Refining the Genetic Mutations That Cause SLO in Bearded Collies

Author: Sharon M. Albright, DVM, CCRT

Symmetrical Lupoid Onychodystrophy (SLO) is a painful inflammatory disease of the canine nail bed seen in Bearded Collies, German Shepherd Dogs, Gordon Setters, English Setters, and Giant Schnauzers. Inflammation and secondary bacterial infection lead to sloughing of the nail and regrowth of abnormal and brittle claws. Data suggests that autoimmune diseases in dogs, such as SLO and hypothyroidism for example, may result from a shared set of genetic mutations. Additional genetic mutations and environmental factors then contribute, resulting in clinical autoimmune disease.

With funding from the AKC Canine Health Foundation (CHF) and in collaboration with the Bearded Collie Club of America and BeaCon for Health, investigators at the University of California, Davis have been working for more than a decade to refine our understanding of the genetic mutations that cause SLO. Thanks to improvements in genetic technology and a dedicated search for the responsible genes, results were recently published describing several genetic mutations that are highly predictive for SLO in this breed.1

Genome-wide association study (GWAS) revealed two genetic regions associated with SLO. Whole genome sequencing (WGS) was then performed to determine the genetic sequence of these suspect regions. One region of interest contains various mutations in areas associated with immune system function – including proteins involved in connective tissue structure, immune system development and cell signaling, and, most importantly, DLA Class II genes which regulate the immune system and are already known to be associated with SLO development in dogs.

Investigators have refined our knowledge of genetic mutations associated with immune system function that predict the development of symmetrical lupoid onychodystrophy (SLO) in the Bearded Collie.

Because the DLA gene variations that predict SLO development are so common in Bearded Collies, excluding carrier dogs from the breeding pool would cause a great loss of genetic diversity and likely lead to an increase in other health problems. However, thoughtful breeding of dogs with these gene variants may reduce the incidence of SLO in the Bearded Collie.

The AKC Canine Health Foundation and its donors remain committed to advancing our knowledge of the genetic and environmental factors that cause disease in dogs. With continued collaboration among investigators, breed clubs, and veterinary professionals, we work to prevent, treat and cure canine disease. Learn more about our work at

Related grants:
02488: Addison's Disease and Symmetrical Lupoid Onychodystrophy in Bearded Collies Provide Common Ground for Identifying Susceptibility Loci Underlying Canine Autoimmune Disorders
02187-MOU: Investigating Symmetrical Lupoid Onychodystrophy in Bearded Collies
01236-A: Hypothyroidism and Autoimmune Susceptibility Genes in the Bearded Collie


  1. Gershony, L. C., Belanger, J. M., Hytönen, M. K., Lohi, H., & Oberbauer, A. M. (2021). Whole Genome Sequencing Reveals Multiple Linked Genetic Variants on Canine Chromosome 12 Associated with Risk for Symmetrical Lupoid Onychodystrophy (SLO) in the Bearded Collie. Genes, 12(8), 1265.

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