This is called "base narrow canines" or to a veterniary orthodontist "MAL BN".
Personally I would not go to the Vets at this stage in the game if both these pups still have their baby teeth and the rest of the bite is correct, ie scissor bite at the front. If it is a mild case, the lower canine is just marginally out of place and not too far inside the mouth, as Katina says it can be rectified.
Keep an eye on the area in the roof of the mouth and make sure it stays clean. Watch for the baby lower canine coming out. If it starts to wobble and the adult tooth is a) coming up inside it or b) not directly underneath it then wobble the baby tooth until it comes out, leaving both the baby tooth AND adult tooth side by side for any period of time can affect the way the adult tooth will grow in.
Once the baby tooth is out and you see the tip of the adult canine coming through, massage it outwards daily, get puppy relaxed (that can be hard!) on your knee and gently place you finger on the tooth and massage outwards, pushing ever so slightly, best to do when they are a bit sleepy.
Purchase some balls that are about golf ball size, or which fit inside the pups mouth so that when they bite down on it, it is slightly too big for the mouth and will push the teeth outwards as the pup bites down. Take away all soft toys and concentrate on the balls and hard rubber toys as the adult lower canines are coming through.
If you follow the ball therapy you have a VERY good chance of fixing this yourself and saving yourself hefty vet bills.
Ball therapy – if there is adequate space between the maxillary 3rd incisors and canines then ball therapy may be suitable. This treatment uses a firm rubber ball, of the appropriate size, to act as a removable orthodontic appliance. The ball applies lateral force to the mandibular canines when held in the mouth, gently forcing them into a more normal occlusion. Once in this position, the natural interlock of the teeth acts as a retainer. This treatment is most appropriate for young dogs with no major jaw length discrepancies.
Hope that helps