Certain horses apply the protractile end of the nose against the lower lip and spend hours in succession in moving it rhythmically forward and backward, or from side to side.
Weaving. Movement like a Bear in a Cage.
This consists in a lateral rocking of the head and neck, and sometimes of the chest as well with alternate stepping on the right and left fore feet. It has been supposed to represent the movement of the weaver in working a hand loom, or still better the movement of a caged wild beast in constant turning toward the right and left of the front of his cage. The motions are as regular as a pendulum, and involve the contraction of corresponding groups of muscles on the two sides of the body.
They seem, in some cases, to begin in impatience in waiting for the feed, while other horses in the same row are being attended to first, but when the habit has been formed it may be continued most of the time in the intervals between feeds as well. Nervous horses and those that are hearty feeders are the most subject to this infirmity.
Disorderly Movements of the Limbs.
Some horses have a habit of continuously raising one hind limb, others raise the right and left alternately, rocking the hind quarters from side to side, others stand with the heel of one hind foot resting on the front of the coronet of the other, while still others paw continuously with the fore feet while standing in the stall.
Treatment. These various conditions even when begun as an expression of impatience, soon become fixed habits, that prove in the end virtually uncontrollable by an animal, which has no strong will and no consciousness of anything to be gained by resisting the impulse. They become virtual psychoses. In cases in which the habit can be traced to a peripheral irritation, the cutting off of this by complete section of the afferent nerves leading to the irritable nerve centre will sometimes succeed in effecting a cure. In other cases in which the source of the disorder is probably largely central in the cerebral ganglia, nerve tonics, and sedatives, and generally corroborative treatment are the most obvious means of palliation. Such measures are, however, rarely successful. Nourishing food and invigorating outdoor exercise are useful auxiliaries.
VERTIGO. MEGRIMS. BLIND STAGGERS.
Disadvantage of lack of subjective symptoms. Causes, varied, narcotics, overloaded stomach, cerebral anæmia or hyperæmia, degenerations, parasites, tumors, jugular obstruction, valvular heart disease, disease of internal ear, plethora. Susceptible animals, horse, ox, dog, pig, sheep. Direct causes: tight collar, or throat latch, flexion of head, heart disease, pulmonary disease, embolisms, gastric distension, hepatic disorder, optic vertigo, aural vertigo, injections into ear, rhigolene, chloral, acariasis, seasickness, railroad sickness, cholesteatoma, cœnurus, concussion, degeneration, softening, œstrus, linguatula, narcotics, essential oils: essential vertigo. Symptoms: in irritable animal, highly fed, and without exercise, crowds pole, his mate or a wall, shakes or jerks head, staggers, trembles, rears, plunges, falls, struggles, sweats, rolls eyes, recovers. In gastric or hepatic cases, dullness, pendent head, swaying gait, dull eye, dilated pupil, pendent lids and lips, leans on adjacent object, staggers, falls. In optic cases are obvious cause in transition to light, etc., and palliation by covering the eyes. In aural cases, rolling eyes, constrained position of ear, deafness, pharyngeal or Eustachian trouble, wax or acari in ear, tender or itchy ear. Plethoric cases in spring, in overfed, etc. Brain lesions may have fever and disordered innervation, but retained consciousness, and no marked spasm. Duration. Sheep: parasitic vertigo. Turning. Rotation. Treatment: according to cause: restrict ration, give exercise, purgative, adjust collar, breast strap, check, avoid sudden transitions of light, overdraw check, blinds, treat nasal, pharyngeal, ocular or aural trouble; during attack, stop in shade, cold to head, deplete, bleed, purge, shady pasture or light work, bromides, blisters, etc.
In dealing with vertigo or giddiness in animals we are confronted by the impossibility of realizing the subjective feelings of the animal, as we can so easily ascertain by interrogation in the case of man, and thus our conclusions are largely inferences drawn from certain unsteady, reckless or uncontrollable movements, or from an apparent inability to maintain a stable equilibrium. The condition is rather a symptom of a variety of morbid conditions, functional and structural, than a disease sui generis. It may be due to alcoholic or other narcotic intoxication, to overloaded or otherwise deranged stomach, to shock, to a stroke of lightning, to disturbances—anæmic or hyperæmic—in the circulation in the encephalon, to degenerations, parasites or tumors in the brain, to compression of the jugular veins, to valvular or other disease of the heart, to disease of the internal ear, to the plethora of spring or early summer, to the qualms of sea sickness, to insolation.