My dog has developed a lump on his foreleg the past few weeks. It has definitely grown in the last 2 weeks and is now about 1/4 to 1/2 inch across. It doesn't bother him at all - it is scaly and hard , dark coloured - should I be worried?

I would have the vet look at it. How young? Are you still running infor shots all the time? If you will be in again soon, wait until then.