|thanks wikimedia commons (PD: old)|
Apparently there was a very tiny Russian Lapdog breed in the 1800's for sure; you can see a taxidermied example on this page. I think this creature is too leggy to be that, and that breed is no longer to be found today anyway. Here's a recently developed breed that looks somewhat like, though: the RTB, Russkaya tsvetnaya bolonka. Have a look at these puppies from an RTB breeder and see if you think they look like our Imperial friend.