I know what you mean. I lost Fletcher (11 yr old) three weeks ago, and Molly, also 11, has been a bit off. She is not obviously grieving, they got along fine but weren't close, and I have another greyhound. However, I believe part of her behavior is related to the change in the household, I am certainly still grieving, and I know she picks up on that. She has been doing that panting thing, but I am fairly sure it is related to the heat, even though she doesn't go out for more than a few minutes at a time. She is also getting more wobbly, although she doesn't have corns. I am going to see if her vet can see her next week, just to do a general checkup. You know your dog best, and if you feel there is something off, there is, although it may just be corns and age. It wouldn't hurt to have a checkup done, to ease your mind if nothing else.