I generally advice against the use of tagamet in middle-aged ferrets.
Many of these animals have advanced Helicobacter (which could be
contributing to the development of ulcers.) The long-term effect of
Helicobacter is damage to the acid-secreting cells of the stomach, and
an over all increase of the pH of the stomach.  These changes culminate
in difficulty in digesting food, and the use of tagamet only worsens this
problem.
 
The use of carafate at 75 mg/lb 10 minutes before every meal, coupled
with a bland, highly-digestible diet is the best way to go in most cases
of ulcers.
 
With kindest regards,
Bruce Williams, DVM
[Posted in FML issue 3698]