Changes

* Venous drainage is through '''sattelite veins''', except in ruminants.

* Venous drainage is through '''sattelite veins''', except in ruminants.

* During lactation in ruminants, the external inguinal vein cannot drain the extensive amount of blood present.  Thus, the '''cranial and caudal superficial epigastric veins''' anastamose to form the '''milk vein'''. Also, right and left mammary veins anasamose to form a ring around the base of the udder.  Valves become non-functional to accommodate the increased venous return and allow blood to flow in either direction.  This is important, for example if a cow were to lie down, the weight on one side would collapse the thin-walled veins on that side so anastamoses ensure continued venous return.

* During lactation in ruminants, the external inguinal vein cannot drain the extensive amount of blood present.  Thus, the '''cranial and caudal superficial epigastric veins''' anastamose to form the '''milk vein'''. Also, right and left mammary veins anasamose to form a ring around the base of the udder.  Valves become non-functional to accommodate the increased venous return and allow blood to flow in either direction.  This is important, for example if a cow were to lie down, the weight on one side would collapse the thin-walled veins on that side so anastamoses ensure continued venous return.