  Some carnivorous mammals (e.g., cats and dogs) lap water with their tongues
to drink water at high frequencies. Such a fast moving tongue creates a liquid
column out of a bath which is bitten by the mouth for drinking. Presumably, the
animals bite just before the pinch-off time of the water column to maximize the
water intake. Otherwise, the water column falls back to the bath before being
bitten. Such a pinch-off phenomenon in the liquid column can be described as
the acceleration-induced (i.e., unsteady) inertia balances with the capillary
force. The classical Rayleigh-Plateau instability explains the competition of
the steady inertia with the capillarity, but not with the unsteady inertia. In
this study, we modify the Rayleigh-Plateau instability in the presence of the
fluid acceleration, and show that the most unstable wavenumber and growth rate
increase with acceleration. The pinch-off time is theoretically predicted as
the -1/3 power of the Bond number (i.e, a ratio of the acceleration-induced
inertia to capillarity). Finally, measured pinch-off times from previous
physical experiments and dog \& cat jaw-closing times are shown to be in good
agreement with our theoretical pinch-off time. Therefore, our study shows that
animals presumably modulate their lapping and jaw-closing time to bite down the
water column before the pinch-off to maximize the water intake.
