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).
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.
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.