My 16 month old GSD recently finished her second heat & has begun her second false pregnancy. Vet that treated the first pregnancy told me not to massage or apply any kind of heat (moist or otherwise) to her breasts, which had filled with milk. Also, put her on Clavimox for 2 weeks to prevent a mammatory infection. 2nd Vet (2nd round) told me the exact opposite -- to apply warm moist towels to the area. He also put her on Clavimox, but did so because she had a wound infection -- not to prevent a mammatory infection. Anyone know which is right or wrong? And, if Clavimox is really necessary? Also, what causes this to happen? Being neurotic perhaps? Or could her hormones actually be tricked from being around a lot of other dogs in training classes even though we didn't go the weeks of her season. The whole thing is totally bizarre to me.

Whether you breed her or not, every time a female goes into heat they experience a "pregnancy" afterwards (a large progesterone load). The empty pregnancy can be very hard on the reproductive system and is a leading cause of infertility in females. The other risks are an infection of the uterus itself, which can be very nasty. On the teats, the proper treatment depends on whether or not she has mastitis (an infection of the breast)

My guess (and I am not a vet) is that in the first case, she just had milk and was not infected and the vet did not want her to become infected. The reason he told you not apply any heat or mess with them is because messing with them would stimulate more milk production.
The 2nd vet I am guessing thought she might have an infection and therefore was trying to stimulate them to keep the ducts flowing.
So, if not infected leave them alone, if infected stimulate them to clear/clean the ducts (plus give antibiotics)

I think you have a bigger concern though. I am assuming you are keeping her whole to breed her. If that is the case I certainly would have bred her after the problems you had on the first heat. If you are planning on breeding her you REALLY need to breed her on the next heat. If for some reason you have no desire to breed her then have her fixed. IF you want to breed her but for some reason just can't right now, then you need to have her cycles chemically suppressed. Chemical suppression will run around $75 per month and is a liquid that is given orally, daily. The common name for the drug is CHEQUE® Drops, the generic name is Mibolerone. Your vet should be able to get it for you. If your interested and he can't find it for you, I will give you the name of a pharmacy that can compound it for you.

In any case, my advice (again I'm not a vet) is either fix her, breed her, or chemically suppress her until you are ready to breed her.

Hope that helps

Thomas