I have been schooled quite intensley in Red Leg care. lol because i worked at Petco for 3 years...
Ok, first, a very diluted bath in 1part betadine to 15 parts water. (give or take) for about 30 minutes 2x daily. Just a slight tint of 'tea brown' to the water.
Also, a water conditioner for fish called Stress Coat can be applied to the frogs belly to soothe the burining.
I would keep him on dry paper towel for a while, just in case. Cane toads can take the dryness, and that will stop the infection from spreading further. Keep a shallow (very clean) bowl of water with stress coat and possibly some activated carbon.
This should help to catch the infection, just be sure to watch that the blisters dont spread. If you notice the reddness getting worse after the baths and all other treatments, the infection may be spread to the organs.
After the treatments are all done (when the bellyt is white and there are no more blisters) i would make sure to keep the toad's substrate super clean. These guys tend to sit in one place for long periods of time, giving chance to the bacteria to invade. Adding activated carbon to his substrate will help to stop this from happening between cleaning. Good luck with this.
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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
0.1 russian tortoise- Manja
0.1 collared lizard-O-ren
0.1.1 leos- Boji and Kodama
0.1 beardie- Indie
1.0 BTS- Griffon
0.1 Iggy- Sunny
0.0.2 Red american toadlets with 0.0.7 legs total (er, i have one w/3....)
0.0.1 gray tree frog toadlet
0.0.6 land snails
0.0.2 millipedes of unknown species from TN
0.0.1 spotted slug
5.3 bettas
0.1 pacific parrolet- Mishka
1.1 cats- Cairo and Oberon
2.3 ratties Rizzo, Bounce, Bree, Blitzkreig, and Zelda