The Dog

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.

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

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,

, is of no unusual occurrence. The fistula will be recognised by a constant, although perhaps slight, discharge of pus.

structure and office of the

, 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

is smaller; the tensor muscle, so beautifully described by Mr. Percivall, is weak, but the circumflex one is stronger and more developed. When

in the dog runs on to catarrh, and the membrane of the pharynx partakes of the inflammation, the

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.

, or first pair of nerves, have a double origin, namely, from the

and the base of the

. 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

of the seventh pair, eluding the eye, but existing in sufficient substances for the performance of its important functions.

We have frequent cases of

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.

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.

. — 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.

, in his work on the

, very properly observes, that

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

. 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

, a work that is justly and highly approved.

Mr.

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.

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.