Abstract figure legend A significant fraction of inbred C57Bl/6J mice have congenital portosystemic shunt (PSS). We report PSS incidence in 9.2% of C57Bl/6J mice. PSS was detected directly by liver magnetic resonance angiography and brain ¹H-magnetic resonance spectroscopy. Elevated plasma total bile acids indicated PSS presence with 100% accuracy. For cost-effective PSS screening, we propose using total bile acid detection by the Thio-NAD enzyme cycling method. Brain anatomy and function in mice with PSS: altered neurometabolite profile, higher brain weight and volume, enhanced brain glucose utilisation. Behavioural changes in mice with PSS: hyperlocomotion, enhanced balance, altered gait, attenuated fear memory. Mice with PSS have altered internal organ weights, blood cell counts and blood clinical chemistry. PSS significantly distorts diazepam pharmacokinetics. Conclusion: in line with the principles of 3Rs, we recommend screening C57Bl/6J mouse cohorts for PSS presence as a significant refinement of any experiments involving this popular inbred strain.

Abstract figure legend Contacting an obstacle during locomotion activates cutaneous afferents to maintain balance and co-ordinate all four limbs. Spinal cord injury (SCI) disrupts neural communications between spinal networks controlling the fore- and hindlimbs, impairing balance and limb co-ordination. Cutaneous reflex pathways can be used to develop therapeutic approaches for restoring ascending and descending transmission to facilitate locomotor recovery.