Texas Tech University

The Pheromone Site

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Dr. McGlone began studies of mammalian pheromones in 1979 after he concluded that pheromones must be at play in the modulation of pig aggressive behaviors. For over 35 years, this laboratory has published scientific findings about the fascinating world of mammalian pheromones. We have examined pheromones in pigs, cats, dogs, rats, mice, horses – with more species to come over time.

Semiochemicals, Pheromones, Interomones and other chemical signals

Animals communicate with all of their senses.  For some species, the olfactory sense drives animal behavior more-so than other sensory systems.  The broad term that describes all chemical signals animals percieve is Semiochemical.  Semiochemicals include pheromones, attranctants, smells that identify an individual (ex., adult male), Interomones, Kairomones, Alomones, and others.  

Pheromones have a very specific definition that was published in 1959.  To be called a pheromone, the checmial signal must be (1) species specific, (2) be produced by one animal of a given species, and 93) be both percieved by another animal of that species and it must change the recieving animal's behvior and/or physiology.  Examples of chemical signals that are not pheromones include rodent repellants, a attractive food odor, a plant molecule that prevents other plants from growing, and much more.  

In 2022, we published a review of semiochemicals in pigs and dogs. Ckick the title to open a PDF of this paper: 




What is a pheromone?

A Pheromone is a chemical produced by a given species that affects the behavior or physiology of the same species – first coined by Karlson and M. Luscher in 1959. Early work was in insects, but scientists soon discovered that pheromones operate in other animals, including mammals.

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How do Pheromones work?

Mammals sense chemical signals in aerosol or for liquid from. There are many olfactory organs. The two most prominent olfactory organs are the main olfactory epithelium with it is associated olfactory bulb and the vomeronasal organ which transmits neurons to the accessory and main olfactory bulbs (see figure on the left).

As a general, historical convention, aerosol chemicals were perceived by the Main Olfactory Epithelium (MOE) and liquid signals by the Vomeronasal Organ (VNO). And pheromones were thought to be sensed by the VNO. We know now that mammalian pheromones can be sensed by either the MOE or the VNO. However, the MOE perceives primarily gas or aerosolized chemicals and the VNO primarily liquid signals.

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For more information see this presentation
John McGlone presentation to the NVAC in Jan, 2012

The Pheromone and Interomone Concepts
John J. McGlone, PhD

Pheromones are chemicals produced by one species that affects the physiology or behavior of animals of the same species. Pheromones assist in reproduction, feeding, social interactions and maternal-neonatal bonding in mammals. By definition and according to evolutionary theory, pheromones work within a species.

Some chemicals operate between species. Because evolution drives signs and signals that benefit a species, inter-species chemical (olfactory, primarily) cues must benefit either or both the emitting or receiving species. However, sometimes inter-species chemicals have unexpected effects on animals. The inter-species effects may be unexpected or out of context for the original intent of the within-species pheromone.

We propose here a new term for inter-species olfactory communication called the Interomone (pronounced either Inter-oh-mone or inter-mone). An Interomone is a chemical produced and released by one species that has an effect on another species' behavior or physiology. Interomone is a broad term that applies to chemicals that benefit or do not benefit the emitting, receiving or a third party species. Some Interomones have powerful effects on some species. Thus-far, we have three examples of Interomones among vertebrates.

  • The rabbit maternal pheromone 2-Methylbut-2-enal, aids neonatal rabbits in finding and attaching to the maternal nipple. We have shown that the rabbit pheromone (1 ug/mL) has an effect on dog heart rate and behavior. It reduces heart rate of nervous dogs and increases heart rate of overly calm dogs.
  • The pig pheromone 5-α-Androst-16-en-3-one (androstenone) and related steroids is produced by the male pig (boar) and causes sows in estrous to show typical lordosis behavior. Androstenone causes dogs that are barking/jumping in an excited state to immediately stop barking. It also stops dogs from begging and generally lowers their excitability.
  • The pig pheromone androstenone also causes a calming effect on horses. Horses that are “head shy” will resist the human hand touching their head. This makes it difficult to put on a halter or bridle. One shot of androstenone (1 ug/mL) to the nostril of a head shy horse will make it calmer. The handler will be able to place a halter or bridle on the horse. Other applications include horses that are afraid of trailers or other novel environments.

Interomones may have some benefit to the emitting species or not. The key point is that they are chemicals that function across species and in the case of known interomones, to the benefit of a third party species (humans in this case). Interomones can be used to manage, manipulate, change, or modify animal behavior. Generally we have identified examples, with three uses over three species (See # 1-3 above) – all of which benefit humans.

Now we can see that Interomones will have many uses. The odor signal of one species can be used, for example, to encourage or prevent marking of territories, in the aide of trapping rodents and other animals, in feeding behavior stimulation or suppression and a host of other uses.

Literature Cited

  • Allomone. 2011. Wikipedia. http://en.wikipedia.org/wiki/Allomone. Accessed 8-9-2011.
  • Lord, K., M. Feinstein and R. Coppinger. 2009. Barking and mobbing. Behav. Processes 81:358-368.
  • Sales, G., R. Hubrecht, A. Peyvandi, S. Milligan, and B. Shield. 1997.  Noise in dog kenneling: Is barking a welfare problem for the dogs? Appl. Anim. Behav. Sci. 52:321-329.

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Sentry Good Behavior - Pheromone Therapy

Back to top Table 1. Definitions of within and between species chemical communication terms.


Defintion:A chemical produced by a given species that affects the behavior or physiology of the same species.
Ex:The first example was bombykol produced by the female silkworm to attract males (A. Butenandt)

P. Karlson and M. Luscher, 1959. Pheromones: a new term for a class of biologically active substances. Nature 183 (4653): 55–56.


Defintion:Broad class of chemicals produced by a given species that can have beneficial or harmful effects on the same or other species.
Ex:Many examples in plants, insects and vertebrates. Ex., plant chemicals that prevent the growth of other plants in the surrounding soil.



Defintion:Chemical produced and released by one species that affects the behavior or physiology of another species to the benefit of the originator but not the receiver.
Plant chemicals released to defend against insect species.

Grasswitz, T.R. and G.R. Jones (2002). "Chemical Ecology". Encyclopedia of Life Sciences. John Wiley & Sons, Ltd. doi:10.1038/npg.els.0001716


Defintion:Chemical produced and released by one species that benefits another species, but not benefiting and often harming the emitter.
Ex:Insect predators use them to find prey. Ponderosa Pine produces a terpene called myrcene when the Western pine beetle damages the tree which lures more beetles to the tree.

Wyatt, T.D. (2003). Pheromones and Animal Behaviour: Communication by Smell and Taste, First Edition (Cambridge, UK: Cambridge University Press).


Defintion:Chemical produced and released by one species that benefits both the emitter and receiver.
Ex:Plant odors that attract bees. Plants attracts bees to feed and then the bees take the pollen to fertilize other plants/flowers.



Chemical produced and released by one species that has an effect on another species behavior or physiology. Interomone is a broad term that applies to chemicals that benefit or do not benefit the emitting, receiving or a third party species.
Ex:Pig sexual/social pheromone that causes barking/jumping/begging dogs to stop. 


Graphic representation of a Kairomone and its dependence on the Vomeronasal Organ (VNO). In this example, the mouse is fearful of the cat or rat. This benefits the mouse in that is avoids capture and it is detrimental to the cat or rat because it is less likely the catch and eat the mouse. Adapted from Fabio Papes, Darren W. Logan, Lisa Stowers . 2010. The Vomeronasal Organ Mediates Interspecies Defensive Behaviors through Detection of Protein Pheromone Homologs. Cell - 14 May 2010 (Vol. 141, Issue 4, pp. 692-703).

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Laboratory of Animal Behavior, Physiology and Welfare