A recent study from the United Kingdom looked at the efficacy of pheromones to help calm the waters, using the commercial products Feliway Friends and Adaptil. Both products contain synthetic appeasement pheromones that can help signal a safe environment to cats and dogs, respectively.
A six-week period of testing was done with 17 participants in two groups, with each group using one of the pheromone products. Owners did not know which product they were using and were asked to report weekly on the frequency of 10 specific undesirable interactions and seven specific desirable interactions.
The 10 undesirable interactions were: cat blocking dog’s path, dog chasing cat/cat running away (not in play), dog growling at cat, cat hiding from dog or up high, staring, cat swiping at dog, dog barking at cat, cat hissing at dog, dog interrupting fuss over (attention toward) the cat (i.e., causing disruption when the owners fuss over the cat), and cat interrupting fuss of dog. The seven desirable interactions were: playing (pets enjoying play together), sleeping near each other, dog grooming cat, friendly greeting, cat grooming dog, sharing a bed, and both relaxed in the same room.
At the end of the study, the researchers determined that both pheromone products worked, with no major differences in effectiveness between the two. Both were associated with a decrease in dog chasing cat/cat runs away, cat hiding from dog, cat/dog staring at the other, and dog barking at cat. Adaptil also appeared to increase friendly greetings and time spent relaxed in the same room. The least successful situations had multiple cats, which may have been a confounding variable.
https://www.frontiersin.org/articles/10.3389/fvets.2020.00399/full