Not monitoring your pet/s carefully.
It is important to monitor pets on a daily basis. Pets are so good at hiding their illnesses, that often by the time we notice anything seems odd, the disease may be quite advanced. For this reason,  it is important to look for early signs of problems.  Monitor your dog’s urinations, defecations, attitude and appetite every day. If there is any change, and it lasts more than 24 hours, bring them to the vet for a checkup.

*Not pet-proofing you home properly.
In the same way that a house has to be baby-proofed to avoid a child hurting itself, humans need to keep items dangerous to pets out of their reach. There are many toxins in our home, such as rat poison, anti-freeze, medications (dog and human) or the trash, filled with dangerous items like chicken bones, string, rubber bands, and so on.
The same is true of the garden. Be extra-vigilant about pesticides, ‘repellent’ designed to stop pets from inappropriate urination, and so on.