Part 7

The feces show, to a certain extent, the thoroughness of digestion. They should show that the feed has been well ground, and should, in the horse, be free from offensive odor or coatings of mucus. A coating of mucus shows intestinal catarrh. Blood on the feces indicates severe inflammation. Very light color and bad odor may come from inactive liver. Parasites are sometimes in the dung.

Rectal examination consists in examination of the organs of the pelvic cavity and posterior portion of the abdominal cavity by the hand inserted into the rectum. This examination should be attempted by a veterinarian only, and is useless except to one who has a good knowledge of the anatomy of the parts concerned.

THE EXAMINATION OF THE NERVOUS SYSTEM.

The great brain, or cerebrum, is the seat of intelligence, and it contains the centers that control motion in many parts of the body. The front portion of the brain is believed to be the region that is most important in governing the intelligence. The central and posterior portions of the cerebrum contain the centers for the voluntary motions of the face and of the front and hind legs. The growth of a tumor or an inflammatory change in the region of a center governing the motion of a certain part of the body has the effect of disturbing motion in that part by causing excessive contraction known as cramps, or inability of the muscles to contract, constituting the condition known as paralysis. The nerve paths from the cerebrum, and hence from these centers to the spinal cord and thence to the muscles, pass beneath the small brain, or the cerebellum, and through the medulla oblongata to the spinal cord. Interference with these paths has the effect of disturbing motion of the parts reached by them. If all of the paths on one side are interfered with, the result is paralysis of one side of the body.

The small brain, or cerebellum, governs the regularity, or coordination, of movements. Disturbances of the cerebellum cause a tottering, uncertain gait. In the medulla oblongata, which lies between the spinal cord and the cerebellum, are the centers governing the circulation and breathing.

The spinal cord carries sensory messages to the brain and motor impressions from the brain. The anterior portions of the cord contain the motor paths, and the posterior portions of the cord contain the sensory paths.

Paralysis of a single member or a single group of muscles is known as monoplegia and results from injury to the motor center or to a nerve trunk leading to the part that is involved. Paralysis of one-half of the body is known as hemiplegia and results from destruction or severe disturbances of the cerebral hemisphere of the opposite side of the body or from interference with nerve paths between the cerebellum, or small brain, and the spinal cord. Paralysis of the posterior half of the body is known as paraplegia and results from derangement of the spinal cord. If the cord is pressed upon, cut, or injured, messages can not be transmitted beyond that point, and so the posterior part becomes paralyzed. This is seen when the back is fractured.

Abnormal mental excitement may be due to congestion of the brain or to inflammation. The animal so afflicted becomes vicious, pays no attention to commands, cries, runs about in a circle, stamps with the feet, strikes, kicks, etc. This condition is usually followed by a dull, stupid state, in which the animal stands with his head down, dull and irresponsive to external stimuli. Cerebral depression also occurs in the severe febrile infectious diseases, in chronic hydrocephalus, in chronic diseases of the liver, in poisoning with a narcotic substance, and with chronic catarrh of the stomach and intestines.

Fainting is a symptom that is not often seen in horses. When it occurs it is shown by unsteadiness of gait, tottering, and, finally, inability to stand. The cause usually lies in a defect of the small brain, or cerebellum. This defect may be merely in respect of the blood supply, to congestion, or to anemia, and in this case it is likely to pass away and may never return, or it may be due to some permanent cause, as a tumor or an abscess, or it may result from a hemorrhage, from a defect of the valves of the heart, or from poisoning.

Loss of consciousness is known as coma. It is caused by hemorrhage in the brain, by profound exhaustion, or may result from a saturation of the system with the poison of some disease. Coma may follow upon cerebral depression, which occurs as a secondary state of inflammation of the brain.

Where the sensibility of a part is increased the condition is known as hyperesthesia, and where it is lost--that is, where there is no feeling or knowledge of pain--the condition is known as anesthesia. The former usually accompanies some chronic disease of the spinal cord or the earlier stages of irritation of a nerve trunk. Hyperesthesia is difficult to detect in a nervous, irritable animal, and sometimes even in a horse of less sensitive temperament. An irritable, sensitive spot may be found surrounded by skin that is not sensitive to pressure. This is sometimes a symptom of beginning of inflammation of the brain. Anesthesia occurs in connection with cerebral and spinal paralysis, section of a nerve trunk leading to a part, in severe mental depression, and in narcotic poisoning.

URINARY AND SEXUAL ORGANS.

In considering the examination of the urinary and sexual organs we may consider, at the beginning, a false impression that prevails to an astonishing extent. Many horsemen are in the habit of pressings upon the back of a horse over the loins or of sliding the ends of the fingers along on either side of the median line of this region. If the horse depresses his back it is at once said "his kidneys are weak." Nothing could be more absurd or further from the truth. Any healthy horse--any horse with normal sensation and with a normally flexible back--will cause it to sink when manipulated in this way. If the kidneys are inflamed and sensitive, the back is held more rigidly and is not depressed under this pressure.

To examine the kidneys by pressure the pressure should be brought to bear over these organs. The kidneys lie beneath the ends of the transverse processes of the vertebrae of the loins and beneath the hind-most ribs. If the kidneys are actually inflamed and especially sensitive, pressure or light blows applied here may cause the horse to shrink.

The physical examination of the sexual and generative organs is made in large part through the rectum, and this portion of the examination should be carried out by a veterinarian only. By this means it is possible to discover or locate cysts of the kidneys, urinary calculi in the ureters, bladder, or upper urethra, malformations, and acute inflammations accompanied by pain. The external genital organs are swollen, discolored, or show a discharge as a result of local disease or from disease higher in the tract.

The manner of urinating is sometimes of considerable diagnostic importance. Painful urination is shown by frequent attempts, during which but a small quantity of urine is passed; by groaning, by constrained attitude, etc. This condition comes from inflammation of the bladder or urethra, urinary calculi (stones of the bladder or urethra), hemorrhage, tumors, bruises, etc. The urine is retained from spasms of the muscle at the neck of the bladder, from calculi, inflammatory growths, tumors, and paralysis of the bladder.

The urine dribbles without control when the neck of the bladder is weakened or paralyzed. This condition is seen after the bladder is weakened from long-continued retention and where there is a partial paralysis of the hind quarters.

Horses usually void urine five to seven times a day, and pass from 4 to 7 quarts. Disease may be shown by increase in the number of voidings or of the quantity. Frequent urination indicates an irritable or painful condition of the bladder or urethra or that the quantity is excessive. In one form of chronic inflammation of the kidneys (interstitial nephritis) and in polyuria the quantity may be increased to 20 or 30 quarts daily. Diminution in the quantity of urine comes from profuse sweating, diarrhea, high fever, weak heart, diseased and nonsecreting kidneys, or an obstruction to the flow.

The urine of the healthy horse is a pale or at times a slightly reddish yellow. The color is less intense when the quantity is large, and is more intense when the quantity is diminished. Dark-brown urine is seen in azoturia and in severe acute muscular rheumatism. A brownish-green color is seen in jaundice. Red color indicates admixture of blood from a bleeding point at some part of the urinary tract, usually in the kidneys.

The urine of the healthy horse is not clear and transparent. It contains mucus, which causes it to be slightly thick and stringy, and a certain amount of undissolved carbonates, causing it to be cloudy. A sediment collects when the urine is allowed to stand. The urine of the horse is normally alkaline. If it becomes acid the bodies in suspension are dissolved and the urine is made clear. The urine may be unusually cloudy from the addition of abnormal constituents, but to determine their character a chemical or microscopic examination is necessary. Red or reddish flakes or clumps in the urine are always abnormal, and denote a hemorrhage or suppuration in the urinary tract.

The normal specific gravity of the urine of the horse is about 1.040. It is increased when the urine is scanty and decreased when the quantity is excessive.

Acid reaction of the urine occurs in chronic intestinal catarrh, in high fever, and during starvation. Chemical and microscopic tests and examinations are often of great importance in diagnosis, but require special apparatus and skill.

Other points in the examination of a sick horse require more discussion than can be afforded in this connection, and require special training on the part of the examiner. Among such points may be mentioned the examination of the organs of special sense, the examination of the blood, the microscopic examination of the secretions and excretions, bacteriological examinations of the secretions, excretions, and tissues, specific reaction tests, and diagnostic inoculation.

FUNDAMENTAL PRINCIPLES OF DISEASE.

By RUSH SHIPPEN HUIDEKOPER, M. D., VET.

ANIMAL TISSUES.

The nonprofessional reader may regard the animal tissues, which are subject to inflammation, as excessively simple structures, as similar, simple, and fixed in their organization as the joists and boards which frame a house, the bricks and iron coils of pipe which build a furnace, or the stones and mortar which make the support of a great railroad bridge. Yet while the principles of structure are thus simple, for the general understanding by the student who begins their study the complete appreciation of the shades of variation, which differentiate one tissue from another, which define a sound tendon or a ligament from a fibrous band--the result of disease filling in an old lesion and tying one organ with another--is as complicated as the nicest jointing of Chinese woodwork, the building of a furnace for the most difficult chemical analysis, or the construction of a bridge which will stand for ages and resist any force or weight.

All tissues are composed of certain fundamental and similar elements which are governed by the same rules of life, though at first glance they may appear to be widely different. These are (a) amorphous substances, (b) fibers, and (c) cells.