Full-size Left-side Hidden

Under normal conditions, glucose is freely filtered at the glomerulus and reabsorbed in the proximal tubules by facilitated diffusion in a cotransport mechanism with Na+. The transport mechanism has a maximum capacity, which is exceeded at a blood glucose concentration of 180 to 220 mg/dL in dogs and 260 to 310 mg/dL in cats.[36] When hyperglycemia (e.g., stress hyperglycemia, diabetes mellitus) exceeds the transport maximum, glucosuria occurs. Proximal tubular defects caused by tubular damage or inherited disorders can result in glucosuria in the absence of hyperglycemia.[12,36-38]

Primary renal glucosuria is rare but has been reported in Scottish Terriers, Basenjis, Norwegian Elkhounds, and mixed-breed dogs.[36],[39]Persistent glucosuria typically causes polyuria and polydipsia from osmotic diuresis, although some dogs are asymptomatic. Evaluation of serial blood glucose measurements or the serum fructosamine concentration should be considered to diagnose renal glucosuria …