In the Netherlands, petting zoo's, or better translated, children's farms, have angled self closing gates to help the kids keep the animals in their pens. In these "kinder boerderijen" the parents and kids are allowed to wander in and out of the animal pens, and the kids and animals are encouraged to interact with each other. To keep the animals, especially the goats, from wandering out with the kids some bright mind came up with a self closing gate.
The gate in this picture is paired with a shuttle entry and another gate at the end entering the main pen - double the security, and especially useful at petting zoo's where there is a lot of traffic in and out (or which house escape artists).All in all, it's just a standard gate but with the hinge post at an 15 -20 degree angle. The weight of the (wooden) gate will help it swing back shut, and also help with animals trying to shove it back open. We use a gate latch to keep it shut when were not around since we do keep goats :-)
