At least yearly, but more often depending on winter conditions. If the horse blanket or sheet becomes muddy or caked with manure, etc., certainly more often. When these materials are left on the horse blanket for extended periods of time staining may occur and may not wash out. At a minimum, as soon as the winter temperature breaks and it is no longer necessary to blanket the horse, come in for horse blanket cleaning. Immediately doing horse blanket cleaning ensures that excrement, urine and mud will not stain, fade or breakdown the fabric. This will extend the life of your horse blanket.
If you live in a long winter climate… have a spare blanket, then get horse blanket cleaning about every 6 months. This will allow the horse blanket to recover.
Blankets absorb sweat, dirt, excrement, urine, blood- this causes bacteria and an unhealthy condition for your horse. You may wish to consider washing more often.
Never put a dirty blanket that has been sitting over the summer back on a horse. Also, never put a blanket on a different horse other than its previous owner. Give us an opportunity to clean the blanket for you.
Eventually a blanket that has not been cleaned for years will likely dry rot, fabric will have broken down and the fabric may not hold water repellent.