[Dailydrool] food question

[Cheryl Stafford]

The dogs have been totally grain free since Saturday.  At what point is 
it safe to consider all the grain has exited the body?  I am trying to 
see if Otter is allergic to wheat or if it is seasonal/grasses.  Once I 
am sure everything is out I want to try and reintroduce a treat with 
wheat in it to see if his skin reacts.  So far, it has only been a 
couple of days, he still has red skin.
Any info. will be appreciated,

Cheryl