Snakes can suffer from pneumonia. This usually happens when a snake is weakened from some disease (wild-caught snakes) or because the climate conditions in the terrarium are not good.
The most noticeable symptoms are a difficult, heavy respiration that is not noiseless any more. Often you can hear a gurgling sound and there is usually more mucus than normally present which eventually drips from the mouth. Sometimes there is blood in the mucus.
When the breathing gets really difficult, the snake will keep its beak open all the time.
Without treatment a snake with pneumonia will die!!
Place the snake in a quarantine terrarium and make sure the temperature is high. When the snake only has a cold, the symptoms will diminish and disappear.
If the symptoms do not disappear contact a vet. The treatment normally will be a course of antibiotics.
Follow the advice that is given to you by the vet and complete the course, even if it seems the snake is healed midway treatment.