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(MUO) in dogs. MUO is an autoimmune different mutation is responsible for DM in Bernese
condition striking mostly small dogs suddenly, Mountain Dogs).
causing brain and spinal cord inflammation and
affecting coordination, balance and mobility—- In the current study, Joan Coates, DVM, MS,
and its incidence is increasing. It has been called DACVIM, at the University of Missouri, sought
canine multiple sclerosis. Its cause is unknown, to determine how the SOD1 genotype affects the
but there appears to be a link with changes in the risk of developing DM in different breeds. They
gut microbiome. Jeffrey has found that dogs with found no difference in probability or age on onset
MUO have different levels of Prevotella microbes attributable to sex. Of the more than 2000 dogs they
compared to controls. Unfortunately, it’s not compared, they only had sufficient numbers (more
practical to give dogs Prevotella, but in his new than 100) of Ridgebacks, Boxers, Bernese Mountain
study he is giving it through pills containing fecal Dogs, German Shepherds, Chessies and Pembroke
matter from dogs with high levels of Prevotella. It’s Welsh Corgis. (Borzoi, Poodles and Cardigans
too soon for results, but if positive, it may open the had more than 50 dogs, followed by Bloodhounds,
door for treating MUO. Canaan Dogs, Kerry Blues, NSDTRs (all more than
30), Shiloh Shepherds and Puli (15 or more)). Of
DEGENERATIVE MYELOPATHY the six major breeds, Ridgebacks developed DM at
Degenerative myelopathy (DM) has a late onset the earliest age. Overall, by 12 years of age, over 50%
of homozygous at-risk dogs developed a DM-like
(9-14 years) characterized by progressive hind limb disease and over 60% developed signs when older.
weakness that progresses forward to the point the Heterozygotes had an increased risk of developing
dog can’t walk within a year; eventually the dog DM before 12 years of age, but even so fewer than
is completely paralyzed and loses the ability to 5% developed signs by 14 years of age.
swallow or breathe. There is no treatment.
As canine DM represents the best naturally
Since the SOD1 mutation and resultant DNA test occurring model of human ALS (Lou Gehrig’s
for DM was discovered over a decade ago, there’s disease), a major goal to help both dogs and people
been increasing interest— and misunderstanding— is to use dogs as models to develop therapies. Since
regarding testing. In a recent survey of 152 genetic DM dog spinal cords contain a type of SOD1 that
disease variants looking at more than 100,000 correlates with disease severity, Coates hypothesized
dogs, the DM (SOD1) mutation was ranked #1 in that perhaps using selective messenger RNA
disease allele frequency in both mixed breeds (8%) targeting could slow or stop SOD1 production.
and purebreds (5%). Dogs homozygous for the Introducing MRNA to the part of the nervous
SOD1 mutation are AT RISK for DM. Not all will system presents difficulties, but they tried several
develop it, and the risk varies depending on breed, techniques on dogs. Seven affected dogs completed
with some breeds having a high risk and others a the clinical trial, which lasted one year during which
very low to almost nonexistent risk. This leads to the dogs received the treatment monthly while
speculation about other genes that might also need under anesthesia. Their gaits were evaluated on a
to be present, or even environmental factors. To standardized rating scale by researchers blinded
further complicate matters, carriers in some breeds as to their treatment group. All dogs continued
(Ridgebacks, Chessies, Bernese Mountain Dogs, to worsen, but the median time it took them to
German Shepherds, Australian reach non-ambulatory stage was longer in treated
Shepherds, Alaskan Huskies, and some mixed dogs compared to historical controls. However, the
breeds) sometimes also develop signs of DM, difference was not statistically significant.
though they tend to do so at a later age. (Note that a

Originally published October 10, 2021 in The Canine Chronicle - www.caninechronicle.com

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