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DEGENERATIVE MYELOPATHY - DM

DM Degenerative Myelopathy - sometimes referred to as CDRM - exists among our Frenchies and resembles the human diagnose MS - but DM-researchers have compared it to ALS, as it is caused by the 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).

French Bulldog Club of England Health News
New DNA Testing Scheme 22 July 2016


"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 happy doggie breeds with rear wheelchairs at eddieswheels.com - let's just hope they won't be needed in the future! DM is hard for owners to cope with to avoid euthanasia - and breeders must realize, that the solution to the problem is their responsability. 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 rear weakness in DM is noticed little by little and it is to start with not painful. The reflexes get slower and typically the dog starts dragging the rear paws to the ground, so that the claws are worn on the top surface. It doesn't seem painful. The gait gets wobbly and the dog loses its balance at sharp turns and falls down on the hind legs and then developes a paralysis. In the terminal phase, which can take several years, the sense of feeling is completely lost and the dog then loses control over bowel and bladder.

There is a breed disposition for DM in Frenchies, but as the symptoms show up late in life between age 5-14 years, the carriers unfortunately may have been used in breeding. One should of course never breed two Frenchies, in case both have near relatives who have shown symptoms of DM or CDRM with a progressive weakness in the hind legs.

Now an American research team, among them the Swedish microbiogeneticist professor Kerstin Lindblad-Toh, sponsored by the AKC Health Foundation and many Breed Clubs, such as the FBDCA have identified the defective gene - called A - which causes Degenerative Myelopathy in a great number of breeds, among others the French Bulldog. The normal, not mutated allele of the same gene is called G by the researchers - but it is now called N=Normal in OFA's statistics. All the DNA-tested dogs with symptoms of DM so far had the gene combination A/A and have inherited this defect mutation from both its parents: the sire and the dam have both been carriers of Degenertive Myelopathy. Dogs DNA-tested with the gene combination A/G - now called Carriers A/N in OFA's statistics - usually have not shown any symptoms of DM, and have been hidden carriers. All dogs DNA-tested with the gene combination A/A have not developed symptoms, but are at risk doing so with progressive age.

This defect gene allele can be detected by a buccal DNA- sample on a FTA-card, now being sold in OFA's webshop - read more by clicking on these two banner links below for information. It is a simple saliva sample, see photos for cells from the inside of the cheeks, which the owner can collect without veterinary assistance. FTA-cards are mailed to the research lab by 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 up to date been proven f.ex. in a Pug but not yet in a French Bulldog)"

According to the Breed Statistics published by OFA 22 French Bulldogs - 4 of them (18%) carried this single gene mutation A/N - have been tested so far. Three (14%) had the double gene combination A/A and are "at risk" to develop symptoms with age.


The defect mutation DM - Degenerative Myelopathy causes a progressive weakness in the rear end, which sooner or later will lead to euthanasia. This suffering often called 'Wobbling disease' is found in many dog breeds, including French Bulldogs and Pugs.

This kind of hind leg paralysis has been presumed to be mostly due to natural ageing, because dogs show symptoms of DM late in life, between 5-14 years of age.

Ataxia and gait disturbances with muscle attenuation can of course have other causes, such as an anatomically too short back and neck, as well as various skeleton malformations, HV HemiVeterebra or a prolapsed disc rupture, etc.

Swedish and American biogeneticists now have found, that the disorder DM is genetical and inherited and from 2009-03-04 a simple and inexpensive DNA-test kit is availible from OFA to detect if a dog is carrying this defect gene, called A or its normal allele, by the research team called G, but in OFA's statistics called N. An affected dog (A/A) has inherited this allele from both parents and has given it to all its descendants in breeding.

- A DM-affected dog always has the gene combination A/A and carriers without symptoms have the gene combination A/N. A dog getting DM in his or her old age has given the defect gene A too all its puppies earlier in life. All of them are at least hidden carriers, even if they should never show any symptoms during their lifetime. - A dog DNA-tested free from DM carries the gene combination N/N -

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


 

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