Pets In Your Garden
There are two general issues to consider when you have pets and a garden landscape: keeping pets from harming your landscape, and keeping the landscape from harming your pets.
Dogs and cats will use the yard to releive themselves, and this will cause problems, as larger dogs can leave enough urine in one spot to kill off the grass. Some veterinarians might have dietary suggestions that can help remediate this issue. Cats have a strong tendency to favor recently-turned bare soil for use as a litter box. As a rule, you should never leave bare soil uncovered. Cats are less likely to use beds mulched with pine straw.
The SPCA has an excellent list of plants poisonous to cats and dogs.