Leather collars are unfit for swimming, bathing and outings in heavy rain. If the collar is drip with wet, use a dry cloth to wipe it and let dry at room temperature. Oil the collar when it is dried with a balm.
It is better to keep the collar in a special bag of natural material, which is ventilated. This will save the item from excessive humidity, dryness and dust.
Use leather care products from time to time to keep the collar flexible, soft and shiny.