Envision an AlQaida trainee taking along a rat on an airplane ~ obviously doesn't work ~ too much surveillance, so envision the same trainee taking along a bunch of rats in rat cages on a ship ~ maybe an oil tanker.
More likely it was a liquid natural gas tanker using Western Backwaters LNG facility. That'd get you from Karachi to Algeria.
More than likely you'd need a compliant captain to let you take a long and care for the little critters.