giving medicine to a pregnant dog

Hello,
Two weeks ago we tried to breed our Cocker Spaniels.  Although there was no lock, last night we were able to hear two fetal heart beats with a doppler.  My question is this...we had been holding off on giving shots and heartworm meds until we knew, and now that there is a chance that she is pregnant, should we wait until after the pup(s) are weaned?
Thanks very much.

[Aleda M Cheng, D.V.M., C.V.A]

Please go to:  www.peteducation.com/article.cfm?cls=0&cat=1303&articleid=856

For the article of "Drugs to Avoid in Pregnant or Nursing Dogs"
by Dr. Holly Nash DVM, MS
The article is from the Veterinary Services dept. Drs. Foster and Smith Inc

The article provides an extensive list of medications, topicals (such as Frontline) and more.  There is also a search component if you don't see a specific medication that you use.