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DEGENERATIVE MYELOPATHY - DM
- validated in Pugs by DNA-tests and postmortem examination of spinal cords


www.eddieswheels.com - with a link about DM

DM Degenerative Myelopathy - sometimes referred to as CDRM - exists among our Pugs and resembles the human diagnose MS - but DM-researchers have compared it to ALS, as it is caused by a missense mutation SOD1 - one DNA-base is changed to code for a different amino acid which builds a defective protein. It is a neurological disorder (and it is not caused by skeletal malformations or other).

"Pug wobbling" and "Alsatian wobbling" is the same chronic neurological disorder and affects many other breeds. According to the patent application DM-researchers have genotyped more than 6 600 DNA-samples from dogs in a collection at the University of Missouri. The marker SOD1 A was found in 57 of 147 breeds and in mixed breeds. It was found in 23% of the samples from French Bulldogs and in 38% of the samples from Pugs. This mutated allele A is assumed to be of autosomal recessive inheritance with an age related incomplete penetrance.

See many other doggie breeds using rear wheelchairs on eddieswheels.com with a link to DM - let's just hope they won't be needed in the future! DM is a difficult thing for owners to cope with to avoid euthanasia - and breeders must realize, that the solution to the problem is their responsibility. In the patent application the DM-researchers point out, that it will take at least ten years to breed out DM, if the breeders start using marker-based breeding - and in the meantime many thousands of privatly owned dogs will develop symptoms with progressing age.

The DM rear weakness usually shows little by little and is to start with not painful. The reflex movements slow down and typically the dog drags its hind leg paws to the ground, so that the claws are worn on the top surface. The dog does not seem to be in pain. The gait gets wobbly and the dog loses balance at sharp turns and falls down with the rear end. In the terminal phase, which may last several years, the sense of feeling is lost completely and then the dog loses control over bowel and bladder.

There is a breed disposition for DM in Pugs, but because symptoms show up late in life between the ages 5-14 years, the carriers unfortunately may have been used for breeding. Of course, two Pugs should never be mated in case both of them have close relatives showing symptoms of DM or CDRM with a progressive rear weakness or hind leg paralysis.

Now an American research team, among them the Swedish microbiogeneticist professor Kerstin Lindblad-Toh sponsored by the AKC Health Foundation and many Breed Clubs, has identified a defect gene - called A - that causes Degenerative Myelopathy in many different breeds, among others French Bulldogs and Pugs. The normal, not mutated allele of the same gene, by the research workers called G - is now called N=Normal in the OFA statistics. All dogs tested with symptoms of DM have carried the gene combination A/A and have consecuently inherited the defect gene from both parents: both the sire and the dam have been carriers of Degenertive Myelopathy. Dogs DNA-testated with the gene combination A/N have shown no apparent symptoms, and have been hidden carriers. Every dog tested with the gene combination A/A has not yet developed symptoms, but is at risk doing so with progressing age.

This defect-mutated gene can now be identified by a simple DNA-sample on a FTA-card, now for sale in the OFA webshop - click on these two banner links below for info. It is a buccal saliva sample, see photos for cells from the inside of the cheeks, which can be collected by the owner without veterinary assistance. The FTA-cards are sent to the research lab by mail in an ordinary letter.




OFA statement: "Although any dog can be tested for DM, it is possible that the genetic background that predominates in some breeds prevents the development of symptoms even in dogs testing affected (at risk). At this time we are reluctant to recommend testing for members of breeds where the University of Missouri has not yet proven susceptibility to DM through microscopic examination of spinal cords from deceased dogs that exhibited symptoms of the disease. At this time the required evidence of association between the genetic mutation and actual spinal cord evaluations (has been verified in Pugs, but not yet in a French Bulldog)."


The defect mutation in DM - Degenerative Myelopathy causes a progressive rear end weakness and hind legs paralysis, which sooner or later leads to euthanasia. This condition is called 'wobbling disease' and affects many breeds, incl. French Bulldogs and Pugs - so far 82 Pugs have been tested according to OFA's statistics. 26 of them (32%) carried this mutation from one parent A/N and could pass it on to its offspring. Four Pugs (5%) carried the mutation from both parents A/A and are "at risk" to develop symptoms with age.

Until now such a progressive weakness in the rear parts has been regarded as mostly due to natural ageing, because dogs are affected late in life, usually between 5-14 years old.

Ataxia, gait disturbances and muscle attenuation can of course have many other causes, - like an anatomically too short back and neck - or various orthopedical skeleton defects, HV HemiVertera, or ruptured prolapsed discs, etc.

A team of American and a Swedish biogeneticists now has discovered that the disorder DM is genetical and inherited - and from 2009-03-04 OFA distributes and registers the results of a simple and inexpensive FTA-card DNA-test kit to detect if a dog carries this defect gene, called A or its normal allele by the research team called G, but now in the OFA statistics called N=Normal. An affected dog (A/A) has inherited the mutation from both its parents.

- A dog affected by DM carries the gene combination A/A and carriers without symptoms have the genes A/N. A dog affected by DM in its old age has consequently given this defect mutation A to all its puppies earlier in life. All offspring by a DM-affected dog are at least hidden carriers - even if they should never show any symptoms of DM in their lifetime. - Dogs DNA-tested free from DM carry the gene combinaton N/N -

OFA: Explanation of DM DNA Test Results
OFA DM Test Results by Breed


 
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