I would try warm soaks in diluted betadine baths (1:20 ish with water) for about 15 minutes 2x a day. Switch the substate in his tank to dry paper towel and change that daily or every other day as long as it is dry and clean. This will work ....i have used this method on dozens of snakes (i used to be a reptile specialist). Continue the soaks for a bout a week.. Oh, and before you soak with betadine, make sure that your snake is properly hydrated so he doesnt injest any of the solution. Good luck.
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1.0 ball python- Azazel
1.0 columbian boa- Brooklyn
1.0 red blood python-Hiss
1.0 peach phase thayeri-Sancho
0.1 creamsicle corn- Pandora
0.1 partial stripe ghost corn- Raven
1.0 Sunglow motley corn-Ernie
1.1 hognose- Pricilla and Odd
0.0.1 smooth green snake- Raziel
0.1 russian tortoise- Manja
1.0 juvie red phase crested- Ichi
0.2 leos- Boji and Kodama
0.1 beardie- Indie
1.0 BTS- Griffon
0.1 Iggy- Sunny
0.0.1 gray tree frog toadlet
4.3 bettas
0.1 pacific parrolet- Mishka
1.1 cats- Cairo and Oberon
2.3 ratties Rizzo, Bree, Blitzkreig, kaos, and Takashi