Pups are 23 days old today, the age at which they should be safe from Canine Herpes. Many adult dogs and most show dogs have been exposed to the disease and developed an immunity to it. They show no symptoms and it's a non-issue for them. For baby pups however, it is usually fatal. Puppies don't have body temperatures high enough to kills the virus, so if their mother has been exposed but doesn't have sufficient immunity, she can pass it on to them. She will be just fine, but the pups will sicken and die, often between 2 and 3 weeks of age.
Some years ago we had a gorgeous litter out of a bitch I leased from a friend. Pups all heard, had complete trim, and beautiful markings. On day 18 the first two pups showed symptoms and were dead in a few hours. The littermates all died within the next few days. If you've heard of "fading puppies", this would be one of the causes. It was a horrible experience, one I'll never get over, right up there with losing my first Dal during a botched caesarian. The dam of the litter went on to have two more litters, both healthy, but not bred by me. I just couldn't do it. Intellectually I knew that the chances of a repeat were slim to none - but I just couldn't take that chance.
Losing a litter to herpes is uncommon, but is always a possibility. Losing a second litter is very unlikely - so they say, but there is always that fear lurking in the back of my mind. There's no vaccination for Herpes, so no way to actually prevent it. I keep my whelping box really warm (probably doesn't help but makes ME feel better) and wait for the day the pups are 23 days old, a magical number to me, an age where they should be able to fight off the virus if they are exposed to it.
We made it!