Myelodysplasia (spinal dysraphism)

What is ... ?: 

 Myelodysplasia refers to a number of malformations of the spinal cord that occur as a result of  abnormal pre-natal development of the neural tube (which becomes the spinal column). Lesions are most severe in the lumbar (lower back) region. See also spina bifida.

How is ... inherited?: 

In the Weimaraner, the mode of inheritance appears to be co-dominant with variable penetrance. The trait is lethal in the homozygous state (ie. a pup inherits the defective gene from both parents).

What does ... mean to your dog & you?: 

 Clinical signs usually become evident around 4 to 6 weeks when puppies begin to walk around. The signs seen with this condition vary with the severity of the spinal cord malformation. Most commonly you will see a "bunny-hopping" hind limb gait with or without other hind end abnormalities. 

The condition is non-progressive (does not get worse) and mildly affected animals - those with a tendency to bunny-hop and a slightly awkward gait - can lead a fairly normal life.

How is ... diagnosed?: 

 Diagnosis is made based on the clinical signs and by ruling out other possibilities with the aid of tests such as x-rays and cerebrospinal fluid analysis. Diagnosis can also be made on post-mortem, where a veterinary pathologist will find microscopic abnormalities typical of this condition.

How is ... treated?: 

 There is no treatment. The condition will not get worse.

For the veterinarian: 

  Definitive diagnosis can only be made by histopathologic examination of the spinal cord. Lesions are most severe in the lumbar region.

Besides the typical bunny-hopping gait, there may be a crouching stance, abduction or overextension of one or both pelvic limbs, decreased pelvic limb conscious proprioception, or scoliosis. Spinal reflexes and pain perception are normal.

Breeding advice: 

 Affected animals should not be bred.



 LeCouteur, R.A., Child, G. 1995. Diseases of the spinal cord. In S.J. Ettinger and E.C. Feldman (eds.) Textbook of Veterinary Internal Medicine, pp. 629-696. W.B. Saunders Co., Toronto.

What breeds are affected by ... ?