Presented to the BCG Symposium at Bristol on 23rd March 2002.
The Oxford dictionary describes the word ‘hibernate’ as follows:
Hibernate: 1) of some animals, spend the winter in a dormant state; 2) remain inactive.
This sums up hibernation well, but does not explain the actual phenomenon, which is not fully understood. It is a logical course of action on the part of the animals: Mediterranean tortoises live in a climate where the summers are hot, dry and sunny, and the winters are mild, wet and less sunny. Tortoises are ectothermic, meaning they are dependent on an external heat source (in nature the sun) before they can actually digest their food, and in winter the sun is not readily available or hot enough and the light intensity is comparatively low. Tortoises are mainly herbivorous and their digestive system is based on the digestion of cellulose, so they are dependent on fresh green plants and fruits, not easily obtainable in winter. So the solution is simple: they shut down their system for a long sleep.
The species of tortoise that hibernate are: the spur-thighed tortoise (Testudo graeca), Hermann’s tortoise (Testudo Hermanni), Horsfield’s tortoise (Testudo Horsfieldi), the marginated tortoise (Testudo marginata) and Kleinmann’s tortoise (Testudo Kleinmanni).
THE HIBERNATION PROCESS
The actual process starts during August. As the days grow shorter, the light intensity decreases and temperatures begin to fall at night. The amount of food intake decreases, and with a large herd this is really noticeable. Before letting the process start, give your charges a check over. Start with the mouth: it should be a healthy pink, with no internal or external wounds or infections. Weigh and measure the tortoise, using the Jackson graph* and checking with your own records. Does your tortoise smell right? A healthy tortoise has a mild aroma of herbs and dung. Give the animal a good wash, scrubbing the rear end with an old toothbrush.
Inspect the motion: is there any sign of diarrhoea, which could indicate a worm infestation? To check for worm eggs, your vet can test a sample under laboratory conditions, but if you have access to a test tube and a microscope you can easily do this yourself. Break up the motion, mix with either a saturated salt or sugar solution, and fill the test tube with this mixture. Shake vigorously, then leave to stand for an hour or so. The debris should now be at the bottom with a clear layer at the top. Transfer a drop from the very top onto a glass slide, and under the microscope any worm ova will show up as bright specks. Your vet will be able to tell from the shape of the ova which type of worm your tortoise is suffering from (ascarids or oxyurids). Use a pony wormer such as fenbendazole (Panacur, Intervet) or a sheep wormer such as oxfendazole (Systamex, Schering-Plough), but be sure to avoid wormers containing piperazine salts, which are harmful to tortoises.
Any tortoise that is not up to weight, or has an ailment such as worms, infections or wounds which have not yet healed, or is egg-bound, should be over-wintered. This is achieved with the help of conservatories, heated greenhouses, and thermostatically controlled environments using heat lamps and vivaria. (Be careful with heat lamps: if using newspaper as a substrate, secure it. Fires start easily and tortoises can be badly burned.)
Healthy animals can safely be allowed to hibernate. Their metabolism slows down, and their physiological functions go into a state of suspended animation. The kidneys normally filter waste out of the blood, but during hibernation the process is almost shut down. For every fall in temperature of 10 degrees Celsius, the heart rate drops by 50%, until it is almost imperceptible. At 4 degrees Celsius the respiratory movements are negligible. Energy stores are used up very, very slowly, resulting in slight weight loss. An adult tortoise loses about 1% of its pre-hibernation weight monthly, so a 1,000g tortoise can safely lose 10g in weight per month. A drastic weight loss indicates that something is wrong: take the animal out of hibernation and warm it gently.
LENGTH OF HIBERNATION
This is where we can go seriously wrong in the UK. We should not give every tortoise the same treatment and expect them all to cope with a 4-5 month period of hibernation. Hibernation time depends on the animal’s natural habitat: spur-thighed tortoises originating from North Africa will therefore have a far shorter hibernation than those from eastern Europe. The closer the animals are to the Sahara, the shorter the hibernation. The Tunisian dwarf spur-thighed tortoise and the Kleinmann’s tortoise from Egypt and Libya live quite close to the Sahara, and hibernate for far shorter periods than their cousins of more northerly regions. Their state of hibernation is also much lighter.
WAYS OF HIBERNATING
The basic method if hibernating is well documented: an inner box with a substrate of shredded paper or vermiculite - no hay or straw, to avoid the fungal disease aspergillosis, which can come from mouldy hay; then an outer box which is well insulated, with air holes covered in wire to make it rodent-proof. The site must be frost-proof and waterproof with a temperature range of 4-10 degrees Celsius. In areas with the right conditions, animals may be hibernated outside. My own area consists of heavy and easily waterlogged clay, but there are people with light sandy soil and south facing gardens where tortoises have hibernated themselves successfully for years. Some people hibernate their animals in cooling cabinets where the temperature can be completely controlled. This has been the case in Scandinavia, for instance: the houses are so well heated and insulated there is nowhere suitably cool to hibernate tortoises, and cooling cabinets are a solution. I once tried a small cabinet for four tortoises. Although the temperature was easily controlled, the airflow was not ideal, nor was the humidity. One tortoise developed a growth of algae on the shell so I abandoned the idea.
WEIGHING DURING HIBERNATION
The general advice is to check and weigh your tortoises during hibernation. Try explaining this weighing procedure to three of my male Hermann’s tortoises. As soon as they are taken out of their box and put on the scales, one eye opens. When they are put back, two eyes are open. They are pumping up their lungs, and the next morning they are still moving around in their boxes. If you have characters like this, my advice is to weigh on a gloomy day. Some animals are very sensitive to movement around them, so alternatively you can weigh the inner and outer boxes together, and check by just touching the leg. Whatever your arrangements, use your own judgement and knowledge of the animal, and keep records. Record the results of a long hibernation, a short hibernation, or a particularly cold hibernation, so that you can develop your own strategy.
HATCHLINGS IN HIBERNATION
During the BCG visit to SOPTOM (the tortoise village at Gonfaron in the south of France) in the first week of March last year, we were very lucky. It had been cold – in fact there had been snow in the nearby mimosa forest the previous week – but our visit coincided with lovely warm weather, and in the hatchling pens there was movement everywhere. Hundreds of tiny hatchlings, with earth still stuck to their backs, were emerging out of hibernation. There were pens with the previous year’s hatchlings, born in September/October, which had been down since the end of November/beginning of December, and none of them seemed the worse for wear. Again, the time you hibernate your own hatchlings depends on the regions from which the animals originated, and you should also remember that the climate in the UK does not provide natural circumstances for them. Babies born in this country do not have the advantage of a mild sunny autumn, and in consequence do not have the same reserves as their counterparts in the wild.
Hatchlings that have been kept permanently outdoors during the summer (which is not recommended for the more northerly parts of the UK) will follow the pattern of their elders. During September/October they will slow down, gradually reducing their intake of food, and eventually do not emerge from their shelters. The procedure for putting them into hibernation is the same as for the adults, but initially a hibernation of no more than 8-12 weeks is recommended. Hatchlings used to a vivarium will be slightly more difficult to settle down to hibernation. My method is as follows: I switch the light off, and just offer water and perhaps some tomato (peeled and de-pipped). After a fortnight or so the hatchlings no longer come out of their shelters. Move the entire vivarium to a cool, dark room and cover it with a blanket or newspapers. The hatchlings can safely remain there for the shorter and colder days of the year. After 6-8 weeks reverse the process by returning the vivarium to the light and slowly warming the surroundings. When the hatchlings emerge, give a long lukewarm bath and offer food.
EMERGING FROM HIBERNATION
The emergence from hibernation is again well documented: take the animal out slowly, and give it some time to come round, quietly pumping up its lungs. Check it for any discharges front and rear, and wash the eyes and face. Leave the tortoise sitting in a sheltered position, then offer a warm bath to give the urates (waste products that have collected in the bladder during hibernation) a chance to be discharged. Keep the animal reasonably warm during the day (a heated greenhouse is ideal) and bring it in overnight. Once they have emerged from hibernation, do not allow them to go back down again.
POST HIBERNATION PROBLEMS
Temperatures too low
If there have been very low temperatures during the winter, many tortoises wake up with frost damage, causing blindness. This manifests itself as a degree of opacity within the eye. The tortoise appears to wake normally and has a drink. The eyes are bright, but it refuses to feed and seems to have no sense of direction, merely moving round in circles as if following its own tail. If you move your hand suddenly in front of the animal’s face, it should shrink back, but if there is no reaction you should seek veterinary attention. With the help of vitamin injections (including vitamin A) from your vet, and the appropriate nursing care on your part, the tortoise can regain its sight, but this can take up to three years in some cases. At first you will need to force feed (preferably tube feeding initially) to start the system working, and give lukewarm baths. These should last at least half an hour, and for the first couple of days activate the liver by dissolving glucose in the water at the rate of approx. 25g (one tablespoon) to 4 litres. (If you have no glucose handy, use 1 tablespoon of sugar and 1 teaspoon of salt; but it is wise to keep powdered glucose in your store cupboard for such emergencies).
You can actually teach a blind tortoise to feed itself. Cut up its favourite food finely, and place it on a half moon shaped tray with a rim (this can be made from a plastic lid cut in half). Pile tomato, sliced green beans and grated cucumber on top to provide a strong smell, then sit behind the tortoise, open the mouth and put some food in. It will soon get the hang of feeding by itself.
In females the problem is usually restricted to the eyes, but in males (especially the Hermann’s with a very long tail) the frost can damage their rear end. This can result in difficulty with passing motions due to loss of muscle power. Much time and patience is required, with hours of soaking in warm tubs and liquid feeds. Sometimes difficulty in retraction of the penis can occur: surround the afflicted part with a wad of cotton wool soaked in a strong sugar solution, and the osmotic effect will eventually enable it to retract normally.
Temperatures too high
At the other end of the spectrum, temperatures during the winter may have been too high; the animal may have woken up several times and moved about too much. The hibernation may also have been too long; in either case the animal has used up too much valuable energy, and may have become too lethargic to start up its system.
Post hibernation anorexia requires veterinary attention. Do not wait until June before you seek help; every year there are people with this problem who leave it too late. The animal will need a vitamin injection, and tube feeding with specially prepared foods. A blood sample may be taken to assess the general health of the tortoise, although not much blood can be taken from a very small animal, especially if it is already sick.
Traumatic injuries due to rat, mouse or even fox bites require immediate attention. You must protect your animals really well because rats can be ferocious. The mild weather last winter brought about a rat plague in East Anglia and Hertfordshire. One owner who checked her tortoises on the third day of every month saw that they were fine on 3rd January, but when she opened the boxes on 3rd February there were just two empty shells, completely cleaned out.
Mouth rot (stomatitis or infectious stomatitis) is another very common condition. It manifests itself in a combination of symptoms: there may be watery swollen eyes, drooling, a plugged nose and laboured breathing. If you open the mouth of the victim, the gums, palate and throat may be covered in a yellow sponge-like growth that slowly chokes the animal. The tongue may show white spots and the gums may bleed. Isolate the animal immediately, and seek veterinary help, as it will need antibiotic treatment, vitamins, and fluids to compensate for the drooling. The whole infected area needs to be cleaned surgically, and wounds treated topically with an antiseptic solution twice daily. A swab for bacterial culture will establish which antibiotic is required. The organisms found are usually bacterial, though fungi, yeasts and viruses are sometimes implicated. Great attention is required, with tube feeding, and a temperature-controlled vivarium or heat lamp.
Whatever ailment your tortoise may be suffering from, it is essential that you try to get your animal’s system working so that treatment can start immediately. Start fluid replacement by dripping water into the mouth with a pipette, or even via a stomach tube. A shallow lukewarm bath can work wonders, because even if there is difficulty in swallowing, some water can be absorbed through the cloaca. A long soak also encourages passing of the urates that have accumulated in the bladder.
When your charges emerge from hibernation, hopefully you will never encounter any of the problems described, and they will all be ready for the summer.
Testudo Volume Five Number Four 2002