194 The Diseases of Animals 
During the period of heat, the milk secretion, if 
the animal is giving milk, is usually lessened. Sexual 
excitement is exhibited by the female jumping upon 
other animals, and appearing more or less nervous 
and excited. The vulva is swollen, and mucous dis- 
charges from the vagina seem to have an odor that is 
attractive to males and causes sexual excitement in them. 
STERILITY 
Sterility, or impotence, is inability of an animal to 
reproduce its kind. In common language, such an 
animal is “a non-breeder.” In the male, impotence is 
usually due to an absence of the spermatozoa, or male 
eells. This condition may be associated with advancing 
age or excessive service; in some cases it is a con- 
genital defect,—that is, a defeet peculiar to the indi- 
vidual. In those males in which the impotence is due 
to debility, rest and nourishing food combined with 
good tonic medicines, especially those which contain 
nux vomica, comprise the best treatment. There is no 
specific medicine for the treatment for this condition, 
and all hope of recovery is to be based on strengthen- 
ing and toning up the whole system. In other cases, 
impotence in the male may result from some malfor- 
mation or disease of the genital organs. A thorough 
and careful examination should be made in order to 
discover the cause. When there is doubt as to the 
cause of impotence, the male may be allowed sexual 
mtercourse and some of the spermatic fluid collected 
and examined under a compound microseope. If 
