Chapter VIII — The Eye and its Diseases

The diseases that attack the same organ are essentially different, in different animals, in their symptoms, intensity, progress, and mode of treatment. In periodic ophthalmia — that pest of the equine race and opprobrium of the veterinary profession — the cornea becomes suddenly opaque, the iris pale, the aqueous humour turbid, the capsule of the lens cloudy, and blindness is the result. After a time, however, the cornea clears up, and becomes as bright as ever; but the lens continues impervious to light, and vision is lost.

Ophthalmia in the dog presents us with symptoms altogether different. The conjunctiva is red; that portion of it which spreads over the sclerotica is highly injected, and the cornea is opaque. As the disease proceeds, and even at a very early period of its progress, an ulcer appears on the centre; at first superficial, but enlarging and deepening until it has penetrated the cornea, and the aqueous humour has escaped. Granulations then spring from the edges of the ulcer, rapidly enlarge, and protrude through the lids. Under proper treatment, however, or by a process of nature, these granulations cease to sprout; they begin to disappear; the ulcer diminishes; it heals; scarcely a trace of it can be seen; the cornea recovers its perfect transparency, and vision is not in the slightest degree impaired.

There is a state of the orbit which requires some consideration. It is connected with the muscles employed in mastication. Generally speaking, the food of the dog requires no extraordinary degree of mastication, nor is there usually any great time employed in this operation. That muscle which is most employed in the comminution of the food, namely, the temporal muscle, has its action very much limited by the position of the bony socket of the eye; yet sufficient room is left for all the force that can be required. In some dogs, either for purposes of offence or defence, or the more effectual grasping of the prey, a sudden violent exertion of muscular power, and a consequent contraction of the temporal muscle, are requisite, but for which the imperfect socket of the orbit does not seem to afford sufficient scope and room. There is an admirable provision for this in the removal of a certain portion of the orbital process of the frontal bone on the outer and upper part of the external ridge, and the substitution of an elastic cartilage. This cartilage momentarily yields to the swelling of the muscles; and then, by its inherent elasticity, the external ridge of the orbit resumes its pristine form. The orbit of the dog, the pig, and the cat, exhibits this singular mechanism.

The horse is, to a certain extent, also an illustration of this. He requires an extended field of vision to warn him of the approach of his enemies in his wild state, and a direction of the orbits somewhat forward to enable him to pursue with safety the headlong course to which we sometimes urge him; and for this purpose his eyes are placed more forward than those of cattle, sheep, or swine. That which Mr. Percivall states of the horse is true of our other domesticated animals:

"The eyeball is placed within the anterior or more capacious part of the orbit, nearer to the frontal than to the temporal side, with a degree of prominence peculiar to the individual, and, within certain limits, variable at his will."

In many of the carnivorous animals the orbit encroaches on the bones of the face. A singular effect is also produced on the countenance, both when the animal is growling over his prey and when he is devouring it. The temporal muscle is violently acted upon; it presses upon the cartilage that forms part of the external ridge; that again forces itself upon and protrudes the eye, and hence the peculiar ferocity of expression which is observed at that time. The victims of these carnivorous animals are also somewhat provided against danger by the acuteness of sight with which they are gifted. Adipose matter also exists in a considerable quantity in the orbit of the eye, which enables it to revolve by the slightest contraction of the muscles.

We should scarcely expect to meet with cases of fracture of the orbital arch in the dog, because, in that animal, cartilage, or a cartilago-ligamentous substance, occupies a very considerable part of that arch; but I have again and again, among the cruelties that are practised on the inferior creation, seen the cartilage partly, or even entirely, torn asunder. I have never been able satisfactorily to ascertain the existence of this during life; but I have found it on those whom I have recommended to be destroyed on account of the brutal usage which they had experienced. Blows somewhat higher, or on the thick temporal muscle of this animal, will very rarely produce a fracture.

A few cases of disease in the eye may be interesting and useful.

Case I. — The eyes of a favourite spaniel were found inflamed and impatient of light. Nothing wrong had been perceived on the preceding day. No ulceration could be observed on the cornea, and there was but a slight mucous discharge. An infusion of digitalis, with twenty times the quantity of tepid water, was employed as a collyrium, and an aloetic ball administered. On the following day the eyes were more inflamed, The collyrium and the aloes were employed as before, and a seton inserted in the poll.

Three or four days afterwards the redness was much diminished, the discharge from the eye considerably lessened, and the dog was sent home. The seton, however, was continued, with an aloetic ball on every third or fourth day.

Two or three days after this the eyes were perfectly cured and the seton removed.

Case II. — The eye is much inflamed and the brow considerably protruded.

This was supposed to be caused by a bite. I vainly endeavoured to bring the lid over the swelling. I scarified the lid freely, and ordered the bleeding to be encouraged by the constant application of warm water, and physic-ball to be given.

On the following day the brow was found to be scarcely or at all reduced, and the eye could not be closed. I drew out the haw with a crooked needle, and cut it off closely with sharp scissors. The excised portion was as large as a small-kidney-bean. The fomentation was continued five days afterwards, and the patient then dismissed cured.

Case III. — A pointer was brought in a sad state of mange. Redness, scurf, and eruptions were on almost every part. Apply the mange ointment and the alterative and physic balls. On the following day there was an ulcer on the centre of the cornea, with much appearance of pain and impatience of light. Apply an infusion of digitalis, with the liquor plumbi diacetatis. He was taken away on the twelfth day, the mange apparently cured, and the inflammation of the eye considerably lessened. A fortnight afterwards this also appeared to be cured.

Case IV. — A spaniel had been bitten by a large dog. There was no wound of the lids, but the eye was protruded from the socket. I first tried whether it could be reduced by gentle pressure, but I could not accomplish it. I then introduced the blunt end of a curved needle between the eye and the lid; and thus drawing up the lid with the right hand, while I pressed gently on the eye with the left hand, I accomplished my object. I then subtracted three ounces of blood and gave a physic-ball. On the following day the eye was hot and red, with some tumefaction. The pupil was moderately contracted, but was scarcely affected by any change of light. The dog was sent home, with some extract of goulard, and a fortnight afterwards was quite well.

Case V. — A dog received a violent blow on the right eye. Immediate blindness occurred, or the dog could apparently just discern the difference between light and darkness, but could not distinguish particular objects. The pupil was expanded and immovable. A pink-coloured hue could be perceived on looking earnestly into the eye. A seton was introduced into the poll, kept there nearly a month, and often stimulated rather sharply. General remedies of almost every kind were tried: depletion was carried to its full extent, the electric fluid was had recourse to; but at the expiration of nine weeks the case was abandoned and the dog destroyed. Permission to examine him was refused.

I have, in two or three instances, witnessed decided cases of dropsy of the eye, accumulation of fluid taking place in both the anterior and posterior chambers of the eye; there was also effusion of blood in the chambers, but in one case only was there the slightest benefit produced by the treatment adopted, and in that there was gradual absorption of the effused fluid.

About the same time there was another similar case. A pointer had suddenly considerable opacity of one eye, without any known cause: the other eye was not in the least degree affected. The dog had not been out of the garden for more than a week. The eye was ordered to be fomented with warm water.

On the following day the inflammation had increased, and the adipose matter was protruded at both the inner and outer canthus. The eye was bathed frequently with a goulard lotion. On the fourth day the eyeball was still more inflamed, and the projections at both canthi were increased. A curved needle was passed through both eyes, and there was considerable bleeding. On the following day the inflammation began to subside. At the expiration of a week scarcely any disease remained, and the eye became as transparent as ever.

A curious ease of congenital blindness was brought to my infirmary. A female pointer puppy, eight weeks old, had both her eyes of their natural size and formation, but the inner edge of the iris was strangely diseased. The pupil was curiously four-cornered, and very small. There hung out of the pupil a grayish-white fibrous matter, which appeared to be the remainder of the pupillary membrane.

Six months afterwards we examined her again, and found that the pupil was considerably enlarged, and properly shaped, and the white skin had vanished. In the back-ground of the eye there was a faint yellow-green light, and the dog not only showed sensibility to light, but some perception of external objects. At this period we lost sight of her.

A very considerable improvement has taken place with regard to the treatment of the enlarged or protruded ball of the eye. A dog may get into a skirmish, and have his eye forced from the socket. If there is little or no bleeding, the case will probably be easily and successfully treated.

The eye must, first, be thoroughly washed, and not a particle of grit must be left. A little oil, a crooked needle, and a small piece of soft rag should be procured. The blunt end of the needle should he dipped into the oil, and run round the inside of the lid, first above and then below. The operator will next — his fingers being oiled — press upon the protruded eye gently, yet somewhat firmly, changing the pressure from one part of the eye to the other, in order to force it back into the socket.

If, after a couple of minutes' trial, he does not succeed, let him again oil the eye on the inside and the out, and once more introduce the blunt end of the needle, attempting to carry it upwards under the lid with two or three fingers pressing on the eye, and the points of pressure being frequently changed. In by far the greater number of cases, the eye will be saved.

If it is impracticable to cause the eye to retract, a needle with a thread attached must be passed through it, the eye being then drawn as forward as possible and cut off close to the lids. The bleeding will soon cease and the lids perfectly close.

Ophthalmia is a disease to which the dog is often liable. It is the result of exposure either to heat or to cold, or violent exertion; it is remedied by bleeding, purging, and the application of sedative medicine, as the acetate of lead or the tincture of opium. When the eye is considerably inflamed, in addition to the application of tepid or cold water, either the inside of the lids or the white of the eye may be lightly touched with the lancet. From exposure to cold, or accident or violence, inflammation often spreads on the eye to a considerable degree, the pupil is clouded, and small streaks of blood spread over the opaque cornea. The mode of treatment just described must be pursued.

The crystalline lens occasionally becomes opaque. There is cataract. It may be the result of external injury or of internal predisposition. Old dogs are particularly subject to cataract. That which arises from accident, or occasionally disease, may, although seldom, be reinstated, especially in the young dog, and both eyes may become sound; but, in the old, the slow-growing opacity will, almost to a certainty, terminate in cataract.

There is occasionally an enlargement of the eye, or rather an accumulation of fluid within the eye, to a very considerable extent. No external application seems to have the slightest effect in reducing the bulk of the eye. If it is punctured, much inflammation ensues, and the eye gradually wastes away.

In amaurosis, the eye is beautifully clear, and, for a little while, this clearness imposes upon the casual observer; but there is a peculiar pellucid appearance about the eye — a preternatural and unchanging brightness. In the horse, the sight occasionally returns, but I have never seen this in the dog.

The occasional glittering of the eyes of the dog has been often observed. The cat, the wolf, some carnivora, and also sheep, cows, and horses, occasionally exhibit the same glittering. Pallas imagined that the light of these animals emanated from the nervous membrane of the eye, and considered it to be an electrical phenomenon. It is found, however, in every animal that possesses a tapetum lucidum. The shining, however, never takes place in complete darkness. It is neither produced voluntarily, nor in consequence of any moral emotion, but solely from the reflection that falls on the eye.

The eye and its diseases being so concisely treated by Mr. Youatt, we are emboldened to add a more full and particular treatise on this interesting subject, couched in language the most simple, and we trust sufficiently plain to be understood by the most unscientific patron of the canine race.

Also read: Dog Health Info.