Technical note: Vapor release of 2-methyl-2-butenal from dog collars and spray containing pheromone or interomone measured by solid-phase microextraction and gas chromatography-mass spectrometry

The molecule 2-methyl-2-butenal (2M2B) is a maternal pheromone in rabbits and an interomone in dogs eliciting behavioral and heart-rate changes. The molecule 2M2B is manufactured in dog collars (Nurturecalm 24/7 Canine Calming Pheromone Collar, Meridian Animal Health, Omaha, NE) and in aerosol sprays (Sentry Calming Spray for Dogs, Sergeant's Pet Care Products Inc., Omaha, NE). To determine volatile release of this molecule in the collar and liquid, solid-phase microextraction followed by gas chromatography-mass spectrometry was performed on the headspace over the test materials. In Exp. 1, a snippet of dog collar and 3 mL of aerosol liquid were compared with a standard of 2M2B in isopropyl alcohol. In Exp. 2, a dog collar was removed from its wrapping and placed at room temperature for 49 d. On d 0, 7, 14, 21, 28, 35, 42, and 49 relative concentrations of molecules volatilized were calculated from area under the corresponding gas-chromatography peak. Release of 2M2B followed an exponential decay rate over time. In Exp. 3, collars were placed on 3 dogs for 35 d. Dogs were variable in their level of activity. Dog-worn collars had smaller and more variable concentrations of the 2M2B in the head space at 35 d than the same collar kept in the laboratory at room temperature. This paper authenticates a technique for the assay of low concentrations of pheromones or interomones released from plastic collars or a liquid formulation. Furthermore, pheromone or interomone release over time was documented both in laboratory and field settings.