Parasites are less common in the spleen than might be expected yet the
encysted parasites of the liver and pancreas, are also to be found in
the spleen. Thus _echinococcus_ is found in the spleen of cattle, and
headless hydatids in that of the horse; _cysticercus tenuicollis_ in the
spleen of sheep; _cysticercus cellulosa_ in that of pigs; _distomata_,
and _pentastoma denticulata_ in the spleen of cattle; _coccidia_ in the
spleen of rabbits; and _actinomyces_ in that of horses and cattle.
In addition to these the spleen is a general _rendezvous_ for the
different pathogenic organisms that can survive in the blood stream,
such as the bacilli of tubercle, glanders, septicæmia, anthrax, black
quarter, swine plague and hog cholera, and for the cocci of suppuration,
strangles, contagious pneumonia, etc. (See Parasites and Contagious
Diseases).