When dogs know their life is about to end, many of them offer clues through slight changes in behavior and physiology to let their owners know that it’s time to say goodbye.
Solitude

Dogs will instinctively want to be alone somewhere quiet, dark and private when they feel death is near. In the wild, sick or dying animals will retreat away from the pack to avoid being hunted. This ingrained instinct is still hardwired into our domestic pets.
They may try to isolate themselves in the back of a closet, under a bed or table, or somewhere out of the way in your garden. Don’t take it personally that they want to be left alone.
Clinginess

Some dogs become incredibly clingy when they know they’re dying. Your dog may feel weak and defenseless, so they stick by their favorite person for comfort and protection. They want to be with you because you’re their safe space.
This could look like following you from room to room incessantly, even if having trouble walking, or whining if you’ve left the room for a few seconds. Staying by your side allows them to feel close to you, comforting them with your scent and presence.
Appetite

Dying dogs lose their appetite. They will refuse food and stop drinking water altogether. When the body begins to shut down, one of the first functions to go is digestion.
You can try offering them steak, their favorite biscuit, or even attempt feeding them with your fingers. But your dog will most likely refuse them. This is because the body has reserved all of its energy for other functions, and chewing has simply become too difficult.
Energy

Have you noticed your dog sleeping almost all day and all night? They’ll fall into a deep sleep that they won’t easily wake from. Your dog may no longer react to the doorbell or people entering the house. It will feel tired beyond all tired.
Getting up and moving to a new position will require all their effort. During this stage, your dog will slowly slip in and out of a deep sleep, as their body and mind prepare to rest forever.
Breathing

Your dog’s breath may become very shallow, or you may notice they start rasping as their lungs try desperately to clear themselves. Some dogs will even breathe fast for several minutes, then take long periods of time between each breath.
Your dog’s heart isn’t pumping blood as it used to, so their lungs and breathing are affected. This will be one of the first indications that they’re beginning to let go.
Temperature

Have you noticed that your dog’s paws, ears, and tail feel cooler when you touch them? This is because as your dog’s heart begins to fail, it’s unable to pump blood into the extremities of their body.
Instead, it prioritizes keeping your dog’s vital organs functioning, like their brain and heart. You may also notice that your dog’s gums have become a pale color. Try wrapping your dog up with cozy blankets to help warm them up.
Awareness

Dogs who know they’re dying might appear to space out. They may have trouble staying awake, or their eyes may look glassy. You’ll notice your dog will drift into their own world and become oblivious to their surroundings.
When you try to interact with your dog, they may seem indifferent or even confused about where they are. Many dogs seem to disconnect from our world when they know they’re dying.
This may be their minds’ way of detaching themselves from reality so they can pass without fear.
The Surge

Some dogs will experience what is known as the final surge. This happens when your dog has been laid up for weeks without any signs of improvement. Then all of a sudden, they snap back to life.
They may jump up to greet you at the door or even start drinking water. You may even find your dog wagging their tail and grabbing a toy to have some playtime with you.
This is their body’s way of draining the last of its energy. The surge is a gift that allows you to say one last goodbye while your dog is still themself.
Sources: Please see here for a complete listing of all sources that were consulted in the preparation of this article.