A listmate asked:

A friend of mine took her cat in today. The cat was diagnosed with a uti and possible crf. (waiting to check numbers after antibiotics)

Is there any good reason to give sodium chloride instead of lactated ringers?

If a cat has been hit by a car, is in shock or has lost massive amounts of blood, sodium chloride is generally used to quickly restore circulating volume. Also to maintain volume during surgery, when some blood is of course lost. If general rehydration is desired, Ringer's solution is a much better balanced electrolyte solution which evenly rehydrates the whole system including the cells instead of simply filling the vascular space.

Since many if not most vets are more accustomed to treating trauma victims than they are chronic diseases (and since they're not all research scientists and like many of us don't remember everything they learned in school) they may reach for saline out of habit whenever an IV solution is needed. Generally, renal patients need a more balanced solution like LRS, Normasol or Plasmalyte.