Is it posible for young pups to have this problem? - Yes
Is it a heriditary problem? - Sort of.
Are there any long term problems? - Definitely, but it depends on where in
the urinary tract that the problem originates. For example, a nephritis
(kidney infection) is very serious and can lead to renal(kidney) failure.
A cystitis (bladder infection) can also be very serious and difficult to
treat. This can also turn into a nephritis or cause a rupture of the
bladder if the walls of the bladder become weakened due to infection. A
vaginitis is less severe and without knowing exactly what symptoms your dog
has I would guess that this is probably your problem. Kerri alluded to this
possibility in her post with the part about the little females "piddling" so
close to the ground and contaminating their vaginal area with bacteria. This
is probably the most common urinary tract problem in young female puppies.
I also believe that part of the problem is due to the fact that female
puppies are so "tight" in their vaginal area. A lot of times the vaginal
opening is almost recessed and there is a lot of skin folds in the area.
These folds will hold moisture and become infected and then the infection
will spread to the vaginal opening itself. Like Kerri said wipe her vaginal
area off frequently and check the folds around the vagina to make sure they
are dry and not holding a lot of moisture. If the dog does have a vaginitis
then yes antibiotics are needed to combat the infection. Schedule a visit
with the vet and get the proper prescription.

FYI some urinary tract problems like cystitis and nephritis can be present
in very young dogs but in my experience it is rare. There are other
possibilities also. I once took a golf ball sized bladder stone out of 12
week old female dog.

To answer your question about whether or not these problems can be
hereditary. Not really, bacterial infections in and of themselves are not
hereditary, but it certainly is possible that certain breeds or lines could
be more susceptible to problems. Say for example the females that are
very tight in the vaginal area would be more prone to developing these
problems than others.

Hope this helps.

DR.J
Good Luck and Good Hunting!!!!!!!!!!!!!!!