Mastitis increases the activity of more than 20 enzymes in the glandular secretions of dairy cattle, including
esterase. We hypothesized that milk esterase activity provides an inexpensive, rapid, and practical cow
-
side
method for diagnosing subclinical ma
stitis (SCM). Our objective was therefore to determine the clinical utility of
measuring esterase activity in quarter milk samples using
Multistix
®
and
PeriScreen™
strips
to predict SCM.
Quarter foremilk samples were collected from 115 dairy cows at dry
-
of
f and 92 fresh cows within 4
-
7 days post
calving. Quarter somatic cell count (SCC) was measured using Delaval
®
cell counter with SCC≥200,000
cells/mL as the reference method for diagnosing SCM. Milk esterase activity was measured using Multistix
®
and
PeriS
creen™
strips
. The area under the receiver operating curve (AUC), kappa coefficient (κ), and positive
likelihood ratio (+LR) were calculated and P
trace, the
PeriScreen™
strip
had an AUC=0.75, κ=0.32, and +LR=25.5 at dry
-
off, and AUC=0.66, κ=0.38, and +LR=∞ in
fresh cows. At the optimal cut
-
point≥trace, the Multistix
®
strip had an
AUC=0.71, κ=0.31,
and +LR=4.2 at dry
-
off, and AUC=0.63, κ=0.31, and +LR=14.0 in fresh cows.
The AUC,
κ, and +LR
values for the
Multistix
®
and
PeriScreen™
strips
are considered suboptimal for a diagnostic test because clinically useful tests typically have
an AUC >0.80,
κ
>0.6
, or +LR>10. We therefore conclude that
Multistix
®
and
PeriScreen™
strips
do not provide
clinically useful cow
-
side tests for diagnosing SCM in lactating dairy cattle.
(3) CLINICAL UTILITY OF TWO LEUKOCYTE ESTERASE REAGENT STRIPS FOR THE COW-SIDE DIAGNOSIS OF SUBCLINICAL MASTITIS IN LACTATING DAIRY CATTLE. Available from: https://www.researchgate.net/publication/321315620_CLINICAL_UTILITY_OF_TWO_LEUKOCYTE_ESTERASE_REAGENT_STRIPS_FOR_THE_COW-SIDE_DIAGNOSIS_OF_SUBCLINICAL_MASTITIS_IN_LACTATING_DAIRY_CATTLE [accessed Feb 22 2018]. |
