Dogs have different eating habits than humans do, but that doesn't mean they can just eat as much as they want. While some dogs can be trusted to only eat as much as they need, others will gorge themselves into poor health if you let them. Monitoring your dog's food intake is one of the most important things you can do as an owner, as it ensures she gets the nutrition she needs without overdoing it.
Basic Calorie Guidelines
No two dogs are the same, period. Your dog's metabolism, exercise level and nutrient processing are uniquely her own, so there are no hard and fast rules governing how much she should eat. One defining factor is the quality of her food -- cheaper brands are generally chock full of fillers and byproducts that don't necessarily provide much energy, while higher-quality brands are nutrient-rich. Defer to the instructions on your bag of dog food, which typically give a weight-based guideline for how much your dog should each daily. It may not prove exact, but it gives you an idea of where to start.
The Exercise Factor
All breeds burn calories in different ways, and this makes a major impact on how much they should eat daily. For example, a sedentary breed like a pug doesn't burn off much energy in a day and can be especially prone to obesity. Bigger, more athletic dogs, on the other hand -- especially ones who get plenty of daily exercise -- can eat more proportionally because they burn more calories. Working dogs like police dogs, for example, may eat around 50 percent more than another dog of the same breed, just because they expend so much energy.
When to Feed
The daily amount of dog food that your pooch consumes shouldn't just be doled out in one big bowl -- for your dog's sake, you should space it out over the course of the day. Generally, dogs should eat twice daily, so divide the total recommended amount of food by two, then feed your dog once in the morning and once in the evening. Some dogs are able to govern themselves if you leave the food out all day, but others will gorge. Generally, dogs benefit from a regular feeding schedule, and you shouldn't just leave food out all the time.
Day After Day
Dogs don't generally require variety in their diets. In fact, dogs prefer consistency on a daily basis, from their walking schedule to what they eat. Once your dog gets used to eating the same food every day, she doesn't just get used to it psychologically -- her body adjusts itself to work with the nutrients it regularly receives. Should you or your vet ever decide to switch your dog's food, it should be done gradually by slowly mixing increasing amounts of the new food with her current diet.