Sequel to acute. Result of sprains and spinal injuries. Symptoms:
paresis on exertion, lameness in one or more limbs, knuckling,
circumductive movement of feet, uncertain planting, dropping, worse if
blinded, phenomena progressive. Lesions: sclerosis of cord; absorption
of nerve cells and fibres, in gray horns, and columns, superior,
lateral and inferior, cord, altered in color, unduly firm, in points
softening. Stains deeply in carmine, lightly in osmic acid or
hæmatoxylin. Meninges thickened, nerve roots atrophied. Diagnosis:
previous acute myelitis; later muscular weakness, and paresis, under
exercise; from embolism. Treatment: hopeless if advanced: progress
delayed only. Good hygiene, tonics, open air, gentle exercise, pure
water, grooming, succulent pasture, nourishing food, alkalines, common
salt, phosphates.
Cases of this kind have not been satisfactorily diagnosed, and as a rule
domestic animals affected with partial paralysis are rarely allowed to
live in a condition in which they are offensive to themselves and
owners, a source of constant expense with little or no hope of recovery
nor profit. Again, in the case of the large mammals, the prolonged
recumbency and the low grade of nutrition in the semi-paralyzed parts,
usually entail unhealthy sores and septic poisoning which sooner or
later prove fatal. It is only, therefore, in the slighter cases, in
which a fair measure of control over the limbs remains, that these cases
are likely to survive. Trasbot suggests that many cases which pass for
lumbar sprains are really chronic myelitis and on careful examination
will show spinal sclerosis.
_Causes._ These are largely speculative, yet doubtless the same causes
which determine the acute form, will produce the chronic when acting
with less force and greater persistency. The lesions that are left after
an acute attack are calculated to keep up a measure of vascular and
trophic disorder which will be found associated with more or less
sclerosis.
_Symptoms._ In Weber’s case in the horse (Recueil de Med. Vet., 1884, p.
432) the advance was slow, so that for nearly a year the manifestations
were not diagnostic. At first there was weakness of the hind limbs when
worked to fatigue. Perfect rest led to improvement, and work, to
aggravation which became steadily worse and worse. For a length of time
the horse maintained good condition, glossy skin, elevated head, alert
expression, keen sight and hearing, and normal breathing and pulse.
Standing in the stall there was no abnormal position of the limbs, nor
evidence of lack of perfect control.
But when moved all this was changed. He showed first lameness in the
right fore limb and soon in all four members. The feet were swung and
planted uncertainly, the animal swayed and staggered, the limb would
knuckle over at the knee or fetlock, or bend at the hock, and be
recovered with difficulty. After going slowly for a few steps he moved
with greater freedom though still with difficulty, and the trouble was
greatly aggravated when the eyes were blindfolded. Then every step
threatened to precipitate him to the ground. The symptoms were
essentially those of locomotor ataxy.
The tactile sensibility was unimpaired, the loins had the normal
sensibility, urination and defecation were natural and the appetite
remained good. After ten months he showed loss of condition, dullness of
the special senses, stupor, and a special sensitiveness about the head,
and resented its handling.
_Lesions._ Thirteen months after the commencement of the attack this
horse was destroyed and the cord was found to be profoundly altered by
fibroid degeneration of the neuroglia and absorption of the nerve
elements (cells and fibres), the lesions affecting different portions of
the gray horns, and the columns—superior, lateral and inferior. The
affected portion of the cord usually shows in man a grayish, opaque or
translucent appearance, with in some cases a shrunken aspect and undue
firmness of texture, with at points, centres of softening. If hardened,
the sclerosed sections take the carmine stain deeply, but the osmic acid
or hæmatoxylin stain very slightly, contrary to what holds in health. In
recent cases there is only slight thickening of the neuroglia, but when
the disease is advanced the trabeculæ are thick, dense, and firm, and
the nerve fibres have largely disappeared. The coats of the blood
vessels adjacent to the sclerosis are thickened and their lumen is
narrowed. Thickening of the meninges is not uncommon, either confined to
those covering the diseased portion of the cord or extending completely
around it. Atrophy of the nerve roots is often appreciable by the naked
eye.
_Diagnosis._ This depends largely on the fact that the condition follows
an acute attack of myelitis, on the supervention of muscular weakness
and lack of muscular control, whenever the animal is exercised to
fatigue, the morbid symptoms subsiding promptly when he is allowed to
rest, the aggravation of these symptoms when the patient is blindfolded
and a gradual though slow advance of the symptoms with the lapse of
time. From arteritis and embolism it is to be distinguished by the
absence of the local symptoms of pain and tenderness, and by the absence
of pulsation in the same artery distal of the obstruction and of
improvement by the lapse of time or a run at grass.
_Treatment_: Unless in the very early stages even a partial recovery is
not to be looked for. By a run at grass or by gentle well regulated
exercise the impaired nerves and muscles may be educated to a better
control for a limited period but the progress of the disease is not
really arrested and the final issue is likely to be ruinous. Even in
man, where 90 per cent. of the cases are connected with syphilis, the
fibroid hyperplasia (sclerosis) is not remedied asgummata are, by
mercury and iodides. In the soliped, where no such specific disease can
be charged, the repair of the structural changes is no more hopeful. The
many different methods of treatment in man,—electricity, blisters,
firing, stretching of the spine, stretching, of the sciatic and crural
nerves,—though inducing transient improvement in many cases, produce no
real permanent benefit, and are to be remanded to the region of psychic
inferences which have little or no place in the therapeutics of the
lower animals. Strychnia, veratrin and other spinal stimulants are of
little permanent value. A general hygienic and corroborative treatment
may be used with the view of retarding the progress of the disease
rather than of curing it. Open air exercise, sunshine, succulent
pasturage, an ample supply of pure water, and active grooming are
valuable. Nourishing food is all important. Lecithin or the hypodermic
injection of spermin or other rich albuminous animal product is useful.
A course of bicarbonate of soda and carbonate of iron with or without
bitters may be tried. When the animal must be kept on dry winter food,
he should have free access to common salt and water. This favors at once
absorption, assimilation, and elimination, and by fostering nutrition
and the removal of waste matters, it contributes to keep the disease in
abeyance. Phosphoric acid and the various phosphates have been largely
used and largely rejected, their main value being in the tonic effect on
the spinal centres. Trasbot especially recommends the neutral gelatinoid
phosphate of lime as having proved especially valuable in his hands. He
gave from 1 grain upward to dogs twice a day.