Page 567 - Small Animal Internal Medicine, 6th Edition

CHAPTER 34 Diagnostic Tests for the Hepatobiliary and Pancreatic System 539

esterases is less likely to occur. Recent studies in dogs sug- and disadvantages of the different assays are outlined in
gested good agreement between the DGGR lipase assay and Table 34.2. Overall, PLI has the highest sensitivity and likely
VetBooks.ir PLI (Kook et al., 2014; Goodband et al. (2018)) and two the highest specificity in both species. Recent studies of PLI
for the diagnosis of acute pancreatitis in dogs suggest a sen-
other studies suggests that it may also be useful in cats,
unlike the older lipase assay (Oppliger et al., 2013 and 2014).
Immunoassays, however, use an antibody against a part sitivity of between 86.5% and 94.1% and a specificity of 80%
to 90% or 66.3% to 77.5%, depending on the cut-off and
of the enzyme molecule distant from the active site and thus methodology used in the studies, respectively (Mansfield
will also measure inactive precursors (e.g., trypsinogen); et al., 2012; McCord et al., 2012). The positive predictive
these tend to be organ- and species-specific. The advantages value is high in animals with a high likelihood of acute

TABLE 34.2

Catalytic Enzyme Tests and Immunoassays in the Diagnosis of Acute and Chronic Pancreatitis in Dogs and Cats

ASSAY ADVANTAGES DISADVANTAGES
Catalytic Assays
Dogs only; of no use in May be normal in severe ± chronic
cats except for DGGR pancreatitis caused by enzyme depletion
lipase (see following and ± loss of tissue; degree of elevation of no
text for more details) prognostic value, except where stated;
both renally excreted and elevated two or
three times in azotemia
Amylase Widely available on in-house analyzers; Low sensitivity and specificity because of
steroids do not elevate it, so can help high background level from other sources,
diagnose pancreatitis in dog with including small intestine
hyperadrenocorticism
Lipase Widely available on practice analyzers; Extrapancreatic sources so high
more sensitive than amylase; degree of background level
elevation may have prognostic significance Steroids elevate up to five times
New DGGR lipase has higher sensitivity and
specificity than older assays and correlates
well with PLI in both dogs and cats (see
details in text)
Immunoassays
Canine TLI Elevations—high specificity for pancreatitis Low sensitivity for diagnosis of pancreatitis
(but high sensitivity for EPI); said to rise
and fall more quickly than lipase or
amylase; renally excreted: elevated two
or three times in azotemia
May be inappropriately low in severe ±
chronic cases caused by pancreatic
depletion ± loss of tissue mass; no clear
prognostic significance
Feline TLI No advantages for diagnosis of Lower sensitivity and specificity than canine
pancreatitis— reserve for diagnosis of EPI TLI, better used for diagnosis of EPI;
renally excreted so elevated in azotemia
Canine PLI Most sensitive and specific test for canine Increased in renal disease but may not be
pancreatitis together with DGGR lipase significantly increased (?) (unclear yet if
(see text for figures); organ-specific, so no affected by steroids)
interference from extrapancreatic sources
Available as in-house test (see URL in text)
Feline PLI Most sensitive and specific test available for Very little published data yet available on its
feline pancreatitis, together with DGGR use
lipase (see text for figures); available as
in-house test (see URL in text)
PLI, Pancreatic lipase immunoreactivity; TLI, trypsin-like immunoreactivity.