I entered a toll booth on the New Jersey turnpike, and the attendant practically reeled backward, making a face.

“What do you think it’s like inside here?” I asked him.

I was traveling to training grounds and had six dogs along with me. One of them had arrived at my house just a few days prior. Just before her owner brought her to me, he changed the dog food she’d been eating; reasoning, that with her ramped-up schedule of training, she should have a food with a higher amount of protein.

He’d made a basic mistake. When you change a dog’s food, you must do it gradually. For example, if a dog is eating one cup of kibble two times a day, you can change that to ¾ cup of the original food, with ¼ cup of the new food, and gradually change the percentages.

Due to the sudden change in her food, the dog was having a canine gaseous emission problem. In the confines of my Chevy suburban, conditions were brutal.

The choices available for dog food can be overwhelming, and the advertising designed to appeal to that part of us which admires our pets’ wild canine heritage. If you’re to believe commercials, wolves and domesticated dogs enjoy running together. I wince when I see that type of advertising – in the real world, a wolf would see the pet dog as an easy meal.

So, what’s good, and what’s bad? Let’s work with myths and facts.

Myth: Dogs are carnivores and should be fed a meat-based diet; perhaps even raw meat.

Fact: Even wild carnivores don’t do this. I read a study about coyotes, where scientists examined the stomach contents of more than 50 coyotes. There were more than 60 “items” found, including meat, but also plenty of vegetative matter, berries, and in one case, an unopened tuna can. Domestic and wild canines are omnivores.

The folks at Purina have been conducting research on dogs (cats, and many domesticated animals) and developed a dog food manufacturing process designed to increase the digestibility of protein by gelatinizing the collagen. The process also increases the digestibility of grains and starchy foods.

Myth: Grains are just used as “fillers” in dog food. Dogs can’t digest grains to use as energy.

Fact: Grains are a nutritionally valuable ingredient in dog food, as they are an important source of many nutrients such as protein, fiber, essential fatty acids, B-vitamins and minerals. Grains can also provide a source of readily digestible carbohydrates, helping to meet a crucial physiological need for glucose, the most important energy source for all cells in the body.

Well, if that’s true, why do Purina and other dog food companies make a grain-free food? Companies have done this for those dog owners who are selective about particular ingredients and choose to feed an appropriate grain-free diet. There are grain-free formulas that are nutritionally complete and balanced.

Myth: By-products are just cheap, low-quality fillers used in dog food.

Fact: By-products are a common ingredient in dog food and can provide a highly digestible and nutritious source of protein and essential amino acids, vitamins, minerals and healthy fats. By-products – often manufactured from organ meats such as livers and kidneys - can deliver more essential nutrients than regular muscle meat. Foods made with by-products also are more sustainable, allowing the use, rather than the waste, of nutritious components.

Is your canine hunting companion properly fueled for hunting season? If you plan to make a change, start now – it could take at least a month for a dog’s system to adapt to change.