CHAPTER V 
PREDISPOSING CAUSES 
As previously emphasised, nothing whatever can cause 
distemper except exposure to its specific contagium, but 
many circumstances can arise which tend to render the 
animal more susceptible to its reception. It is univer- 
sally accepted that any condition which tends to weaken 
or debilitate the animal, impairs the natural defence of 
the body, and reduces its power of resistance to the 
invasion of pathogenic organisms, which. are perpetually 
seeking a suitable soil upon which to grow. The human 
or animal body only becomes a suitable soil when its 
resistance has been broken down, and the invader is 
victorious. 
Influence of Breed and Age.—Breed and age have a 
marked influence on predisposition, and, as pointed out 
in the chapter on “ Susceptibility,” age particularly plays 
an important part, young dogs being much more prone 
to contract the malady than old. Similarly, highly-bred 
and delicate pampered lapdogs offer very little re- 
sistance to the infection, and when attacked in puppy- 
hood large numbers succumb to it. The mongrel has 
ever proved itself to be the stouter animal in disease, 
and the more remote its breed is from the pure, the 
greater seems its power of resistance and recovery. 
Influence of In-breeding.—\n-breeding exerts a weaken- 
ing influence on the constitution, and is too frequently 
responsible for rickets, deformities, alopecia, sterility, 
and mental incompetence ; thus such an animal, robbed 
of its vital faculties, becomes an easy prey to disease, 
which probably terminates fatally. 
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