The BT-PABA or PABA test is a highly sensitive test that indirectly measures pancreatic enzyme activity in the small intestine by measuring the absorption (plasma concentrations) or excretion rate (in urine) of PABA which is split from BT-PABA (a synthetic peptide consisting of n-benzyol-1-tyrosine and p-aminobenzoic acid) by the action of pancreatic enzymes (peptidases) in the intestine.

Although this is a sensitive test it is difficult to perform in dogs and therefore not widely used in general practice.

This test cannot be used in dogs that have been under treatment with diuretics, sulphonamides, chloramphenicol or pancreatic abstracts within 5 days of the test due to interference. It is also not applicable in dogs with impaired renal function.

0.25ml (16.7mg)/Kg body weight of the patient of BT-PABA is given by stomach tube to a patient that has been starved for 18 hours, followed by 25-100ml water. After 6 hours confinement urine is collected by catheterization of the bladder and analysed for PABA.

A similar test can be used and plasma concentrations are measured. Peak plasma concentrations of PABA are greater than 350 m g/dl in normal dogs

Normal dogs excrete over 70% of the PABA administered orally in the urine within 6 hours.

In dogs with exocrine pancreatic insufficiency peak plasma concentrations are less than 150m g/dl and less than 15% of orally administered PABA is excreted in the urine in a six hour period.