Just because you bought it "on the road" doesn't mean it is deductible. The IRS will look at whether or not the item in question is necessary for the performance of your job...things like work gloves, work boots, safety glasses, maps, etc. If it is not necessary, it is not deductible. In your example, deducting your dog's food is asking for trouble unless it is certified as a guard dog, service dog, or some other "necessary" use. Just 'cuz he's your little buddy and you want him riding shotgun to keep you company does NOT make his supplies "necessary" for the performance of your job. Same with the DVD's...asking for trouble if you're ever audited. Unless they are training or instructional videos directly related to the job, they aren't deductible. Your food...groceries, prepared meals, etc...also isn't deductible, because that is covered in the per diem deduction for nights spent on the road.
...and if you are actually getting $4-5K back, you should claim a few more deductions so that your employer withholds less from each check. That $4-5K refund check would be an extra $300-400/month in your paycheck if you weren't giving the government an interest-free loan. What could you do with an extra $300-400/month?