Lepto, what about it?
Leptospirosis:
While puppy shots may seem like a routine procedure, in fact more and more
controversy has been stirring up around vaccinations.  Sometimes a pup will get through
the first shot just fine and experience allergic reactions  with the second.  This usually
occurs if a combination vaccine is used.  This has led some breeders to give the parvo
shot separately from the combination shot.

There is further concern though, regarding leptospirosis.  Because of the need for Lepto
vaccine to have added a protein, usually called an adjuvant, added to it, serious
problems arise.  The adjuvant is extremely inflamatory and biochemically can be toxic
when given to a small dog.  It is usually the choice of breeders to skip the lepto part of
the combination immunization but if it cannot be skipped, it is diluted with saline for
Yorkies and other toys.  So what is the risk of not using the lepto vaccine?  Not very
great since lepto is spread via the urine of infected animals, usually wild animals.  
Certainly urban dogs have a lower risk of contacting it.  In 1989 I had a puppy react to
the shot and almost die.  The reaction came on within minutes after injection and was
diverted with Benedryl, but not before it terrified me.
The puppy seemed to have fainted and I thought it died.  Then it's face began to swell,  
and the Bebedryl was none too soon!
As a rule I do not administer Lepto to any of my Yorkies.