A Century-Old Mystery in Cat Kidneys Solved by BFA Discovery

A collaborative international research team led by Iwate University published a study in Current Biology on September 10, 2026, revealing that domestic cats use 13 unusual branched-chain fatty acids (BFAs) found in their urine as stable chemical calling cards to identify one another across time and distance. Researchers discovered that neutral lipid droplets in the renal cortex store BFA-containing lipids, solving a century-old physiological mystery regarding the biological purpose of these abundant kidney lipid structures. The author highlights how these semi-volatile BFAs evaporate much slower than highly volatile odor molecules, maintaining stable individual profiles for at least 24 hours at 25 degrees Celsius and preventing short-term physiological or dietary fluctuations from erasing a cat's scent identity. Through behavioral observations utilizing the flehmen response and controlled chemical tests, the team confirmed that domestic felines can actively perceive and distinguish these donor-specific BFA mixtures. The essence of this discovery lies in identifying a novel mammalian chemical communication system that differs from the major urinary proteins used by mice. By linking specialized renal lipid storage directly to urinary scent stability, the study explains how chemical signals persist reliably in the environment despite environmental degradation and natural molecular breakdown after deposition. This fundamental biological insight opens future pathways for better feline odor management, advanced investigations into renal lipid metabolism diseases, and non-invasive wildlife conservation methods utilizing environmental scent marks to monitor elusive wild felid populations globally.