Listeria can be life threatening. She can be started on a course of antibiotics as a preventative measure.
Otherwise make sure the boarding facility works with an emergency vet that she could be taken to if she did get sick, I would contact said vet to approve treatment just in case, and then make sure the boarding kennel keeps a close eye on her. ANY signs of illness, lethargy, vomiting, diarrhea, circling, drooping face, etc... she should be taken to a vet immediately and started on treatment.
~Emergency Vet Tech
Berlin vom Spartanville 1/13/13
5/25/07 - 2/9/15
2008 - 7/23/12
"Make sure my shepherd dog remains a working dog, for I have struggled all my life long for that aim." - Max Von Stephanitz