1) Can a bitch carry pups from more than one sire in a litter?
Yes. This phenomenon is called superfecundation. Because the spermatozoa from the male can live for up to a week in the bitch and may be present well before the eggs are ready to be fertilized, a bitch bred by more than one male has spermatozoa from all males involved adhering to the lining of the reproductive tract, available to fertilize the eggs once they are mature. Parentage testing can be done to determine who is the sire of the pups; DNA samples from the dam, all possible sires, and the pups in question are required.
2) My bitch had a litter of five pups with one runt. Was that small pup conceived later than the other four?
Probably not. Dogs release all their eggs over about a 24-hour span. Even if conception of that small pup occurred later than conception of the other pups, all the pups float around free for 17 days before implantation and formation of the placenta. Runt pups most likely are the same age as their littermates but had poor placentation.
3) My vet says gestation length from breeding can vary from 58 to 71 days. How can there be such a huge range if the dog only is bred once or twice?
Bitches stand to be bred for a large window of time around ovulation and spermatozoa from the male live in the bitch’s reproductive tract for an extended period, too. Date of breeding is not necessarily date of conception. If no workup was done to allow determination of ovulation date, more exact determination of likely whelping date cannot be made.
4) How many days before term can puppies be born safely?
That is a good question! Puppies lay down surfactant, which allows normal expansion of the lungs, very late in gestation. No one ever has done a study in which pups were removed by C-section various days before term to see when they would survive, nor is anyone likely to do such a study. If the ovulation date is known, I prefer not to take pups any earlier than 61 days from ovulation.
5) Do human early pregnancy tests (EPTs) work in dogs?
No. The hormone measured in human EPTs is human chorionic gonadotropin. This is produced only in humans. Dogs do not produce a similar hormone early in pregnancy.
6) I could see the pups moving in my pregnant dog yesterday but cannot see anything today. How can we determine whether the pups are okay?
Lack of movement does not necessarily mean there is a problem. The pups simply may be running out of room in there! The best way to determine whether the pups are okay is by ultrasound.
7) Is it safe to take x-rays late in pregnancy?
Yes. The amount of radiation used in x-rays is as safe for the pups as it is for the bitch and the humans performing the procedure. The pups are no longer developing and so are not sensitive to radiation as a cause of birth defects.
8) My Labrador retriever threw a litter of four pups. What are some reasons for this small litter size?
The most likely culprit is breeding at the wrong time. Optimal breeding day for litter size is 2 days after ovulation as determined by measurement of progesterone by your veterinarian. Other possible causes include hypothyroidism, uterine infection, and advanced age of the bitch.
9) I had x-rays taken at about 55 days from breeding, and the vet could see only one large pup. Is my dog going to have trouble whelping?
She may have trouble whelping. Pups grow to fill the size available to them, and this pup had the whole uterus to himself. Singleton pups also may be associated with prolonged gestation because the single pup may not be able to set off the hormone cascade that initiates labor. Talk to your veterinarian about emergency care or performance of elective C-section.
10) Are red raspberry tea leaves recommended for use during pregnancy in dogs?
There is no evidence that red raspberry tea leaves are beneficial during pregnancy.
11) I just lost a litter to canine herpesvirus. Do I need to worry about myself and my family getting herpes?
No. Canine herpesvirus cannot infect humans, and human herpesvirus cannot infect dogs.