Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Reptile Skin Shedding

Snakes, Lizards and Chelonians

©1996, 2002 Melissa Kaplan

All animals, at regular intervals, shed their skin. Some, like humans, do it relatively unobtrusively in a sort of ongoing process (we shed 1.5 million skin cells every hour with a new skin surface every 28 days or so). Others do it quickly and cleanly, like the one-piece sheds produced by snakes and tarantulas. Most lizards are rather more leisurely about it, with their skin coming off in patches. Some lizards are like snakes, tarantulas, and stick insects: they climb out of their old skin, leaving it behind in one piece.

Chelonians
Iguanas
Other Lizards
Snakes

Behavioral Changes
Problem Sheds
Shed Aid Products
Where'd it go?
Shedding Myths
What The Vets Say

Chelonians
Turtles and tortoises, terrestrial and aquatic alike, shed their skin. Just as they are anatomically structured rather differently than snakes and lizards, so, too is their shed a bit different. The skin of the head, neck, limbs and tail sheds off on a regular basis, just as it does in snakes and lizards, with the skin coming off in pieces.

If the terrestrial chelonian is too dry, the skin may hang like tattered rags, waving in the breeze made as the chelonian walks around. A quick spray with water, or a chance to wallow a bit in a shallow pan of water is generally all that is needed. Do not let species from arid climates do a lot of soaking. Some, like Russian tortoises, seem to be "programmed" to take as much time soaking as possible whenever water is available, as it is not often available in their native range. Provide a constant source of soaking water for them, and they will stay in it to the point of causing shell rot. Some species of tortoise and other terrestrial chelonians may take advantage of more humid microclimates in the wild, burrowing under plants, digging into the earth around their roots where moisture may be retained long after it has dried up on the surface of the ground. These species may benefit from the occasional wallow, soak or spray when they appear to be having problems shedding.

The skin of aquatic species, on the other hand, hangs off of the limbs, tail, neck or head in a sort of filmy flag until it finally tears completely away.

The skin covering the bony scutes also shed off. These are more often seen in aquatic species, found by panicked owners who spot them at the bottom of the tank or see them in mid-shed.

Iguana

Pre-Shed Indicators
Prior to a shed, you will notice that the iguana starts to change colors. The iguana's overall color will get dimmer, duller. Starting around his head and hands, gray or white patches will start to appear (they will look like they are wearing a white glove on one hand). The patches will appear first in the head, then back, arms, then tail, as the different areas get closer to actually shedding. Typically, iguanas start shedding at their heads, with the progression going down the body, limbs, and finally tail. Everything comes off, including the skin, over their ears, and the spikes along the back.

The skin on their eyelids will also shed off. At one point in the pre-shed period, you may walk in to find your iguana has suddenly turned into some wild, bug-eyed monster. Lying quietly, its closed eyes are puffed out 2-3 times their normal size. This is quite natural - they are puffing them up with air as a way to loosen the old skin. In a few days you will notice them rubbing their closed eyes against any handy surface as they begin to loosen and rub the skin off. Gentle head rubs, with your thumb and finger sliding over the closed lids, are particularly welcomed at this time.

If you do not regularly bathe or spray your iguana with water, you may wish to do so during pre-shed and shed periods. In the wild, the natural humidity in the air and the free access to rivers and streams helps the oily fluid build-up between the skin layers keep the old skin soft and supple as it peels off. In our much drier captive environments, the loosened pieces may dry out too quickly, resulting in a much slower shed. Spraying with plain tap water is all you need to do; the expensive vitamin and moisturizing sprays are of unnecessary and not any better than plain water in a $0.99 spray bottle.

Shed
Generally speaking, don't pull the skin if it isn't ready to come off. Iguanas and other lizards will rub themselves against things to help loosen and rid themselves of skin. Mostly, though, they just sort of look like they are wearing raggedy clothes, with strips and patches of skin hanging loose and flapping around. If the skin is ready to come off, you can help it do so by gently pulling at it. If the skin is not ready to come off, there will be resistance, and the skin you remove will be damp.

Often times, spikes need help to shed completely; gently working at them over the course of several days, loosening the skin at the base and spraying them with water will help. If shed is left on, it may constrict the growth of the living tissue from which the spikes are made, resulting in the tissue dying and the spikes falling or breaking off.

The same problem can happen with toes and the narrow tail ends. If old shed is not removed, it can constrict the toes and tails, killing the tissue by strangling the nerve and blood supply that feeds it. Many books and vets claim that carpet fibers are dangerous for this reason yet, in all my years of free-roaming iguanas on wall-to-wall carpeting, I have never had such a problem. I have taken in many iguanas, however, with two, three, up to five layers of retained skin shed on toes and spikes...many of who lost toes and spikes as a result. Part of your regular weekly, if not daily, overall examination of the iguana should be checking toes, tails, and spikes to ensure that they are clean, free of skin, fibers, and human or pet hair.

Sometimes the grommet-shaped pieces of skin around the nostrils may not come off and, as your iguana nears its next shed, you begin to hear a sort of distant whistling sound as it breathes. After the next bath, work at this area gently to remove any such retained shed.

A healthy iguana will shed every 4-6 weeks. Iguanas aged 2-3 years may easily shed more often. It is not uncommon to have an iguana be in the middle of one shed when the next shed starts. During these times, they seem to be little more than skin-producing machines, inhaling food and producing prodigious amounts of both poop and mounds of shed. It is common for such growth to slow down during our winters, and during this time of slowed growth and reduced food intake, iguanas will often not shed. Where I live in Northern California, the last shed usually occurs in November, with the fist shed of the new year occurring in January or February, depending upon our weather patterns.

If your iguana is not shedding, and it is not the winter slow-growth period, then there is a problem. It may be that the environment is wrong, the diet is not nutritious enough to promote growth or normal skin renewal processes, or your iguana is sick. The iguana may also be psychologically stressed. A review of the environment and diet is necessary, as is a review of any other factors that may affect how the iguana responds psychologically/socially to his environment. Slow growers should also be seen by a reptile veterinarian to ensure that they are not suffering from bacterial infections, parasite infestations, or other medical problems.

Other Lizards
Much of the information in the iguana section pertains to other lizards, whether they shed in one piece (alligator lizards) or in many pieces. As with iguanas, a change in overall color will occur, usually a dulling. A healthy lizard will shed completely within a week or two. An unhealthy or stressed lizard will take much longer (see Problem Sheds).

Like iguanas, other lizards with movable eyelids will puff out their eyes in the days before their head shed starts. This can be particularly alarming, especially on chameleons (Chameleo, etc.) whose already large, protruding eyelids may swell to several times their normal size, immediately deflating when gently touched.

Many lizards who, in the wild, live in more arid areas are often kept too dry in captivity. In the wild, they would make use of more humid microclimates, burrowing down into the sandy ground, or heading into rocky crevices or burrows where moisture remains despite the heat of the day. In captivity, we also need to provide them with these microclimates, either by keeping a patch of sand or other substrate damp (as for many agamids), or by providing an easily accessible humidity retreat box.

In the wild, some larger lizards (monitors and tegus, for example), will soak in standing water or in river shallows. In captivity, standing water can be provided by putting into their enclosure a tub of water bowl, one large enough for the lizard to comfortably sprawl in, but deep enough so that when the lizard is fully submerged, the water doesn't overflow the tub and soak the enclosure. With large lizards, the need for such a water tub must be accounted for when designing and building an enclosure for the lizard.

Snakes
Snakes, like many lizards, utilize microclimates in the wild, laying in underground burrows or in rocky crevices, under windthrow (or under discarded boards around human habitation) where it is more humid. In captivity, smaller snakes can be provided with a water bowl large enough for them to comfortably (loosely) coil up in, deep enough so that when they are fully submerged, the water doesn't overflow the top of the bowl.

Small to medium sized snakes (up to 5 feet / 1.5 m) snakes can instead be provided with a humidity retreat box, either as a permanent fixture in their enclosure, or one that is put in when the color changes associated with the start of the shed period are noted.

Snakes will also undergo color changes prior to a shed.

Boids (boas and pythons) will tend to grow dull, then get darker, sometimes becoming so dark that it is hard to differentiate their normal markings from a distance. Those boids with normally light colored bellies will often show signs of reddening and increased blotching of the belly scutes. This is normal in boids, especially pythons. Unfortunately, it can freak out the unprepared keeper as a reddening of the belly scutes is also an sign of advanced septicemia (systemic infection) and Salmonella. A good rule of thumb as to when to panic and when not to is if the reddening belly occurs in conjunction with an overall pre-shed darkening and associated behaviors, don't worry. If the reddening happens without the pre-shed color changes, and/or in conjunction with other signs of illness, worry and make a vet appointment.

Most colubrids lighten up a bit, getting a milky cast to their skin, including their bellies. Sometimes you will notice a dulling of the skin on their back and sides; a look at their belly will tell you that it is a pre-shed change as the belly starts to gray or lighten up.

Snakes go through a several day period where their eyes cloud up as the fluid builds up between the old and new spectacles. At its peak, the eyes are milky white with a bluish cast to them (called "white" or "blue"). Once the eyes clear, the snake will soon be ready to start its shed. I have found that if I bathe a snake (in a warm bath, for 15-20 minutes) the day the eyes are clear again, it will shed completely within the following 24 hours. I bathe the large snakes in the bathtub rather than wrestle a tub full of water into and out of their enclosure; smaller snakes are left to use their water bowl or humidity retreat boxes ad lib.

Many snakes will defecate at the same time that they shed. Before reaching in grabbing a handful of shed skin that is partially obscured by substrate or furnishings, you might want to check it out first...or always wear a glove!

A cautionary note of snake skin sheds: It is estimated that between 16-92% of snakes carry one or more serotypes of Salmonella (tables and citations can be found in my Salmonella Precautions article). Researchers in one university laboratory found viable Salmonella organisms on skin sheds that had been hanging in their lab for years. Since testing for Salmonella is not very effective, use caution when letting anyone who is at high risk for salmonellosis come into contact with snake skin shed or in contact with anyone who has been handling shed skin.

Always check your snake's head shed to make sure that both eyecaps ("spectacles") have come off. If they have not, take steps to removed the retained eyecaps.

Pre-Shed Behavioral Changes
Going into shed is apparently not a real fun thing for snakes and lizards. Most get rather cranky during this time, with some individuals becoming hissy or snappy, objecting to being held or touched. The best thing to do is to respect their ill-feeling as much as possible. If you need to get in and service their enclosure, do it, but restrict actual handling to that which is necessary.

While reptiles may still eat when in the very early phase of the pre-shed period, as the period progresses, they usually lose their appetite. Most greatly reduce their food intake; others stop eating altogether until after they have shed. Some snakes will not eat while their eyes are milky; some will take a meal once the eyes have cleared but before they shed, while others will not eat until after they shed.

Problem Sheds
A problem shed is a shed that isn't happening like a normal, healthy shed should. With a snake or any other reptile who is supposed to shed in one piece, a problem shed would be a patchy shed. Instead of working the whole skin off in one session, only bits and pieces come off, with lots of skin retained on the body. A normal shed would be done within a period of several hours or less from the time the shed is initiated; a problem shed goes on for days or weeks with little progress. With lizards who normally shed in pieces, a problem shed would be where it is taking too long, or where skin is retained in problem areas, such as around toes, spikes, and tails.

A problem shed is a sign of an even greater, underlying problem. New snakes, especially imports, typically have poor sheds their first one or two sheds in captivity. The import and pet store process is less than healthy and stress-free, and so their sheds reflect that period of prolonged stress (psychological as well as environmental). Once they are housed properly, treated for dehydration and parasites, and begin to psychologically acclimated to captivity, they become healthier, and by the third shed, should be shedding properly - quickly and in one piece.

The same problems may be seen in sick and stressed lizards, especially imported ones. While their skin may normally come off in patches, instead of the shed being completed within the usual 1-3 weeks it would take for a healthy lizard, it may go on for months, with areas never shedding at all. (I took in a savanna monitor one time who had five layers of shed embedded on its back and head!)

When a problem shed occurs, or one that is too slow to start or finish, you need to figure out why it is happening and correct the problem:

•  Analyze its environment, diet, etc. Signs of Illness and Stress discusses the factors that should be considered when evaluating a reptile as well as other common signs of illness and stress.

• Correct the problem (adjust heat, lighting, photoperiods, microclimates, diet, separate from conspecifics, etc.).

If the reptile has started, but not properly completed, a shed, you can help it along:

•  For small lizards and snakes, set up a humidity retreat box (see the Microclimates article to find out how to make one) and introduce the reptile to it.

• For larger lizards and snakes, soak them in a tub of warm water (85-88 F / 29-31 C) for 10-15 minutes, then begin gently rubbing their skin.

  Snakes
  The old skin will start to balloon out and become easy to get off as you rub gently with your fingers and thumbs.

  Always work in a head-to-tail direction.

  Pay close attention to the eye caps, tail, and vent. If the eyecaps won't come off, you will have to take steps to carefully and safely remove them.

  Lizards
  With lizards, make sure the skin is removed from their toes, dorsal crest spikes or fans, dewlaps, and tails. If left in place, it can constrict the tissue, eventually causing an autoamputation of toes, tails and spikes.

  If there is still retained shed in these problem areas, wrap the damp lizard in a warm damp towel, then wrap that in a dry towel. Sit down with it for 5 minutes or so, then expose a small area of the crest, or a foot, and begin to gently work at the retained skin.

  If there are several layers or one very resistant layer of retained spike or toe shed, rub some mineral oil into the area while the lizard is still wet from the bath. This will help lock the moisture from the bath into that area. Do this for a couple of days (bath followed by the mineral oil worked into the spikes); this should get enough water wicked up between the layers of skin to make them very easy to remove.

  If the retained shed is still resistant, bathe again and, if necessary, do the towel wrap/focused work again on these areas.

Shed Aid Products
They are, in a word, useless. Well, that is not exactly true. The primary ingredient, by volume, is water. Water is very useful to humidify and loosen resistant skin and help it shed off appropriately. The water from your sink, tub or garden tap works just as well as the very expensive water and minuscule amount of vitamins, emollients and other nonessential and unhelpful ingredients in the shed aid products. Buying them may make you feel better, but if the shed problem is due to illness or improper environment, the products may be dangerous in that they lull you into thinking you are doing what needs to be done.

If your reptile is having a problem shedding, troubleshoot the environment and the animal's overall health status. Fix the physical and social environment and get the reptile healthy, and problem sheds are simply not an issue.

Where'd it go?
"But wait!" you say. "Where is all that shed?" Some species of lizards will occasionally eat some of their shed. This is not a problem as long as the lizard is maintained in a clean environment. Your house very likely has some lovely fat and happy skin mites living in the carpets, mattresses and upholstered furniture.

Shedding Myths
There are many misunderstandings about shedding. Two common ones are:

Reptiles only shed 2-4 times a year.
Shedding is a reflection of normal growth and renewal in a healthy animal. If a reptile is not healthy, it will not shed as often as it should. For example, healthy iguana will shed every 4-6 weeks, more often during the peak growing season of spring and summer. A formerly neglected and malnourished reptile who is started on a healthy diet in a properly constructed environment may seemingly shed nonstop (each shed followed closely by another shed) for several months as it undergoes a period of rapid growth, almost like it is making up for all the years of retarded growth from the poor care it had received.

As with full-grown humans, full-grown reptiles will continue to shed regularly as their old skin is ready to slough off to be replaced by the newly formed layer underneath.

If you pull off shed that isn't ready to come off, you will cause mites.
You won't cause mites - they aren't created out of thin air. However, pulling off skin before it is ready to come off can damage the not-fully formed keratinous scales growing in place on the new skin layer beneath the old. This can also injure the new skin layer...and mites always look for the path of least resistance when looking for a blood meal. Thin or defective (injured) skin provides less resistance to their mouthparts than does the thickened skin with its protective covering of keratinous scales.

The only way for your reptile to "get" mites if you pull of skin that isn't ready to come off is if your reptile's environment is already infested with mites. There may be so few that you haven't noticed them yet...but given the right environmental conditions-and easy access to food-they will multiply with abandon. If there are no mites in the environment to begin with, there won't be any mites after you impatiently pull off a piece of shed that you shouldn't have. But your over-eagerness to be helpful will still make the iguana uncomfortable, so restrain yourself!

What The Vets Say
The following excerpts are from Mader, Douglas R. (ed.). 1996. Reptile Medicine and Surgery. WB Saunders, Philadelphia PA. ISBN 0-7216-5208-5

Douglas. R. Mader, DVM. Dysecdysis: Abnormal Shedding & Retained Eyecaps. p 368-370
Improper shedding, or dysecdysis, is a symptom of a problem and not a primary problem....Other management factors that cause improper shedding include: low temperatures in the cage, low humidity, improper nutrition, and insufficient cage furniture (logs, rocks, etc.) for rubbing. Once these husbandry factors are corrected, shedding should return to normal.

...The best method to remove tattered skin is to soak the snake in tepid water in a container deep enough to cover the snake's body but not so deep that the animal drowns. Never leave a soaking animal unattended!

Some people advocate adding various medicines to the soaking water, but in the author's opinion, plain water is usually sufficient. If it becomes necessary to add an agent to the water, such as an antibacterial agent, then a diluted iodine solution (e.g., Betadine) can be used. The recommended dilution is approximately 1:50 (iodine:water), resembling weak iced tea. If the container being used is clear, you should be able to read newsprint through the dilute Betadine. If this is not possible, then the solution is too concentrated.

Stephen. L. Barten, DVM. Lizards. p 324-332
Dysecdysis, or difficult shedding, may result in dry flaking, adherent patches of dead skin. The most common cause of dysecdysis is a lack of humidity. Retained skin surrounding the digits, dorsal spines, or tail tips shrinks as it dries, which compromises the blood flow. This results in necrosis and sloughing of the affected part. Retained skin must be removed by soaking and gentle peeling as soon as possible after the shed is initiated by the lizard.

The species, age, state of nutrition, reproductive status, parasite load, hormonal balance, infection with bacterial or other skin pathogen, ambient temperature, and humidity may have an effect on the frequency of ecdysis.

John V. Rossi, DVM. Dermatology. p 104-117
Normal ecdysis in squamates is a complex process in which cells of the intermediate zone (upper stratum germinativum) replicate and form an entirely new three-layer epidermis (called the new inner epidermal generation). Once the new surface is complete, lymph diffuses into the area and enzymatic action results in the formation of a cleavage zone, after which separation occurs (i.e., the outer generation is sloughed). This growth and shedding requires about 2 weeks in most lizards and snakes, while the resting phase may vary from days to months.

One of the practical applications of this process is the increased permeability of the skin during the growth and shedding phase. Snakes sprayed with anti-mite medications at this time appear much more susceptible to such toxins than those sprayed at other times. Hence the use of topical insecticides should be sharply curtailed at this time. Another observation is that severely malnourished snakes and lizards appear to have a very difficult and irregular slough (dysecdysis). This is likely due to the fact that hypoproteinemic animals are unable to produce the full complement of enzymes necessary to complete the breakdown between new and old epidermal generations. Further more, this may explain why excessively dry environments retard normal ecdysis. Drying out the fluid in the cleavage zone compromises the enzymatic and lubricating action of the fluid, hereby resulting in an incomplete separation.

Related Articles:

Removing Retained Eyecaps

Bulging, Drooping, Distended Eyes in Reptiles

Reptile Mites

Signs of Illness & Stress

Winter Advisory

Reptile Skin Basics: Construction, Infection, and Color