  We present evidence for chaotic dynamics within the spin-down rates of 17
pulsars originally presented by Lyne et al. Using techniques that allow us to
re-sample the original measurements without losing structural information, we
have searched for evidence of a strange attractor in the time series of
frequency derivatives for each of the 17 pulsars. We demonstrate the
effectiveness of our methods by applying them to a component of the Lorenz and
R\"ossler attractors that were sampled with similar cadence to the pulsar time
series. Our measurements of correlation dimension and Lyapunov exponent show
that the underlying behaviour appears to be driven by a strange attractor with
approximately three governing non-linear differential equations. This is
particularly apparent in the case of PSR B1828$-$11 where a correlation
dimension of 2.06\pm0.03 and a Lyapunov exponent of $(4.0\pm0.3)\times10^{-4}$
inverse days were measured. These results provide an additional diagnostic for
testing future models of this behaviour.
