If you're like me, you find overweight dogs cute. But canines that are 20% or more over their ideal weight are considered obese and are at risk for some serious health issues. If you're a dog owner whose pet needs to go on a diet, then pharmaceutical giant Pfizer (NYSE:PFE) has some good news for you. Last week, the Food and Drug Administration approved the company for marketing Slentrol, its treatment to help overweight and obese dogs slim down.

Leaving aside that in many cases dogs become overweight from being overfed or underexercised, Slentrol could be used by the owners of the 25%-35% of dogs who are overweight and 5% who are obese. How it causes weight loss is not exactly known, but it's hypothesized that the liquid solution causes dogs to eat less and also absorb less of the food that they do eat into their bodies.

Lest you think that there isn't big money to be made in lifestyle drugs for pets and other animals, in its most recently announced quarter Pfizer had more than $500 million in sales (up 12% year over year) for drugs to treat livestock and other animal disease. Last year, its $2.2 billion worth of animal healthcare products accounted for over 4% of its overall revenues.

With many of Pfizer's pharmaceutical competitors like Abbott Laboratories (NYSE:ABT) and Wyeth (NYSE:WYE) also selling drugs to help pets, it can't be much longer before fat cats like Garfield will also have the option to slim down.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.