The other day I heard someone saying that a bitch's first litter is always smaller than her subsequent litters, and that's not a theory I've ever come across. Is it a  known fact or a load of toot?

Bunkum I would say.  May have been true in teh days when very young immature bitches were mated on second seasons.

My Kizi had 9 in her first litter at just over 2 years of age, then 3 years later her disaster litter she carried 8 but we only reared 4 (two stillborn, one didn't thrive and one laid on). 

Her third litter was 4 pups at 6.5years of age.

I doubt it but a little study of the statistics in the BRS should tell us yay or nay :)

My Skye's first litter was 8 and her second 5.

Eve has just had her second litter, first of 9 and second of 8.

So not in my experience.

Mine usually have the same number at birth each litter.

My Inca had 9 in her first and 6 in her second (and final)

My foundation girl had 9 in her first litter and 2 in her second.

My girl of my other breed had 13 in her first litter and 5 in her second, so defo not in my cases. :)

">Is it a  known fact or a load of toot?

Sounds like BS to me.

If anything my experience  has been the opposite -which no doubt is just coincidence anyway. However in CATS I'd say the majority of my litters are smaller the first time.

>a little study of the statistics in the BRS should tell us yay or nay

Not really - that would only tell us the number of puppies registered, not the number of puppies born. It doesn't take into account stillbirths, neonate deaths or those unregistered for whatever reason.

I'be always had bigger litters second time, 12 litters and bigger or the same every time, the same only twice!

1st litter 2, 2nd litter 1. :-)

Number of whelps is down to the number of ripe eggs released at the right time so I doubt it has anything to do with age but may be the general health of the bitch and the timing of the mating. Believe there was a study done a good while back that decided that a bitch would release about the same amount of eggs at each season during her prime therefore all things being equal an individual bitch would always have the same size litter but, of course, all thing are never equal.

I can imagine that a litter on a bitch's first season would be smaller than a first litter when she was mature, but otherwise I find the theory hard to believe.

I find the theory hard to believe.

Don't still have a copy of the paper JG and they did state in her prime, I am sure they would have stated an age band but I can't now remember. It does take a couple of seasons for a bitch to settle so I would think they meant 2 to 5 or may be 6.

I did wonder when I read it is the hormonal state of a bitch would have an effect and I guess it would but you know what studies are like they can reject so many examples because of outside influence that it is difficult to remember what the criteria of the sample bitches was.

Toot, toot and toot again! :-D

Been rattling my brains and I actually can't think of anyone I know of whose bitches first litter was the smallest. Certainly not in my experience either.

Its quite scary when all your girls have bigger subsequent litters and they are producing 9 and 10 at first litter. My girls went on to produce 12 at a third litter ( litter one and two 9 and 9)  14 at a second litter ( 10 in first litter). In the last 2 years I have had first litters of 10 and 11.................I would almost bet my life these girls will have bigger second litters. I ALWAYS blood test on every mating so its not that some are blod tested rtesulting in bigger litters, it just seemsto be the way things are here!

What I have read by the American repro specialist who gives talks Dr Hutchinson is that progesterone has a negative effect on the uterine lining.

It is rising progesterone levels after the LH surge that drive ovulation, and maintain pregnancy.  In the unmated bitch the progesterone levels remain high much longer than in one that has been mated and goes on to have puppies.

So the more seasons a bitch has without being mated the more chance there is of deficits in the uterine lining, bubbles cysts etc.

The fertilised eggs are free until at around 3 weeks after mating they need to implant in this lining,a nd if they find a good spot and a good placenta forms you will get puppies continue to develop, the rest of the fertilised eggs will be absorbed. It is thought that many more eggs are fertilised than implant and have the space to develop.

For optimum fertility in our bitches breeders would mate their bitches relatively young (2nd or third season), and have their litters in quick succession and then spay.  Of course for welfare reasons unrelated to reproductive function we prefer to mate our girls later than in the past,a nd rest them between litters, as maximum production is not our aim.

Here is a transcript from a seminar in 2002, http://www.veterinarypartner.com/Content.plx?P=A&A=1224 so may be a bit dated, and I don't know what cheque drops are/were, or whether and what name they may have existed by in UK.