Sensory neuropathy of the Border Collie is an inherited neurodegenerative disorder affecting sensory neurons and, to a lesser extent, motor neurons, with onset of signs between 2 and 7 months of age. It is characterised by degeneration of peripheral sensory nerves and sensory pathways, with progressive loss of proprioception, ataxia and hypoalgesia; motor strength is relatively preserved initially.

The disease is rare and has been documented in several countries. The carrier frequency in the breed population is not established in the verified sources (limited data).

- Progressive incoordination (sensory ataxia)\n- Ataxic gait with exaggerated steps and stumbling\n- Loss of proprioception (limbs in abnormal position without correcting it)\n- Hypoalgesia or loss of pain sensation (variable)\n- Self-mutilation or licking of the limbs due to lack of sensation\n- Muscle atrophy and weakness in advanced stages\n- Onset between 2 and 7 months of age

Described as a clinical entity in the Border Collie, its molecular basis was identified by Forman and colleagues (2016) using GWAS with 3 cases and 170 breed-matched controls and genomic sequencing: an inversion that disrupts the FAM134B gene (also called RETREG1). RNAseq analysis showed cryptic splicing with transcription of novel exons, supporting causality. The same variant has been confirmed in mixed-breed dogs with sensory neuropathy (Amengual-Batle et al., 2018).

- Test the breeding line (genotyping of the FAM134B/RETREG1 inversion)\n- Do not mate two carriers\n- Affected animals must not be bred\n- Carriers should only be mated to non-carriers\n- Keep genetic records in the pedigree

The differential diagnosis includes other hereditary neuropathies and demyelinating diseases; the genetic test targeting FAM134B/RETREG1 is definitive. There is no curative treatment: supportive management with physiotherapy and environmental adaptation to prevent injuries (falls, self-injury). The variant is the same in the Border Collie and in other affected breeds.

1. Forman OP, Hitti RJ, Pettitt L, et al. An Inversion Disrupting FAM134B Is Associated with Sensory Neuropathy in the Border Collie Dog Breed. G3 (Bethesda). 2016;6(9):2687-2692. PMID: 27527794
2. Amengual-Batle P, Rusbridge C, José-López R, et al. Two mixed breed dogs with sensory neuropathy are homozygous for an inversion disrupting FAM134B previously identified in Border Collies. J Vet Intern Med. 2018;32(6):2082-2087. PMID: 30307654
3. Correard S, Plassais J, Lagoutte L, et al. Canine neuropathies: powerful spontaneous models for human hereditary sensory neuropathies. Hum Genet. 2019;138(5):455-466. PMID: 30955094