Falsifying papers, giving shots when puppies are too young, these are just some of the problems that puppies face when they are traded on the black market. Rabies is a very serious disease that kills 55000 people a year, and is a global problem that affects more than 150 countries. Dogs account for 99% of all rabies related killing.
However, a crackdown on these rings and increased security can help significantly, with the UK being a good example. The last case of rabies in the UK was in 1970 (outside of quarantine).
However this will be more difficult for poor countries where it is not feasible for security to monitor all networks.
To read more: http://www.bbc.com/news/uk-30043935