Before going ahead to take this example Italian has a definite word for rat and topo doesn't mean rat.
topo = mouse ratto/topo di fogna/in coll. language "topone" = rat
topo d'acqua = this is a kind of rat and not of mouse
topo becomes rat only in combination with other words, but never alone.
To confirm this I just asked a colleague of mine (as even translators can be wrong)
There is a problem of this kind but normally this happens when for example there is no translation for a subspecies into the other language.
I don't have an exact example now, but I am sure, we will need it.
This is also a reason for me to work in lists as when asking colleagues to check the cross translations normally these things come out easily.
Going back to work. - For now I'll read the messages but answer only as soon as I have finished my job, sorry.
Ciao, Sabine