Chapter 8

This plant, which is closely related to the death-camas plants, is sometimes known as "stagger grass" and causes a considerable loss in the Southern States. It grows earlier than the grasses, and on this account is more likely to be eaten. Like death camas, it produces pronounced nausea, resulting in vomiting and weakness, and in cases which recover the effects may continue for several days. Apparently the injurious effects are more common in the case of cattle than in other domestic animals. There is no known way of treating these animals, though doubtless purgatives would be beneficial.

YEW (TAXUS BACCATA).

The European yew has long been known as a very poisonous plant. It is cultivated in America, and while cases of poisoning have not been common, it is well to recognize its dangerous character. A comparatively small dose is poisonous and ordinarily acts with great rapidity. It causes respiratory paralysis and the animal dies in convulsions.

LAUREL.

The laurels, including the broad-leafed laurel, _Kalmia latifolia_, the narrow-leafed laurel, _Kalmia angustifolia_, the rhododendrons, and other closely related plants are poisonous and cause considerable losses. It is dangerous to let cattle graze where these plants are abundant at times when other forage is scarce. The symptoms are salivation, nausea and vomiting, spasms, dizziness, stupor, and death.

FERN.

The common brake or bracken fern, _Pteris aquilina_, has been considered responsible for the poisoning of many horses and cattle. Many cases have been reported in England and Germany, and some well-authenticated cases in the United States. Very little has been learned experimentally of fern poisoning, but there seems to be little question that it has been the cause of many deaths. The symptoms are said to be temperature higher than normal, loss of appetite, bloody discharges from mouth, nose, and bowels, and great depression followed by coma and death. Some authors say that the urine is colored by blood. It is thought by some that the disease known as "red water" in the northwestern United States and Canada is caused by eating ferns.

SORGHUM POISONING.

Under certain conditions sorghum contains enough hydrocyanic acid to make it exceedingly dangerous to cattle. These cases of poisoning most commonly occur when cattle are pastured upon the young plant or upon a field where the crop has been cut and is making a second growth. Conditions of drought make the sorghum especially dangerous. There is some reason to think that the frosted second growth is particularly rich in hydrocyanic acid. The cases of poisoning occur when animals are grazed upon the plant, but not from the harvested crop or from silage. If cattle are grazed on sorghum or sorghum stubble they should at first be under constant observation and should be removed as soon as any signs of illness appear. Similar precautions should be used in grazing kafir.

CORNSTALK DISEASE.

Considerable losses of cattle have occurred when they were turned upon cornfields in the fall. Deaths come very suddenly and there is no opportunity to apply remedies. It has been thought that these fatalities, like those from sorghum, were caused by hydrocyanic acid, but there is good reason to think that this is not true, and at the present time there is no accepted explanation of this disease, although there seems to be no doubt that it is connected in some way with the condition of the corn. Whether a given field is poisonous or not can only be determined by experiment, and the wise farmer will keep his cattle under close observation when they are first turned into a cornfield.

WATER HEMLOCK (CICUTA).

This plant, growing in wet places by ditches and along creeks, is the most poisonous of North American plants. The root is the poisonous part, and cattle generally get it when it is plowed up or washed out by high water. Sometimes they pull it up, for the plant occasionally grows out into ditches so that the whole plant will be taken in grazing. The most marked symptoms of Cicuta poisoning are the violent convulsions, which remind one of the effect of strychnin.

_Treatment._--Little can be done in the way of treatment. The logical thing is to attempt to control the convulsions by means of morphia, but in view of the fact that the stomach can not be emptied, the prognosis is not good, and most cases die.

LARKSPURS.

The larkspurs are a source of heavy loss to cattle owners in the higher ranges of the West. There are a number of species, growing at altitudes from 4,000 feet to timber line, and all are poisonous. A few cases of poisoning by larkspurs have been reported in the eastern United States, but most of the losses are confined to the West, both because larkspurs grow there in greater profusion and because cattle are grazed in that region on the open ranges. The losses are confined to cattle, for sheep and horses can graze on larkspur with no resulting harm. Most of the larkspur losses occur in the spring and early summer, as the plants lose their toxicity after maturing.

_Symptoms._--Larkspur poisoning is accompanied by a definite line of symptoms. In range animals the first symptom noted is generally the sudden falling of the animal and consequent inability to rise. After a while it may rise, only to fall again. This may happen repeatedly. In severe cases the animal lies prone and exhibits nausea, accompanied by vomiting. It dies of respiratory paralysis, death many times being hastened by the asphyxia following the vomiting.

_Treatment._--The animal, if found down, should be turned so that its head is uphill in order to relieve the lungs. Many cases will recover with no further treatment. Nearly all cases will recover if a hypodermic injection is given immediately of physostigmin salicylate 1 grain, pilocarpin hydrochlorid 2 grains, strychnin sulphate 1/2 grain.

LOCO.

The loco plants have caused especially heavy losses of cattle, horses, and sheep. They grow in the semiarid regions of the West and sometimes in great luxuriance. The best known are the "blue loco," the "woolly loco" or "purple loco," and the "white loco" or "rattle-weed." The blue loco is common in parts of New Mexico, Arizona, and Utah. It affects both horses and cattle. The purple loco, _Astragalus mollissimus_, is common in Texas and the adjoining States and extends north as far as Nebraska and Colorado. It is especially destructive to horses. The white loco, _Oxytropis lamberti_, is still more widely distributed, being found in the plains region from Alaska to Mexico and west of the Rocky Mountains to central Utah. The white loco is much more important than the purple loco, for it affects not only horses but cattle and sheep. These plants belong to the pea family, and there are a number of other species of this family that are loco plants and produce the same symptoms.

_Symptoms._--Loco poisoning is a chronic condition and symptoms are shown only after somewhat prolonged feeding. The condition is one of cumulative poisoning, and animals sometimes decline very rapidly after the first symptoms appear. In many cases animals acquire a habit of eating loco and prefer it to any other feed. The poison affects the central nervous system. There is a lack of muscular coordination and the animal performs very erratic movements. In the later stages the animal becomes emaciated and eventually dies of starvation.

_Treatment._--Locoed animals are badly constipated, and it is important that this condition should be remedied at the start. Any purgative can be used, but Epsom salt has been found especially effective. If locoed animals can be turned into a field of alfalfa, a large proportion of them will recover with no further treatment. Recovery may be aided by giving cattle, hypodermically, daily doses of three-twentieths to four-twentieths of a grain of strychnin. By this treatment cattle can be cured and put in condition for market.

WHITE SNAKEROOT (EUPATORIUM URTIC∆FOLIUM).

White snakeroot, frequently known as "rich weed," is a plant growing in great abundance in some of the eastern and central regions of the United States. It is particularly abundant in parts of Ohio, Indiana, and Illinois, and in western North Carolina. It is responsible for most, if not all, of the cases of a disease which is commonly known as "milk sickness."

_Symptoms._--The animals are constipated, sometimes have bloody feces, become weak, and exhibit muscular trembling. This trembling is very characteristic, so that the disease is sometimes known as "the trembles."

_Remedy._--There are no remedies which will work very efficiently. It is desirable to give the animals purgatives like Epsom salt and, of course, to remove them from fields where this plant is abundant.

RAYLESS GOLDENROD (ISOCOMA WRIGHTII).

The rayless goldenrod is a plant growing in especial abundance in parts of the Pecos Valley in New Mexico and Arizona, and there produces a disease so much like that produced in the East by white snakeroot that it is sometimes called milk sickness. More generally this disease goes under the name of "alkali disease." The plant has produced heavy losses in the regions where it grows abundantly.

_Symptoms._--The symptoms are much like those produced by the white snakeroot. The animals are constipated, sometimes have bloody feces, become weak, and exhibit muscular trembling. There is good reason to think, too, that the milk of cows eating this plant is more or less injurious.

_Treatment._--A purgative like Epsom salt will aid an animal in recovering, but most important is to remove the cattle from pastures where the plant is abundant and give them an abundance of good forage. Under such conditions they are almost certain to recover.

MILKWEEDS.

Many of the milkweeds have long been known to have more or less poisonous properties. Within the last few years it has been discovered that certain of the milkweeds going under the popular name of whorled milkweeds are especially toxic. There are at least four species of whorled milkweeds, but two of them are particularly important from the standpoint of people handling livestock. One, known scientifically as _Asclepias galioides_, is harmful in Colorado, Utah, Arizona, and New Mexico, while another, known as _Asclepias mexicana_, has produced losses, especially in California and Nevada. These whorled milkweeds are distasteful to all animals and are eaten only when the stock is closely confined to pastures where there is little else in the way of forage.

_Symptoms._--The most prominent symptoms are weakness, producing staggering, and this is followed in acute cases by violent spasms.

_Treatment._--There is no treatment which will effectively antidote the effect of the poison. In practically all cases, however, poisoning may be avoided if care is taken to prevent animals from being closely confined where this plant is abundant, as they never eat the plant by choice.

CHERRY.

In the leaves of the cherries more or less hydrocyanic acid is produced, and when these leaves are eaten in any considerable quantity cases of poisoning are likely to arise. It is popularly supposed that these cases arise from eating wilted cherry leaves, but there is every reason to think that the fresh leaves will produce the same results. These cases are easily prevented, because no harm results from eating a small quantity of the leaves, and if the fact is recognized that poisoning may result from eating a large quantity, it is not difficult to care for the animals so as to prevent poisoning.

ERGOTISM.

The poisonous effects of ergot (Pls. V, VI) appear chiefly in the winter and spring of the year and among cattle. It is developed among grasses grown on rich soil in hot, damp seasons. Rye seems more liable to ergot than any of our other crops. Of the grasses which enter into the composition of hay, bluegrass is the most likely to become affected. Ergot may also affect redtop, oats, grasses, and grains. On the plant the fungus manifests itself on the seeds, where it is easily recognized when the hay is examined in the mow. The ergotized seeds are several times larger than the natural seeds--hard, black, and generally curved in shape.

The effect of the protracted use of ergot in the feed is pretty well understood to be that of producing a degeneration and obstruction of the smaller arterial branches. The result is to shut off the blood supply to the distal parts of the body, where the circulation is weakest, and thus to produce a mummification or dry gangrene of the extremities, as the ears, tail, feet, etc. Cattle seem to be more susceptible than other animals to the influence of ergot, possibly on account of the slowness of the heart's action. When the effect of the poison has become sufficient to entirely arrest the circulation in any part, the structures soon die. The disorder manifests itself as lameness in one or more limbs; swelling about the ankle which may result in only a small slough or the loss of a toe, but it may circumscribe the limb at any point below the knee or hock by an indented ring below which the tissues become dead. The indentation soon changes to a crack, which extends completely around the limb, forming the line of separation between the dead and living structures. The crack deepens till the parts below drop off without loss of blood, and frequently with very little pus. Ergot may cause serious irritation of the digestive tract, or by acting upon the nervous system it may cause lethargy or paralysis. It also operates to cause contraction of the uterus, and may thus cause abortion.

_Treatment._--Regarding the treatment, change of feed and local antiseptics are, of course, indicated. The former may be useful as a preventive, but when the symptoms have appeared the animal is necessarily so completely saturated that recovery is likely to be tedious. Tannin may be given internally in doses of one-half dram twice daily for a few days to neutralize the unabsorbed alkaloids of the ergot. At the same time give castor oil. To dilate the blood vessels give chloral hydrate. Bathe the affected parts with hot water. If sloughing has gone far, amputation must be resorted to.

OTHER POISONOUS FUNGI.

Many other fungi poison herbivora. In some instances, however, where fungi are blamed for causing disease their presence on the feedstuff or herbage is but coincidental with some other and more potent disease-producing factor. For example, if the conditions are favorable to the growth of fungi they are also favorable to the growth of bacteria, and bacteria may produce poisons in feeds. In general it may be said that any feed that is moldy, musty, or putrid is possibly dangerous. Silage, properly cured, does not belong to this class, because the curing of silage is not a bacterial process. But spoiled silage and silage matted with mold is dangerous and should not be fed.

POISONING BY ANIMAL PRODUCTS.

SNAKE BITES.

The poison contained in the tooth glands of certain venomous reptiles, particularly some of the snakes, which is injected into or under the skin of an animal bitten by the reptile, is a very powerful agent. It is likely to produce a serious local irritation, and in the case of the more poisonous snakes serious constitutional disturbances, even to causing death, which it may do in either of two ways: First, when very strong, by exerting a narcotic influence similar to that of some of the powerful poisons, checking heart action. Second, by diffused inflammation of the areolar tissue, gangrene, and extensive sloughing.

_Symptoms._--The symptoms of snake bite are a local swelling caused by an intense local inflammation, pricks showing where the fangs penetrated, depression, weakness, feeble pulse, difficult breathing, bluish discoloration of the visible mucous membranes, stupor, or convulsions. If the poison is not powerful or plentiful enough to produce death, it is, at any rate, likely to cause severe local abscesses or sloughs.

_Treatment._--The treatment may be divided into local and general. Locally every effort should be made to prevent absorption of the poison. If discovered at once the bitten part had better be excised. If that is impracticable and a ligature can be applied, as in the case of a bite to one of the limbs, no time should be lost in applying it above the injury. It should be made sufficiently tight to so far as possible arrest circulation in the bitten part. The wound should be freely incised, so that it will bleed freely, and the poison should be extracted by cupping, or pressed out by squeezing with the fingers. Permanganate of potassium in 5 per cent solution should be applied to and injected into the wound. The depressing effect of the poison on the general system should be counteracted by hypodermic injections of strychnin, or by liberal drenching with stimulants, such as coffee, digitalis, or the aromatic spirits or carbonate of ammonia. In animal practice the alcoholic stimulants and local treatment above described are likely to meet with best success. A special antitoxin for use in treating snake bite is now prepared and may be had from the leading druggists. It is quite effective if used promptly.

WASP AND BEE STINGS.

Wasps and bees secrete a poisonous substance which they are able to insert through the skin of an animal by the aid of their sharp stings. This poison is a severe local irritant and may even cause local gangrene. It also has a depressing effect upon the central nervous system and destroys the red-blood corpuscles. To produce these general effects it must be introduced in very large quantities, as when an animal is stung by a swarm of bees or wasps.

_Treatment._--The treatment is to wash the parts with diluted ammonia or permanganate of potassium solution and to give stimulants internally. If there is so much swelling about the head and nostrils as to interfere with breathing, tracheotomy may be necessary.

POISONING WITH SPANISH FLY.

Spanish fly, in the form of powdered cantharides, may be given in an overdose, or when applied as a blister to too large a surface of skin enough may be absorbed to poison. If given by the mouth, it causes severe irritation of the gastrointestinal tract, shown by salivation, sore throat, colic, bloody diarrhea, etc. It also produces, whether given by the mouth or absorbed through the skin, irritation of the urinary tract, as shown by frequent and painful urination. If death results, it is due to respiratory paralysis.

_Treatment._--Give protectives and the white of egg, with opium. Do not give oils or alcohol.

DISEASES OF THE HEART, BLOOD VESSELS, AND LYMPHATICS.

By W. H. HARBAUGH, V. S.

[Revised by Leonard Pearson, B. S., V. M. D.]

THE CIRCULATORY SYSTEM.

In cattle, as in human beings, the heart, blood vessels, and lymphatics may be described as the circulatory apparatus.

The heart is in the thoracic cavity (chest). It is conical in form, with the base or large part uppermost, while the apex, or point, rests just above the sternum (breastbone). It is situated between the right and left lungs, the apex inclining to the left, and owing to this the heart beats are best felt on the left side of the chest, behind the elbow. The heart may be considered as a hollow muscle, containing four compartments, two on each side. The upper compartments are called auricles and the lower ones ventricles. The right auricle and ventricle are completely separated from the left auricle and ventricle by a thick septum or wall, so that there is no communication between the right and left sides of the organ.

At the bottom of each auricle is the auriculo-ventricular opening, each provided with a valve to close it when the heart contracts to force the blood into the arteries. In the interval between the contractions these valves hang down into the ventricles.

The muscular tissue of the heart belongs to that class known as involuntary, because its action is not controlled by the will.

The cavities of the heart are lined by a serous membrane, called the endocardium, which may be considered as a continuation of the veins and the arteries, forming their internal lining. The walls of the ventricles are thicker than those of the auricles, and the walls of the left ventricle are much thicker than those of the right.

The heart is enveloped by a fibrous sac (or bag), called the pericardium, which assumes much of the general shape of the outer surface of the heart.

The action of the heart is similar to that of a pump and its function is to keep the blood in circulation. The auricles may be considered as the reservoirs or receivers of the blood and the ventricles as the pump chambers. During the interval between contractions, the heart being in momentary repose, the blood pours into the auricles from the veins; the auriculo-ventricular orifices being widely open, the ventricles also receive blood; the auricles contract and the ventricles are filled; contraction of the ventricles follows; the auriculo-ventricular valves are forced up by the pressure of the blood and close the auriculo-ventricular openings and prevent the return of blood into the auricles; the contraction of the ventricles forces the blood from the right ventricle into the lungs through the pulmonary artery and its branches, and from the left ventricle into the aorta, thence through the arteries to all parts of the body. After the contraction of the ventricles the heart is again in momentary repose and is being filled with blood, while the valves in the aorta and pulmonary artery close to prevent the return of blood into the ventricles. (See Pl. VII.)

The average weight of the heart of an ox is said to be from 3-1/2 to 5 pounds; but, of course, owing to the many breeds and sizes of cattle, it must vary in different animals.

The vessels that convey the blood from the heart to all parts of the body are called arteries; those which return the blood to the heart are called veins. The arteries divide and subdivide (like the branches of a tree), become smaller and smaller, and ultimately ramify into every part of the body. Between the ultimate ramifications of the arteries and the beginning of the veins there is an intermediate system of very minute vessels called capillaries, which connect the arterial with the venous system of the circulation. The walls of the arteries are possessed of a certain amount of rigidity, sufficient to keep the tubes open when they are empty.

The blood leaves the left ventricle through a single vessel, the common aorta, consisting of the anterior and posterior aortas, which give off the large arteries.

The veins take the blood from the capillaries in all parts of the body. They begin in very small tubes, which unite to become larger in size and less in number as they approach the heart.

In its course an artery is usually accompanied with a vein and in many situations with a nerve. The more important arteries are placed deep within the body; when they are superficial, however, they are generally found where least exposed to injury, as, for example, on the inner side of the legs. Arteries are less numerous than veins, and their total capacity is much less than that of the veins. A great number of veins are in the tissue immediately beneath the skin and do not generally accompany arteries.

The blood, throughout its course in the heart, arteries, capillaries, and veins, is inclosed within these vessels. Except where the large lymphatics empty into the venous blood, there is no opening into the course of the blood.