Leaving a lizard alone: holidays, power cuts and the equipment failures that kill

Quick answer

A lizard's life support is electrical. Everything that keeps it alive runs from a socket, and none of it tells you when it stops.

Lizards do not get separation anxiety. They do not form the attachment that produces distress at being left, and a lizard that hides, goes off food or paces the glass while you are away is responding to temperature, light, season or illness, not to your absence.

What actually harms a lizard left alone is equipment. A thermostat that fails high cooks the animal in hours. A tripped socket in winter cools it until it cannot digest, cannot mount an immune response, and quietly declines. Both happen while nobody is watching, which is exactly the point.

• Every heat source must run through a thermostat, and the thermostat type must match the heat source.
• Fit a second thermostat as a high-temperature cut-out on any enclosure you leave unattended.
• Take one photograph of the correct setup, with every plug, dial and probe visible, and leave it with whoever is checking on the animal.
• Never leave live insects loose in the enclosure while you are away. They chew on a sleeping lizard.
• A cold lizard must not be fed. Below its working temperature it cannot digest, and food sits and ferments in the gut.

:::danger
A thermostat failing high is the fastest way to lose a reptile.

Heat mats, ceramic emitters and basking lamps do not regulate themselves. If a thermostat fails, or its probe falls off the glass, or the probe is in the wrong place, the heat source keeps delivering full output into an enclosure with nowhere for the heat to go.

Lizards do not always move away in time. They are drawn to warmth, they will burrow onto a mat that is burning them, and a basking site that has run away in temperature can produce fatal overheating within hours.

Fit a second thermostat in line with the first, set slightly higher, so that if the primary one sticks on the second one cuts the power. Check that the probe is fixed where it cannot fall, and verify the temperature with an independent thermometer before you go anywhere.
:::

Decide in 60 seconds

What "alone" actually means to a lizard

It is worth being clear about what is not happening, because the popular framing sends owners in the wrong direction.

A lizard does not miss you. It does not pace because you left, and it cannot be desensitised to your absence with graduated departures.

Behaviour that owners read as distress usually has a physical explanation.

Hiding and reduced activity point first at temperature, then at season, then at illness. A lizard that cannot reach its preferred temperature retreats.

Glass surfing and constant pacing point at enclosure size, sightlines, a reflection, an enclosure that offers no cover, or a lizard that can see another animal.

Going off food points at temperature, at shedding, at season, or at illness. In several species a seasonal slowdown is normal and expected.

Restlessness in a female may be egg-laying behaviour, which needs a laying site rather than reassurance.

The useful version of "alone training" for a lizard is therefore an enclosure and a monitoring setup that keeps it correct when nobody is looking at it.

The four failures that kill an unattended lizard

One: heat runaway.

The thermostat sticks on, the probe falls off, or the wrong type of thermostat is paired with the wrong heat source. Output goes to maximum and stays there.

Match the pairing. Pulse-proportional thermostats are designed for heat sources that produce no light, such as ceramic emitters and mats. Dimming thermostats are for light-emitting bulbs. Using a pulse unit on a light bulb flickers it and shortens its life, and using the wrong pairing anywhere is a reliable way to produce an unstable enclosure.

Fix the probe where it cannot move, at the point you intend to control, and check its position every time you clean.

Add a second thermostat in line, set a little above the first, as a cut-out. It does nothing all year and then saves the animal once.

Two: heat loss.

A bulb blows, a fuse goes, a socket is switched off by someone tidying, or a whole ring circuit trips because a freezer failed in the garage.

The lizard does not die of cold immediately. It stops digesting, stops moving, stops eating, and its immune function drops, so what you find later is an animal that is quietly unwell and has been for days.

Keep spare bulbs of every type in the house. Put the enclosure on its own socket where possible, and label the plug so nobody unplugs it for the vacuum cleaner.

Three: light and photoperiod chaos.

A failed timer that leaves lights on all night, or off all day, disrupts the day-night cycle the animal's physiology runs on. In seasonal species this can also trigger or interrupt brumation at the wrong time.

Four: water and humidity.

A misting system that empties, floods, or runs continuously. A water dish that is fouled on day two of a ten-day trip. Humidity that collapses in a heated house in winter, causing retained shed that constricts toes and tail tips.

None of these four announce themselves. That is what the monitoring is for.

How long a lizard can safely be left

There is no single answer, and anyone who gives one is guessing on your behalf. What determines it:

Species and diet. A large adult herbivore that eats salad daily has different needs from an insectivore fed every few days, which in turn differs from a species that naturally fasts for long periods.

Age. Juveniles eat daily or near daily, grow fast, and have far less reserve than adults. Leaving a juvenile on automation is not comparable to leaving an adult.

Health and season. A lizard that has been ill, is underweight, is shedding badly, is gravid, or is entering brumation needs eyes on it.

What can be automated. Heat, light and humidity can be automated. Noticing that the animal is unwell cannot be.

A practical rule: automation covers the environment, and a human covers the animal. If you will be away longer than a day or two, someone competent needs to look at the lizard itself, not just at the plugs.

Monitoring that actually tells you something

Before any trip, verify the enclosure the way you would if you were setting it up from scratch: basking surface, cool end, hides at both ends, water, and every probe where you intended it to be.

Use a maximum and minimum thermometer at both ends of the enclosure and read it daily for a week before you leave. It records what happened overnight, which is when most failures show up.

Verify surface temperatures with an infrared thermometer aimed at the basking surface itself. Air temperature and surface temperature are different numbers, and the animal lies on the surface.

Consider a plug that reports whether power is flowing, and a camera pointed at both the lizard and a thermometer you can read on screen. A camera that shows the animal and the number at the same time answers almost every remote question.

Set an alert if your equipment supports it. A temperature alarm is worth more than any amount of checking.

Whatever you use, test it a week before you travel. Equipment fails when it is switched on, so switch it on while you are still at home.

What to do in a power cut

Insulate first. Blankets, towels or foam board over the top and sides of the enclosure hold the existing heat, which buys hours. Leave a ventilation gap.

Add safe external warmth. Hot water bottles or hand warmers wrapped in towels, placed against the outside of the enclosure, not inside it where the animal can contact them. Direct contact with anything hot causes burns, and reptiles do not reliably move away from a heat source that is damaging them.

Do not feed. A lizard below its working temperature cannot digest, and food in the gut in that state ferments and causes serious illness.

Keep water available, and keep handling to a minimum.

Move the animal if the cut will be long. A car with the heater on, or a friend's house with power, is a legitimate answer, transported in a secure container inside an insulated box.

When power returns, restore the gradient and let the animal warm up on its own timetable. Do not force heat to catch up quickly. Then watch for the delayed consequences: appetite, droppings, breathing and activity over the next week or two, because respiratory infection is the classic sequel to a cold period.

Briefing whoever checks on it

If someone else will feed, show them in person once before you leave. Written instructions plus a demonstration produce a competent sitter, and written instructions alone often do not.

Most sitter failures are not laziness. They are ambiguity: nobody told them what the numbers should be, or which plug does what, or that the reptile should not be fed at all this week.

Give them a photograph of the correct setup with every plug, dial, timer and probe visible, and a second photograph of the thermometer showing the target readings.

Tell them explicitly what to do and what not to do. The most common well-meaning disasters are adding a heat source because the lizard "looked cold", opening the enclosure repeatedly, feeding an animal that should not be fed, and leaving live insects in overnight.

Give them the reptile vet's name, address and phone number, and tell the practice that someone else may bring the animal in.

Agree a check-in message with a photo each day. A daily photograph of the thermometer and the animal is a five-second task that catches almost everything.

The away sheet

Coming home: the first hour

Read the maximum and minimum thermometer before you do anything else, and write down both numbers. That single reading tells you whether anything went wrong while you were away.

Look at the animal from a distance first: posture, alertness, colour, whether it is at the warm end or hiding, and whether it is breathing normally.

Check the water, the substrate for droppings, and whether food has been eaten.

Weigh the lizard and compare against the pre-trip weight.

Look for the specific injuries that happen unattended: chew marks on toes and tail from feeder insects, retained shed on toes and the tail tip, burns on the belly, and abrasions on the nose from pushing at the glass.

Compare the animal with how it looked before you left. Posture, alertness and body condition are the things that change first.

What never to do

Never run any heat source without a thermostat, including heat mats sold as "low wattage".

Never use a heat rock. They are a burn injury waiting to happen and they cannot be safely regulated.

Never leave live insects in the enclosure overnight or while you are away.

Never feed a lizard that is cold, or immediately before a period when heating may fail.

Never put a hot water bottle, hand warmer or heat pack inside the enclosure.

Never leave the enclosure in direct sunlight or against a radiator as a backup plan. A glass enclosure in the sun becomes an oven with no cool end.

Never ask an inexperienced sitter to make judgement calls. Give them numbers, photographs and a phone number.

Never assume the UVB lamp is working because it is lit. Note the replacement date on the fitting.

When to get help

Contact a reptile-experienced vet the same day if you come home to a lizard that is cold and slow to respond, has been overheated, is gaping and flat, has stopped passing droppings, or has visible burns.

Contact a vet within a few days for a lizard that has lost weight while you were away, has retained shed on toes or tail, has bite marks from feeder insects, or is not eating once the enclosure is confirmed correct.

Watch for the delayed problems in the two weeks after any cold period: increased breathing effort, open-mouth breathing, mucus at the nose or mouth, lethargy and appetite loss. Respiratory infection follows chilling, and it is far easier to treat early.

Bring your maximum and minimum readings, the dates, and your record of what failed. In reptile medicine the equipment history is usually the diagnosis.