Voltage "Overload" Syntax
I would assume the worst case is +-12.5V absolute is damaging. 

Since your input can only measure up to +-10V anyway, you should use back to back zeners to allow your input to deviate within that while protecting your input to under the 12.5V value.

The input itself may however include that kind of protection anyway. In which case, you should limit how much current the signal can over-drive it with. Read the documentation for the cards carefully, and if need be, contact the manufacturer.