Chapter VI 



SYSTEMIC DISEASES AND DERANGEMENTS 

 INTERFERING WITH REPRODUCTION 



Reproduction is the culminating function of animal life. 

 The fundamental demand of the individual is the mainte- 

 nance of life, and it is only when this has been reasonably 

 assured that any additional power may be directed to the 

 reproduction of the species. During the most active stages 

 of growth, most animals do not breed. When old age comes, 

 and the maintenance of nutrition is difficult, reproduction 

 becomes uncertain or ceases. Throughout adult life, any 

 element which interferes seriously with nutrition promptly 

 imperils reproduction. 



During the course of acute infectious diseases, with rare 

 exceptions, male animals do not elaborate spermatozoa and 

 females do not ovulate. At the same time, sexual desire 

 ceases. In the pregnant female such diseases imperil the 

 life of the fetus. So it is frequently said of cows that foot- 

 and-mouth disease, pleuro-pneumonia, and similar fevers 

 tend to cause abortion. This does not imply that the in- 

 fectious fever directly causes the abortion, but rather that 

 the infection present within the pregnant uterus, capable 

 under favorable conditions of causing the death and expul- 

 sion of the fetus, is rendered virulent by the general de- 

 pression of the system due to infectious fever. Such chronic, 

 debilitating affections as the bone diseases — osteoporosis, 

 rickets, spavin, ringbone, and others — commonly lead to 

 sterility through their devigorating influence. 



A. Overwork 

 Animals subjected to severe work are strongly inclined 

 to be sterile for the tima In stallions which are being 

 trained for the turf, there is usually temporary sterility, 

 without any evidence of disease or degeneration of the 

 glands. The resources of the animal are wholly consumed 

 in the physical work which is demanded, and there remains 

 no reserve force to provide reproductive energy during this 

 period. 



