You're looking forward to the arrival of puppies, but without good prenatal care, these little creatures might arrive loaded with worms. You can prevent that, but always check with your vet before worming your pregnant dog. Your vet likely will request that you bring your dog's stool sample for testing early on in the pregnancy, so the presence of any worms can be detected. During her pregnancy, keep your expectant dog away from the feces of other animals.
If your pregnant dog is already on a monthly heartworm preventive, you can continue to administer this medication while she's expecting and while she's nursing her puppies. Most heartworm preventives also eliminate other types of worms, with the exception of tapeworms. That means you shouldn't have to worry about the most common types of worms affecting pregnant dogs and their unborn puppies -- roundworms and hookworms. A mother dog with these worms can transfer them to her offspring in several ways.
Roundworms and Hookworms
If your dog isn't receiving heartworm medication, your vet will recommend a dewormer to prevent roundworm and hookworm infestation. Otherwise, your dog can pass these parasites on to her puppies while they're in utero or through her milk or from exposure to her contaminated stool. Puppies infested with roundworms often fail to thrive, typically presenting a "potbellied" appearance -- a belly full of worms. Puppies infested with hookworms might suffer from anemia, diarrhea and growth issues. Severely affected pups might die.
If you notice rice-like bits in your dog's feces or around her anus, she's probably got a tapeworm infestation. Since heartworm medication won't eradicate tapeworms, you'll need another type of dewormer. Praziquantel, marketed under the brand name Droncit, will kill tapeworms. While the product is safe for use in pregnant or lactating dogs, do not give it to your expectant mother without veterinary approval. Your vet might advise you to wait and worm the mother dog and puppies when the latter are at least 4 weeks old.
If your dog doesn't receive heartworm medication, your vet likely will recommend that she receive appropriate deworming medication about two weeks before her due date, or about six weeks into the pregnancy. That two-week window reduce the chances of roundworms or hookworms passing to the fetuses or the nursing puppies. Your vet will then recommend a deworming schedule for the puppies, generally starting as young as 2 weeks of age.