Usually just when they get really dirty, and then you can just spray them down with the hose. That's assuming you're talking about plastic jump boots and not polo wraps (which can be washed in the washing machine).
Magnetic boots can be wiped down with a slightly damp cloth. If they are very dirty you may have to scrub them a bit.
Get a knife, and scrape it down, be sure not to cut into the boot just run it back and forth, when it's off and your boots are scuffed wash them with some saddle soap.
I wash it like washing my sweater.
dry wash it
no
It is not recommended.
A fresh combat boot from factory can be shine to a higher shine, but it'll be troublesome in the future, as the layer will get crack because the nourishing layers did not absorb into the boots. However, to achieve the best result, first break in the pair of boots, then wash it with saddle soap. Buff the saddle soap with a brush and then soft cloth for a soft luster. Then apply a layer of leather balm and the boots is good for polishing now.
You can ether groom the horse or wash it gently by hand to clean off the dirt. Otherwise, you can lightly wash down the horse (you can use a hose, but on a low water pressure, and make sure not to touch their face or neck, and go in proper grooming order in terms of how you wash and where on the horse's body you wash).
It is not recommended that a washer or dryer by used to clean Ugg boots. Ugg recommends wetting the entire boot with cold water and then using Ugg Sheepskin Cleaner and the provided brush to clean the entire boot. Once clean, thoroughly rinse the boot with cold water, stuff the inside of the boot with paper towels to keep the shape and then at least a day for the boot to dry.
sleep all day
When it's a hot day and the horse is dirty or sweating
You cannot wash suede in a washing machine.