Snakes do not have eyelids; instead they have specially adapted scales over their eyes called eye caps (also known as spectacles). These are normally shed along with the skin during each shed cycle, but sometimes they do not shed properly -- a condition called retained eye caps.
Causes of Retained Eye Caps
A common cause of retained eye caps is insufficient humidity or other husbandry issues that contribute to shedding problems. However, snake mites or infections of the eye or surrounding tissues may also contribute.
Determining if Your Snake Has Retained Eye Caps
First, always examine the shed skin from your snake. The eye caps should be shed along with the skin, which means there should be no holes where they eyes were. If the eye caps were are not present on the shed skin, it's possible they fell away separately, but you should have a close look at your snake's eyes as they eye caps may still be on your snake. Normally snakes have clear eyes, except for a short period prior to shedding where they turn a milky blue color. If the eye caps are not shed, your snake may appear to have cloudy or foggy eyes. However, the appearance of eyes with retained eye caps is variable, and not all abnormal looking eyes have retained eye caps, so when in doubt consult a veterinarian. For a detailed explanation of detecting retained eye caps, see Reptile Eye Care Issues (external link).
If Your Snake has Retained Eye Caps
There are mixed opinions in the herp community about the necessity of removing retained eye caps (as opposed to leaving them to come off with the next shed); your best bet is consult with your reptile veterinarian. Usually an attempt is made to remove retained eye caps, as they could potentially impair your snake's vision (which may make it nervous, aggressive, or reluctant to feed). Certainly, eye caps that are retained through subsequent sheds need veterinary attention.
If the eye caps are retained, you must re-evaluate your husbandry methods, particularly humidity levels. Your vet can check your snake for other possible causes of retained eye caps as well.
Removing Retained Eye Caps
It is best to get the help of a reptile veterinarian to remove the eye caps, as it is important not to do anything that could damage your snake's eyes. Soaking the snake in warm (not too hot) water a couple of times a day (e.g. just deep enough to cover your snake's body, and supervise to prevent drowning) may help the eye caps come off. However, if this isn't successful after a day or two, a trip to the vet is in order. You will find different methods described online for removing retained eye caps, but I don't recommend trying this yourself, at least until have experience with it, due to the risks of damaging the eye.
Just like us, snakes constantly grow new skin cells and must shed the old skin cells. We shed our old skin cells continuously in small quantities, but snakes shed their old skins in a continuous sheet (a process called ecdysis). The interval between sheds depends on several factors, including age, growth rate, and environmental factors. Young, growing snakes shed frequently (every few weeks); adult snakes shed less often, perhaps a few times a year, sometimes less.
Signs Your Snake is About to Shed
Eyes turn a cloudy, bluish color (the eye cap, a specially adapted scale which covers the eye, is loosened up in order to be shed along with the skin, which causes this change). Just prior to shedding, the eyes will clear up again.
Skin becomes dull or hazy in appearance (sometimes the belly may appear a little pink at first)
Your snake may hide more than usual and go off food.
Your snake may become more skittish or defensive because it can't see well.
When your snake is ready to shed, he or she will seek out rough surfaces in the enclosure to help rub the skin off.
Care for Your Shedding Snake
Provide some cage accessories to help your snake rub off the old skin such as clean driftwood and rocks (which should still be pretty smooth, not rough).
Make sure your snake has enough humidity - a shallow dish of water in which it can soak, and / or a humidity hide box (an enclosed plastic container, with an entry hole just big enough for the snake to fit in, containing damp sphagnum moss).
Avoid handling your snake as much as possible (gentle handling is okay if necessary, but the process is stressful and the new skin is delicate, so avoid unnecessary handling)
If your snake goes off food, don't worry (a healthy snake can go a couple of weeks without eating). However, if your snake wants to eat, it may be best to feed a smaller meal than usual to minimize the effort your snake need to digest a meal during the shedding process.
When your snake has shed, examine the shed skin to make sure the shed was complete. Ideally, the whole skin will come off in one piece, and the eye caps should be shed along with the skin (there should not be holes where the eyes were). If your snake has not shed the whole skin or the eye caps, see ore about shedding problems below.
Shedding Problems [br[If your snake does not completely shed its skin (an incomplete shed, also called dysecdysis), it can signal health problems or problems with husbandry (e.g. humidity levels). Retained eye caps (where the eye caps are not shed along with the skin) may occur with an incomplete shed, but may also occur even if the rest of the skin was shed intact. For help with either of these problems.
There are many problems that can contribute to shedding problems or incomplete sheds, but the most common problem in inadequate humidity levels. Other factors include skin infections, injuries to the skin (including old scars), parasites, malnutrition, and inadequate heating or lighting. For this reason, if incomplete shedding is a problem, it is a good idea to consult with a reptile veterinarian to rule out medical causes. It is always important to make sure you are providing adequate humidity levels to prevent shedding problems, but remember that too much humidity can cause other problems. Find out the ideal humidity for whatever species you are keeping, and get a hygrometer to make sure you are keeping the humidity in the proper range for your reptile. As well, make sure you are providing proper temperature ranges, lighting (e.g. quality UVB lamps for species that need them), and an ideal diet.
Shedding Problems in Snakes
Snakes generally shed their skins in a complete sheet, starting at the nose and working down to the tail (their skin comes off a bit like a sock being turned inside out as it is removed). When there are problems with shedding, the shed skin is not complete and the skin comes off in patches (and in some areas the skin may not come off at all). Retained eye caps, where the protective scale that covers they eye is not shed with the skin, may also be a problem.
For a snake having problems with shedding, you can try soaking the snake in a tub of warm water a few times a day. Make sure the water covers the body but is not too deep or your snake may drown, and supervise your snake during the soak. Wrapping your snake in warm wet towels may also work as the friction from the towels as your snake moves around may help remove the skin; some keepers place snakes with shedding difficulties in a wet cloth bag (such a pillowcase) for a few hours. Providing a humidity hide is also a good way to give a shedding snake access to a higher humidity area. For arboreal snakes, try regularly misting.
Shedding Problems in Lizards
Lizards usually shed their skin in patches, but a problems can occur when parts of the skin are do not come off during the shed. This can especially be a problem around toes, the tail, and the base of dorsal spines (e.g in iguanas). In these areas, skin that does not come off can dry up and constrict around the toes, tail or spines, and can cause loss of these appendages. Shedding is usually completed within a week or two, and sometimes sheds occur one on top of the other, so sometimes it can be hard to tell whether a shed is progressing normally or not. Generally, all the skin should be shed within a couple of weeks once shedding has begun.
For lizards with shedding problems, treatment is much the same as for snakes. Providing a warm soak a few times a day can help. A humidity hide can also be very helpful for some lizards, such as leopard geckos; for others, such as water dragons, try regular misting. Again, make sure the enclosure is kept in the ideal humidity range for the species you are keeping. Bits of skin around the toes, dorsal spines and tail tips may need to be gently massaged off, but be especially careful with the tail as some lizards will just drop their tails as a defence.
Shedding Problems in Turtles
Turtles shed the skin on their heads, tails and legs. The skin on their bodies is often shed in ragged chunks. For aquatic species, problems with skin shedding are not common. For terrestrial species, soaking or misting is usually sufficient to aid shedding. Aquatic species also shed the outer layer of the scutes on their shells. Retained scutes, where the outer layer of the scute is not shed, can be a problem. Retained scutes are prone to infection and are usually a result of husbandry problems. Particularly, turtles should bask out of the water long enough to dry out their shells (lower the water temperature a bit if your turtle is not coming out to bask). Also, sufficient exposure to UVB light and good nutrition are important in proper shedding of the scutes. If your turtle is retaining scutes, see your reptile vet for advice.
Sometimes owners are curious if their snake is a male or female, but telling the difference is not a simple matter as male and female snakes look similar externally. However, with a bit of experience there are ways to tell, but these methods should be done by experienced keepers only. If you are a beginner and want to know the sex of your snake, please find an experienced keeper or vet to demonstrate for you, as the methods carry a risk of injury if done incorrectly.
Relevant Male Snake Anatomy
Male snakes have a pair of hemipenes (sex organs) that normally sit (inverted) inside the snake from the cloaca down along the tail on either side of the snake's midline.
Visual Clues
Since the sex organs are held internally, sexing visually is difficult, but there are visible clues. Because of the presence of the hemipenes, these visual clues relate to the shape and lenght of the tail:
Male: tail thicker and longer than in females, and also tapers less evenly to the tip (thicker for a bit then suddenly thinning).
Females: tail thinner and shorter than in males, and tapers smoothly, evenly and more quickly.
While the differences can be fairly notable when comparing snakes, it is more difficult if you don't have males and females side by side. Pictures showing side-by-side comparison can be found on on this page from PetClubUK (which also features the other, more reliable methods mentioned below).
Probing
Probing a snake involves inserting a thin metal rod (probe) into the vent or cloaca. The probe can be inserted further in males due to the presence of the spaces in which the hemipenes sit. A visual demonstration of the method is shown nicely at PetClubUK. This method is best left to the pros because inserting the probe incorrectly can badly injure the snake.
Popping
In very young snakes, the hemipenes can often be visualized with a fairly simple maneuver called popping. A visual demonstration of popping can also be found at PetClubUK. It is recommended that you do not try this yourself either, though; if done incorrectly, the snake could be injured (or at best you might just get the sex wrong).
Question: Should I Feed My Pet Snake Pre-Killed Prey, or Live Prey?
Answer: This is a controversial area among reptile keepers, but I recommend feeding feed pre-killed prey to pet snakes. If your snake is unable to quickly kill a live prey item, the prey can inflict some nasty wounds on a snake. This is especially true if you are feeding rats (for example to a python or boa), but even a small mouse can cause injury to a snake.
Injuries can happen if your snake isn't hungry enough to hunt the prey right away, or if it tries to kill the prey but doesn't have full control over the prey or is unsuccessful with its strike.
Additionally, feeding killed prey allows you to buy frozen prey items and stockpile them in the freezer so it is easier to have the proper sized prey on hand at all times. Running out to the pet store for food every time your snake needs to eat or raising your own prey can also be more expensive and time consuming, and doesn't guarantee you will be able to get the right sized prey at the right time. Some pet stores will sell frozen prey or fresh killed prey which you can then freeze for later.
Most snakes take fairly well to prekilled prey, although it is best if they have been accustomed to pre-killed prey at a young age. If your snake is eating live prey, you may need to start out offering freshly killed prey at first. Frozen prey should be completely thawed and warmed slightly before feeding (defrost in the fridge or in cold water, not at room temperature, then warm slightly in warm water just before feeding). Dangling the killed prey and wiggling it a bit with tongs (never hold prey with your fingers) can help entice a snake to take the prey. If your snake is still reluctant to eat, you can try dipping the prey in chicken broth, or pithing the prey (puncturing the skull to expose the brain).
