I have a female Caucasian and a female Boerboel. They are both lovely even though my favorite is the Caucasian simply because she is very neat. They both came on heat at the same time and I crossed them around day 8 of their heat period. They both exhibited symptoms of pregnancy at the same time. I was really happy expecting puppies soon. After two months from the last mating, I just noticed nothing was happening. I called my vet to check them, he said they were not pregnant. I was heart broken. I decided to do swap test for all my dogs. Lo and behold, they all had infections which is what most likely affected the pregnancy. So what happened to all the antibiotics and multivitamins I have been giving them? I was just asking myself.
I have started treatment for them before the next heat. So, the big question is - How often do you check and treat your dogs?

Sorry for your experience.
One way to ensure your dogs are at optimum health is to use their vaccination schedule times to also do check ups. For producing dams you can plan those checks around their heat cycles. For GSDs especially long hair which is our main focus they will normally come into season after they have shed their coat and put on a new coat. You can also use the cycle that has been established for older dams by getting them checked out before they come on heat.
You can also have a vet come around monthly to just check on your dogs as some infections are asymptomatic she may not show up with physical signs but on investigation.

dcasca:
I have a female Caucasian and a female Boerboel. They are both lovely even though my favorite is the Caucasian simply because she is very neat. They both came on heat at the same time and I crossed them around day 8 of their heat period. They both exhibited symptoms of pregnancy at the same time. I was really happy expecting puppies soon. After two months from the last mating, I just noticed nothing was happening. I called my vet to check them, he said they were not pregnant. I was heart broken. I decided to do swap test for all my dogs. Lo and behold, they all had infections which is what most likely affected the pregnancy. So what happened to all the antibiotics and multivitamins I have been giving them? I was just asking myself.
I have started treatment for them before the next heat. So, the big question is - How often do you check and treat your dogs?

that the mistake most people make, there are several antibiotics for different kind of infections, so when u use the wrong antibiotic without swab test u might not get disire result while the infection is there casing u nd ur dog problem. the swab the test tell u the growth stage of the infection and the right antibiotics that would kill it after several testing in the lab.
so probably u have been using the wrong antibiotics for ur dams all this while.

the swab test is ideal like a month or 2months to ur dam heat cycle once u have study her heat cycle then u commence treatment prior to her heat: then mk sure the stud u ar using is also infection free.