Oh yes, they can including cats as well...
My cats understand my sign languages. My cats know we are deaf. They use their claws to pat my arm to tell me something what they want... and sit on front of the door to tell me that they want go out... I said
Their expression of grumpy and went off... I know their own expression langauges
It's no problem when you expose the pets/animal as babies to know who you are.
Example: monkey, apes, chimps, etc.