Persistence after scent marking: Because these BFAs are semi-volatile and evaporate slowly, BFA profiles in urine-soaked samples held at 25°C remained comparatively stable for at least 24 hours—unlike many more volatile urinary odorants.

Flehmen and recognition experiments: Cats showed the open-mouthed flehmen response more often to unfamiliar urine than to their own. The response waned with repeated exposure to the same sample and returned when urine from another individual was substituted. In a controlled exposure experiment, cats habituated to a sample increased sniffing when only the donor-derived BFA fraction was changed while other urinary lipids were controlled—evidence that they detect donor-specific BFA mixtures.

What “buffering” means: The reservoir model predicts that storing BFA-containing lipids in renal droplets smooths short-term effects of diet, health/physiological condition, and other transient influences, allowing a cat’s urinary identity signal to remain relatively consistent. This is a proposed function supported by the chemical and behavioral findings, rather than a directly demonstrated dietary intervention result.

Other felids: Related urinary compounds and kidney lipid droplets were reported in lions, tigers, leopards, jaguars, lynxes, and the Iriomote cat. Profiles and droplet amount/distribution varied across species; the Iriomote cat and Tsushima leopard cat also differed, suggesting evolutionary diversification. Whether wild felids actually use these compounds for individual recognition remains untested.

Potential applications: If an individual’s BFA profile proves reliably repeatable in field samples, urine could become a non-invasive means to monitor rare wild cats for conservation. Understanding the system could also eventually inform ways to manage domestic-cat urine odor, though it does not yet yield an immediate product or treatment.

Key open question: The researchers do not yet know how BFAs stored in renal lipids are released into—or otherwise enter—urine.

Persistence after scent marking: Because these BFAs are semi-volatile and evaporate slowly, BFA profiles in urine-soaked samples held at 25°C remained comparatively stable for at least 24 hours—unlike many more volatile urinary odorants.

Flehmen and recognition experiments: Cats showed the open-mouthed flehmen response more often to unfamiliar urine than to their own. The response waned with repeated exposure to the same sample and returned when urine from another individual was substituted. In a controlled exposure experiment, cats habituated to a sample increased sniffing when only the donor-derived BFA fraction was changed while other urinary lipids were controlled—evidence that they detect donor-specific BFA mixtures.

What “buffering” means: The reservoir model predicts that storing BFA-containing lipids in renal droplets smooths short-term effects of diet, health/physiological condition, and other transient influences, allowing a cat’s urinary identity signal to remain relatively consistent. This is a proposed function supported by the chemical and behavioral findings, rather than a directly demonstrated dietary intervention result.

Other felids: Related urinary compounds and kidney lipid droplets were reported in lions, tigers, leopards, jaguars, lynxes, and the Iriomote cat. Profiles and droplet amount/distribution varied across species; the Iriomote cat and Tsushima leopard cat also differed, suggesting evolutionary diversification. Whether wild felids actually use these compounds for individual recognition remains untested.

Potential applications: If an individual’s BFA profile proves reliably repeatable in field samples, urine could become a non-invasive means to monitor rare wild cats for conservation. Understanding the system could also eventually inform ways to manage domestic-cat urine odor, though it does not yet yield an immediate product or treatment.

Key open question: The researchers do not yet know how BFAs stored in renal lipids are released into—or otherwise enter—urine.