Hope this finds you well, just read your message on my wall ! We did a seminar 2 years ago on vector-borne diseases like Lyme disease. Indeed transplacental transmission of the disease has been described but my understanding is that consequences are only seen when the bitch declares the clinical form of the disease during pregnancy. Here are the slides of the lecture we did http://www.slideshare.net/EmmanuelFontaine2/vector-borne-diseases-what-breeders-should-know they contain scientific publication on the topic that should definitely help here. Let me know if you have more questions !