4 month old shih tzu

Question
Our Shih Tzu had 4 pups. One of them tends to want to stay away from our other pups. They are 1 month old. She always naps away from the other ones. Meanwhile the other three are always snuggled up against each other. This pup is smaller in size, but yet, wags it's tail and seems to be happy when we play with her. We even give this pup one on one alone time with the mother so she can nurse without being trampled by the other 3 bigger pups. My other 3 are much bigger and nice and plump. Is there something wrong or unhealthy about this "loner" pup?

Answer
There is probably nothing at all wrong with this little pup, I would however not encourage the behavior by continuing to separate her from the pack.  She is probably just going to be a little passive and not as dominate..they usually work this out as a pack.  At 1 month old they should start on mash/gruel  as well as nursing with mom and this smaller pup may like it better than mom (I know my little ones usually do) if there were something wrong with her the mom would have pushed her out a long time ago.  You should have wormed them at 2, 3, and 4 weeks and again at 6 and 8 weeks of age and at 4-5 weeks they are usually using the potty on their own so if you notice really loose stools check for any signs of worms, if clear of worms then check with your vet to make sure they are cleared for coccidia and Guardia if they are cleared for those little tummy virus' then you are good to go until vaccine time at either 6 or 8 weeks which ever you or your vet has determined.  Hope this helps
Deanna Isenhour