An Uncommon Disease, Myelomalacia
Myelomalacia – The Hidden Threat
by Laurie Miller, RVT
In my 25+ years of clinical experience as a registered veterinary technician, I’ve found that Myelomalacia, although rare, is a devastating disease when it strikes your pet. Myelomalacia refers to a condition in which the nerve tissue of the spinal cord begins to die. It is most commonly associated with a severe, acute, spinal cord trauma.
It is a fairly rare finding in IVDD dogs who have ruptured a disc, but when a dog has had a very severe, traumatic rupture, Myelomalacia is always a potential complication that must be considered.
The typical clinical presentation of a dog who is at high risk for myelomalacia is one who has had an acute onset of paralysis with sudden loss of deep- pain recognition. These dogs may also have ascending or descending signs of lower motor neuron dysfunction, meaning that their cord is no longer transmitting or receiving signals from muscle tissue.They will be flaccid above as well as below the disc rupture. (Not typical of most common intervertebral disc who are just numb below the rupture site.)
On occasion, these acute ruptures will also be accompanied by fever and will be very painful when manipulated, especially above the area of the rupture, to the point that the dog will attempt to bite.
More commonly though, myelomalacia does not show up for several days after an acute rupture. Even when surgery is performed, the cord may or may not give a visual clue as to what is coming.
In extreme cases, the surgical site will be heavily bruised and the cord will appear blue at the rupture site and on either side. The surgeon may open the dura (outer covering of the cord) to explore its condition further. In cases of myelomalacia, the cord may already be liquefying and when the dura is opened, the damaged cord material will simply run out. This is a case where it is necessary to euthanize on the table.
Unfortunately, myelomalacia may take time to progress. In these cases, sadly, the pet will seem fine post-operatively or with conservative treatment, and appear to be doing relatively well for a few days after the rupture. Then, as the death of the cord moves forward, the pet will become increasingly painful and sick. In my experience, this scenario takes place anywhere from 5 to 7 days after the initial rupture. No amount of pain medication alleviates these pets’ pain.
As the cord death moves towards the head, it will eventually reach the diaphragm and cause paralysis which leads to the patient’s death. The most humane option is to euthanize these pets as once the progression starts, there is nothing that can be done to stop it.