Getting mud out of white sheets

[AliciaWhiskers]

Muddy paw prints and white bedding = disaster!

I’ve washed it twice at 60 degrees, once also with vanish stain remover in the wash, with no success.

What else can I try?

Put it on the line and let the sun bleach it out naturally.

Unfortunately if you've already washed at 60oC you've probably set the stain in. Mud is best got out by soaking in cold water with detergent then washing. If plain white you could try a soak dilute bleach or try Napisan.