Urinary 3-hydroxypropyl mercapturic acid (3-HPMA) is a metabolite of acrolein. In dogs with intervertebral disc herniation, urinary 3-HPMA concentrations were higher than in control dogs. Urinary 3-HPMA concentrations were not correlated with the severity of canine acute spinal cord injury (ASCI). Urinary 3-HPMA concentrations of intact dogs were higher than that of neutered dogs. 3-HPMA is a potential biomarker in canine acute spinal cord injury (ASCI).