Get written permission to take the pet to the vet and release yourself of responsibility for payment.  Click the link for more information and a sample.

Your clients will fill out and sign the veterinarian release form which will give you permission to take their pet(s) to the vet if something should happen.  It will state where their vet is located and allow you to use a different vet should that vet not be available.  It also releases you from payment responsibility.

The veterinarian release is very detailed to relinquish you from liability.

This form is created in Microsoft Word and is completely editable.