One problem that would occur when sustaining a third-degree burn is dehydration. When a person is burned and depending on the severity of burn, the blood vessels including the capillaries may be affected. Combined with the release of chemical substances into the blood, this will lead to increased capillary permeability to fluids, leading to the leaking of fluids from the blood vessels into the tissues. The higher the percentage of burned skin, the more severe the loss of fluid will be and the greater the dehydration will be. In a third-degree burn, the entire thickness of the skin is involved and with the nerve endings destroyed, the barrier against water loss is no longer there. Without the protective covering, fluid just seeps out and also allows bacteria to grow and infect the wound.
I sincerely hope this answer helps! ^w^