check DSA keys

hi!

i have a scenario where the dsa key's might be tampered in the remote host.
My shell script is doing something like this

/bin/ssh -v -i /home/erp/.ssh/dsa ref@host ls /home/test/auto.log

it is working fine .but the problem is that it returns an exit code of 1 both for the absence of the file and if the dsa keys is tampered.

i am doing an scp similar way. it also seems to have a similar issue.im using ksh.

please suggest