Puppies shiver for a variety of reasons, some normal (even beneficial) and some potentially hazardous. Puppy shaking can be a sign of happiness, coldness, active dreaming, or illness and it is important to know which your puppy is experiencing. Understanding why your puppy shivers can help to provide the best care possible and to allay any fears you have.
My puppy keeps shivering
If your puppy shivers in his sleep, it may be the result of intense dreaming. After 20 minutes asleep, your puppy will fall into a deeper rapid eye movement (REM) sleep, during which dreams are normally experienced. Although puppies only enter into this deeper state of sleep for short periods, they are sufficient to produce shivering, vocalizations and body movements. If this is the case with your puppy, the shivering you witness is completely normal and you don't need to intervene.
Puppies do not reach their normal temp of 101.5 until 2 - 3 weeks of age. As a result, they begin to shiver a lot at around this age as a way for the body to warm itself (just as in humans). Before then, they are unable to shiver and are at risk of hypothermia, which is why their mother (or you) must provide all of their warmth for them before they reach 3 weeks or so. Afterward, they are more able to warm themselves (to an extent) via shivering when their body temperature falls below normal. While it is not abnormal for puppies to shiver when cold, take steps to warm your dog or the area where he spends most of his time if you find that he's shivering too frequently. Try using heating pads, hot water bottles, a heat lamp or extra blankets.
So much excitement
Excitement is a normal reaction when your puppy greets you on returning home, or sees his mother or siblings after being separated. Shivering or trembling is a natural byproduct of overexcitement. When excited, your puppy may exhibit all manner of frantic behavior including jumping, barking, urinating and shivering or shaking violently. While it may seem scary at first, there is nothing wrong with the puppy.
An illness indicator
A puppy shivering and lethargic may be ill. Puppies who have not yet had all her shots will sometimes exhibit shivering as a result of illness. Distemper is one of the most common causes and is the result of a virus. Because a puppy's ears aren't fully formed at birth they can be susceptible to ear infections, which might cause a puppy to not just shake his head, but his whole body. You might also notice your puppy shivering after shots. As in humans, puppies can shiver when they have a fever. Seizure disorders can also lead to twitching and shaking.
Generalized tremor syndrome (GTS) can begin in puppies as young as nine months and is most often diagnosed before a dog is two. Steroids like prednisone can help reduce the shivering and trembling from this disease.
Sometimes your puppy may eat something that does not sit well in his system. A dog that is shaking can occur along with nausea in these cases. Poisoning can also cause shivers and may occur if your puppy ingests anything hazardous or toxic. Contact your vet immediately if you suspect your puppy's shivering is due to an illness.