USDA APHIS Rules Explained:

As well as we are able!

Currently the new rules are being reviewed by attorneys to try to figure out what they actually say.

The most important thing they say is:
American citizens can no longer buy the dog of their choice anywhere in the country without going in person to see the animal first unless the breeder is willing to become USDA licensed.

A USDA license has any number of rules that can't be met by a person whose dogs live in the house and sleep in their bed.  They require the surfaces be impervious.  No fluffy, no stuffed toys, no carpet, etc.

It requires that the owner be at home to allow APHIS to inspect 5 days a week during business hours.  No going to a dog show.  No working during the week.  To be USDA inspected you have to either go really big or stop. 

There are exceptions that are complicated and convoluted.  Some of the published questions and answers contradict one another. 

However this an article that explains the new rule insofar as we are able to understand it.  MDMC makes no assurances that this is 100% complete or totally correct.  It is correct insofar as we can figure out.  If new evidence emerges, we'll modify and notify.  
Article about the APHIS Rule

The only way to be certain what you are reading is correct is to read the original rules as written and try to figure them out yourself. 

Here is the final USDA-APHIS rule as published: