Tortoise Hibernation - Factsheet

In Britain most tortoises should be winding down for hibernation by mid-September. The trigger is mainly the decrease in day temperature, but the reduction on daylength also plays a part.

The safe hibernation of tortoises depends on several factors:

Sufficient nutrients to last the winter
Absence of any disease
Sufficient hydration
Careful monitoring of Temperature
Empty stomachs before hibernation
Re-awakening at a suitable temperature and before it becomes too warm

Food & Water

When the temperature drops the tortoise will stop eating. Wait for this to happen naturally and continue to allow food but make sure that there is a four week period before hibernation so that the stomach can empty. Failure to do so means that food rots in the stomach and can cause ear disease or mouth rot and bowel diseases in the spring.

The tortoise is likely to drink up until he/she sleeps. This is important because metabolic processes that keep the body ticking over whilst asleep require water. It can be useful to allow your tortoise to bath in tepid water every few days, but stop this when the tortoise becomes very sleepy as co-ordination for swallowing will be lost.

Note where your tortoise urinates - if the fluid is white or has a bright white core to it, then the tortoise is probably dehydrated, and baths become essential. Over winter, all the toxic products of metabolism are broken down to urate crystals (the white you see in the urine) which are insoluble. These are stored in the kidneys, and will be voided in the Spring. The crystals are sharp and damage the kidneys unless they are 'floated' in enough fluid through the winter, hence the need for baths before hibernation. White material in the autumn should give cause for concern.

Good Health for a Good Sleep!

Mediterranean tortoises can be weighed and their carapace length measured so that a ratio can be obtained - the Jackson Ratio. If it is too low then the tortoise should be kept awake, and only allowed a brief period to doze. Use the graph attached to check. To get the proper length place the tortoise between two boards. (If in doubt then contact the Practice and we will carry this out for you). Many spring-time problems stem from pre-hibernation faults, which is why it is essential to check the health before hibernation is started. The factors you should look out for, and consult us about are:

Shell damage - if flaky, or broken. Do NOT oil the shell
Eyes - should be black and bright. Watch for a skin developing as a sign of problems
Shoulder skin. If bulging then the tortoise is too fat and this could lead to liver problems
Urine - should be clear, with only minimal amounts of white (urate crystals)
Droppings - look for worms - long brown or white and wriggly! - be concerned if the droppings contain undigested food.

Temperature

In Britain hibernation is much longer than in the natural climate. This therefore drains nutrient and energy levels to a far greater extent. The amount of energy used is directly dependent on the temperature, so avoid variations. In the spring be careful that the tortoise doesn't wake up in short warm spells only to re-hibernate a week or so later. There is only enough energy for one attempt to 're-start', so if you find your tortoise is awake it may be necessary to then keep him/her warm enough from then on.

The other important factor regarding temperature is that below 4oC there is a real danger of permanent frost damage. When water freezes to become ice it expands. If this happens in a confined space, such as the skull, the cells die and brain damage occurs. The eye is also very sensitive to the cold, and cataracts will form after frost bite. To avoid such problems be very careful where the hibernation box is placed: sheds and outhouses get very cold indeed and should be avoided. Insulation of the box containing the tortoise with a second straw filled box will help reduce variations in temperature. A maximum-minimum thermometer can be left near the tortoise.

Checking your tortoise

Check the tortoise weekly, but be careful not to disturb the sleep. If the tortoise has urinated, or if there are any signs of disease then it may be better to wake the tortoise, but speak to a veterinary surgeon first about how to go about this properly and safely. The Tortoise Trust are very knowledgeable and approachable and can be contacted for advice. They welcome telephone calls and can be contacted on 01267 211578.

Waking your Tortoise

In the spring the tortoise should be encouraged to wake when the temperature increases, and certainly by mid-April since energy levels will become too low if they are still asleep. If a warm spell occurs and the tortoise starts to eat do not let him/her go back to sleep if a cold period follows.

Encourage drinking as soon as the tortoise is awake; use a shallow tepid waterbath twice daily. This should encourage urination too - most tortoises do not urinate until they have been rehydrated because the waste products have to be flushed out.