There are MANY things that can cause pregnancy loss in the dog, Brucellosis is one of them but even with the recent outbreak it is still not terribly common, unless you live in the South US and some other parts of the world. Stress can also be a huge factor, and dipping is most definitely a stressful event. I would never recommend dipping for a pregnant dog but if the poor thing is covered with fleas and/or ticks you sure want to do something. Brucellosis- http://www.veterinarypartner.com/Content.plx?P=A&C=15&A=2428&S=0 Robin