Hypo-Dysmyelinogenesis (Shaking Pup) in Dogs

The lack of the production of a substance known as myelin is the cause of Hypo-Dysmyelinogenesis as it serves a vital function for the nerve cells. Acting as an insulator protecting the nerve from outside effects, it helps to forward cellular communications of the entire central nervous system (CNS). Puppies born with this condition usually exhibit the shaking after the first week or two of life, with the symptoms affecting the hind legs at first. After the nursing period, they will need to be fed on their own as siblings will compete for food in bowls, overpowering the slower pup.

Some breeds of dogs seem more affected than others, such as Golden Retrievers, Welsh Springer Spaniels, Chow Chows, Weimaraners, Dalmatians, and Samoyed breeds. Your male pup has a higher rate of this condition.

Hypo-Dysmyelinogenesis is a congenital condition caused by lack of myelin in the body, a fatty substance providing protection and pathway for cellular transmissions within the nervous system.

This condition affects both the central nervous system and the peripheral nervous system, initiating differing symptoms in both cases. 

• Head tremors
• Leg tremors
• Balance problems
• Coordination is lacking
• Absence of reflexes
• Muscle atrophy
• Abnormal stance
• Convulsions, in some cases

Types

• Hypo-Dysmyelinogenesis is a disorder of the myelin development 
• There are two possible pathological classifications 
• Thinly myelinated axons that have mostly normal myelin with some non-myelinated axons
• Thinly myelinated axons with abnormal myelin and mostly non-myelinated axons
• The axons are the area of the nerve cells where the transfer of impulses to other cells in the body occur

• Your dog’s tremors will increase when your dog is excited or during active phases, where the shaking will be quite pronounced but they will subside or stop altogether while your dog sleeps
• It has been proven to be a CNS genetic recessive disease in the Springer Spaniel and some other breeds such as the Golden Retriever and the Welsh Springer Spaniel 
• Viral or toxic sources seem to be the agreed source for other breeds 
• PNS disease is suspected to be genetically based
• Within the CNS, clinical symptoms appear within days of birth
• Shaking appears to worsen with activity, and decrease with rest 
• Symptoms will improve with age in most breeds 
• Springer Spaniels and Samoyeds are affected for life
• Peripheral nervous system (PNS) symptoms appear around the age of 5 weeks
• The rear legs will show signs of incoordination and weakness
• Your puppy will have below normal or absent reflexes
• Muscle wasting will become obvious

Once you are alerted to your dog’s condition, and have booked your puppy or dog in for an examination your veterinarian will want to know your dog’s genetic history. If you can compile as much information as possible it will help the specialist in his diagnosis. The normal tests your specialist will run on your dog will include a blood profile, chemical blood profile and a complete blood count. The veterinarian will also include a urinalysis test to help him to find out the reason for your dog’s condition. 

A sample or biopsy of nerve tissue will provide the information about the amount of myelin at the axon of the nerve. There are other tests that your specialist may choose to carry out to enable him to provide a conclusive diagnosis. These include an electromyography to measure the electrical activity to calculate the potential of the nerve cells. 

Your veterinarian may also decide to perform a brain biopsy. It is a hard to determine condition, with some puppies growing out of it and leading normal lives after a year or two. For the severely affected animal the prognosis is not good and for all pups born with this condition, it can be passed to the next generation so breeding with these animals is not advisable.

There is no treatment for this condition, although some puppies that are born with Hypo-Dysmyelinogenesis do grow out of it and lead long healthy lives. Other dogs learn to live with the condition, with the shaking more noticeable when they are active or excited. Sadly, those that are born with severe cases of this condition do not live a long life, or are put to sleep out of kindness to their condition. Even if your dog grows out of it, the general consensus is that it is best not to breed from these dogs, as there is a very high possibility that they will pass the condition onto their young. If you have a puppy that has this condition and you decide to keep him, he will need help in feeding once he is passed the nursing stage, as his siblings will overpower him and he will get left out of the feeding frenzy. 

As with all puppies, the little shaker will need plenty of nourishment to grow stronger and help him to develop. Many puppies who have had a start in life with this condition have gone on to become beloved pets that are raised in a caring way and have eventually outgrown the shakes and tremors. A lot depends on the severity of the case and how much your dog is affected. Given time, some less affected dogs develop and grow out of this condition by 12 to 18 months of age.

A young puppy born with hypo dysmeylinogenesis needs solid support. If it is a mild case, then the chance that he will grow out of the tremors and shakes is high. Additional feeding will be necessary to raise him to become stronger and healthier. Management of your dog’s condition requires providing a calming environment and preventing your dog from over excitement which is when the shakes and tremors will really intensify. Providing a loving environment and gentle stimulation rather than loud activity is preferable.

Because of the strong probability that dogs with this condition will pass on this condition to their young, it is recommended that dogs with this condition are not used for breeding.  While there is no known cure for this condition, prevention involving selective breeding for inheritable syndromes, and immunization to prevent viral-induced syndromes is vital to prevent this condition being passed onto the next generation.