Degenerative Myelopathy

Canine degenerative myelopathy (DM) is an adult-onset, progressive spinal cord disease causing weakness in the hind limbs and eventually paralysis. Because common spinal cord injuries can mimic DM, a definitive diagnosis currently can only be made by a postmortem examination of the spinal cord. To date, DM has been confirmed by postmortem examination in 17 breeds ([1]).

In 2009 a DNA mutation was found that explained the observed DM cases ([2]). A cheek swab DNA test is available for this simple recessive mutation - meaning that a dog has to have two copies of the DM-allele - one from each parent - to be consider DM-affected (at high-risk for developing DM).

A March 2014 paper in the Journal of Veterinary Internal Medicine ([3]) has reported that this DM-allele has been found in 124 breeds so far.

1. One of the breeds where the DM-allele was found is Norwich terriers. The paper reports that 74 Norwich terriers were tested and 16 were found to be DM-carriers (no DM-affecteds).

2. NTCA member Denise Faulkner has made the DM-carrier status of a Norwich that she owns ([4]) public on the OFA web site (

3. The Norwich Breed Club Health Survey on the OFA web site ([5]) lists one Norwich terrier with DM - although we do not know who the dog is or how the diagnosis was made.

I conclude from this that the DM allele is in the Norwich gene pool, and that I can use the DM DNA test to reduce the chances that I will breed a DM Norwich. All I have to do is never breed a DM-carrier to a DM-carrier. Of course, the only way to know the status of a dog is by testing.

In my opinion, DM DNA testing joins PLL (primary lens luxation) DNA testing as something done by responsible Norwich breeders.

Blair Kelly


[2] Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy that resembles amyotrophic lateral sclerosis, Awano, Proceedings of the National Academy of Sciences of the United States of America, Feb 2009.

[3] Breed Distribution of SOD1 Alleles Previously Associated with Canine Degenerative Myelopathy, Zeng, Journal of Veterinary Internal Medicine, March 2014.

[4] Denwich The Lion Hearted (Leo), RN16047102.