-A mare lies in the straw, devotedly licking dry her newborn foal. As she does so, she breathes deeply of the baby’s scent, memorizing it so that ever after she can identify the foal as hers out of the herd. -A young gelding being turned out with a group for the first time trots optimistically towards his new pasturemates. Out of the herd swaggers the "alpha male" of the gelding group, neck arched and ears flicking back and forth. He meets the newcomer nostril to nostril, and both breathe deeply of the other’s scent. After several seconds of breathe-snuffling, the pair shift to sniff each other’s flanks, then under the tail. A couple of squeals ensue from the contact, then, introductions having been made, the alpha gelding accepts the new horse as a submissive youngster who won’t be a threat to his position, and the youngster immediately acknowledges the elder as his new leader. With the pecking order thus established, peace reigns in the herd.
-A group of feral horses grazes in a valley, enjoying the late summer sun on their backs. Some 50 yards away from the herd, even the stallion seems relaxed, until he suddenly flings up his head. Nostrils flaring, he’s instantly on full alert, although his eyes can’t perceive any visible threat. The faint predatorial scent of a cougar has registered in his olfactory sensors, and it’s time to get his herd moving away from the danger.
-Scent recognition plays such a large role in relationships that orphan foals are more readily accepted by nurse mares when they’re rubbed with the sweat or manure of their new adopted dams, or draped with the skin of the mare’s own dead foal.
It’s suspected that the famous ability horses have to find their way home from unfamiliar territory stems largely from their talent for retracing their steps by sniffing out their own footprints and manure markers along the trail.
According to David Whitaker, PhD, of Middle Tennessee State University, "Horses depend on their sense of smell the way we depend on language."
video: Anima Equi.Turismo Ecuestre Valle de Benasque
Lavender is the secret to keeping a horse calm,scientists find
Lavender is the secret to keeping a horse calm, a new study by scientists have found. Horses are constantly put through stressful events such as being moved on trailers, bathing, clipping, vet visits, hoof trims, bridling, and saddling. But now theUniversity of Arizonahas discovered that a quick sniff of lavender can lower heart rate and keep the animal calm.
The new study, which was published in the Journal of Equine Veterinary Science found found significant signs of stress reduction in horses that inhaled lavender from a diffuser.
Ann Baldwin, Professor of physiology and psychology, said: "Some horses don't like to be shod. So, when the farrier comes and starts banging around with their hooves, it would be good for that.
"You don't need a diffuser, really. Just put a few drops of lavender essential oil on your hand and let your horse sniff." For the study horses were startled by an air horn and then provided with humidified lavender air.
The horses' heart rates increased in response to the air horn but returned to normal more quickly in those that inhaled lavender.
In a second study, Prof Baldwin enlisted nine dressage horses of varying breeds and ages. Each horse was led to a small paddock and held by a volunteer while a diffuser containing lavender essential oil was held near the horse's nose.
A monitor tracked heart rates and heart rate variability for 21 minutes total - seven minutes beforethe introduction of the diffuser, seven minutes with the diffuser in close proximity, and seven minutes after it was removed.
"The heart rate didn't change; what changed is what's called the parasympathetic component of heart rate variability," she said.
"One of the parameters of heart rate variability is RMSSD, which is the relaxation part of the autonomic nervous system. If RMSSD goes up, that indicates the horse is relaxed. We found that when the horses were sniffing the lavender, RMSSD significantly increased compared to baseline."
The data were supported by the horses' observed behavior, which often included relaxation signals such as neck lowering and licking and chewing while the lavender was being inhaled.
The experiment was repeated with water vapor and chamomile, neither of which produced a similar calming effect.
The researchers say lavender may be a better alternative to tranquilizers which have a long term effect.
Olfatory system.
The horses have two mechanisms to detect odor;
1. One is by means of the main olfactory system (MOS), with the main olfactory receptors (MOrs) located in the posterior part of the mucosa of the nasal cavity. The olfactory nerves project to the main olfactory bulb (MOB), from where the olfactory tracts transmit their inputs to specific areas of the brain: the anterior olfactory nucleus, piriform cortex, olfactory tubercle, anterior cortical amygdaloid nucleus, the lateral entorhinal cortex and the periamygdaloid cortex.
2. The other option is through the accessory olfactory system (AOS), commonly named the vomeronasal system (VNS). It is integrated by three different structures: the vomeronasal organ (VNO), the accessory olfactory bulb AOB, and the vomeronasal amygdala (VNAg). Inside the VNO are the vomeronasal receptors (VNrs), which project through the vomeronasal nerves to the AOB. The horse uses its VNO during the flehmen response, activation of pheromone uptake, in which it raises its head and rolls back its upper lip , forcing smell-laden air through slits in the nasal cavity into the VNO . The pheromone is a secreted or excreted chemical factor that tiggers a social response in member of the same species. The response is often seen in horses conducting a thorough investigation of other horses' urine and feces but may also occur when they encounter novel flavors and nasal irritants. Although gravity assists in this sampling procedure, it has been shown that the lumen of the tubular portion of the VNO alternatively expands and contracts to pump its content in the direction of the accessory olfactory bulb. In contrast to many other species, the VNO of horses does not open into the oral cavity.
Flehmen Response in Horses
Stallions show the flehmen response most frequently, often after sniffing a mare's urine or simply when they are in the presence of a mare in estrus. Visual cues may be important in the stallion's response, as stallions whose vision was blocked showed a lower frequency of flehmen than stallions that could watch mares urinating. "It appears that flehmen facilitates chemosensory priming of stallions for reproductive behavior, rather than being an immediate component of sexual behavior," said Crowell-Davis (Veterinary Biosciences and Diagnostic Imaging).
Mares commonly show a peak in flehmen response during the first few hours after giving birth. Smelling the newborn foal and the amniotic fluids associated with birth often produce the reaction.
Geldings show the behavior less frequently than other mature horses, although any horse is likely to flehmen when it encounters a novel scent such as a new dietary supplement or feed ingredient. Odors like smoke or fresh paint may also cue flehmen. Sniffing another horse's urine or feces, or even their own waste, is likely to invoke an upturned lip, and horses produce the reaction from time to time when there is no stimulus that their owners can detect.
Foals of both sexes show the flehmen response. Young colts flehmen up to five times more frequently than fillies, and fillies flehmen more frequently than mature mares.
"Evidence to date suggests that exposure to urine may be important for normal physical and sexual maturation in colts," said Crowell-Davis. "Therefore, it is important, especially for orphaned colts that may be kept as stallions, to expose colts to urine during their early development, particularly during the first three months of life when the rate of showing flehmen is especially high among colts living in a natural herd environment."
