The long-term effects on your pet's health and lifespan could be disastrous and pet obesity has the potential to make existing health problems and concerns worse. It is important to keep in mind that obesity can also play a role in the length and quality of your pet's life span.
Putting your pet on a diet is a lot easier than doing the same to yourself. Your pet can only eat what it's given, so you can take control of the situation. The weight of your pet is essentially your responsibility,
Rub your pet gently over their ribs, you should be able to feel them without any trouble and the skin should move over the ribs quite easily. Then take a look at your pet from the side from a few feet away. If your pet has a hanging stomach and looks like it could be expecting some babies, then it's definitely time to introduce a diet.