What does an increase in urine specific gravity usually indicate?

An increase in urine specific gravity typically indicates dehydration. Specific gravity is a measure of the concentration of solutes in the urine; when an animal is dehydrated, the body conserves water leading to a more concentrated urine. This increased concentration reflects higher levels of solutes such as urea and electrolytes.

In contrast, conditions that might lead to lower specific gravity values, such as overhydration, kidney failure, or urinary tract infections, often result in diluted urine. Overhydration decreases solute concentration due to excess fluid intake, while kidney failure can impair the kidneys’ ability to concentrate urine, leading to lower specific gravity. Urinary tract infections can also result in changes to urine concentration but are more commonly associated with specific symptoms and clinical signs rather than simply affecting specific gravity. Thus, a rise in urine specific gravity is a reliable indicator of dehydration.