To answer your question, your dragon has a prolapse. Salt water will not help at all, in fact it will cause more problems, not to mention being very uncomfortable for your dragon. BDLvr advise about putting your dragon into a barebones cage is very good advise. You can soak your dragon in luke warm (around 70-75F) sugar water (not salt, but sugar) may help reduce swelling and allow the prolapse to correct itself. It it doesn't after soaking for about 20 minutes and then removing the dragon, and giving about 12 hours, take him to a vet.
If the prolapse doesn't go in, it will mean the tissue will dry out, become infected and eventually, kill your dragon. Even if the prolapse does go back in on its own, it may come again.
If you feel your dragon is straining to poop, or keeps prolapsing after each bowel movement, this indicates other problems that need to be treated by a vet. Internal parasites, dehydration (about the only thing that doesn't require a vet to fix, just rehydrate your dragon by misting, soaking, offering high water content foods (pureed carrots, squash, sweet potatoes are great ways to do this, or just misting his greens). Some vitamin/mineral deficiences may cause prolapses as well. Oh and impaction/blockage of the bowel or intestines can lead to it as well. As finding the cause of prolapse is just as important as fixing it, taking your dragon to a qualified vet is important.
Infection can still happen even if the prolapse goes back in on its own. Any bit of debris brought into the body can cause irritation and infection, which can in the head seriously threaten the health of your dragon. A vet will flush out the extruding prolapse and reinsert into the body, may even proscribe some anti-biotics as a preventative to infection.
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PHLdyPayne