What factors dictate the birth weight of puppies?

Hopefully, all new puppies should have an appropriate birth weight to give them the best possible start in life, and allow them to thrive and grow. Puppies that are underweight at birth are exponentially more likely to be unhealthy, fail to thrive, and have problems catching up to a normal weight as they develop, and stand a greater chance of dying in infancy than puppies that are robust, plump and healthy at birth.

Various factors influence the ultimate birth weight of puppies, and while some of these factors are outside of our control, there are some elements that we as dog owners can have an effect on, and ensure that everything goes smoothly to enable healthy weight puppies to be produced.

Read on to learn more about the various factors that dictate the birth weight of puppies.

The breed of the parent dogs

Obviously the main factor that dictates the birth weight of any given puppy comes down largely to the breed of the parent dogs! Understandably, a giant Great Dane will produce much larger puppies than a tiny Yorkshire Terrier! For every pedigree breed of dog, there are deemed to be average birth weight norms for the breed, which can provide an indication of how appropriate the birth weight is for any individual puppy.

Bear in mind also that even within a breed, the size and build of the parent dogs can vary considerably too, so smaller parents will lead to smaller puppies, which will still be healthy and well!

The age of the dam

The age of the dam and to some extent, the age of the sire also goes some way towards determining how large the puppies will be, as well as potentially the number of puppies in the litter as a whole. Young dams, such as those under two years old and particularly under one year old will generally have both smaller litters, and smaller puppies within each litter, as will mature dams over the age of seven or so. It is recommended that the best age to breed from a dog is between the ages of two and six, in order to give the puppies the best chance of a healthy start to life.

The dam’s nutrition

Understandably, an underweight dam that does not get enough food while she is pregnant will produce smaller puppies, and it is vitally important to ensure that the dam is fed plenty, and fed only top quality, nutritionally complete food. This is something that is very much within the control of the owner of the dam, and feeding the dam should be undertaken carefully, with her food rations increasing exponentially as the pregnancy gets further along. Towards the end of the pregnancy, the dam should be allowed to free-feed and eat as much as she wants to, when she wants to, to ensure that the puppies are able to reach their ideal weight before delivery, and to ensure that the dam is in top condition for the birth.

Not only does ensuring that the dam is well fed and properly nourished throughout the pregnancy mean that the puppies have the best chance of being born at a healthy weight, but it will also ensure that the dam is all ready to produce colostrum and milk to support the puppies after they are born. Dams that are underweight and not fed enough leading up to the birth may have problems with their milk production, and difficulty delivering healthy pups too.

The position of the puppy in the womb

In a multiple birth situation such as with most litters where more than one puppy is born, the position that each puppy is situated in within the womb can have an effect on the birth weight too.

The womb of the dog is Y-shaped, and the puppies that are positioned towards the three ends of the “Y” will be placed closest to the blood supplies that feed them, and provide them with the nutrition and food supply that they need to reach a healthy weight before birth. The puppy or puppies that lie further from the points of the “Y” such as those in the middle of it, will find themselves last in the queue for the nutrient-rich blood vessels that feed their placentas, and will often be smaller than the puppies on the outside. The runt of the litter, if there is one, is generally the puppy that lies in the womb in the middle of the pile, furthest from the blood supply.

The number of puppies in the litter

The birth weight of each puppy also depends on how many puppies are born in total! Smaller litters will tend to produce larger puppies than large litters, as there is only a finite amount of nutrition to go around, as well as of course, room to grow! However, younger dams will usually have smaller litters without producing particularly large puppies either, so this rule really only holds true in the case of litters of adult dams over the age of around two years old.