I have written numerous times about the use of pheromones to reduce stress and stress-related problems in cats and dogs (1, 2, 3). Overall, the evidence for these products is weak, and it is likely they have little to no meaningful benefit. A new study of pheromone therapy in shelter cats appears to support this conclusion.
Chadwin RM. Bain MJ. Kass PH. Effect of a synthetic feline facial pheromone product on stress scores and incidence of upper respiratory tract infection in shelter cats. J Am Vet Med Assoc. 2017 Aug 15;251(4):413-420.
In this study, several hundred shelter cats were exposed to a pheromone diffuser or a placebo diffuser and assessed in terms of behavioral indicators of stress and incidence of upper respiratory infections (URI), which appear to occur more commonly with increases stress.
The methodology was generally sound, with appropriate randomization, blind assessment, and placebo controls. The study was under-powered, which means it is possible that a small difference between the groups may have not been detected in the statistical analysis. The authors also performed a large number of statistical comparisons of many variables. This is an approach which can raise the risk of falsely positive findings.
The findings, however, were pretty consistently negative. No difference was seen in stress scores or in the occurrence of URI between cats exposed to the pheromone and those exposed to the placebo. No evidence of harm from the pheromone treatment was seen, though this was not specifically sought.
As usual, no single study should be taken as the definitive answer to any medical question. However, in light of the fact that pheromones have been in use and studied extensively for decades and strong, consistent evidence of significant benefits has not been seen, this study strengthens the argument that these products do not, in fact, provide such benefits.