According to John McGlone of Texas Tech University in Lubbock, he discovered it by chance . He was researching the qualities of androstenone – a pheromone found in the saliva of male pigs that prompts females to mate when they smell it – and his dog wouldn't stop barking.
So he decided to spray it on it to see what would happen. The pet immediately fell silent.
Then McGlone did experiments to see if the effect was repeated. One group of dogs were sprayed with androstenone, while the rest were given water and alcohol.
They all heard a loud noise that normally made them uncomfortable and made them bark, but the former were calmer. His heart rate did not change. Now a North American company markets the substance in spray form under the name PetSTOP.
At the moment, it is not known exactly why it works.
In Spain collars are also sold with a synthesis of pheromones emanated by lactating bitches that supposedly reduce fear and stress in dogs.
