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.