River otters love to roll in sand, dirt, or mud when they come out of the water. Any excrement of their own or their family's mixed in with that seems to be an added bonus. Back into the water cleans all that off their fur and this process seems to help retain healthy fur. I don't know if that is true, but Nature appears to know.
Canon EOS R5m2RF100-500mm F4.5-7.1 L IS USM lens500mmf/6.71/250s5000 ISO+0.5 EV