Saint Bernard Laryngeal Paralysis & Polyneuropathy

Saint Bernard dogs may suffer from neuromuscular diseases collectively termed Laryngeal Paralysis and Polyneuropathy. Affected dogs may have noisy breathing, a change in their bark, and difficulty breathing due to involvement of the larynx and laryngeal folds in the throat.  Additionally, they 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. 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 laryngeal paralysis and polyneuropathy within the Saint Bernard breed is a group of several genetically distinct, but clinically similar diseases. We have mapped one major genetic risk loci (originally identified in Leonberger dogs) and identified the causative mutation that we now term Leonberger Polyneuropathy type 1 (LPN1).

LPN1 - ARHGEF10

LPN1 is a polyneuropathy resulting from a 10 base pair deletion within the gene ARHGEF10; dogs homozygous (D/D) for the LPN1 mutation typically develop clinical signs of disease before they reach 3 years of age.

At present, LPN1 D/D dogs represent ~20% of all diagnosed cases of Saint Bernard laryngeal paralysis and polyneuropathy.

  • Population testing of >350 Saint Bernards indicates that the carrier rate of this mutation is ~2%

Ongoing Research

The test for LPN1 does not account for all confirmed or suspected cases of laryngeal paralysis and polyneuropathy in the Saint Bernard breed. Until additional DNA-based test(s) are developed, the only way to confirm a suspected diagnosis of laryngeal paralysis is via laryngoscopy and/or nerve conduction study; polyneuropathy is diagnosed via a nerve and muscle biopsy. 

Dogs showing clinical signs of laryngeal paralysis or polyneuropathy may qualify for free LPN1 testing.  Special forms and instructions, as well as pre-approval, are required for free testing.  Please e-mail lpninfo@umn.edu to see if your dog may be eligible.  

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Scientific References

Ekenstedt KJ, Becker D, Minor KM, Shelton GD, Patterson EE, Bley T, et al. (2014)  
PLoS Genet 10(10): e1004635. doi:10.1371/journal.pgen.1004635