Part 29

Inhaled it produces intoxication, excitement, general anæsthesia and finally collapse. In rabbits it causes intense excitement, giddiness, swaying from side to side, and reckless leaps forward, followed by profound sleep with deep stertor, and paraplegia for half an hour after the return of consciousness (Oliver). When taken for a long time in smaller quantity it caused weakness, emaciation, tremors, paraplegia, and death in convulsions. There was polyuria, with excess of sugar but neither urea nor albumin. The large cells in the motor areas of the brain, when stained by Golgi’s method, showed the axis cylinder distorted and varicose, and the cytoplasm stained unequally. The action on dogs was essentially the same, and in neither animal were changes in the blood globules observed (Oliver).

In man slow poisoning caused headache and exhilarate intoxication, followed by depression, mental apathy, dullness, loss of memory, impaired vision, hearing, sexual desire and muscular power. Cramps are common (Delpech, Curtis).

Treatment consists in giving pure air, good food, massage, galvanism, tonics, and for the persistent nervous failure phosphorus.

TETANY.

Definition. Casual and experimental cases in animals. Causes: Excision of the thyroid, indigestions with fermentation, rheumatism, infection, malaria, rachitis, want of hygiene, hereditary or developmental irritability, microbian poisons. Symptoms: intermittent spasms with semi-flexed limbs, tremors. Diagnosis: by the complete intermissions of spasms, and by pressure on nerve or artery, rousing them. No fever. Like spasms of ergot. Treatment: thyroid extract, grafting thyroid; remove sources of irritation, antispasmodics, warm or tepid baths, electricity.

Definition. Tetany is the name given to a limited contraction of a group of muscles usually in the extremities occurring paroxysmally with intervals, during which it may usually be roused into activity by compression of the nerve or artery proceeding to the muscles in question.

The disease has not been accorded a place in systematic works on veterinary medicine, though cases have been recorded which are supposed to have been of this nature, and in cases occurring in man and associated with dyspepsia and gastric dilation, Bouveret and Devic have extracted from the contents of the stomach a toxic substance which caused tetanic convulsions in animals. The total removal of the thyroid gland, or even of four-fifths of it (Eiselsberg), in the cat is found to be invariably followed by tetany.

Causes. Beside the origin from the removal or general disease or degeneration of the thyroid, it has been attributed to digestive troubles, associated with fermentations and the production of toxic matters, to rheumatism, infection and malaria, to rachitis and unhygienic conditions. The systemic changes and trials of growth and development, of pregnancy and lactation, seem to be factors in certain cases. A peculiar irritable nervous organization transmitted by heredity is undoubtedly a potent cause, and upon this, bacteridian, leucocytic and other poisons operate so as to rouse the paroxysms.

Symptoms. There are usually prodromata in the shape of dullness, prostration, weariness, and some dullness of the special senses. Fever is commonly absent and the contractions tend to affect both flexors and extensors, but as the force of the first predominates, the affected member is usually held more or less rigidly semi-flexed. The spasm appears suddenly, often taking occasion of some voluntary movement, and may last for several minutes or hours. It is followed by an interval of relaxation of equally uncertain duration. Though usually attacking the limbs and causing the victim to walk on the toes, it may extend to the face, neck or trunk, and constitute an intermittent trismus, oposthotonos, or emprosthotonos.

Diagnosis. Tetany is to be distinguished from tetanus by the complete intermissions of the spasms, and by the voluntary development of these by compression of the presiding nerve or artery. Pressure on the nerve arouses its excitability, and compression of the artery shutting off the supply of blood from the disordered and susceptible muscles, tends to increase their irritability. Ligature of an artery supplying healthy muscles causes simple trembling of such organs. From the spasms of cerebral, spinal or meningeal inflammation tetany is distinguished by the absence of fever, and the complete intermissions of the paroxysms. The spasms of ergotism bear the closest relation to those of tetany and in the absence of proof of the ingestion of ergot, might well be confounded with them.

Treatment. This consists mainly in doing away with the causes, when these can be ascertained. Portions of thyroid may be grafted if complete thyroidectomy has been performed, or thyroid extract may be given. In the human subject recoveries have followed the expulsion of intestinal worms, the cure of gastric dilation, dyspepsia, fermentations, diarrhœa, rachitis, menstrual irregularity, or auto-intoxication. Fíré has seen recovery follow the extraction of a carious tooth.

The spasms may be met by the internal administration of antispasmodics (chloral, belladonna, bromides, opiates), and the external application over the affected muscles of anodynes and antispasmodics (belladonna, opium, chloroform, oil of cajeput, oil of peppermint, menthol, etc.). Warm or tepid baths are often of great value and a mild electric current has been found useful.

CONGESTION OF THE SPINAL CORD IN THE HORSE AND COW.

Under this heading Trasbot describes hæmoglobinuria and parturition paresis, but this tends to cover up the more important causes and phenomena of these diseases, which should be kept in the foreground. Spinal congestion is undoubtedly a feature of both these affections, and the sudden onset and rapid recoveries often seen, indicate the absence of inflammatory action, yet this is but an accompaniment of a constitutional morbid state which we think fully warrants a special consideration of each elsewhere (see Hæmoglobinuria; Parturition paresis).

Apart from these affections congestion habitually merges into myelitis or spinal meningitis, and may be considered as the initial stage of these disorders. It owns the same causes and is manifested by closely allied symptoms, but these are less persistent, and may subside abruptly into a condition of health. The treatment will be on the same general lines as for myelitis, but with much better hope of success.

ACUTE MYELITIS. POLIOMYELITIS. INFLAMMATION OF THE SPINAL CORD.

Causes: Stimulating food to excess, sexual over-stimulation, violent overexertion, hot sun, chill, rheumatism, traumas, injury to spinal nerves, vertebral caries, microbian infection, narcotics, vegetable poisons, cryptogams. Lesions: discoloration of white or gray matter, swelling, friability, softening, extravasations in points, leucocytes in excess, nerve cells cloudy, granular, nucleus enlarged, stain highly, chromophile granules irregular, neuroglia thickened. Symptoms: Hyperthermia, rigor, hyperæsthesia, tonic contractions in neck and limbs, intense lameness, paresis, palsy, muscular atrophy, areas of heat followed by coldness, such parts may not perspire, palsy less complete than in broken back, circulation and breathing accelerated or slow, paraplegia in large herbivora. Diagnosis: progressive onset, hyperæsthesia or rigidity merging into palsy, retention and later incontinence of urine, extreme spinal tenderness, rapid atrophy of affected muscles, skin sloughing. Prognosis, always grave. Treatment: purgation, bleeding, hot fomentations, ice bags, compresses, derivatives, bromides, chloral, potassium iodide, atropia, ergot, electricity, strychnia, soft laxative food, bitters, phosphates.

Causes. Like congestion this may be a result of =plethora= in overfed animals, in those subjected to specially stimulating food like gluten meal, cotton seed meal, beans, peas, vetches in excess, animal food for herbivora (the waste of hotels and restaurants for cows, compressed meat products for pigs), a period of absolute rest on full rations in horses habituated to hard work and full feeding; of =sexual over-stimulation= in males (stallion, bull, ram); of =violent overexertion=, especially if =under a hot sun=; of =sudden chill= when over-fatigued and perspiring; of =cold rain storms= (Freirier); of =rheumatism= (Kowalski); of =traumatism= (fractures, sprains, slipping with overdistension); of =falls upon the point of the ischium=; of blows upon the back (Cruzel, Trasbot); of =tumors implicating the cord=; of =too violent efforts in serving= by stallions; of =injuries of the great nerve trunks= passing off from the cord (Gull, Trasbot, etc.); of extensions from =caries or suppurations of the vertebræ= (Decoste, Trasbot); of =microbian infection=, as in rabies, distemper, tubercle, dourine, louping ill, milk sickness, contagious pneumonia, influenza, and suppurations; of =narcotic poisoning=, as from ergot, smut, the poisons of the cryptogams and bacteria of mouldy bread, musty fodder, spoiled meats, fish, etc.; also the poisons of =lolium=, =vetch=, =lupin=, =astragalus=, =oxytropis=, =arsenic=, etc.

Lesions. These consist in a yellow or pink discoloration of the white and especially of the gray matter, and a special prominence of the puncta vasculosa in the affected part. Swelling or distortion of the part is not usual. This may involve only a single gray horn, the two horns on the same side, the two inferior horns, or all four at once, or the white matter adjacent may also show the rosy tint, the large puncta, and a characteristic softness and friability. Minute blood extravasations are very significant. Microscopically examined leucocytes are found in abundance in the perivascular spaces and in the neuroglia. The neurons (nerve ganglion cells) are degenerated, being cloudy, swollen, with enlarged nucleus, stain highly, and show enlargement of the chromophile granules. In a more advanced stage the cell has an indefinite outline and the nucleus is indistinct and may fail to take a stain; the chromophile granules are irregular and do not radiate evenly from a centre and many vacuoles appear. This may lead to fatty softening, or to fibrous increase of the neuroglia, and sclerosis.

Symptoms. These vary greatly in different cases according to the part involved, the meninges or some special region of the cord, to the essential cause of the inflammation and its acuteness. Usually the attack sets in slowly in contradistinction to the abrupt attack of congestion. =Hyperthermia= and =rigor= are usually among the first symptoms, though in many cases =hyperæsthesia= is the most marked early symptom. The skin covering the muscles which derive innervation from the affected section of the cord is the most sensitive. This is often so extreme along the vertebral column that percussion on the spinous processes or pinching between the fingers and thumb causes the most pronounced wincing and dropping of the back. Copland and Laposso have noticed that a sponge of hot water drawn along the line of the vertebræ causes acute pain and contractions of the muscles of the back and limbs, which are almost tetanic in their force. This probably implies the existence of meningitis, since the absence of rigidity of the muscles of the neck, back and limbs, usually implies the absence of meningeal inflammation. It may, however, occur in localized or commencing myelitis. The existence of unilateral lesions and rigidity determines intense lameness, which is further characterized by the most marked hyperæsthesia.

The =morbid phenomena of the motor system= are more characteristically paretic or paralytic than spasmodic. When rigidity or spasm ushers in the attack it is superseded in a few hours or in two or three days by flaccidity of the muscles of the affected part, with imperfect control or even complete paralysis. The muscles affected will depend on the seat of the spinal lesion. If in the neck it may affect fore and hind limbs, and even the chest and abdomen; if in the back or loins it will induce paraplegia, the anterior limit of which will correspond to the seat of the lesion; if near the caudal extremity of the cord, (lumbar portion), paralysis of the tail and of the sphincters ani and vesicæ may be prominent features. Retention of urine and fæces (spasm) may precede incontinence (palsy).

=Common sensation= may be dull or abolished on one or on both sides. If on one side only, the other may show hyperæsthesia.

=Trophic modifications= are very marked though they may not be noticeable at first. The paralytic muscles waste rapidly and the impaired nutrition is manifested in the rapid formation of sloughing and intractable sores where pressure comes in recumbency (the hips, stifles, hocks, shoulders, etc.). This is especially noticeable on parts supplied by the cord at or behind the seat of the lesions.

=Vaso-motor changes= are usually marked by a preliminary hyperthermia of the affected parts, followed by a corresponding hypothermia. Sometimes the affected part of the skin will remain quite dry while the rest of the body is covered by perspiration.

=Choked optic disc= and retinitis are sometimes present.

The =febrile reaction= which is at first moderate, gradually increases in force; the animals become dull, drowsy, careless of food, and the hyperæsthesia merges into paresis or paralysis. This is rarely so complete as in fracture of the vertebræ. If the inflammation is restricted to the lower columns only, there may be akinesis without change of the sensitiveness or with hypersensitiveness. If restricted to the upper columns there may be sensory paralysis only on the opposite side.

The =heart sounds and pulse= are usually altered, palpitations may appear early with acceleration and sharpness of the pulse, and this may alternate with a tardy slow pulse with intermissions. =Breathing= also becomes accelerated and in violent cases with trembling, though in moderate inflammation with effusion, softening and degeneration, it is liable like the heart beats to become slow and tardy.

When =vertigo= appears it may be attributed to extension to the bulb or cerebellum, or to the sympathetic implication of these organs.