04/23/2023
Diagnostic test results prove that German Shepherd Dog Myelopathy (GSDM) is different than the Degenerative Myelopathy of other breeds. Here, in lay person's language, is the different results shown in diagnostic tests between the Degenerative Myelopathy of German Shepherds, compared to Degenerative Myelopathy in Boxers and Corgis. Clearly, these are two very different diseases!
DM Corgis, Boxers, : motor unit disease
DM GSD: Auto-immune disease
DM Corgis, Boxers : Protein is normal in the AO CSF
DM GSD: Protein is normal in the AO CSF but Protein is elevated in the Lumbar CSF. CSF changes in DM occur in the lumbar CSF and if there are changes in the AO sample, there is something other than DM.
DM Corgis, Boxers: Oligoclonal bands of IgG are uncommon
DM GSDS: Oligoclonal bands of IgG are common in MS
DM Corgis, Boxers: affects cell bodies of neurons
DM GSDS: Does not affect cell bodies of neurons
DM Corgis. Boxers: muscle spams
DM GSDS: no muscle spasms
DM Corgis, Boxers:EMG is affected early in the disease
DM GSDS: EMG is normal
All breeds can get a degenerative condition of the spine, which is both chronic and progressive, called Degenerative Myelopathy. However, the Degenerative Myelopathy of other breeds is not the same disease German Shepherd Degenerative Myelopathy. German Shepherd Dog Myelopathy (GSDM) is unique.
DR Coates has worked under the theory that DM is ALS. Amyotrophic Lateral Sclerosis and related diseases are motor unit diseases where the nerve cells in the body responsible for controlling movement die off leaving the patient weak and with varying degrees of Lower Motor Neuron dysfunction (loss of reflexes and flaccidity) or Upper Motor Neuron dysfunction (hyperactive reflexes and spasticity). Those causing LMN disease affect the EMG early in the course of the disease. Those causing UMN disease result is selective shrinkage of the motor cortex visible on MRI. Neither of these conditions exist in GSDM.
Immune diseases like MS attack varying parts of the nervous system and one of them, Primary Progressive MS, specifically targets the myelin and axons of the spinal cord leading to UMN signs but without affecting the cell bodies of the neurons (which is what is seen in GSDM on histopathology). The CSF protein is usually normal in ALS, but abnormal in MS. Oligoclonal bands of IgG are common in MS and uncommon in ALS. The recessive forms of ALS are extremely slow in development and do not result in shortened life-span. Even the one motor unit disease known in dogs, Spinal Muscle Atrophy in Brittany Spaniels occurs in young dogs with progressive EMG changes leading to death. That might be more consistent with the “early onset DM reported in the GSD which is not the same disease as GSDM on histopathology.
ALS diseases cause motor problems but not sensory ones. That is they do not cause CP deficits or hypermetria (ataxia in which movements overreach the intended goal.). People do not knuckle and scrap their toes when they walk, they only show weakness. Most of them are painful because of muscle spasms. (Does that sound like GSDM?....NO!)
So, even if there is a genetic change in SOD1, Dr Clemmons believes that a change must also be explainable based upon the clinical signs. If not, it may just be a CASUAL relationship not a CAUSAL one! There is a world of difference between the two!!! GSDM as a pure motor unit disease just does not fit all of the available data. (Not just DR Clemmons…everyone's!)
"ALS does not affect a person's ability to see, smell, taste, hear, or RECOGONIZE TOUCH."
You can pinch the foot of a dog with DM, and they wont feel it, so how can this be reconciled with ALS not affecting the ability to recogonize touch?
" ALS Patients usually maintain control of eye muscles and bladder and bowel functions, although in the late stages of the disease most patients will need help getting to and from the bathroom.""
In DM, when the hind end goes, so goes bladder and bowel and bowel control...ask anyone who has had a DM dog if that dog has been able to maintain bladder and bowel control. The answer is "NO!" Again, how can this be reconciled with ALS, when DM dogs lose control of bladder and bowel?
" Not all familial ALS cases are due to the SOD1 mutation, therefore other unidentified genetic causes clearly exist."
unidentified genetic causes --- >Exactly what Dr C has been saying for years...
Only 5-10% of ALS is familial- only 5-10% of people with ALS have a change to their SOD1 gene. Again, is this a CASUAL change or a CAUSAL change? The truth is, no one knows!
"The parts of the body affected by early symptoms of ALS depend on which muscles in the body are damaged first. In some cases, symptoms initially affect one of the legs, and patients experience awkwardness when walking or running or they notice that they are tripping or stumbling more often. Some patients first see
the effects of the disease on a hand or arm as they experience difficulty with simple tasks requiring manual dexterity such as buttoning a shirt, writing, or turning a key in a lock. Other patients notice speech problems-slurred and nasal speech; or difficulty chewing or swallowing."
Interesting- DM always progresses from the rear, moving towards the front of the body. I have never heard of a dog with DM having problems with its front end, front legs, or chewing and swallowing, before it is already down in the rear.
I would be curious to know if anyone knows of a dog definitively dx with DM that was not first affected by the disease in the hind end...2+2 has to=4..... This is more than puzzling, to me. Doesnt it puzzle anyone else?
IMPORTANT FOOTNOTE!
From the OFA "At Risk" explanation of the OFA DM DNA Test!
"recent evidence suggests that there are other causes of DM in some breeds"
DUH! EXACTLY WHAT I HAVE BEEN SAYING!
