This forum doesn't deal with STDs in animals! Maybe you need a veterinary medicine forum, but I will have no further comments on this one.
1) BERTARELLI, Ernesto
Ueber die Transmission der Syphilis auf das Kaninchen, in Central blatt. für Bakteriologie, LI (1906), pp. 320-326.
2) http://discovermagazine.com/2008/sep/09-how-often-do-animals-get-stds
Well this is a new one. I doubt the forum has ever had a question like this!
The syphilis bacteria (Treponema pallidum) is specific to humans. I doubt it can infect dogs. Don't worry about it.