From all I've read about this medical problem, it is inherited,
or strongly suspected to be. In a pup that's 13 weeks old, it
could hardly be acquired so early.Perhaps the breeder should
not breed the sire & dam anymore. I hope the pup recovers
well, but it's a shame you & the puppy have to deal with this at
all. Good luck.

http://regaliapyrs.tripod.com/medica...ng_defined.htm