Part 24

Cold applications to the head are generally commended. Bags of ice or snow, irrigation with cold water, or cooling by running water at a low temperature, through a pipe coiled round the head or extended along the spine, will meet the purpose. Applied continuously this constringes the blood-vessels within the cranium as well as on its surface, lessens the exudation, and controls the pain and spasms. This may be advantageously associated with warm fomentations to the feet and limbs, friction, or even the application of stimulating embrocations to draw the blood to these parts. In the smaller animals even warm baths may be resorted to as a derivative, cold being meanwhile applied to the head and spine. This not only lessens the vascular pressure within the cranium, but secures elimination of toxic matters by both skin and kidneys. Cold pure water should be constantly within reach.

A most important thing in the horse is to put him in slings, if he is at all able to stand with their assistance. In decubitus he rests on his side, with the head on the ground, and lower than the splanchnic cavities. The result is a gravitation of blood toward the head. In the sling, with the head fairly raised the gravitation is the other way and the head is depleted. If the patient is too ill to be maintained in the sling, he may be packed up with bundles of straw on each side, so that his breast may lie on a thickly littered bed, and his head may be elevated.

When convalescence sets in care must be taken to nourish with non-stimulating, easily digested food, gruels, soft mashes, pulped or finely sliced roots. In vomiting animals rectal alimentation may become necessary. The rise of cranial temperature or the aggravation of brain symptoms should be met as needed by the local application of cold, and potassium iodide and iron or bitter tonics may be given if they do not interfere with digestion.

ABSCESS OF THE BRAIN.

Infection, in traumas, meningitis, encephalitis, strangles, etc. Symptoms: evidence of trauma, chill, hyperæsthesia irritability, drowsiness, giddiness, stupor, spasms, paresis, coma, dilated pupils, congested mucosæ, vomiting. Location indicated by muscular groups involved. Treatment: As in meningitis: trephining in hopeful cases.

The formation of abscess in the cranial cavity has been referred to in connection with injuries to the cranium and meningo-encephalitis. It may here be said in general terms that this abscess is a product of infection. In the horse the most common cause is strangles, and especially such cases as run a tardy or irregular course with imperfect softening and limited suppuration in the submaxillary or pharyngeal region. It is to be looked on as an extension of the purulent infection so as to cause a secondary abscess. The same may occur in case of ordinary abscess in any distant organ. In the brain as elsewhere suppuration may result from direct local injury as in the case of blows by clubs, or yokes, running against walls or posts, falls, the effects of butting, injuries by bullets and otherwise. In these cases, as noticed under concussion, there may be two points of injury (and two abscesses) one, in the seat of the injury, and one in a deeper part of the brain, at the opposite wall of the cranium. Again abscess may result in the brain from extension from a similar process going on in the vicinity. Thus otitis extends through the middle and internal ear to the brain, and its starting point may have been more distant, namely, in the Eustachian tube, or pouch, or in the pharynx.

The symptoms vary according to the size of the abscess, the rapidity of its formation and the amount of attendant congestion. In the common cases resulting from strangles, I have usually found the animal down, unable to rise, blind, amaurotic, with dilated pupils, congested mucous membranes, and occasional spasmodic movements of the limbs, neck and head. The symptoms may, however, vary through hyperæsthesia, irritability, drowsiness, giddiness, stupor, local or general paralysis with occasional spasms or convulsions. There may be an initial shivering, and a rise of temperature, yet as pressure on the brain increases it may become normal or subnormal. In circumscribed abscess the symptoms may be much less severe, not perhaps exceeding irritability, drowsiness, and some paresis or local paralysis.

In some such cases one can trace the connection to some primary disease, (traumatic injuries to the cranium, abscess of the diplöe or sinus, parasites in the sinus, otitis, or pharyngeal disease) which serve as an indication of the true state of things. In others there may be circumscribed local manifestations, (anæsthesia, hyperæsthesia, hemiplegia, paralysis of special muscular groups, or spasms of the same ) which may indicate more or less accurately the exact seat of the lesion. When well defined, this localization of the resultant phenomena, serves to distinguish this and other local lesions, from meningitis which is apt to be much more general in its diffusion. In the carnivora and omnivora vomiting is a marked symptom.

Treatment of brain abscess is usually hopeless, yet the attendant inflammation may be met as in other cases of meningitis. If the seat of abscess can be ascertained surgical interference is fully warranted.

TUBERCULAR MENINGITIS.

Little seen in cattle. Acute and chronic cases. Miliary tubercles in pia. Hydrocephalus. Progresses slowly. Irritability, hyperæsthesia, photophobia, congested conjunctiva, grinding teeth, spasms, squinting, dilated pupils, congested disc, drowsiness, stupor, coma, palsy.

Tubercle of the encephalon has been little noticed in the lower animals, partly because it is especially a disease of early life, while animals usually contract tubercle later in life, and partly because subjective symptoms are inappreciable, and the cranium is seldom opened in post mortem examinations. As the affection usually appears as a secondary deposit, the tubercles elsewhere go a long way toward identifying the nature of the disease in the brain. It has usually been found consecutive to pulmonary tuberculosis.

In a case reported by Fischœder as seen at the Bromberg abattoir, in a 350 lbs. calf, the animal had shown weakness, stupor and a tendency to fall toward the right. The brain lesions consisted of small foci of tubercle on the posterior pillars of the fornix (trigone) and adjacent parts. The left eye had on its inner aspect, near the junction of sclerotic and cornea, a firm mass with tubercular centres, extending inward as far as the retina. The bronchial mediastinal, prepectoral, brachial and precrural glands were tuberculous.

In a case in a cow reported by Lesage there were unsteady gait, impaired vision, and great timidity. Necropsy showed a suboccipital tubercle extending into the frontal sinus and cranium, and invading the brain near the parietal lobe for more than an inch. There were retro-pharyngeal and pleural tubercles as well.

In a case of Routledge’s, with extensive recent exudate, the condition advanced from apparent health to extensive paralysis in three days, while in a case which the author obtained in slaughtering a tuberculous herd no special nervous symptoms had been noticed during life. Much therefore depends on the rapidity as well as the seat of development.

The primary lesions in the brain are of the nature of miliary tubercles in the pia mater which becomes congested, rough, granular, and throws out a free serous secretion. Thus hydrocephalus is a usual concomitant of the affection.

The disease is characterized by its slow advance in keeping with gradual increase of the tubercle and is thus distinguishable from the more acute congestions and inflammations. The earlier stages are usually marked by nervous irritability, hyperæsthesia, intolerance of light, closed eyelids, congested conjunctiva, grinding of the teeth and even spasms partial or general. The second stage shows somnolence, deepening into stupor or coma, or there may be going in a circle or other irregular movement. Squinting usually convergent, dilated pupils and congestion of the optic disc frequently occur. The sleep, stupor, paralysis or coma may set in early and is usually largely due to the amount of exudation and the rapidity of its effusion.

TUMORS OF THE BRAIN. NEOPLASMS.

Existence inferential with similar external tumors. Cholesterine tumors on plexus of lateral, third or fourth ventricle: pea to egg: in old; concentric layers with abundant exudate. Symptoms: slight, or excitability, dullness, vertiginous paroxysms with sudden congestions, as in encephalitis, sopor, stupor, paresis, coma. Melanoma: mainly meningeal; pea to walnut; with skin melanomata in gray or white horses. Cases. Pigmented sarcomata. Diagnosis, inferential. Psammoma: advanced cholesteatoma, melanoma, fibroma, etc.: osteid tumors. Nervous irritation, delirium, spasms, nervous disorder, and paroxysms. Myxoma: contains mucin: cells (in homogeneous matrix) round, spindle-shaped or stellate. Changes to fat (cholesterin). Œdematous connective tissue, neoplasm. Myxolipoma. Myxo-cystoid. Symptoms.

Tumors in the brain are not marked by distinct pathognomonic symptoms, so that their presence is to be inferred as a probability rather than pronounced upon as a certainty.

The most common forms in the horse are cholesterine (cholesteatoma), melanotic (melanoma), sandy, gritty (psammoma), and fibrous (fibroma).

CHOLESTEATOMA.

These are tumors formed largely of the peculiar fat which is found in bile and brain matter, and that crystallizes in flat oblong scales with a notch at one corner. The tumors are usually connected with the choroid plexus and developed beneath the pia mater, and may be of any size from a pea to a hen’s egg, or in exceptional cases a sheep’s kidney. As a basis there is a stroma of connective tissue permeated by blood vessels from the plexus. Groups of spherical or polygonal cells fill the interstices while fusiform cells are found in the stroma. There is a variable amount of phosphate or carbonate of lime which in oldstanding cases may give a cretaceous character to the mass. These constitute sandy tumors (psammomata).

Cholesteatomata are especially common in old horses and are manifestly connected with congestion of the choroid plexus and exudation. In a recent case or in a case which has shown a recent cerebral hyperæmia, we may find a central mass of yellowish cholesterine, and surrounding this an abundant yellow gelatinoid exudation. This latter is rich in cholesterine which fails to dissolve along with the rest of the exudate on the occurrence of resolution, and is therefore laid up as the solid fatty material. For the same reason the fatty element is usually laid on in layers, one corresponding to each access of local hyperæmia and exudation. The great tendency to calcareous degeneration has been attributed to the abundance of phosphate of lime in the cerebral exudate.

The symptoms of these tumors are exceedingly uncertain. Many such tumors of considerable size have been found after death in animals in which no disease of the brain had been suspected during life. In these it is to be inferred that the accretions were slow, gradual, and without any serious congestion. In other cases the tumor is attended by paroxysms of vertigo, or indications of hyperæmia or meningitis, which will last for several days and gradually subside. It is reasonable to suppose that the tumors are largely the result of such recurrent attacks of encephalitis, and are no less the cause of their recurrence. The intervals of temporary recovery correspond to the subsidence of hyperæmia and the reabsorption of the liquid portion of the exudate. The manifestations during an access correspond directly to those met with in encephalitis. As in that affection there is usually an initial period of excitement and functional nervous disorder tending to more or less somnolence, stupor, paralysis or coma, with long intermissions of apparently good health. In other cases the stupor or paretic symptoms may persist up to the fatal issue.

MELANOMA OF THE ENCEPHALON.

Black pigment tumors have been found in connection with the brain and especially the meninges, varying in size from a pea to a walnut, and as a rule, secondary to similar formations elsewhere. They are most common in gray horses which have turned white, and may give rise to gradually advancing nervous disorder. Bouley and Goubaux record a case of this kind attended with general paralysis. W. Williams reports the case of an aged gray stallion with melanomata on the meninges and in the brain substance which were associated with stringhalt of old standing. Mollereau in a vertiginous horse found a pigmented sarcoma in the right hemisphere between the gray and white matter, and like an olive in size and shape. There were melanomata around the anus. (Annales de Medecine Veterinaire, 1889). So far as such have been examined they follow the usual rule in melanomata in having a sarcomatous structure.

While it is impossible to make a certain diagnosis without opening the cranium, the condition may be suspected, in gray horses, when melanotic tumors are abundant in the usual external situations (anus, vulva, tail, mammæ, sheath, lips, eyelids, etc.), and when brain symptoms set in and progress slowly in such a way as to suggest the gradual growth of a tumor.