The symptoms of compression and atrophy of the brain differ greatly, a fact which is easily understood, inasmuch as the seat of the change may vary, and therefore it is possible only to trace the chief manifestations, which suggest the existence of a cerebral tumour.
The general changes are indicated by signs precisely similar to those so common in horses with dropsy of the ventricles (general depression, inability to back, long intervals between the prehension of successive mouthfuls of food, sudden cessation of mastication, etc.), by an impulsive or automatic gait, and by the assumption of strange attitudes (kneeling down in front, etc.). When at rest the animals appear to be in a state of continual torpor.
Special symptoms sometimes occur, which enable the seat of the injury to be localised in more or less exact fashion. These symptoms affect the vision (amblyopia, amaurosis, strabismus, nystagmus), general sensibility (hyperæsthesia, anæsthesia, etc.), and the power of movement (total, partial or crossed hemiplegia, want of co-ordination of movements, etc.).
Trifling stimuli almost always lead to marked and even epileptiform attacks.
The diagnosis of cerebral tumours is very difficult, particularly when attempts are made to indicate their exact seat, but that of other cerebral lesions is somewhat easier.
The prognosis is very grave, and in the case of domestic animals nothing can be done. In the ox intra-cranial operations are difficult, by reason of the presence of the sinuses which obstruct the approach to the brain cavity; economically surgical treatment is seldom advisable.
INSOLATION.
Insolation is an exceptional accident in animals of the bovine, ovine, or porcine species. If at liberty these animals move about, and always seek shelter when the sun is fierce. If, on the contrary, they are harnessed and kept standing for long, exposed to the full midday sun during June, July or August, they may suffer from insolation.
During the International Cattle Show attached to the Exhibition of 1900 in Paris, a considerable number of cases of insolation occurred in animals of one class, exposed to the full midday sun, in an ill-ventilated spot. The other classes only received sunlight from the sides, and in them not a single case occurred.
Death may follow in a few hours; it is difficult to say precisely how it is brought about, but it is always accompanied by congestion of the cerebro-spinal centres and general blood stasis.