Obesity is a common problem in pet dogs and cats. Many pets are mildly to moderately overweight. A good test to determine whether your pet is overweight is to feel along the sides of the rib cage. If you can feel a layer of fat your pet is overweight. If you can't feel the ribs, your pet is obese.
As in people, the condition of being overweight is caused by taking in too many calories and not getting enough exercise. Just like people, pets are born with different rates of metabolism. Neutering does seem to increase the incidence of obesity.
If it is determined that your pet is overweight the first step might be blood testing to rule out metabolic or endocrine disorders. Then a look at the pet's diet is the next step. Is the diet too high in fat or calories for the pet's age and lifestyle? Are you feeding too many treats or extras from the table?
It is likely that a change should be made to a diet that is lower in fat and calories and higher in fiber. Several commercial diets meet these needs including Purina Fit and Trim, Purina One Lite, Cycle Lite, Science Diet Light and Eukanuba Light.
In cases of obesity a recommendation might be made to use a more restricted diet, such as Hill's Prescription r/d, to result in weight loss.
A diet program should include a record of initial weight, the weight loss goal, and periodic weight recording while on the program. The pet should be fed the diet food exclusively with only low calorie treats (commercial products are available and some dogs like frozen vegetables as a treat.)
A regular plan for exercise will benefit your pet and you too!