The sense of smell in horses
The horse's sense of smell is much more developed than that of humans and performs several functions. In addition to the fact that it allows the animal to sort its food, smell plays a role in mutual recognition between horses but also between humans and them. Each individual, horse or human, is characterized by its own odor. When two horses meet, they first start by blowing into each other's nostrils and sniffing each other, this behavior will determine their future relationships. In this article, discover everything you can know about the horse's sense of smell.
Smell: a tool that allows the horse to recognize danger
The horse's sense of smell plays a major role in recognizing dangers. In the event of fear, the horse must be given time to sniff out the object of its fear (access ramp to the van, ford, tarpaulin, etc.) so that it can reassure itself. If a person does not do this and tries to force the horse to pass by force, he will make the situation worse by increasing its stress, and the animal may then rear up or turn to flee, putting the worker in danger.
The ability of horses to perceive other chemical molecules
In addition to the odors that are more or less perceptible to the nose, there are also other chemical molecules that can be perceived by horses: pheromones (intervening in intraspecific relationships) and allomones or kairomones (intervening in interspecific relationships). The best-known pheromones are the sexual pheromones that allow the stallion to detect the mare in heat. These substances are finely analyzed by the horse thanks to a small gland located in the nasal cavity: the Jacobsen organ or the vomeronasal organ.
In order to bring the substances to be analyzed to the level of this gland, the horse performs a characteristic mimic: the flehmen. These molecules are not perceptible to the human sense of smell and can give rise to reactions incomprehensible to humans on the part of the animal, for example, the excitement of a stallion smelling the pheromones of a mare in heat, even if the latter is several kilometers away.
There are other pheromones in addition to sex pheromones, for example, stress pheromones that are found in the urine of some individuals. They are produced when the animal feels in danger at the time of boarding for example and will have the effect of stressing other individuals perceiving them, even if there is no real danger.
It is therefore not recommended to load the most nervous horse first so as not to stress the following ones. On the other hand, appeasement pheromones such as apaisines calm the animals. These substances can be found commercially in the form of sprays or at La Sellerie Française and can be used to calm the horse before, for example, a trip or a visit from the farrier .
To be effective, they must be given before the animal is stressed, i.e. at least 30 minutes before the procedure. They are only a sticking plaster on a wooden leg and should only be used as a last resort, the optimal preventive solution being of course good basic education of the horse.
Humans can also emit chemical substances (allomones and kairomones) that are perceived by horses. It is well known that horses "feel" their rider's fear. In fact, when feared, humans secrete these chemical molecules and transmit their stress to the animal.
In case of fear or great nervousness (the day before a competition, death of a loved one, etc.) it is better to keep your distance from the horses. The animal, sensing the stress of its rider, will itself be stressed and nervous and may have reactions (swerving, rearing, etc.) which will themselves stress the rider even more.
It is a vicious circle that can lead to an accident. Some riders also panic at the thought of riding certain horses. Rather than forcing the person, it is sometimes better to avoid putting them on the object of their fear in order to avoid any accident.