The hair may be freely shed during convalescence from debilitating diseases, a condition that must not be confounded with the yearly shedding of the winter coat and the moulting of birds, which is a perfectly normal process. Yet even the spring shedding and the growth of the new coat makes a great drain on the system, and must always be taken into account as a probable cause of derangement of health.
The lesions of the skin in the different cutaneous affections must be remanded to the special chapter on skin diseases. The following however may be named as having a general bearing.
Emphysema may be due to a local wound, (elbow, trachea, rib); it may indicate black quarter, or it may occur subcutaneously in cattle without marked impairment of health.
Anasarca, from diseased blood, heart, liver or kidneys is denoted by swellings, often painless, or a general infiltration which pits on pressure. It often shows primarily in the lower parts of the hind limbs. Warty looking elevations must be carefully discriminated, having in mind primarily papilloma, tubercle (grapes), actinomycosis, condyloma (in dogs), cancer, melanosis. The secretions of the skin (sweat, sebum) may be suppressed, or in excess, producing at times a special odor, as in thrush and canker of the horse, cowpox and sheeppox, and rheumatism. Before death the cadaveric odor may be marked, and attracts crowds of flies to the victim.
Facies. The countenance may be expressive. Between the bright, full, clear, prominent eye of health, and the dull, sunken, lifeless, semi-closed eye of serious disease the contrast is extreme. The drooping lids (ptosis) may be paralytic and even unilateral, in which case drooping ear, and flaccid lips and alæ nasi complete the picture. With paralyzed lips there is usually drivelling of saliva, and dropping of half chewed morsels in the manger and stall. The eye may show dropsical lids in kidney or liver disease and in anæmic conditions like distomatosis in sheep. It may show the upper lid bent at an angle in recurrent ophthalmia of solipedes. The mucosa may be red in ophthalmia, yellow in jaundice, dusky brown in Southern cattle fever, anthrax, cerebral meningitis, and other fevers attended with destruction of red globules and liberation of their hæmatin. The pupils may be all but closed in internal ophthalmias, or widely dilated and irresponsive to light in amaurosis. The iris may lack its normal lustre or may be distorted or torn in various ways from adhesions. Opacities of the cornea, lens, or vitreous may be recognized.
The facial muscles may be flaccid and devoid of expression in palsy, and prostrating diseases; they may be firm, giving the bright, intelligent look of health; or they may be painfully drawn in the agonized expression of spasmodic colic or enteritis.
Nasal Mucosa. The pituita is bright red in sthenic fevers, simple acute coryza, strangles, laryngitis and inflammation of the larger bronchia. It assumes a violet hue in capillary bronchitis, pulmonary congestion, glanders, and petechial fever. Petechiæ appear in the last named affection, and in a number of bacteridian diseases, such as anthrax, swine plague, hog cholera, the red fever of swine etc.; a yellow tinge in shown in jaundice. Millet-like or pea-like nodules, or elevated patches, and ulcers show in glanders and may be felt by the fingers. In cattle hard millet-like nodules appear in a chronic coryza with hypertrophy of the mucosa. The orifice of the lachrymo-nasal duct, seen in the horse on the floor of the chamber at the friction of the mucosa with the skin of the false nostril and in ass and mule on the outer ala near the upper commissure, is sometimes plugged with inspissated mucus. Among other lesions of the nasal chamber may be named polypi—soft and calcareous,—thickening and obstruction in purpura hemorrhagica, osteoporosis and hypertrophy of bone, and parasites—pentastoma denticulata (in the horse and dog), and the larva of the œstrus (in sheep and buffalo). Disease of the upper molars and abscess of the fronto-maxillary sinus may be manifested by swelling beneath and on the inner side of the eye, fœtid discharge from the nose, and obstruction of the air current. Dullness on percussion will show the filling of the sinuses. These conditions must be carefully differentiated from actinomycosis, sarcoma and other morbid growths in the same situation.
Costiveness with fœtor and lack of the normal color in the stools may suggest liver torpor or inflammation, while fatty stools may suggest pancreatic disease. The uneasy movements of colic, should lead to a careful investigation of the chylo-poietic organs (see digestive organs). Weakness of the hind parts, tenderness of the loins, and altered condition of the urinary discharge should demand a close enquiry into the state of the kidneys and bladder. Satyriasis or nymphomania would suggest disease of the generative organs or the nerve centres that preside over them. The same is true of impotence, sterility and abortion.
In eruptions on the skin (erythema, eczema, pustule, squama) a cause may be found in the local action of heat, friction, or other direct irritant, but in the absence of any such manifest cause, an enquiry should be made into the functions of sanguification, digestion, urination and the action of the liver. It may further suggest parasitism (ring worm, phthiriasis, fleas, acariasis, verminous disease, etc.)
Symptoms of nervous disorder are too numerous to be here traced to local lesions. Motor paralysis of one limb may, however, suggest injury to its motor nerves, to the same side of the spinal cord, or of the opposite half of the cerebrum. Paraplegia almost always indicates injury to the cord. Sensory paralysis of one side may depend on disease of the opposite corpus striatum. The animal moves in a circle when a tumor (coenurus in sheep) exists in the roof of the lateral ventricle presumably pressing on the ganglia on its floor. An animal rolls on its axis when there is a lesion of the median cerebral peduncles, of the supero-external portion of these peduncles, of the posterior part of the encephalon, or of different parts of the hemisphere. Amaurosis suggests disease of the corpora quadrigeminia. Loss of coördination of muscular movement usually implies some lesion of the cerebellum. Vertigo may imply disease of the encephalon (congestion, anæmia, inflammation, dropsy, hæmorrhage, tumor, abscess); it may be disease of the internal ear; it may be digestive disorder connected often with cryptogamic poisoning; it may be heart disease with obstruction of the jugular veins; it may be parasites in the nasal sinuses; or it may be disease of the eye. Coma occurs in most congestions and pressures on the encephalon, and like vertigo in poisoning by alcohol, solanine, monoxide of carbon, etc. In acting on any ganglionic centre the agent may, according to its degree, operate positively or negatively, producing spasms, or paralysis as the case may be. As in the case of other visceral affections the specific diseases must be referred to for particular symptoms.