Yes, the integrity of the wallet can be verified.

As a security feature, if you want to check the integrity of a QT wallet.dat file without initiating a transaction all steps can help you.
>>Do not sync the wallet and unlock it.
>>Check that the balances correspond to the explorer.
>>Run bitcoin-cli verifychain in order to examine the integrity of the blockchain.
>>Use bitcoin-cli getbalance to view available balance.

If these verifications are satisfactorily passed, probably the wallet.dat file is intact and the balances are ready to be utilized.

Note: Check whether the height of the blockchain of the given wallet is equal to that of the current height of the chain so that one can be sure the wallet is up-to-date.