
4. Legs Up, Back Down

Similar to the “Crazy Legs” position, this option sees a dog’s front paws laying over their chest while their back legs are extended completely in the air. In this position, a dog can be lying on either their back or their side.
This position may be a sign that your dog is warm and trying to cool down; since a dog’s paws contain sweat glands, and their belly has the least amount of fur on their body, this is the ideal position for bringing down body temperature.
Be aware careful, though — if your dog has their paws curled over their chest while in this position, they are telling you they don’t want to be bothered. They could be on-guard if you try waking them up.
5. Belly Curl

Yes, dogs can be tummy sleepers, too! In the “Belly Curl,” your dog will be sleeping on their tummy, often with their front paws tucked backward.
This tightly-wound position may indicate your pup is not getting the best quality of sleep. According to Dog’s Best Life, this is because the position does not allow for a dog’s muscles to relax enough to enter the deep, REM stage of sleep.
Many dogs who tend to curl are gentle and shy, but they can often be adventurous and sweet animals.
6. Curled Up

Similarly to the “Belly Curl,” dogs in the “Curled Up” position are sleeping in a tight, unforgiving position.
Because this position allows a dog to protect their belly and share heat in a pack, it is the most common position amongst wolves and wild dogs. If you catch your pup sleeping like this, it likely means they are either a bit cold or apprehensive about something, like a new environment or people.
But don’t worry, plenty of happy pups sleep this way! It’s just an incredibly warm, comfortable way for them to nod off.
7. Back-to-Back

If you have more than one dog in your home, you might notice that they sleep back-to-back. Wild dogs tend to huddle to together for protection and warmth in the wilderness, so back-to-back sleeping is an instinctual way for a dog to show you are one of the pack.
Pups can also do this with their human pack, too! According to Dog Time, back-to-back sleeping is a way for your pup to bond with you, showing you that they can trust you 100%. So, if your pup crawls into bed with you and presses their back against yours, they’re just showing you some extra love!
From: http://tiphero.com/7-dog-sleeping-positions/
