"Leonberger dogs may suffer from neuromuscular disease collectively termed Leonberger Polyneuropathy (LPN). LPN affected dogs may suffers from slowly worsening exercise intolerance and develop gait abnormalities, such as an exaggerated hitched step, especially in the hind limbs. There is often wasting of the hind limb muscles as well. Additionally, these dogs may have noisy breathing, a change in their bark, or even difficulty breathing due to involvement of the larynx and laryngeal folds in the throat. Eventually the disease may progress to the point where the dog cannot support its own weight and surgical intervention for laryngeal paralysis may be required. Biopsies of nerve from affected dogs show degradation of the nerve fibers and loss of myelin, the insulating material that normally helps speed messages along nerves. Muscle biopsies show atrophy resulting from nerve loss. Research carried out at the University of Minnesota, the University of Bern, and the University of California, San Diego - Comparative Neuromuscular Laboratory indicates that polyneuropathy within the Leonberger breed is a group of several genetically distinct, but clinically similar diseases. We have mapped two major genetic risk loci and identified the causative mutations that we now term LPN1 and LPN2." [From University of MN]