Sterility.

Sterility.

Sterility may be in the male or in the female. If due to the stallion, then all the mares put to him remain barren; if the fault is in the mare, she alone fails to conceive, while other mares served by the same stallion get in foal.

In the stallion sterility may be due to the following causes: (a) Imperfect development of the testicles, as in cases in which they are retained within the abdomen; (b) inflammation of the testicles, resulting in induration; (c) fatty degeneration of the testicles, in stallions liberally fed on starchy feed and not sufficiently exercised; (d) fatty degeneration of the excretory ducts of the testicles (vasa deferentia); (e) inflammation or ulceration of these ducts; (f) inflammation or ulceration of the mucous membrane covering the penis; (g) injuries to the penis from blows (often causing paralysis); (h) warty growths on the end of the penis; (i) tumors of other kinds (largely pigmentary), affecting the testicles or penis; (j) nervous diseases which abolish the sexual appetite or that control the muscles which are essential to the act of coition; (k) azoturia with resulting weakness or paralysis of the muscles of the loins or the front of the thigh (above the stifle); (l) ossification (anchylosis) of the joints of the back or loins, which render the animal unable to rear or mount; (m) spavins, ringbones, or other painful affections of the hind limbs, the pain of which in mounting causes the animal to suddenly stop short in the act. In the first three of these only (a, b, and c) is there real sterility in the sense of the nondevelopment or imperfect development of the male vivifying element (spermatozoa). In the other examples the secretion may be imperfect in kind and amount, but as copulation is prevented it can not reach and impregnate the ovum.