, and ramify over the membrane of the tongue. On opening the mouth, and keeping it open by means of two pieces of tape, one behind the upper canine teeth, and the other behind the lower ones, and drawing the tongue from the mouth and exposing its under surface, a cuticular fold or ridge will present itself, occupying a middle line from the base of the tongue to its very point. If this is opened with a lancet, a minute fibrous cord will be exposed through its whole extent. It is the cord which governs the motions of the tongue.
This
cord
is, sometimes, foolishly and uselessly detached from its adhesions, so far as we can effect it, and drawn forward with a tenaculum and divided. There is one abominable course pursued in effecting this. The violence used in stripping down the tendon is so great, and the lacerated fibrous substance is put so much on the stress, and its natural elasticity is so considerable, that it recoils and assumes the appearance of a dying worm, and the dog is said to have been wormed. For the sake of humanity, as well as to avoid the charge of ignorance, it is to be hoped that this practice will speedily cease.
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The blain is a vesicular enlargement on the lateral and under part of the tongue in horses, oxen, and dogs, which, although not of unfrequent occurrence, or peculiarly fatal result, has not been sufficiently noticed by veterinary authors. In the horse and the dog it is often unaccompanied by any previous indisposition, or by other disease; but suddenly there is a copious discharge of saliva, at first limpid and without smell, hut soon becoming purulent, bloody, and exceedingly fetid. On examination, the tongue is found apparently enlarged. It is elevated from its base between the maxillary bones, and on the side and towards the base of it are seen large vesicles, pellucid, red, livid, or purple; and, if the discharge is fetid, having near their bases ulcers, irregular, unhealthy, and gangrenous.
In the horse and the dog the progress of the disease is slow, and seldom extends beyond the sides of the tongue. The vesicles are not of such magnitude as to interfere with respiration, and the ulcers are neither many nor foul.
In cattle it is sadly different. The vesicles attain an enormous size. They quickly break and form deep ulcerations, which are immediately succeeded by other vesicles still larger. The whole membrane of the mouth becomes affected; the inflammation and swelling extend to the cellular substance of the neighbouring parts, and the head and neck are considerably, and sometimes enormously, enlarged; the respiratory passages are obstructed; the animal breathes with the greatest difficulty, and is, in some cases, literally suffocated.
The primary seat of blain, is the cellular substance beneath the integument of the part. As the sublingual glands stretch along the under part of the tongue, and their ducts open on the side of the frænum, it is possible that this disease may proceed from, or be connected with, obstruction or inflammation of these ducts. Dissection, however, has not proved this; and the seat of the disease, when the swellings are first discovered, is chiefly the cellular tissue between the integument and the lateral parts of the tongue, and also that between the membrane of the mouth and the sublingual glands.
Post-mortem
examination shows intense disease: the small intestines are highly inflamed with red and black patches, which are also found in the cæcum, colon, and rectum.
The blain is more frequent in spring and summer than at other seasons of the year. These are the times when the animal is debilitated by the process of moulting, and is then more than usually disposed to inflammatory complaints. It is usually an epidemic disease. Many cases of it occur about the same time in certain districts, and over a great extent of country. When it appears in towns, the country is rarely exempt from it. I am not prepared lo say that it is contagious either in the horse or the dog. I have not seen any instance of it. At all events, it is not so virulent in these animals as it is in cattle.
The vesicles should be freely lanced from end to end. There will not, perhaps, be much immediate discharge; for the vesicle will be distended by a substance imperfectly organised, or of such a glassy or inspissated nature as not readily to escape. It will, however, soon disappear; and in four-and-twenty hours, in the majority of cases, the only vestige of the disease will be an incision, not, perhaps, looking very healthy, but that will soon become so and heal. If there have been any previous ulcerations, or the slightest fetor, the mouth should he frequently washed with a diluted solution of the chloride of lime; one part of the saturated solution, and eleven of water. This will act as a powerful and useful stimulus to the foul and indolent ulcer. When all unpleasant smell is removed, the mouth should be bathed with a lotion composed of equal parts of tincture of myrrh and water, or half an ounce of alum dissolved in a quart of water, and two ounces of the tincture of catechu added to the solution. I do not recollect a case in the horse or dog, in which these medicines were not employed with advantage. In cattle, before there has been fetor attending the discharge, or the constitution has been materially affected, these simple means will perfectly succeed.
If the practitioner is consulted somewhat too late, when the constitution has become affected, and typhoid fever has ensued, he should still lance the tumours, and apply the chloride of lime and the tincture of myrrh, and give a gentle aperient. He should endeavour to rouse and support the system by tonic medicines, as gentian and colomba with ginger, adding to two drachms of the first two, and one drachm of the last, half an ounce of nitre; but he should place most dependence on nourishing food. Until the mouth is tolerably sound, it is probable that the animal will not be induced to eat; but it will occasionally sip a little fluid, and, therefore, gruel should be always within its reach. More should occasionally be given, as thick as it will flow, with a spoon or small horn.