Olfactory stimulation as an element of environmental enrichment preventing mental disorders in animals

Environmental enrichment is the stimulation of the brain, which involves the enhancement of an animal’s physical or social environment. It influences brain plasticity, stimulates neurogenesis, increases neurotrophic factor expression, and protects against the effects of brain injury[1]. Environmental enrichment reduce the incidence or severity of undesirable or abnormal behaviours, such disorders like; OCD, stereotypy, autism[2], depression or anxiety and phobias. Abnormal behaviours observed in animals include locomotor stereotypies (weaving, pacing, and route-tracing) and mouth-based behaviours such as feather pecking, barbering, cannibalism, bar biting and many more. We distinguish 5 types of enrichment: social, occupational, physical, nutritional and sensory (or stimuli) enrichment. The last one can be: visual, auditory or in other modalities (olfactory, tactile, taste)[3]. The vast majority of animals are macrosmatic. The main sense which they are used in exploration is sense of smell (chemical receptors). We can use this trend in the design of sensory environmental enrichment with olfactory stimuli. For certain animal species we can use a variety of naturally attractive odours. For example- a cats as a predators are interested in feathers. The olfactory stimulation can also use pheromones, such as DAP (dog appeasing pheromone) or feline facial pheromone, which gives calming effect.