• Size at birth has nothing to do with adult size, or the stages in between, provided the puppy is born full-term and without health issues.  Quite often, the smallest pup in a litter ends up bigger than his siblings as an adult dog, and vice versa. 

    It's just like people. A human infant's size, provided he is born full-term and without health issues, has no correlation to the size he will be as an adult. My daughter was the smallest baby in the nursery when she was born. In Kindegarten, she was the tallest child in her class. :) 

    • The runt in Phin's litter is now the 2nd biggest out of all the siblings!

  • My first Springer was the runt and became the largest.

  • To add on to what Karen said though, I would be careful if one pup is significantly smaller than all the other pups in the litter that it is healthy. Sometimes a puppy is just a little smaller but sometimes there is some congenital problem that is causing the puppy not to flourish.

    • Yep - I've seen "runts" of both types.

      I remember when we were picking out Luna there was one male puppy left and he was quite a bit smaller than his sisters.  He was also quite timid and not super active.  It was a big red flag for me (we wanted a female anyway, but still) and I wondered if he was sick.

      Luna on the other hand was leading her siblings on digging adventures (she grew up on a hobby farm), there no concerns about her energy level :p

      My childhood dog (a bichon) though was the "runt" but was only a little smaller than her siblings and seemed otherwise very healthy and active.  She was indeed very robust and lived 18.5 years and never had any serious illnesses.

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