I like the idea of giving the dogs historical first names, and if we think the Malfoys went back to the Norman conquest, some French Norman names include:

Beaufort
Durant
Lisle
Mortimer
Lovell/Lovella (means "wolf")
Reynaud/Reinald

Or if Lucius has a literary bent, you could name the dogs Crapaud and Grenouille, the two characters who discuss Quidditch in Malecrit's play, "Hélas, Je me suis Transfiguré Les Pieds" (Alas, I've Transfigured My Feet), as referenced in Quidditch Throughout the Ages.