washing white and black stained tail

My new horse, Opal, has a black and white tail, but as I have found, it wasn't really looked after. It is very mucky and stained yellow, probs from urine. I tried washing it the other day, and some yellow came off, but does anyone know a cheap (my mum would say no to anything expensive) product or home remedy that I can use to clean her tail. Just to get the stains off, but I don't want to effect the strength of the black colour, so nothing too strong! Thanks so much for your help :)

Our barn owner is an expert at getting stains out of manes and tails - with a stable full of gray Arabians that were shown all over the place. Ms. Jean said to wash the tail in Palmolive to get any and all loose dirt/debris out. Rinse thoroughly. Spray with Oxyclean spray and leave in while you groom the horse. Rinse out thoroughly. Shampoo with a cleaner specifically for blonde/gray hair.

I do this for Biscuit on a regular basis as he is a palomino. He is not a show horse and he is in a pasture 24/7. When I first got him he had diarrhea all the time and his tail was yukky. He still will have loose bowels so cleaning his tail is an on going process!!

I found some cheaper whitners will help youll just have to do it multiple times also if you wrap it after it wont get as dirty and it will help prvent against future stains

When we wash the h/j's at our barn during the first of the season all of the greys that come in from the pasture are yellow and fluff balls! Washing is a 2 day prosess: For the tails we wash them with Dawn soap to get as much dirt off the top of the hair as possible. Next we use Vetrolin white n bright shampoo ($14 for a big 32oz bottle , you can probably find it locally but I get it on DoverSaddlrey.com ) and leave it in for around 10 minutes to let it soak and then rinse. If it is a really stubborn tail do the same thing except from the tailbone down leave in the shampoo then braid where the shampoo is and wrap (if you don't know how you can find tutorials on YouTube) than the next day rinse out well and you have a white tail! If you mom doesn't want to spent $14 then do some chores around the barn, it would only take me 3 stalls! $5 a pop nobody can refuse if they are paying someone else more to muck it for them.

Thanks so much guys! Help appreciated, I will look into it