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REFERENCE BOOKS

GENERAL DISCUSSION OF DISEASE

Disease is the general term for any deviation from the normal or healthy condition of the body. The morbid processes that result in either slight or marked modifications of the normal condition are recognized by the injurious changes in the structure or function of the organ, or group of body organs involved. The increase in the secretion of urine noticeable in horses in the late fall and winter is caused by the cool weather and the decrease in the perspiration. If, however, the increase in the quantity of urine secreted occurs independently of any normal cause and is accompanied by an unthrifty and weakened condition of the animal, it would then characterize disease. Tissues may undergo changes in order to adapt themselves to different environments, or as a means of protecting themselves against injuries. The coat of a horse becomes heavy and appears rough if the animal is exposed to severe cold. A rough, staring coat is very common in horses affected by disease. The outer layer of the skin becomes thickened when subject to pressure or friction from the harness. This change in structure is purely protective and normal. In disease the deviation from normal must be more permanent in character than it is in the examples mentioned above, and in some way prove injurious to the body functions.

CAUSES.--For convenience we may divide the causes of disease into the predisposing or indirect, and the exciting or direct.

QUESTIONS

DIAGNOSIS AND SYMPTOMS OF DISEASE

The importance of recognizing or diagnosing the seat and nature of the morbid change occurring in an organ or group of organs cannot be overestimated. Laymen do not comprehend the difficulty or importance of correctly grouping the signs or symptoms of disease in such a way as to enable them to recognize the nature of the disease. In order to be able to understand the meaning of the many symptoms or signs of disease, we must possess knowledge of the structure and physiological functions of the different organs of the body. We must be familiar with the animal when it is in good health in order to be able to recognize any deviation from the normal due to disease, and we must learn from personal observation the different symptoms that characterize the different diseases. Stockmen should be able to tell when any of the animals in their care are sick as soon as the first symptom of disease manifests itself, by changes in the general appearance and behavior. But in order to ascertain the exact condition a general and systematic examination is necessary. The examiner, whether he be a layman or a veterinarian, must observe the animal carefully, noting the behavior, appearance, surroundings, and general and local symptoms.

Pulse.--The character of the intermittent expansion of the arteries, called the pulse, informs us as to the condition of the heart and blood-vessels. The frequency of the pulse beat varies in the different species of animals. The smaller the animal the more frequent the pulse. In young animals the number of beats per minute is greater than in adults. Excitement or fear, especially if the animal possesses a nervous temperament, increases the frequency of the pulse. During, and for a short time after, feeding and exercise, the pulse rate is higher than when the animal is standing at rest.

The following table gives the normal rate of the pulse beats per minute:

Horse 36 to 40 per minute Ox 45 to 50 per minute Sheep 70 to 80 per minute Pig 70 to 80 per minute Dog 90 to 100 per minute

RESPIRATION.--The frequency of the respirations varies with the species. The following table gives the frequency of the respirations in domestic animals:

Horse 8 to 10 per minute Ox 12 to 15 per minute Sheep 12 to 20 per minute Dog 15 to 20 per minute Pig 10 to 15 per minute

The ratio of the heart beats to the respirations is about 1:4 or 1:5. This ratio is not constant in ruminants. Rumination, muscular exertion and excitement increase the frequency and cause the respirations to become irregular. In disease the ratio between the heart beats and respirations is greatly disturbed, and the character of the respiratory sounds and movements may be greatly changed .

Severe exercise and diseased conditions of the lungs cause the animal to breathe rapidly and bring into use all of the respiratory muscles. Such forced or labored breathing is a common symptom in serious lung diseases, "bloat" in cattle, or any condition that may cause dyspnoea. Horses affected with "heaves" show a double contraction of the muscles in the region of the flank during expiration. In spasm of the diaphragm or "thumps" the expiration appears to be a short, jerking movement of the flank. In the abdominal form of respiration the movements of the walls of the chest are limited. This occurs in pleurisy. In the thoracic form of respiration the abdominal wall is held rigid and the movement of the chest walls make up for the deficiency. This latter condition occurs in peritonitis.

The odor of the expired air, the character of the discharge and the respiratory sounds found on making a careful examination are important aids in arriving at a correct diagnosis, and in studying the progress of the disease.

Body Temperature.--The body temperature of an animal is taken by inserting the fever thermometer into the rectum. In large animals a five-inch, and in small animals a four-inch fever thermometer is used. It should be inserted full length and left in position from one and one-half to three minutes, depending on the rapidity with which it registers .

The average normal body temperatures of domestic animals are as follows:

Horses 100.5260 F. Cattle 101.4260 F. Sheep 104.0260 F. Swine 103.0260 F. Dog 101.4260 F.

There is a wide variation in the body temperatures of domestic animals. This is especially true of cattle, sheep and hogs. In order to determine the normal temperature of an animal, it may be necessary to take two or more readings at different times, and compare them with the body temperatures of other animals in the herd that are known to be healthy.

Exercise, feeding, rumination, excitement, warm, close stables, exposure to cold and drinking ice cold water are common causes of variations in the body temperatures of domestic animals.

Visible Mucous Membranes.--The visible mucous membranes, as they are termed, are the lining membranes of the eyelids, nostrils and nasal cavities, and mouth. In health they are usually a pale red, excepting when the animal is exercised or excited, when they appear a brighter red and somewhat vascular. In disease the following changes in color and appearance may be noted: When inflamed, as in cold in the head, a deep red; in impoverished or bloodless conditions of the body and in internal haemorrhage, pale; in diseases of the liver, sometimes yellowish, or dark red; in diseases of the digestive tract , coated; if inflamed, dry at first, later excessively moist; and in certain germ diseases a mottled red, or showing nodules, ulcers and scars.

Surface of the Body.--When a horse is in a good condition and well cared for, the coat is short, fine, glossy and smooth and the skin pliable and elastic. Healthy cattle have a smooth, glossy coat and the skin feels mellow and elastic. The fleece of sheep should appear smooth and have plenty of yolk, the skin pliable and light pink in color. When the coat loses its lustre and gloss and the skin becomes hard, rigid, thickened and dirty, it indicates a lack of nutrition and an unhealthy condition of the body. In sheep, during sickness, the wool may become dry and brittle and the skin pale and rigid. When affected with external parasites, the hair or wool becomes dirty and rough, a part of the skin may be denuded of hair, and it appears thickened, leathery and scabby, or shows pimples, vesicles and sores.

During fever, the temperature of the surface of the body is very unequal. In serious diseases or diseases that are about to terminate fatally, the skin feels cold and the hair is wet with sweat.

When animals are allowed to "rough it" during the cold weather, the coat of hair becomes heavy and rough. This is a provision of nature and enables them, as long as the coat is dry, to withstand severe cold.

Horses that are in a low physical condition, or when accustomed to hard work, if then kept in a stall for a few days without exercise, commonly show a filling of the cannon regions of the posterior extremities. This condition also commonly occurs in disease and in mares that have reached the latter period of pregnancy. Sheep that are unthrifty and in a poor physical condition, especially if this is due to internal parasites, frequently develop dropsical swellings in the region of the jaw, or neck.

Body Excretions.--The character of the body excretions, faeces and urine may become greatly changed in certain diseases. It is important that the stockman or veterinarian observe these changes, and in certain diseases make an analysis of the urine. This may be necessary in order properly to diagnose the case.

Behavior of the Animal.--When the body temperature is high, the animal may appear greatly depressed. If suffering severe pain, it may be restless. In diseases of the nervous system, the behavior of the animal may be greatly changed. Spasms, convulsions, general local paralysis, stupid condition and unconsciousness may occur as symptoms of this class of disease.

QUESTIONS

TREATMENT

Preventive Treatment.--The subject of preventive medicine becomes more important as our knowledge of the cause of disease advances. A knowledge of feeds, methods of feeding, care, sanitation and the use of such biological products as bacterins, vaccines and protective serums is of the greatest importance to the farmer and veterinarian. We are beginning to realize that one of the most important secrets of profitable and successful stock raising is the prevention of disease; that the agricultural colleges are doing a great work in helping to teach farmers that there are right and wrong methods of feeding and caring for animals; that the practice of sanitation in caring for animals is the cheapest method of treating disease; and that it is advisable to practise radical methods of control, when necessary, in order to rid the herd of an infectious disease.

Medicinal Treatment.--The average stockman or veterinarian is more familiar with the treatment of disease with drugs than he is with the preventive measures just described. This statement does not imply that a knowledge of medicinal therapeutics is not of the greatest importance in the treatment of disease. The ultimate object of all drugs is both to prevent and cure disease, but the injudicious use of a drug does neither. A discussion of this subject cannot be entered into here, and because of its largeness it is not advisable to discuss it further than a brief summary of the methods of administering drugs.

Administration of Drugs.--Drugs may be administered by the following channels: by way of the mouth, in the feed or as a drench; by injecting into the tissues beneath the skin or hypodermically; by rubbing into the skin; by the air passages and the lungs; and by injecting into the rectum.

If the animal is not too sick to eat and the drug does not possess an unpleasant taste, it may be given with the feed. If soluble, it may be given with the drinking water, or in any case, it may be mixed with ground feed if this method is to be preferred. In all cases the medicine must be well mixed with the feed. This is especially important if there are a number of animals to be treated, as there is more certainty of each animal getting the proper dose and the danger of overdosing is avoided. If the young animal is nursing the mother, we can take advantage of certain drugs being eliminated in the mother's milk and administer the drug to the mother.

DRENCHES.--In the larger animals a bulky drench is sometimes difficult to administer, and we should, in all cases, count on a portion being wasted.

Size of the Dose.--The doses recommended in the treatment of the different diseases, unless otherwise stated, are for mature animals. The dose for a colt one year of age is about one-third the quantity given the adult, two years of age one-half, and three years of age two-thirds. In well-matured colts a larger dose may be given. In cattle, the doses recommended are about the same. In the smaller animals the size of the dose may be based on the development and age of the animal. When the drug is administered at short intervals or repeated, the size of the dose should be reduced. The physiological action of some drugs may be changed by varying the size of the dose.

QUESTIONS

DISEASES OF THE DIGESTIVE SYSTEM

The organs that form the digestive tract are the mouth, pharynx, oesophagus, stomach, intestines and the annexed glands, viz.: the salivary, liver, and pancreas. The development of these organs differs in the different species of animals. For example, solipeds possess a small, simple stomach and capacious, complicated intestines. Just the opposite is true of ruminants. The different species of ruminants possess a large, complicated stomach, and comparatively simple intestines. In swine we meet with a more highly developed stomach than that of solipeds and a more simple intestinal tract. Of all domestic animals the most simple digestive tract occurs in the dog. These variations in the development of the different organs of digestion, together with the difference in the character of the feed and method of feeding, cause a variation in the kind of diseases met with in the different species. The complicated stomach of ruminants predispose them to diseases of this portion of the digestive tract. Because of their complicated intestinal tract solipeds are prone to intestinal disease.

DISEASES OF THE MOUTH

GENERAL DISCUSSION.--The mouth is the first division of the digestive tract. It is formed by the lips, cheeks, palate, soft palate, tongue and teeth. Here the feed is acted on mechanically. It is broken up by the teeth and moved about until mixed with the saliva and put into condition to pass through the pharynx and along the oesophagus to the stomach. The mechanical change that the feed is subject to is very imperfect in dogs. In the horse it is a slow, thorough process, although greedy feeders are not uncommon. The first mastication in the ox is three times quicker than in horses, but the process of rumination is slow and thorough.

STOMATITIS.--Simple inflammation of the mouth is frequently met with in horses. Ulcerative or infectious inflammation commonly occurs in young, and occasionally in old, debilitated animals. This form of sore mouth will be discussed along with other infectious diseases, and the following discussion will be confined to the non-infectious form of the disease.

In generalized inflammation of the mucous membrane, the first symptom usually noticed is the inability to eat. On examining the mouth we find the mucous membrane inflamed, hot and dry. A part may appear coated. In a short time the odor from the mouth is fetid. Following this dry stage of the inflammation is the period of salivation. Saliva dribbles from the mouth, and in severe cases it is mixed with white, stringy shreds of epithelium and tinged with blood. In less acute forms of the disease, we may notice little blisters or vesicles scattered over the lining membrane of the lips, cheeks and tongue.

The acute form of stomatitis runs a short course, usually a few days, and responds readily to treatment. Localized inflammation caused by irritation from teeth, or feeding irritating feeds, does not respond so readily to treatment.

DEPRAVED APPETITE

A depraved appetite is met with in all species of farm animals, but it is especially common in ruminants. It should not be classed as a disease, but more correctly as a bad habit, or symptom of innutrition or indigestion. The animals affected seem to have an irresistible desire to lick, chew and swallow indigestible and disgusting objects.

DISEASES OF THE STOMACH

There is a remarkable difference in the development of the stomachs of solipeds and ruminants.

The horse's stomach is simple and has a capacity of three or four gallons. The left portion is lined with a cuticular mucous membrane, and the right portion with a glandular mucous membrane that has in it the glands that secrete the gastric juice. The most important digestive change in the feed is the action of the gastric juice on the proteids and their conversion into the simpler products, proteoses and peptones.

RUMINANTS have a compound stomach . The capacity of the stomach of the ox is between twenty and thirty gallons. The four compartments into which it is divided are the rumen, reticulum, omasum, and abomasum or true stomach. The rumen is the largest compartment, with a capacity of more than twenty gallons. The reticulum is the smallest, with a capacity of about one-half gallon.

The first three compartments possess no glands capable of secreting a digestive juice. However, important digestive changes occur. The carbohydrates are digested by means of enzymes contained in the feed. The most important function of the rumen and omasum is the maceration of the fibrous substances, and the digestion of the cellulose. Between sixty and seventy per cent of the cellulose is digested in the rumen.

THE STOMACH OF THE HOG is a type between the carnivora and ruminant. The digestive changes may be divided into four stages. The first period is one of starch conversion; the second period is the same, only more pronounced; the third period, both starch and protein conversion occurs; and the fourth period is taken up mostly with protein digestion.

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