This time of the year its always great to give your horse a bath. A horse should not be bathed when the weather is cold, any more than you would go swimming when it is chilly.
If you have access to a heated wash bay and a draft free area where he can dry, you can bathe him even in the winter, but if it is cold, try a thorough groom and a hot towel bath instead.
To bathe a horse, you will need several buckets of warm water, a large body sponge, a rubber currycomb, a sweat scraper, towels and a cooler.
First, wet the horse all over down to the skin, using the hose or a body sponge. Horses will accept this better if you start with a trickle of water and work up from the hoofs, wetting the legs and then the body gradually. Wet the mane and tail too.
Make up a bucket of soapy water, and fill a dilution bottle with the shampoo and squirt it all over the horse. Working from the neck back and down. As each section is soaped, use the currycomb gently to massage the skin and work up a lather. You can also use your fingers as when shampooing your own hair. Keep the soapy parts wet, and rinse as you work by running the hose or squeezing out a large spongeful of clean water above the part where you are scrubbing clean and free of soap before you move on.
The face and head should be washed with as much water as the horse will tolerate and as little soap as you can use and get them clean. Often hot towelling works better, especially on horses that throw their heads up and resist. Don't let water run into their ears and eyes, be careful and gentle when working on the head, most horses hate water on their heads, and a bad experience can make your horse difficult the next time.
The mane and tail should also be washed and thoroughly rinsed, with special attention given to the skin and roots of the hair. The shirt of the tail can be doubled up and dunked into a bucket to rinse it.
The wet coat should be scraped, starting high on the neck and working down and backward, in the direction the hair grows. Use a body sponge that has been wrung out nearly dry to pick up water from the head, legs, flanks and other areas that are hard to scrape. The tail is gently wrung out and the skirt can be given a snap to one side to remove excess water.
After bathing the horse should be covered with a cooler, walking cover or a light sheet according to the weather and kept out of drafts until he is dry. Don't leave him where he can lie down-newly bathed horses love to roll in the mud!