Pet snakes lead pretty routine lives. They don't have predators to evade or have much work to do to find food. We can do an excellent, almost perfect, job keeping their environments where they should be in terms of temperature and humidity, but we can't always prevent them from becoming anorexic - that is, not eating. Despite being able to prevent all problems in pet snakes, there is a large number of factors that we can control, some of which play an integral part in keeping your snake eating.
One of the most important things to monitor with pet snakes is the temperature of their enclosures. Snakes need warm environments to be active and properly digest food. If they get too cold they will become very lethargic and possibly develop a variety of illnesses, including a respiratory infection or pneumonia.
Before you call your vet for an emergency "my snake's not eating" visit with your apparently healthy snake, check the temperatures in his cage. What is the basking area temperature? What is the temperature of the coldest part of the cage? And how cold does it get at night? If you've answered below 70 degrees Fahrenheit to any of these questions, chances are your enclosure is too cold. Check your references for the appropriate basking temperatures and cooler acceptable temperatures for your specific kind of snake and make sure yours are as close to those ranges as humanly possible.
You may need to add another heat light or increase the wattage of the bulbs you are currently using. Undertank heaters are alright for supplemental heat but don't do much in the way of ambient temperature.
A common reason pet snakes stop eating is because they are about to shed their skin. Your snake's skin will become very pale and dull looking before they shed and their eyes will look blue or milky colored.
They may not eat for a week or so before and after they shed.
If you've ever had a toothache, canker sore, or have bit your tongue then you know what it is like to have some mouth pain. Mouth rot is a term that describes an awful mouth infection. It is painful and your snake will not want to eat if he has any degree of mouth rot. If you are not sure if your serpent has a healthy mouth get him in for a check up with your exotics vet.
Just like when we have a cold or the flu we don't have much of an appetite, snakes don't want to eat if they have respiratory infections of pneumonia. If your snake is sneezing, has eye or nose drainage, or is breathing through his mouth he could have some form of a respiratory disease and won't eat. Give your exotics vet a call if you suspect this.
Better known as "worms," intestinal parasites are microscopic and actually normal in reptiles. When they become overpopulated in the intestines of your pet snake, though, he may stop eating. You won't see these parasites so you must have a fecal direct smear and a floatation performed on your snake's stool sample. Call your exotics vet to set up an appointment for a fecal screening if you haven't had one done within the last year or you suspect it could be a reason for him to be not eating.
Obstructions and Impactions
Sometimes snakes accidentally get a mouth full of something they can't digest and get obstructed. And other times they don't get enough moisture in their environment to defecate regularly and become impacted. Both obstruction and impaction can cause your snake to stop eating. Warm water soaks for 15-20 minutes twice a day may help an impacted snake pass his stool but an obstruction can require surgery to remove. Call your exotics vet if you haven't seen stool pass within a day or so of your snake's last meal or if you think he could be obstructed.
Of course, there are many other reasons why snakes stop eating, including major organ failure and disease, systemic infections, and more. If you aren't sure why your snake has stopped eating give your exotics vet a call.