You may want to create an enclosed area so that your pet is limited to one part of your garden and is safe from predators. Make sure that it includes a shaded area so that he has a place to retreat to when the sun is too intense. Make sure as well that there is fresh water always available and that it can't be knocked over.
Know which plants in your garden are toxic. Most animals seem to know what plants are poisonous and when they do eat the wrong thing, they usually spit it back up in pretty short order. But if you know what plants are toxic, you can take steps to keep your pets away.
There's a greater chance that your pet could be poisoned by fertilizers and soil amendments than by toxic plants, so keep all containers of pesticides and fertilizers safely out of your pets' reach. Don't assume that even organic products are safe. Amendments like bone meal, blood meal, fish emulsion, and cocoa bean hulls used as mulch can smell very appealing but can make an animal very sick.
Keep other animals safe from your pets. Adding a bell to your cat's collar can make it harder for him to attack songbirds. It may also be necessary to keep pet chickens in a separate part of the garden or install a barrier to a pond containing fish.