Classically, Summoning effects open a gate to an outer plane or other distant location, locate an example of a specified type of creature there, drag it through the gateway, infallibly bind it to obedience, and then send it away again when the spell is complete, despite any intervening dimensional barriers, no matter how powerful.
This seems like a bit much to ask of a first level spell.
In general, we recommend that Summoning spells produce constructs temporarily ensouled by summoned spirits. Summoned entities thus cannot truly die, are bound to limited obedience by constraints built into the body, and cannot bring items or carry them away. They cannot teleport or plane shift unless they are capable of teleporting others along with themselves since the constructed body is not truly a part of them. Similarly, once the body vanishes the spirit departs automatically unless blocked by magic which can affect pure spirits. Finally, since they do not have a true body to anchor their end of the link, they cannot summon other creatures; they would simply be pulled back through themselves.
Any severed parts of a summoned creature will thus vanish as well, neatly eliminating ichor stains and most traces, as well as eliminating any infections, curse of lycanthropy, or similar conditions they would otherwise leave behind.