Newborn size - Controls? Why differences?

Part of this discussion may have originated in one of the threads about "oops" litters.  After doing rescue for as many years as I have, I will stand by my original comment that if a small dog is impregnated by a huge dog the puppies may be too large to pass thru the birth canal.

HOWEVER -- I would urge sanity here.  I'm talking about a difference in breeds here -- NOT two dogs mating of the same breed or the furtherance of a particular breed line.  If there is a natural control in the mother of what 'size' pup will work I'm unaware of it, but I do know of many cases where a bitch was impregnated by a much larger sire of a different breed and in one case I saw the bitch died trying to birth the pups (and I will simply not go into the grisley details of what resulted). 

I would also simply make the comment that c-sections in humans would be pretty rare if the mother's body always goverened the size of the fetus well.  I have a close friend who bore twin girls (13# 3 oz. **each**) simply carried to full term who would argue seriously that her body didn't have any qualms about developing these two children simultaneously!  She *did* have a c-section but the doctor didn't discover it until she was full term (it was about 20 years ago before current ultrasound techniques were prevalent).

 They are also governed by position in the uterus and number of other puppies present, nutrition, and yes, the mother's size.

It's rare for dogs who have average-sized litters to need C-sections for over-large pups- that's more common for very small litters or singletons. An a statistically average litter, the bitch's body WILL regulate size just fine. But in small (1-2 pup) litters, you have all that nutrition (provided sometimes in excess by well-meaning owners) going to just one or two pups rather than spread out over a litter- and those pups WILL grow faster.

It's also rare for dogs with average structure (No giant heads or narrow hips) to need c-sections for pups who won't fit. However, other factors are involved in c-sections- the bitch's condition being primary. According to  Myra Savant Harris (author of Puppy Intensive Care: A Breeder's Guide to Care of Newborn Puppies - this is secondhand, from a seminar), MOST c-sections are elective- vets choose to intervene earlier rather than later because of the fact if you wait till it's TOTALLY obviously necessary, it's much harder recovery and you will most likely have dead puppies. A friend of mine who lost her bitch during a c-section had a HUGE litter- 10 puppies, all of them normal sized. No pups were stuck but she stopped pushing. No clue as to why. It just happens sometimes.

 I know that a fair number of studies have been done in horses about this exact thing- breeding small mares to larger stallions- and found that the mare's size is the major determining factor, but since each animal IS an individual, sometimes the mare's body just doesn't regulate like it's 'supposed to' or she's overfed or underexercised or any number of other things- and that's when you get complications.

 A mismatch in body types will indeed cause failed vaginal births.  This is something livestock breeders are well aware of and I don't know why it would be different in dogs.  The size of the pups, for instance, is determined by genetics gleaned from both parents.  A very small female is likely to cause "averaging out" of size, which increases the odds that such a female could bear the product of a large sire. 

However, other factors come into play, which I can't imagine casual breeders to be aware of.  These include head shape, litter sizes, pelvic size of the dam, rib depth, and considerations which include ability of the female to actually physically take in enough nutrition herself to grow and eventually feed a litter of large sized pups.  Most of these matters are taken care of in the stability of the breed itself, as it proves its ability to recreate healthy pups from the gene pool available to it (or they are addressed by breeders who are aware of the shortcomings of the breed and individual lines).

To take a less charged example, since crossbreeding is done all the time in sheep for excellent reasons and there is no question as to what to do with "unwanted lambs."

To the novice breeder, it might make a lot of sense to cross a Hampton, which is a sheep with a large frame and fast growth rates, and is well-known for producing the kind of lamb for eating - with a Texel mother, which is well known as a superior grazer, gaining rapidly and heavily, extremely efficiently almost on nothing but grass.  This would combine the good qualities of the dam and the sire to produce lambs that are long-boned and become very meaty in a short amount of time, without much feed - right? 

Actually, it would produce a lot of dead sheep.  Experienced breeders know to look at the worst possible outcome of a mating and work to make that outcome fall within their goals and standards.  The Hampton's large head and the Texel's narrow pelvic frame are a deadly combination, as is the fact that both breeds are "non-prolific" - that is, they tend to have singles rather than twins or triplets.  Another deadly factor for the mother - any that survive birth will risk mastitis when that huge lamb starts feeding aggressively.  Finally, one could also end up with the inferior muscling of the Hampton, the lighter frame and smaller size of the Texel, and an inability to grow without supplemental feed.

Instead, Hamptons are usually combined with a prolific breed like a Finn or Romanov, while you'll see a Texel as a meat producing sire in a "three tier" system which uses two generations of lambs to produce a lamb which can take advantage of the qualities of the Texel without having to use a Texel dam.

The limitations of each breed (or distinctive genetic population) is what those who value that breed, focus on in their plans.  But this is what those who breed with more random motivations ignore, unfortunately, at the risk of their breeding animals, the happiness of their customers, and the population of the breeds and species as a whole, in the case of dogs.

brookcove

A mismatch in body types will indeed cause failed vaginal births.  This is something livestock breeders are well aware of and I don't know why it would be different in dogs.  The size of the pups, for instance, is determined by genetics gleaned from both parents.  A very small female is likely to cause "averaging out" of size, which increases the odds that such a female could bear the product of a large sire. 

     That's a bit of a misconception (no pun intended) in dogs. In any given breed, pups will generally be within 2 oz of each other in weight at the time of whelping. What determines their size in utero are the amount of calories the bitch was taking in while in whelp - which is why overweight, oversupplemented bitches are a c-section waiting to happen. Bitches kept in lean condition on a good, basic puppy food, and who are allowed to have a good amount of exercize throughout gestation often produce smaller whelps. Of course, in toy bitches, that size difference of 2 oz can be quite substantial. However, toy breeds also tend to have small litters, which will allow the pups to grow and get too fat to be delivered naturally. Still though, birth size has very little to do with the male. Some smaller males produce larger sized pups, and vice versa, depending on what is in their genetic background.

     I've bred my 15" 30lb male stud to a bitch who was literally half his size - she was about 11" and 15lbs. That litter was perhaps the most consistant in regards to birthweight I've ever bred - all pups were within an ounce of each other, with 9oz being the median weight. Keep in mind that we have one pup who turned out to be smaller than the dam, a few full 13" pups, and two pups that went oversize in a major way. Still, birth weight was average, and the bitch had little difficulty with delivery. All were free whelped. Same thing with a bitch I own who is also about 11". Her sire and dam were both quite similar in size, yet the pups turned out to be a hodgepodge of sizes. All were similar birthweights, and again, the bitch free whelped. 

     Ease of whelping depends greatly on genetics, and because the sire was substantially larger or smaller does not automatically mean that bitches will have difficulty, pups will be too large. Again, lean bitches will deliver small pups. You also have to take into account the feed - because too much calcium in the diet causes labor problems and calcium supplements are an invitation for problems.

Some bitches will ALWAYS have one BIG puppy...regardless of the sire...and this is also passed to their daughters. Puppy size is IMO related more to genetics, than care aside from the case of water puppies which ARE a nutritional thing. That one bitch line can consistently have litters of 3-5 with one MARKEDLY larger puppuy in there..bespeaks genetics.

I have had vastly mroe than a 2ozs difference in my litters, due to the genetic tendencies present in the line for such. It should also be pointed out that 2ozs in a Lab litter is no big deal...while in a Toy litter it can make the diff between puppies living and dying...being whelped or sectioned.

rwbeagles

Some bitches will ALWAYS have one BIG puppy...regardless of the sire...and this is also passed to their daughters.

     Definitely! The bitch in my siggy is notorious for having one *male* pup that is always the largest (and usually the overall best pup) in the litter. She has been bred to a small male, half her size, and has still had pups that topped the scales @ 30lbs full grown - plus the other pups were all in the 15" range. Then I bred her to a male that was her size, and we got mostly 13" pups, lol

rwbeagles

Puppy size is IMO related more to genetics, than care

Any idea whether it is

• the genes that the puppy gets from the dam or
• the dam's genes (as in some sort of growth hormone supplied to the pups)?

IMO it's the same as the way it works with people. Women who come from female lines that tend towards large babies...or long labors...or short...tend to repeat those patterns.

For ex I was a 8+lbs baby girl, firstborn...my firstborn was also a girl 8+lbs...my second born was bigger. We have good sized babies and I expect Lily also will if she has kids.

I skimmed through fairly quickly, and have just this to add-

My toy poodle dam was bred to a mini poodle sire.

I was warned repeatedly that the pups would be too big to pass, and I was absolutely terrified of this.

She had three pups, at birth, raging from 2-3 oz.

The runt of the litter was lost.

Now, 11 days old, my two boys have an INCREDIBLE size difference.
3oz for my little nameless cream colered munchkin, (possible name?)

and 9.75 oz for my monstorous chocolate colored Cocoa.

DellaBella

Now, 11 days old, my two boys have an INCREDIBLE size difference.
3oz for my little nameless cream colered munchkin, (possible name?)

 And you have been repeatedly told that this is not normal. The small ones lack of weight gain is major cause for concern.