As part of the Degenerative Myelopathy Project, we conducted a survey on Degenerative Myelopathy (DM) in Pembroke Welsh Corgi (PWC) dogs from March 15-October 15, 2001. Thanks to all who took the time to participate and particular thanks to those who have volunteered to help with the next phase of the research. The survey suggests that this condition does exist in the breed. As a result, it will be important to continue with the search for the cause.

Survey forms were printed on green paper and mailed with the PWC Club of America newsletter. A total of 1,232 forms were mailed out. Copying of the survey was encouraged and a form posted on the PWCCA website to broaden the identification of cases, but green form were identified separately for quantification purposes. Click HERE to see a copy of the survey form.

DM in PWCs was reported in most states.

Of the 1,232 green forms mailed 64 were returned for a return rate of 5.2%. Of these 64 forms, 35 (2.8% of the forms mailed) reported never owning a dog with degenerative myelopathy, while 29 (2.4%) reported that they had owned a dog with degenerative myelopathy. Including the forms printed on white paper which were returned, a total of 63 cases of degenerative myelopathy were reported and 46 of these were diagnosed between January, 1995 and December, 2000. We determined the number of PWCs registered during the period 11 years (average age of onset of signs) before these dogs were diagnosed (1984-1991), which were 20,483. Using the most conservative assumption that all dogs who were registered survived to be old enough to show signs of DM if affected and all affected dogs were identified with the survey, this would yield an estimate of incidence of 22.5 affected dogs per 10,000 dogs at risk. This presumes that all the dogs reported as being affected with DM were truly affected, but any error in this direction would be outweighed by the error created by the presumptions stated above. While this incidence rate appears small, if compared to the incidence of other common diseases (such as diabetes mellitus with an incidence of 14/10,000) it is comparable. Affected dogs were reported from most states suggesting that it is not a regional problem.

Incidence of DM in different breeds from VMDB
Rank	Breed	DM	Total	%
-	All	821	432,467	0.19
3(1)	German Shepherd	383	19,053	2.01
6(2)	Cardigan WC	10	664	1.51
16(7)	Pembroke WC	6	1,039	0.58

We also looked at the incidence of DM in different breeds in the Veterinary Medical Data Base (VMDB). This database is a record of diagnoses reported by participating veterinary schools and larger veterinary practices around the country. It represents a somewhat skewed sample, since it represents only cases which are referred to these secondary care centers. It is also dependant upon the code entered by the clinician making the diagnosis. Since the main report of DM in the veterinary literature is in German Shepherd dogs, other breeds may not be given a diagnosis of DM, but may be classified as something like "spinal disease; cause unknown". None-the-less, it gives a general idea of the frequency of a disease. Overall, DM is diagnosed in less than 1% of the dogs seen at these institutions. If we look at the percentages, German shepherds are the third most common breed with about 2% incidence. This is somewhat misleading, however. The breed with the highest incidence was the Ibizan hound with an incidence of 2.3%. This represented only one case of DM, but since very few Ibizan hounds are seen, the percentage was high. If we eliminate those breed where less than 5 cases of DM were reported, we get a more realistic idea of how the breeds rank (shown in parentheses). By this criteria, German Shepherds were the most commonly affected breed. Pembroke Welsh Corgis were the 16th most commonly reported breed overall (6th if breeds with less than 5 cases are exclude). Interestingly, Cardigan Welsh Corgis had an even greater incidence of 1.5% with a rank of 6th overall, and second of breeds with 5 or more cases.

The average age of diagnosis with DM was 11.2 years. The average age of dogs with slipped disks is 5 years.

Other information we were able to glean from the survey was the sex and age distribution and approximate length of illness in affected dogs. The age distribution was normally distributed with a mean age of 11.2 years. There was a bias toward females being affected with 39 females and 24 males reported (ratio 1.6:1). The average time from diagnosis to death or euthanasia in the deceased dogs was 1.25 years.

There was a wide variation in how in-depth of a workup was performed to make the diagnosis of DM. Three cases had no workup done and were not diagnosed by a veterinarian. In these cases, the owner concluded that their dog had DM based on the clinical signs. Six cases were also diagnosed as DM by the owner, but had at least spinal radiographs performed (in one case a myelogram also). Six dogs were diagnosed as DM by a veterinarian without any diagnostic tests. Fifty-two dogs had at least spinal radiographs performed, and twenty had myleograms. Sixteen had advanced imaging such as MRI or CT performed, while only two had necropsy confirmation of the diagnosis. As discussed above, this means that some of these cases may have had intervertebral disk herniations, spinal tumors, or some other cause of their weakness, but these errors would be balanced by the cases of DM from dogs who did not participate in the survey.

Accurate diagnosis of the disease affecting the individual dog will be critical to the success of the next phase of the project to characterize the disease in the breed and search for clues to the cause.

Some caveats about this type of survey. A voluntary mail-in survey such as this is not a scientific accurate survey. It requires people to subscribe to the newsletter or hear about the survey through other sources to participate, thus it is not a random sampling of PWC owners. People who have had an affected dog may be more atuned to the disease and more likely to participate in the survey. Conversely, some people may not want to admit to a problem in the breed and avoid the survey as a result. Since we rely on the opinion of the person filing in the survey whether or not their dog had DM, we cannot verify that these dogs were truly affected. Thus this survey only provides a rough estimate of the magnitude of the problem in the breed. To conduct the type of survey that would produce a scientifically valid incidence survey would be expensive and time consuming. We felt that this type of survey would at least provide us with some idea of the magnitude of the problem in the breed, but the limited research resources were better spent on investigations into the cause of the disease.