Hemorrhoids

Hemorrhoids (also called piles) result from varicose dilation of the hemorrhoidal plexus of veins at the ano-rectal junction and also of the anal and peri-anal venous plexuses. They are presumed to be caused by prolonged pelvic congestion, resulting from repeated pregnancies or by straining at stool. IF the external hemorrhoids become thrombosed, they cause pain and itching which can also bleed. Hemorrhoids are frequently reported in humans but there was only one report in a chimpanzee at the Yerkes Primate center.  It is possible that the increased hydrostatic venous pressure resulting form the upright posture of humans predisposes us to this pathology.