Leonberger Polyneuropathy (LPN)

LPN affected dogs may suffer 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.

LPN1: autosomal recessive severe early-onset form, 10 base pair deletion within the ARHGEF10 gene on CFA16
LPN2: partially penetrant autosomal dominant later-onset form, frameshift mutation in the GJA9 gene on CFA15.

This has serious implications for breeders, as half of all offspring from a LPN2-DN dog will inherit a mutant D allele, and thus be genetically-susceptible to LPN2.

For test Interpretation and Breeding recommendations: http://www.genetics.unibe.ch/unibe/portal/fak_vetmedizin/c_dept_dcr-vph/h_inst_genetics/content/e20974/e85824/e95237/e102197/LPN12_Interpretation_eng_2017Jun23_eng.pdf

Scientific Report LPN2: https://link.springer.com/epdf/10.1186/s12864-017-4081-z?author_acc ess_token=DaBDW_PKT39ybU_TeFaRHG_BpE1tBhCbnbw3BuzI2RMOPLqLExTveKr81MXyI8XBVaIKS0kE0LiXmt4B3om38Eb13MBeZYGGLCfvYaNmFXuhqEF9LXb1KzRu-9Fq0-8_qgRlzRBabaMy1absVRo5Q%3D%3D