Torpor: how to prevent, recognise and respond to it

[Daisy]

What is torpor?​

Torpor is a state of low body temperature and low metabolic rate which hamsters may enter when it is very cold. It is very dangerous for hamsters, as they don’t often come out of it, especially unassisted. Therefore it is important to know how to prevent, recognise and respond to torpor, especially if you have a Syrian hamster and/or you live in a cold climate.

Torpor vs hibernation​

Torpor is often confused with hibernation, however the two are actually distinct things.

Torpor refers to a short term reduction in body temperature and metabolic rate, which can develop quickly and tends to last only hours. Some animal species are very efficient at going in and out of torpor regularly and for them it is a key survival strategy. These animals may spend several hours per day in torpor, during which their body temperature will drop by about half, to an average of 18C, and their basal metabolic rate will drop by about two thirds, which allows them to conserve energy during times of food scarcity.(1)

Syrian hamsters can go into torpor, but pet hamsters have lost the ability to come out of it safely, which is why it’s so important to try to prevent it.

Hibernation is a deeper and more long-term torpor, which not only develops over a longer period of time, but can last weeks or months. A hibernating animal’s body temperature may drop to 5C, or sometimes even below freezing! Their basal metabolic rate will drop to just 5% of normal and in this state, they can often survive for several months using just their body fat for energy. Syrian hamsters are known to hibernate when exposed to near-freezing temperatures for several weeks (2), but this doesn’t occur in pet hamsters as they never (or shouldn’t) experience these temperatures for any length of time.

Torpor is also distinct from the general reduction in activity which often happens in winter. Hamsters are often less willing to come out when it’s cold, but this may be an early sign that the environment is too chilly for them, so try to warm the room up if you notice your hamster is less active.

Which hamsters can go into torpor?​

Torpor is mainly reported in Syrian hamsters. Some sources suggest that only Syrians can go into the kind of dangerous torpor being discussed here, but it’s possible that it might affect dwarfs too. It’s worth being aware of the signs and treatment even if you keep dwarfs.

Hairless Syrian hamsters are more at risk than normal Syrians as they lack fur to help them keep warm.

Certain individual hamsters may be much more prone to torpor than others. A hamster that has been in torpor once is more likely to enter torpor again.

Torpor is fortunately relatively uncommon in countries with a temperate climate such as the UK, however it can be a bigger concern for hamster owners in colder countries such as Canada.

What causes torpor?​

The main factor causing torpor is cold. Room temperatures under 15°C are considered a risk factor for torpor, though it’s best to aim to keep them at 18°C or above. Sudden drops in temperature may also be a risk factor, rather than the exact temperature per se.

Torpor is mostly a winter concern, but air conditioning has been known to cause torpor during summer, particularly if the room temperature drops very quickly.

Other factors which may possibly increase the risk of torpor are:

• Lack of a hoard, or lack of food generally.
• Low light levels over a long period
• Lack of access to water

How can I reduce the risk of torpor?​

Make sure your hamster has enough bedding to build a large nest. Your hamster should have several inches of bedding to burrow down into, and a wooden house also helps them stay warm.

Try to avoid sudden changes in temperature. Sudden drops in temperature are often due to unexpected or accidental factors, like windows being left open or central heating failures, so may not always be avoidable. Nonetheless, it’s wise to have a backup plan in case of power failures, especially if you live in a cold climate. You can even buy room thermometers which will send a notification to your phone when the temperature drops below a certain level. As above, giving your hamster plenty of warm bedding will help to mitigate the effects of any sudden temperature changes in the room.

In very cold weather you might need to provide some external heating. Some people will raise their hamster cage up (using books, pieces of wood etc) and then place a Snugglesafe heating pad, hot water bottle or heat mat underneath. Never allow your hamster direct contact with any heat sources, especially hot water bottles. Don’t heat the whole cage, just one end or corner. Your hamster should always be able to get away from the heat if they wish.

Other ideas for keeping your hamster warmer include insulating the cage base by wrapping it with cardboard, fabric or bubble wrap (make sure your hamster isn’t able to reach the insulation), or partially covering the cage with a blanket to keep heat in. Fleece blankets are the best option here as they are unlikely to cause issues if your hamster does manage to pull them through the bars and chew them.

 

[Daisy]

What are the signs of torpor?​

A hamster in torpor will be unresponsive or very sluggish to respond. Their heartbeat will be significantly slower and fainter than normal, and their breathing will be slow and shallow, to the extent that it may be very difficult to detect at all. The heart rate may drop as low as 3-20 beats per minute and the hamster may breathe only once every one or two minutes (3). They will feel cooler than normal to the touch. They will typically be found in their nest in a curled up position. There may be a blue or greyish discolouration (cyanosis) of the nose, feet, lips, gums or genital area.

How should I respond if I think my hamster is in torpor?​

Your first instinct when finding your hamster in torpor may be to get them warm as quickly as possible but you must not do this. Sudden rewarming risks causing organ damage which is likely to be fatal. Don’t place your hamster on any heat sources such as heat mats, hot water bottles etc.

Torpor causes low blood sugar so the first thing to do is to try to get some quick energy into your hamster. You can use sugar, honey or golden syrup dissolved in warm water, warm fruit juice, or an electrolyte powder containing sugar made up with warm water. It should be around body temperature, or no hotter than 40℃.

Place your hamster in your lap, with a towel or cloth underneath them, positioned on their side. If needed, pull the loose skin at the back of their neck very gently to open their mouth (don’t try to prise their jaws apart any other way). Using a 1ml syringe, gradually drop the sugar solution into their mouth at a rate of a few drops every couple of minutes, allowing the excess to run out the other side. Positioning your hamster on their side will reduce the risk of them choking on fluid. I recommend always keeping 1ml needleless syringes in your hamster first aid kit, but if you don’t have one, you can also use a small unused paint brush or piece of cloth soaked in the sugar solution. Warm the sugar solution back up again whenever it cools down, but always check the temperature before giving it to your hamster.

Once your hamster begins to show signs of movement, you can hold them against your body to allow them to warm back up gradually, and also gently massage their body to stimulate blood circulation. Continue to offer the sugar solution from the syringe.

Once your hamster is warm and reasonably alert, you can place them back in their cage and heat the room to a safe temperature if needed. You might wish to provide some additional heating in the form of a heat pad or mat under one corner of the cage, but make sure your hamster has a cooler area to escape to.

Torpor, even when quickly spotted and responded to, is a very dangerous condition for hamsters. It is sadly common for a hamster to initially seem to rally, only to pass away a few hours or a couple of days later, most likely due to irreversible organ damage. Please be prepared that even if you do everything right, your hamster may still die from the aftereffects of torpor and this isn’t necessarily reflective of any error on your part. Torpor is incredibly hard on a hamster’s body and often they simply can’t withstand it.

If after attempting to feed your hamster for half an hour there are still no signs of movement, take your hamster to a vet for assessment and treatment. They may be unconscious for some reason other than torpor. Also take them to a vet if despite feeding and warming, they still seem very lethargic or sluggish after a few hours.

Other conditions that may be mistaken for torpor​

Death​

It is common for owners to worry their hamsters are in torpor when they have actually passed away.

If you are at all unsure, you can follow the rewarming steps above and leave your hamster in their nest for a few hours (making sure the room is now at a suitable temperature, if it wasn’t before). If after this time your hamster hasn’t moved at all, they have unfortunately passed away.

You can also hold your hamster to your ear and listen for a heartbeat. In a healthy hamster there will be a rapid and regular whooshing noise. In a torpid hamster, the heart beat will be slower and fainter. A torpid hamster may have a heart rate as low as 3-20 beats per minute, so listen for at least a few minutes for any sounds. In some cases you might not be able to detect a heartbeat at all in a torpid hamster.

Board-like rigidity of the body (rigor mortis) indicates that your hamster has died within the last few hours, however rigor mortis starts to wear off after this time.

A commonly suggested method of determining whether a motionless hamster is still alive is to hold the back of a teaspoon to their nose, and notice whether any condensation appears. However I tested this with a conscious Syrian hamster and no condensation appeared, so I would not recommend relying on this method. Desert rodents such as hamsters exhale little moisture in their breath.

If you are still in doubt, you can take your hamster to a vet. They should be able to use a stethoscope to conclusively determine whether there is any heart beat and thus whether your hamster is still alive.

Illness​

Some illnesses may cause lethargy or unconsciousness which may be mistaken for torpor. If the room your hamster is in is within the safe temperature range and hasn’t experienced any sudden drops in temperature, it is much more likely that your hamster is ill rather than in torpor. If in doubt, take your hamster to a vet as soon as possible. Note that the rewarming and feeding process may still appear to revive a sick hamster without treating the underlying illness, so do be alert for any other symptoms even if you hamster appears to respond to treatment for torpor.

Dying process​

Many hamsters are unconscious or very lethargic for some time before they die. They will often be in and out of consciousness. As with illness, if the room temperature is appropriate and there have been no sudden drops in temperature, torpor is very unlikely and the torpor treatment process may be excessively disruptive or stressful to a hamster who is dying.

Deep sleep!​

Hamsters can sometimes sleep very deeply and may be mistaken for unconscious. However if your hamster is breathing at a normal rate and feels warm and soft to touch, they are not in torpor and ideally you shouldn’t disturb them. If you are still very concerned about their welfare for some reason, try to wake them up gradually by talking to them and gently stroking them. Don’t try to pick up a sleeping hamster, as you’re likely to be bitten. If you really can’t wake your hamster up, but they’re warm and breathing normally, they’re likely ill rather than in torpor, and need to see a vet immediately.

Citations
1. Torpor: what it is, why it's important and how torpor differs to hibernation and sleep - Discover Wildlife
2. The influence of sex and diet on the characteristics of hibernation in Syrian hamsters - Journal of Comparative Physiology
3. Torpor - Ginger's Guide: How to Care for Syrian Hamsters

 

[Maz]

A real important topic - great piece Daisy

 

[Robert]

Interesting. I wish to discuss hamster light requirements in winter.

I regularly turn two normal lamps on in her room as I get up in the morning.
There is ambient light coming from the window
I turn these lamps off right before dinner.
It gets dark outside after that.

Note - I have several sunlamps pointed at several succulents which could be moved to the hamster cage.

Please advise.

 

[elusive]

That sounds fine Robert, as long as they have a day/night cycle with the light & it’s dark at night they’re ok, they don’t need much light in the day really so those lamps should be perfectly adequate without the need for more.