Our pups have now gone to new homes and we went to visit the smallest boy last night and the new owners informed us that they had just taken him to vets because they noticed in the garden he was looking uncomfortable when walking. Just in the garden not in the house.
They checked his feet and he has open sores on both his front pads and 1 of his back pads. They say they are with him all the time he never bites or licks them and he doesn't dig and he has only been in the garden which is grassed.

The vet isn't too sure what could have caused this, but when he had his first innoculation, he came down with a temperature and was a bit lethargic so was given some metacam and penicilin. They noticed the sores the day after they stopped the penicilin, the vet mentioned that an allergic reaction could cause skin irritations but not typically on the feet.

They were adviced to use just salt water on the sores and he is going back to vets tomorrow but they and we, are worried and confused as to what could have caused this. Other than this he is doing very well and we are really pleased with him, as are his new Mum and Dad.

Please if anyone has a similar experience could they share with us what is was caused by and how it was treated, thank you.

I have seen this twice but am not sure if either scenario would fit. A friend's OH cleaned the floor with bleach and an entire litter of pups ended up with very sore pads like this. And two of my adult dogs ran fast on a tarmacked lane and stopped suddenly so sheered the bottoms of their pads off due to the friction.

I'd definitely look first at what cleaning materials they have used in the house, regardless of whether it is for floors or carpets.

I overdid the disinfectant with one litter and some pups had sore pads but sudocrem sorted them out and they weren't ill or even off colour.

Are the new owners giving anything different diet wise? Any cereal based biscuits/treats? 

I have a couple of doggy lodgers at the moment and the female has always had problems with her pads which look almost shredded, one pad has a little hole almost like a crater which is sore so she is lame. She's always licked her feet, but she got worse when I gave her a couple of dog biscuits which the owner supplied.  She is on a variety of surfaces and no chemicals have been used anywhere so I've ruled that out. Yesterday I ordered some Udder cream so am about to try that.

Again, not identical but knew someone whose lab got sores on his tummy after lying on tiles cleaned with cleaner containing an element of bleach. 

Hope you get to the bottom of it.

Have they used anything on the grass ie fertilizer or cleaner to wash down any paved area, puppies pads are so soft till they do more walking on hard surfaces, it would be very easy to break the skin.

What about carpet burns from playing tug o war and bracing themselves with their paws?

Have they got frozen ground outside? I've been amazed at how hard and frozen the ground has been. Also, you could check that if they have frozen ground, that they haven't been spreading salt around. A combination of hard spiky ground and salt used to melt ice would almost certainly cause problems with a pup's soft pads.

Other than that, I'd tend to agree with what others have suggested, i.e. cleaning products used on floors.

Hope they get to the bottom of what's causing the problem...

Are the sores around the edges of the pads where the pad meets the hair, or have they started there and spread out? Some forms of autoimmune disease can start with blisters, developing into sores, on the edges where skin meets hair. Check the puppy's muzzle for small blisters where the nose meets the muzzle as well. It probably isn't this, and there are lots of much more innocent explanations that others have suggested, but  thought I would mention it because of the reaction to the vaccination--sometimes dogs susceptible to autoimmune diseases can be triggered by vaccination.

Possibly allergic to grass? Had to have my back grass dug up and paved for this reason. I use to think grass was fine for dogs - but apparently it isn't so great in some instances.