  We find and characterize an excitability regime mediated by localized
structures in a dissipative nonlinear optical cavity. The scenario is that
stable localized structures exhibit a Hopf bifurcation to self-pulsating
behavior, that is followed by the destruction of the oscillation in a
saddle-loop bifurcation. Beyond this point there is a regime of excitable
localized structures under the application of suitable perturbations.
Excitability emerges from the spatial dependence since the system does not
exhibit any excitable behavior locally. We show that the whole scenario is
organized by a Takens-Bogdanov codimension-2 bifurcation point.
