I read somewhere not long ago (a decent source, I forget which book), that if you count back 63 days from the date of birth of the litter, you can (always) determine the exact date on which the bitch ovulated.  Is this true?  I have found several reasons lately for wanting to know this.

I also read in another book some time ago that the birth ALWAYS occurs - with no exceptions - on day 63 after ovulation.  I don't see really how this can hold true, since both the eggs and the sperm live for some days in the reproductive tract of the female.

Hi

My toy dog gave birth on day 57 so no, I don't believe that :)

What day of her season was the date of the first mating?  Because if you mate very late in the cycle, then the ovulation took place perhaps several days before that and so it might add up to 63 days from the ovulation to the birth, even though it was only 57 days from the first mating.  If you see what I mean.

Here an excerpt from the internet:  Wird die Hündin 5 Tage nach der Ovulation gedeckt, kann sie bereits nach 57 Tagen werfen.
This says:  If the bitch is mated 5 days after ovulation, she can whelp as soon as 57 days thereafter.

So I am wondering if this statement (Puppies are ALWAYS born 63 days after ovulation)  I read in a reputable book on breeding could be as absolute as the author claimed.  However, the eggs are not viable immediately, so that would already account for some variation, would it not?
I find this confusing and contradictory, as I find so many things about reproduction in general.

I progesterone test and can verify that mine go I to labour 63 days +/_ 1 day from ovulation.  One of the main reason I test is to accurately pin point date of whelping
The eggs may well be fertilised at slightly moments but egg viability is only a couple of days and despite multiple eggs they all implant at same time and thus develop at same rate.

This brings me to another question I have had for a very long time:

One hears again and again that if a female is bred over too many days (thus a time span of many days between the first mating and the last), the puppies may vary in age at birth to the extent that the "younger" ones may not be able to survive.   My question is:  How could this be so, if, as you say, egg viability is only a couple of days, and the implantation and development occur at the same rate?

I test too, if the result is accurate then one mating may only be needed at most two the beauty of idexx testing

Old wives tail :) Any  small underdeveloped pups are either genetically flawed or may be underdeveloped due to placenta dysfunction. You cannot get whelps if different ages as physiologically the eggs all I plant at same time

So if you own both the male and the female whom you want to mate, and they live together in your home, then it doesn't really matter how long they might go on mating during her season? And it is unnecessary to restrict the total number of matings?  It doesn't matter if the female (assuming she is willing) is mated, say, on day 8 through 18 (though perhaps not every day in order to consider the male)?  Or, if this is not so, then in what way should one restrict the matings of a pair living together?  It is quite a different situation altogether when you do a progesterone test and then take the female to the stud on, say, day 13 and again on day 15. 

My last breeding (a few weeks ago) - female and male are both mine and live with me - was pretty confusing to me, as my male suddenly mated her (sort of ho-hum...casually...!) on day 8.  She was OK with that, and he mated her again on day 10 and 12, and then he went really bananas, and mated her a few times more!  Since you read everywhere that the male knows best, I felt that if I intervened, I might be doing exactly the wrong thing. 

She is now very definitely pregnant, and I guess I have no reason to worry any longer about vastly differing "ages" in the puppies at birth.  I have posed this question to other breeders, who had no answers and knew no more than I did, and to vets, who all said something different.

The only problem you have is knowing when she will whelp as you don't know when she ovulated. Behavioural acceptance of mating and physiological status can have little correlation so she may have been at ideal point at first mating or later.  Any puppies will not be different ages at birth, if she has a large litte any smaller puppies may have development delay due to overcrowding effects or placenta dysfunction

It is true +/- a day, and as you say the early whelpers were mated late.

Though perhaps with tiny toy breeds early whelping as in multiple births in humans is caused by overcrowding.

A bitch will generally not stand for more than a week, from just before ovulation to just after the eggs die off, which is why many old breeders say mate the bitch until she goes over to be sure you have got correct timing.

Most timing failure is mating too early, as generally the bitch will only mate for two or three days after the eggs are ripe.

I am so grateful to have your information, and thanks to everyone who has written in.  I've been tearing my hair out for years: feeling stupid for having allowed them to mate over so (too?) many days,  or worrying about the male's sperm,  or feeling guilty for having stopped them from mating (worried about differing ages in the newborns) yet wondering at the same time if I thereby missed the right day(s), and so on.  I recently posed the whole thing yet once again (after my Lulu had stood there willing and able for over 10 days) to a vet I think highly of, asking her how on Earth newborns could differ by up to a week in age at birth due to Mom having been mated over a week or so.  If the eggs are viable only a couple of days, then how could this be possible?  She said it could only happen if the female had had a "split heat", meaning that the eggs were released in two batches.  This is, according to the internet, very rare and occurs mostly in very young bitches.  I'd like to tell you the story of another bitch of mine, now spayed and living a lovely life with friends, age 7 years.  But I will write it in another post, which I will title "Heaven".

Split seasons are fairly common but ovulation doesn't occur during both halves of the season, so even if she mated the first time, ovulation doesn't necessarily occur and therefore no conception.
It is technically possible for people and dogs to get pregnant whilst pregnant as sometimes (we are talking almost medical miracle here with regards to the frequency of this happening) ovulation does occur twice within a couple of weeks and conception can occur at both times..... But this is incredibly, incredibly rare... Like I said, almost a medical miracle and would attract a huge amount of attention from medical professionals and even the general media! It's called superfetation.

Wow!  Many thanks for this!  Love the word Superfetation.  That would be a great final question for "Who Wants to be a Millionaire"!

Think about it in the wild the dominant pair would mate over the whole receptive period, possibly multiple times a day at the peak, and the bitch might even sneakily be mated by a rival.  It's how litters of puppies can have multiple sires.

In my bred the males get so limited use that no stud dog owenr worries about he male getting overworked by mating the bitch as often as they like   If anything with a maiden or young  stud it helps hone his technique.