Dogs are known to communicate through chemical messages known as pheromones, which carry out several important functions. The term pheromone derives from the Greek word "pherein" which means "to transport" and the word "mone" meaning hormone. The term is therefore utilized to depict those volatile, odorous substances that are secreted for the purpose of causing a physiological reaction in the dogs who receives them.
For sake of comparison, the mechanism is similar to an answering service system. A person leaves a message on the answering machine that is then relayed to the receiver when he presses a button. Since dogs do not have a phone or an answering machine, they rely instead on special glands meant to emit pheromones, and a special organ, the Jacobson organ, located in the roof of the mouth with ducts leading to the nose and the mouth, meant to pick up these messages. Dogs can emit pheromones in a multitude of ways so today we'll be taking a look at six fascinating ways dogs release pheromones.
1) Intermammary Sulcus Pheromones
Shortly after being born, puppies are exposed to special pheromones produced by mother dog. These pheromones are secreted by the sebaceous glands found in mother dog's intermammary sulcus, the area in between her breasts where they are detected by the puppies upon nursing.
Because these pheromones have the power to provide calm, comfort and a sense of well-being to the puppies, they're called Dog Appeasing Pheromones (DAP). Nowadays, DAP is produced synthetically (Adaptil) and sold under the form of special sprays, plug-ins and collars that are used as calming aids for dogs.
Their purpose is to provide reassurance, especially when dogs are exposed to new environments that require acclimatization. It has been found that the reassurance properties of DAP persist into adulthood and can therefore provide comfort to dogs of any age.
" The use of pheromones should not be reduced to treatment of behavioral disorders (potentially associated with psychotropes or a behavioral modification program) but should be included in a strategy of improving the welfare of pets in veterinary structures (during examination and hospitalization) and in breeding networks (separation from the mother and transport)." Pageat P, Gaultier E. 2003
2) Anal Gland Pheromones
Anal glands, also known as "scent glands" are paired sacs that are found around each side of the dog's anus approximately at the 4 0'clock and 8 o' clock position.
When dogs defecate, their feces pass through the glands which are lined with sebaceous glands that secrete a semi-oily, brownish fluid that contains pheromones and is used for identification purposes. Dogs who stumble upon a dog's feces can therefore learn more about the dog's sex, age and general identity courtesy of these pheromones.
Yes, this explains why dogs are so interested in sniffing other dogs' poop at the park! Other than used for identification purposes, feces left behind work may also work as powerful territorial posts, telling other animals to stay away as "Rover lives here."
On top of secreting fluid when dogs have a bowel movement, sometimes the anal glands may empty when a dog is particularly frightened. In this circumstance, a dog's anal glands are likely emitting alarm pheromones which are picked up by other dogs. For example, in a veterinary hospital setting, frightened dogs may leave traces of pheromones from their anal glands. It is possible that such pheromones may cause a behavioral and/or physiological response in the dogs who detect them, but studies are still needed to pinpoint the exact dynamics.
" The function of spontaneous emptying of the anal glands during fear has not been extensively studied, but may be related to the release of alarm or aggression-inhibiting pheromones." ~ Sarah Heath, VeterinarySpecialist in Behavioural Medicine.
3) Urogenital Pheromones
Those pheromones aren't only coming from the anal glands, turns out dogs secrete pheromones also from the vulval, preputial area and urinary tract area. Several of these are emitted for reproductive purposes, and with a powerful sniffer as seen in dogs, this isn't even surprising.
Females in heat produce pheromones from their reproductive tracts that are meant to be picked up by male dogs even miles away. When female dogs in heat urinate, their urine is rich in these pheromones which indicate whether she is receptive.
Yes, think about it as a hot chick after a first date leaving a message that says "call me." The specific compound has been identified as methyl p-hydroxybenzoate, and according to a study, when this compound was applied to spayed female dogs, it caused male dogs to attempt to mount. Quite a powerful potion that is!
And of course, every body knows about a dog's fixation with pee. Dogs will urine mark on vertical surfaces leaving pheromones behind that can be easily detected at "nose-level" for other dogs to check out. This explains why dogs pee on car tires, fire hydrants and bushes!
Dogs tend to react differently to pee: some just carefully sniff it and then leave the area, while some others will pee on top of it. This habit is what has triggered the marketing of potty training pads or pee posts treated with synthetic pheromones for the purpose of grabbing a dog's attention and hopefully enticing him to eliminate on them next time nature calls.
Did you know? Dogs have also special glands located in between the toes (interdigital) which are also capable of emitting pheromones. When dogs are scratching dirt after eliminating it's likely that they are basically leaving behind these pheromones for other dogs to detect.
Interdigitial glands are therefore used for marking, but are also used for alarm, explains veterinarian Dr. Bonnie V. G. Beaver in the book "Canine Behavior: Insights and Answers."
Perhaps this provides another facet as to why stressed dogs tend to sweat from their paws. Along with the sweat, they may be leaving behind important alarm messages that will give other dogs a "head's up" about the presence of a threat.
5) Ear Pheromones
Ever wondered why dogs are so attracted to each others' ears? Those doggy ears have special ceruminous and sebaceous glands which also contain pheromones.These pheromones are similar to the dog appeasing pheromones released from mother dog, only that they're applied to a wider basis for social purposes this time, suggests veterinary behaviorist Dr. Cam Day.
Interestingly, these pheromones found in the skin around the ears, make the ears attractive to younger animals creating a cohesion effect with their social group. Adult dogs though may be interested in ears too, and it's not unusual seeing dogs sniffing each other's ears as part of their greeting ritual.
"Dog appeasing pheromones have a calming effect on puppies. It has also been isolated from the ears in some adult dogs and may play a role in social communication and cohesion." ~Nicola Ackerman
6) Facial Pheromones
As with the ears, dogs are often also attracted to sniffing each others' mouths. This is because the mouth area also emits pheromones, more specifically the labial (lip) area.
Many dogs often greet other dogs by first sniffing under their tails, but afterward they may decide to move to other interesting areas where pheromones may also be present such as the lips, remarks Tracie Hotchner, in the book "The Dog Bible: Everything Your Dog Wants You to Know."
The primary pheromone secreting glands in the dog are the labial, auricular, perianal, genital (vulvar or preputial), interdigital (pedal) and mammary complexes of sebaceous glands. Most of the information appearently enters via the vomeronasal organ "~Dr. Bonnie Beaver
To Sum it up: Here are Areas Where Dogs Tend to Secrete Pheromones (excluding the intermammary sulcus as seen in mother dog)
- Pageat, P.; Gaultier, E. (2003). "Current research in canine and feline pheromones". The Veterinary Clinics Small Animal Practice. 33 (2): 187–221
- Donovan,C.A. (1969) Canine anal glands and chemical signals (pheromones). J. Am. Vet. Med. Assoc., 155, 1995–1996.
- Veterinary Nursing Journal, Volume 22, Issue 9, 2007, Understanding pheromones, by Sarah Heath
- Sex pheromone in the dog, Goodwin M, Gooding KM, Regnier F. Science. 1979 Feb 9;203(4380):559-61.
- The Consulting Veterinary Nurse, By Nicola Ackerman, Wiley-Blackwell; 1 edition (September 4, 2012)
- Canine Behavior: Insights and Answers, By Bonnie V. G. Beaver, Saunders; 2 edition (January 5, 2009)