For almost 110 years, biologists have been puzzled by the reason behind domestic cats’ kidney failure. Packed with abnormally large numbers of fat-storing structures known as lipid droplets, Professor Masao Miyazaki and colleagues from Iwate University suggest that these kidney droplets serve as a chemical reservoir, aiding cats in maintaining a stable “scent signature” in their urine even as the scent changes over time.
Animals often rely on odor signatures to communicate identity across time, but how chemically dynamic signals maintain individual information remains an open question. Ichizawa others. We show that the domestic cat has acquired a durable chemical identity through a reservoir buffer system based on branched-chain fatty acids. Image provided by: Ichizawa others., doi: 10.1016/j.cub.2026.07.045.
Animals that mark their territory with scent face a fundamental problem. The molecules that make up odors evaporate and break down when released into the environment, so the message can change after the sender has moved on.
Cats get around this by using a set of 13 branched-chain fatty acids (BFAs), a class of compounds not previously recorded in mammalian urine or other body secretions.
A recent study indicates that each cat possesses a unique combination and ratio of these fatty acids. Unlike many volatile compounds in urine, their chemical fingerprint remains relatively constant over time, evaporates slowly, and stays detectable for at least a day after the urine is deposited.
“For over a century, cats having lipid droplets in their kidneys has been a mystery,” says Professor Miyazaki. “Our findings suggest that one of their functions might be to maintain stable chemical signatures in urine.”
“The release of BFA stored in renal lipids into urine poses an important question for future research.”
To identify the compounds, researchers observed cats’ Flehmen reactions (the gaping look cats make when they inhale scent into a special organ in the roof of their mouth) and noted that these reactions happen more frequently in response to unfamiliar cat urine compared to the cat’s own urine. These reactions disappear after repeated exposure to the same sample but reappear when urine from a new individual is introduced.
In a subsequent study, cats demonstrated the ability to detect differences in fatty acid mixtures even when other urine components were consistent, indicating their ability to interpret this information.
This kind of fatty acid is primarily found in the kidneys, where it is stored in enigmatic lipid droplets in the renal cortex.
Similar compounds and kidney lipid droplets have been identified in other wild cat species, including lions, tigers, leopards, jaguars, and lynx. However, the chemical profiles vary depending on the species.
This discovery could potentially offer insights into how to control the smell of cat urine. Since fatty acid profiles appear to distinctly mark individuals, they could eventually help conservationists track elusive cats in the wild based solely on smell.
“These findings reveal an organ-level mechanism that maintains the chemical identity of domestic cats through small molecules and highlight the diverse chemical substrates supported by reservoirs across the feline lineage,” the scientists concluded.
Their paper was published in today’s issue of current biology.
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Shota Ichizawa others. The characteristics of branched chain fatty acids derived from renal stores give domestic cats a stable chemical identity. current biologypublished online on August 19, 2026. doi: 10.1016/j.cub.2026.07.045
Source: www.sci.news
