My Snake or Other Reptile Won't Eat! What Should I Do?
Perhaps one of the most commonly asked reptile related husbandry questions asked in person, on forums, and elsewhere on the Internet, particularly among new or beginning reptile keepers, is "my snake will not eat! What should I do?" Anorexia, or an apparent refusal or reluctance to feed in captivity, can have numerous underlying diagnoses, many of which may be related to incorrect husbandry, errors in husbandry, potential parasites or illnesses, or sometimes other factors. In order to best answer this frequently asked question (or FAQ), we have compiled a list of the most common underlying reasons for anorexia seen in captive snakes (much of which is applicable to other herps, or reptiles and amphibians as well), and the underlying reasons why each may occur in accordance to the biology and natural history of the species in question, and reptiles in general.
Species: All species of snakes are carnivorous, meaning they must derive their food and nutrition from other animals. In the wild, snakes may feed on a variety of animals depending on the species, ranging from small to large mammals, birds, amphibians, other reptiles (sometimes including other snakes), fish, insects, other invertebrates and so on. The majority of commonly kept pet snake species can be fed appropriately sized rodents (i.e. mice or rats), or rabbits in the case of larger species, although others may be dietary specialists. Some species overall may have obscure or difficult to meet care requirements and generally do not make great pets to begin with in most cases (and thus may be a reason why the species in question has not yet already been established in captivity). Therefore, knowing and understanding a species' diet and other related natural habits/history in the wild, and replicating it to the closest extent possible in captivity may prevent feeding related issues initially.
Some may like the added senses! Different species of snakes and other reptiles may rely more heavily on different senses, particularly through using their Jacobson’s Organ and other olfactory senses. For many reluctant eaters, opening up a prey item to expose more of its internal organs, scents, and smells may help to stimulate them into using these aforementioned organ systems to locate and consume their prey items. This is where the ideas behind such techniques as “braining”, or “gutting” can come into play.
Temperatures/Humidity: All snakes (and other reptiles and amphibians in general not accounting for some slight exceptions to this rule) are known and referred to as ecothermic, or more popularly, "cold-blooded" animals. This means that unlike mammals and other endothermic animals that are able to regulate their internal body temperatures to at least some degree, "herps", or herptiles do not, and instead must rely on their ambient temperatures and environment to maintain adequate thermoregulation, digestion, reproduction, and other physiological processes. This means that if incorrect temperatures and/or humidity (including too high or too low of temperatures) are provided for a captive animal, these processes cannot properly take place. Once more, understanding and closely replicating the animal's biological and natural history in the wild with respect to the climate, regions, and temperatures it occurs and thrives in may prevent feeding related issues.
Some animals like them hot! This is especially the case for some snakes which have labial or loreal heat pits (such as boas, pythons, and many viperids) that rely on these heat and photosensitive organs to be able to detect and locate endothermic prey. Make sure your pre-killed rodent or other food animal is heated up for these animals to potentially be more enticed by them as food!
Hides/Security/Overall Environment: Snakes are an incredibly diverse group of reptiles with a vast array of differing natural histories, habits, and lifestyles. Some snakes are arboreal, meaning they spend much of their lifestyles in trees or other structures in order to locate food and shelter. Some species are primarily terrestrial (or ground dwelling), while others may be fossorial (or secretive burrowers preferring the safety and security of burrows or underground), while some others yet may be aquatic or semi aquatic (seeking refuge or finding food in the water). Even yet again, understanding and closely replicating the animal's biological and natural history in the wild may prevent feeding related issues. Many snakes may also be nocturnal (active at night), crepuscular (active at dawn or dusk), or primarily diurnal (active during the day). Regardless of the species, however, providing an environment in which your snake feels safe and secure (including providing adequate hides, or hideboxes, maintaining the setup in a low traffic area, and so on may help considerably in many cases. Hatchling, or neonate snakes especially are prone to predation, or being eaten, by just about any other animal larger than they are, and will often perceive handling or frequent disturbances as a potential threat and behave accordingly if the proper husbandry conditions are not being met. Any newly or recently acquired snakes especially should be allowed adequate time to adjust and acclimate before attempts to feed them are made.
Parasites/Illnesses: Although very easily another topic, there are numerous parasites and other illnesses and diseases that may affect captive reptiles, particularly when proper husbandry and environmental conditions are not met. Anorexia in reptiles is not in of itself a primary disease or disorder, but is rather very often a sign or symptom of another underlying health related issue. Any disorders or other abnormalities in a non feeding animal’s eyes, mouth, head, bodily condition/appearance, or overall state or level of activity should be noted as a possible cause of the anorexia and the appropriate veterinary treatment or intervention should be sought accordingly. In captivity, an animal’s natural immune system and other related physiological aspects also may be impaired or compromised more so than usual, particularly if the animal being maintained is one of wild caught or questionable origin.
Other Physiological Reasons: There may also be other physiological reasons why your snake may not eat, or feed only sporadically. 1).Ecdysis, or the shedding of the skin, is one such physiological process that all snakes, both in the wild and in captivity undergo periodically depending on the age, size, and growth rate of the snake. Snakes are animals that display indeterminate growth, meaning they do not stop growing (although growth rate slows considerably and becomes nearl indiscernible). Hatchling or neonate snakes typically grow more rapidly than older snakes, and may shed or slough their skin every few weeks, while older snakes may only shed once every 2-4 months or longer. Prior to and during ecdysis, many snakes may have slowed metabolic rates, as well as impaired vision when fluids build up from underneath their ocular scales. 2) Brumation is a state of reduced activity and lowered metabolic and thermoregulation seen in many snakes (particularly at certain times of the year or associated changes in natural light cycles such as autumn or winter and again in the spring) and that differs from true hibernation, which also often results in anorexia. Even captive bred and born animals can sense changes in seasonality and barometric pressures, which often causes them to slow down during certain periods of the year. This is an extremely common cause for non-eating, but typically should not be cause for significant concern unless substantial weight loss or other more serious health problems occur or begin developing. Brumation during certain times of the year is typically not a significant cause for concern for pet owners or reptile keepers provided the animal remains active and alert, and does not drastically lose weight. Many snakes during brumation are able to fast for several months or more before eating again, and will typically do so when they are ready again.
To conclude, these are several of the most common reasons and explanations for anorexia in captive snakes, although other less common causes not covered here do exist as well. Further research and exploration into this, or any topic is always encouraged, and often leads to becoming far more knowledgeable and experienced overall. Some cases of anorexia may be more severe in nature than others, and in cases that do have greater severity, more drastic or immediate changes/improvements to husbandry must be made in addition to seeking a source of qualified and professional veterinary attention, if not already done so. Hopefully, this article will serve as a useful reference, starting point, and resource that will be able to answer and address the causes of the vast majority of anorexia related husbandry questions that can be shared and disseminated to others.