Scientists Discover 13 Fatty Acids in Cat Urine That Form Unique Scents

Researchers in Japan, Germany, and Spain have discovered 13 unusual branched-chain fatty acids in domestic cat urine that form stable, individualized chemical profiles. These semi-volatile compounds evaporate slowly, resist quick environmental breakdown, and may function as a durable calling card that preserves feline identity over time.

Cats live in a world governed by scent, gleaning vital social data from urine and other chemical traces left in their surroundings. This biological communication creates a fundamental puzzle for biologists studying animal behavior. Many volatile odor molecules evaporate or change rapidly once an animal deposits them, meaning chemical signals can degrade long before another cat investigates the spot. Researchers led by Iwate University may have resolved how felines overcome this chemical decay by identifying a specialized lipid signature.

Thirteen Unusual Fatty Acids Form Distinctive Profiles

Before isolating the underlying chemistry, the research team established that cats can actually tell individual urine samples apart. When investigators repeatedly presented the same urine sample to test subjects, the animals gradually spent less time investigating it, demonstrating clear habituation to familiar scents. Using this behavioral response as a guide, Professor Masao Miyazaki of Iwate University and his international colleagues narrowed their search down to a specific lipid fraction within the urine.

After confirming that cats can distinguish individual urine odors, we used the flehmen response as a clue to identify urinary molecules that may contribute to individual scent recognition.

Professor Masao Miyazaki, Iwate University

The scientific team ultimately identified 13 branched-chain fatty acids, or BFAs. A comprehensive review of existing scientific literature revealed no prior records of these exact compounds appearing in mammalian excretions or secretions. While the presence of the compounds was notable, their arrangement proved even more significant. Each cat possessed a unique BFA profile defined by the specific combination and relative abundance of the fatty acids.

These profiles varied considerably from one animal to another while remaining relatively stable when researchers sampled the same cats on different dates. Genetics also appeared to influence the patterns: related cats shared more similar BFA combinations, though each individual maintained a distinct chemical profile even within the same family. Behavioral tests confirmed that cats could detect these differences when researchers controlled for other lipids in the urine.

Renal Lipid Droplets Provide a Century-Old Biological Clue

The physical durability of these chemical markers helps explain how they survive in the environment. Unlike highly volatile scent compounds that transform quickly, BFAs are semi-volatile and evaporate at a much slower rate. Tests on urine-soaked samples stored at 25°C showed that individual BFA profiles remained comparatively stable for at least 24 hours.

To understand how cats maintain this chemical consistency, investigators examined feline tissues and detected BFAs exclusively in the kidneys. Specifically, lipids containing BFAs were found inside neutral lipid droplets located in the renal cortex. These cellular droplets have puzzled scientists for more than a century, as biological authorities have long known cats possess large numbers of them without knowing their exact purpose.

L'urine de chat comme carte de visite chimique / Curr. Biol., 19 août 2026 (Vol. 36, Numéro 17)

Lipid droplets in the cat kidney have been known for more than a century, but why cats have so many of them has remained a mystery. Our findings suggest that one of their functions may be to support a stable chemical signature in urine. How BFAs stored in renal lipids are ultimately released into urine is an important question for future research.

Professor Masao Miyazaki, Iwate University

This anatomical discovery suggests the kidney may function as a biological storage reservoir. By buffering short-term physiological fluctuations caused by shifting diets or temporary changes in condition, the renal lipid droplets could help keep a cat’s chemical calling card steady over time.

Shared Chemistry Across Wild Felid Species

The research team extended their investigation beyond domestic pets to determine whether similar traits appeared across the broader cat family. Analyses confirmed that BFA-related compounds in urine and renal lipid droplets exist in several other felid species, including tigers, lions, leopards, jaguars, lynxes, and the Iriomote cat. However, the exact proportions and profiles differed among the various species.

While mice rely on major urinary proteins to preserve individual information in waste marks, scientists have not established a comparable protein-based identity system across many other mammalian groups. The discovery in felines points to a different evolutionary strategy, relying on semi-volatile lipid-derived molecules backed by renal storage rather than proteins alone.

Researchers emphasize that the work remains fundamental laboratory research and does not immediately yield commercial products or technologies. Future study will need to resolve the exact biological mechanisms that transfer stored BFAs from renal lipids into the urinary tract.