Nervous control of bodily functions: affected through disease of nerve
centres or nerve trunks, sensory, motor, vaso-motor, etc. Modes of
impaired nervous function: objective; subjective. Nervous
characteristics in different breeds, individuals, sexes, castrated
animals. Nervous disorder from microbian toxins, narcotics, nervous
stimulants, etc.
All bodily functions are more or less directly controlled by the nervous
system, hence nervous troubles are interwoven with the diseases of all
other organs. Disorder of the nerve centres or nerve trunks affects the
most distant parts over which these preside, or to and from which they
convey nervous impulse. In different cases we see this operating through
the sensory or motor functions, through lack of coördination or of
balance, through modification of the circulation, respiration,
secretion, absorption, nutrition, metabolism, special sensation,
intellection, emotion, etc. These manifestations are less evident or
less diagnostic in the lower animal, because we cannot fully avail of
the subjective symptoms. While the human patient can tell us his
feelings and experience in their regular order and succession, we can
only infer most of these in the animal, through dependent objective
symptoms. In many cases we cannot even infer for lack of these dependent
symptoms.
The practitioner must carefully watch for and accurately observe all
objective symptoms, and seek to rightly interpret them. Among other
things he must note the nervous conformation, organization and
susceptibility; the hereditary nervous characteristics as seen in
breeds, temperament, habit, aptitude to learn, docility, instinct,
intelligence, emotions and affections, and judge the case in the light
of these. Similarly he must take into account the hereditary, racial and
individual irritability, obstinacy, restiveness, vice, alertness,
sluggishness, stupidity, moroseness, and diagnose accordingly.
Congestion, anæmia, coma, paresis, paralysis, may result from the
nervous disorder and offer valuable concurrent testimony to the same.
Allowance must always be made for the _use_ to which the animal has been
put, thus _sexuality_ tells strongly in the horse, bull, boar, or ram
which has been used for breeding and has become relatively indocile and
even dangerous; _food_ tells in the horse that “shows his corn”, and in
the dog fed on flesh; the comparatively untrained English race horse is
far less docile than the one inured to saddle or harness and the horse
fresh from the range, though previously trained, is far less tractable
than the one in steady work. The _sexual products_ are especially liable
to modify the temper, hence the docility of the gelding, and castrated
mare, and the undisturbed life and steady growth and fattening of
castrated animals from cattle to capons.
_The products of certain diseases_ and many _drugs_ derange the
innervation and intellection. Of this we have examples in the hebetude
of the victims of milk sickness and dourine, in the wild delirium of
rabies, in the varied nervous disorders that attend on the use of
narcotics, essential oils, alcohol, chloral, sulphonal, trional,
strychnia, lead, phosphorus, arsenic, etc.