I haven't messed with editing any of the sound files myself, but after a bit of digging I found that everquest stores many of the sounds files in .pfs files in the Everquest directory you need a program called
S3DSpy to open them.
I think I found the sound that you're looking for in snd5.pfs named wolf_idl.wav. It's the sound the shaman pet and druid wolf form makes when idle.