I have 2 8 month old catahoula bulldogs who for the first 6 months of having them had an intense appetite, would eat their meals (3 times a day) in literally minutes... as of about a week ago their appetite has really subsided, not only do they not eat nearly as quickly, half the time they don't appear interested in eating their food at all... I called the vet to get his thoughts on this, he advised that it could just be a bad bag of dog food, so I bought a new one, same results...could this just be a phase of some sort?