Sensory neuropathy Border Collie type is an inherited progressive neurological disorder which affects the Border Collie breed. Generally, neuropathy is a disease of the peripheral nervous system, which is responsible for sensation feeling to the skin and the muscle control. Clinical signs start from between two and seven months of age and include loss of coordination, joint laxity, lack of awareness where the limbs are in space, and inability to perceive pain. Affected dogs often have self-mutilated limbs, which may be due to tingling or pain in their paws, another manifestation of the disorder. Sensory neuropathy is progressive and as there is no treatment or cure, dogs are usually euthanised for welfare reasons.
The 6.47 Mb inversion in the gene called FAM134B that causes Sensory Neuropathy in Border Collie is Autosomal Recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop FAM134B during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop Sensory Neuropathy as a result of the FAM134B mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop Sensory Neuropathy should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the FAM134B mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Sensory Neuropathy, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.