Subacute Necrotizing Encephalopathy (Yorkshire Terrier Type) is an inherited neurological disease affecting dogs. Affected dogs are unable to produce a protein important in transporting the essential nutrient, thiamine (vitamin B1) into cells of the body and typically present with neurological symptoms before 1 year of age. Cells of the nervous system are particularly dependent upon thiamine for the nutrient’s role in energy metabolism. As seen in this disorder, severe thiamine deficiency leads to death of neurons in the brain and subsequent neurological disease. Symptoms include weakness in limbs, altered mental state, loss of balance, abnormal gait, and blindness. The disease is progressive and affected dogs are typically euthanized due to poor quality of life within several months of initial clinical presentation.