You don't know that. Animals know when they are about to die, ever been to a shelter on euth day? They know.
Dogs are not capable of abstract thought. Death is an abstract thought. Dogs are, however, very astute at reading body language. It is far, far more likely that dogs in a shelter are reading the body language of the shelter workers, which would be different on the days that euthanizations are carried out. Death may indeed carry a smell which is an alarm call to dogs, I don't know. I do not think that the dogs are capable of conciously thinking "I am going to die today."
Any dog who has been to the vet may be afraid of needles, so even seeing the needle and having fear does not mean they know they will die.
Dogs will act as if they are afraid of death, when more likely they are afraid of the pain most causes of death inflict, or their bodies are chemically reacting to outside stimulus.
A dog may have a gut panic reaction if it is drowning, but it is unlikely it understands that the result of drowning is death. An infant will struggle if it is drowning, but even at 3 years old a child has no real concept of death. If you have ever tried to explain to a toddler what death is, it is quite obvious they cannot concieve of the idea. The body has very strong chemical reactions when it is in danger which have nothing to do with conscious thought. If you would like I can get out my psychology book and point out what parts of the brain are reacting with what chemicals. It is very interesting how much of our actions are unconscious.
Which is exactly why I think shelter/rescue dogs are all the more appreciative of the people who adopt/"save" them. I firmly believe they really do know.
My mom's Rottie was on death row at the pound. That was 10 years ago, we bought him for $5. Best $5 ever spent! He is a love-bug and I truly think he appreciates us.
You have a rott. They are by definition cuddly and human pack oriented. I have seen many paid for bred rotts act the same way.
Dogs from a shelter may or may not be grateful, but again, I do not think that dogs are capable of that level of thought. All of my dogs have been rescues, and some seemed 'grateful' and some not. I think it is more likely that we pick dogs which exibit the behaviors we want. I do not look for really cuddly, 'grateful' dogs, so I usually do not get that show of 'gratefulness'. I rescue dogs because usually I am looking for a performance dog, not a warm fuzzy feeling, so I get more drive and independance than velcro dogs. Tess is certainly a lot better off than before, but she acts as any pit bull of that level of drive and affection would. I could read
she is grateful since she loves to be with us and cuddle, but I do not think that is what it is. My border/lab appeared grateful, but she was just a very human driven, very submissive, needy, cuddly dog anyways, and even if I got her at 8 weeks likely would have been the same.
The anthropomorphizing here is astounding. It really does not hurt anything, but if we are going to talk behavior lets stick with that. If we are going to be emotional, I am more than happy to do that. But the two really have little to do with each other.