What is the cause of increased urination in older dogs?

There are many reasons for dogs to urinate excessively. If there is nothing abnormal in diet or spirit, but simply more urine, then consider an increase in the amount of water drunk leading to an increase in urine. It is also possible that the polyuria is caused by impaired kidney function, especially in older dogs. You can visit your vet for biochemical tests to see what the liver and kidney indicators are.