Shaking puppy syndrome, formally known as hypomyelination, affects a young dog's central or peripheral nervous system. The shaking involves the entire body. Since the tremors begin not long after birth, it's unlikely your puppy would experience this disorder unless you were the breeder. Since the vast majority of puppies recover and go on to lead normal lives, ask the breeder of any puppies you are considering if shaking puppy syndrome occurred in your prospective pet.
Hypomyelination in dogs
Myelin insulates and protects nerve cells. It also allows the electrical impulses and signals to travel to and from the brain and spinal cord. If a puppy's body is deficient in this fatty protection in his spinal cord, hypomyelination occurs and the transmission of electrical signals slows down. Shaking is one of the resulting symptoms.
In most breeds, it appears hypomyelination is inherited as a sole gene defect as an autosomal recessive condition. Inheritance of the disorder is not fully understood, but since males more often develop shaking puppy syndrome than females, it may be a sex-linked trait in some breeds.
If you intend to breed your dog and there's a breed predisposition to the syndrome, have a DNA test prior to breeding. Healthy dogs may still carry the defective gene and should not be bred. Dogs that have this disorder should not be bred.
Breeds affected by hypomyelination
Hypomyelination is hereditary, and certain breeds are predisposed to the condition. These include the springer spaniel, Australian silky terrier, Weimaraner, golden retriever, Catahoula cur, Dalmatian, chow chow, Welsh springer spaniel, vizsla, Samoyed and Bernese mountain dog. That doesn't mean that other breeds, or mixed breeds, can't suffer from the disorder.
Golden retrievers inherit a form of hypomyelination involving the peripheral nervous system, rather than the central nervous system. They exhibit all of the other symptoms common to hypomyelination but don't actually shake. The disorder appears somewhat later, between the ages of 5 and 7 weeks.
Of all breeds and sexes, male springer spaniel puppies suffer the most, because the form of genetic transmission is different in this breed. While affected female springer spaniel puppies eventually recover, males do not. They generally die by the age of 6 months. The male springer pups may die after becoming symptomatic, or the breeder may choose to euthanize them if the tremoring is especially severe.
Shaking puppy syndrome symptoms
Symptoms of shaking puppy syndrome occur about the age of 2 weeks, or when the affected puppy starts walking. Shaking and tremors are most visible in the hind legs. Besides the puppy trembling or shaking, the puppy has issues with coordination and balance. His legs appear wide-based, rather than normally positioned. He may have an uncoordinated walk and may drag his feet.
In severe cases, the trembling may make it difficult for the puppy to nurse. Excitement makes the shaking even stronger. Puppies also shake more when eating, but the tremors subside a great deal when the puppy is sleeping. Once he's awake, the shaking starts again. Mentally, the puppy seems fine.
Diagnosis and prognosis
Your vet diagnoses shaking puppy syndrome based on clinical signs, and the results of blood and urine testing. If you want an absolutely conclusive diagnosis, the vet must conduct a nerve or brain biopsy. There's no actual treatment for hypomyelination.
Fortunately, most affected pups eventually recover and are fairly normal by the age of 12 to 18 months. Less severely affected puppies are pretty much back to normal by the age of 3 to 4 months, although any dog who survives shaking puppy syndrome may have mild hind leg tremors for the rest of his life.