Your veterinarian will likely advise against giving your nursing dog a booster shot until after her puppies are weaned. In some circumstances, a nursing dog might require a primary vaccination, but a booster shot is the shot she'll receive only if she's had the vaccination in the past. Since puppies usually nurse for eight to 10 weeks before weaning, that's not a long time to wait if your mama dog's booster shots are due.
Vaccinate Before Breeding
If you're planning to breed your dog, make sure she gets her booster shots before the mating. Of course, you don't have that option if the pregnancy wasn't planned. Veterinarians don't recommend vaccinating pregnant dogs, as it's possible that materials in the vaccine could harm the fetuses. Giving nursing dogs a booster shot, if due, is unwise because common side effects -- weakness or fever -- could temporarily put her off nursing her puppies.
Shelter vaccination protocol differs from that of owned dogs. If a nursing mother comes into the shelter with her puppies, she'll probably receive vaccinations, especially if she's a stray or a dog brought in with no veterinary history. However, those are primary vaccinations, not boosters, unless the person relinquishing the dog submits a veterinary record showing the dog is past due for shots. It's not just stressful for a dog to stay at a shelter; the potential for contagious disease in such an environment is high.
Vaccinating Nursing Dogs
The University of California Davis Koret Shelter Medicine Program website states that it "appears safe" to vaccinate nursing dogs with modified live vaccines. However, shelters with strong foster programs -- where the mother and puppies live in a private foster home until weaning -- don't usually need to vaccinate the nursing mother. Nursing mothers who must remain in the shelter for any length of time should receive the combination DHPP shot -- distemper, hepatitis, parvovirus and parainfluenza -- upon admission. Since kennel cough, formally known as bordetella, runs rampant in shelters, the nursing dog should receive this intranasal inoculation. In most cases, a rabies shot can wait until the puppies are weaned.
No Puppy Immunity
If you do give a nursing dog a booster shot, the immune protection doesn't pass to her puppies through her milk. A dog properly vaccinated before breeding will pass on some immunity to her puppies through nursing, as she should have high antibody levels at that time. That doesn't hold true for dogs vaccinated while lactating; it can take several weeks for antibody levels to peak.