Safer Hibernation and Your Tortoise.

A C Highfield, with additional text By Annie Lancaster

INTRODUCTION

Unfortunately, a great deal of information presented to tortoise keepers in the past has been grossly inaccurate and sometimes positively lethal. Into this category falls such advice as “never disturb a hibernating tortoise”, “make sure you leave plenty of air-holes in the hibernating box”, “give your tortoise one last meal to see it through hibernation” and ” provide plenty of cat or dog food in the diet”. The first is simply incorrect, the last three can kill. How many unnecessary deaths have resulted from owners following such dangerous and misleading nonsense? We have a policy of continually revising and updating this booklet to ensure that it always provides the best information available.

Tortoises and turtles of all varieties are not ‘easy’ animals to care for properly. When the tortoise trade was at its height, more than 90% of all tortoises imported in any given year were dead within 2 years – most died during, or just after, hibernation. This booklet has been prepared by the Tortoise Trust to help you ensure your tortoise does not suffer the same fate.

All of the information presented has been carefully prepared by some of the most experienced tortoise keepers in the world in close consultation with leading veterinary surgeons. The techniques described are in daily use at our own tortoise sanctuaries in Britain, the USA, and South Africa, and have been tried and tested over many years. The effectiveness of these techniques is such that despite hibernating possibly more tortoises each year than anyone else, we have never suffered a single hibernation fatality. In each case, the methods used were those described in this booklet. With proper care and attention to detail, you too can achieve similar results.

Tortoises are now under threat worldwide, mainly from habitat loss and in some cases from collecting for the pet animal trade. Fortunately, some active steps to conserve these animals are at last being taken. Much more needs to be done. The endless destruction of natural habitats must be controlled, and conservation reserves created where these animals can continue to breed and survive without human predation. Land tortoises fresh water, and marine turtles all need our help and consideration if they are to survive as species. They must not be lost forever.

A.C.Highfield Wales, United Kingdom, 1998

HIBERNATION & VARIETIES OF TORTOISE

Contrary to popular belief, most tortoises of the types most commonly kept as pets do actually hibernate in the wild. They do so, however, for much shorter periods than they are frequently subjected to in captive collections. It has been commonplace to attempt a hibernation of up to six or even seven months, whereas in the wild these same tortoises have been used to a hibernation rarely longer than ten to twelve weeks. We believe in replicating natural conditions as closely as possible in respect of hibernation periods, and so we do not recommend giving your tortoise an over-long hibernation. Most fatalities occur either near the beginning, or at the end of the hibernation period. The reasons for some of these fatalities will be discussed in detail later, but you can certainly improve your tortoise’s chances greatly simply by limiting the period of hibernation to not more than 20 weeks at the outside. This, it should be stressed, is for a perfectly fit specimen which is fully up to weight. Tortoises which are anything less than l00% fit, or are in any way underweight, will require a proportionally shorter period of hibernation under carefully controlled conditions; possibly they may even need to be kept awake and feeding over the entire winter season.

None of these creatures are in any way suitable as pets for children, and should not be purchased as such.

The following information applies to the most common species of ‘pet’ tortoise; Testudo graeca ,Testudo hermanni and Testudo marginata. In general, the requirements of T. hermanni, T. graeca, and T. marginata and T. horsfieldii are all very similar.

Many of these tortoises exported to the United States are from the Mediterranean. Some continue to be, due to differences in laws. The same techniques are equally applicable to Gopherus agassizzi, the California Desert tortoise.

Many tortoise owners ask us to identify what species their particular tortoises belong to. The following notes should clarify the position, although specific identification can sometimes be very difficult for non-experts. This is mainly due to the very large range of natural variations in shell pattern, size and colorations encountered, even within members of the same species. However, the general characteristics of each principal terrestrial tortoise are as follows.

TESTUDO GRAECA (“Spur-Thighed” or “Greek” tortoise)

The main characteristic of T. graeca are the two small tubercles or ‘spurs’ found on the thighs, one to each side of the tail. There are a number of different races, and even full species, currently referred to Testudo graeca (e.g., Testudo ibera): there is unfortunately not sufficient space here to describe them all adequately. Their taxonomy is in any case far from straightforward and in some cases is disputed – the Tortoise Trust publishes several guides to identification so contact us if you require more information.

TESTUDO HERMANNI (Hermann’s Tortoise)

The Hermann’s Tortoise is quite obviously different from T. graeca; it lacks thigh tubercles or spurs; the tail is long and fairly pointed, with an additional hard, bony tip. The tail of a male specimen is, of course, much longer than that of a female.

TO SUMMARISE:

Remember that in general the smaller the tortoise the more likely it is to end up as a hibernation casualty. Very small tortoises must be given a shorter, carefully controlled hibernation.

Never ever attempt to hibernate a tortoise which you suspect is ill. To put a sick or underweight tortoise into hibernation is to condemn it to certain death.

Dietary management

Tortoises which are provided with the incorrect diet for their species can suffer serious problems, particularly in respect of the liver and kidneys. If these are damaged, the risks associated with hibernation are very greatly increased. While some tropical tortoises and box turtles do require animal protein, desert species do not, and nor do ‘common’ or Mediterranean tortoises. So, despite what you may have read elsewhere, never provide meat products to ‘common’ tortoises. In the long term, it can and does kill. Tortoises require a diet which is HIGH in minerals and vitamins, LOW in fats and proteins and HIGH in dietary fibre. Meat products are totally the opposite, and lead to enhanced urea levels, which damage the kidneys and cause a massive build-up of fats in the liver. The high phosphorous content of most meat products also seriously affects the Calcium-Phosphorous (Ca:P) ratio of the diet, which in turn leads to acute nutritional osteo-dystrophy or “lumpy shell syndrome”. Our own tortoises not only survive, but thrive without any meat products whatsoever, they breed successfully, and the hatchlings have beautiful, perfectly formed shells without lumps, bumps or pyramids. Living proof that claims of the “necessity” of meat for tortoises are entirely inaccurate.

Suitable dietary items for Mediterranean and Desert tortoises can include:

Romaine or red leaf lettuce, in very limited quantities. Never use head lettuces such as iceberg, head lettuces contain very little in the way of adequate vitamins or minerals. Opuntia (spineless) prickly pear cactus, pads and fruit. Sometimes referred to as “Nopales”, the fruit are often referred to as “tunas”, watercress, dandelion, naturally occurring non-toxic weeds, hibiscus flowers and leaves, white (Dutch) clover, both leaves and flowers, rose leaves and petals, and sow-thistle.

Most land tortoises can and do fare quite well when allowed to graze, offering the other listed items as supplements. Never offer cabbage, spinach, chard, bok choy, or any vegetable related to these, as they inhibit calcium absorption and can cause tremendous health problems.
We do not generally recommend the use of pellet-type commercial prepared diets, though some of these can have a role when rehabilitating sick or severely underweight tortoises. In general, their energy and protein levels, as well as their calcium to phorsphorus ratios are such as to make them unsuitable for use on a regular basis.

Add a mineral-vitamin supplement + extra calcium. The use of cuttlebone left in the enclosures allows tortoises to regulate the amount of calcium in the diet. Some tortoises like this very much, while others will not eat it. For those that won’t, the use of a phosphorous free calcium supplement is recommended.

Grass is actually quite a useful food for tortoises (especially Desert, Leopard and African Spurred tortoises) , but is not adequate by itself. It is particularly useful as a source of dietary fibre. Certainly many giant tortoises enjoy it as part of their natural diet, and young grass shoots are equally favoured by many other species. Dandelions and parsley are excellent, having a positive Ca:P ratio and being particularly rich in vitamin A (14,000 i.u/100g for dandelion, 11,000 i.u/100g in the case of parsley). When feeding weeds or wild flowers, be sure that they are free of weed killer or other lethal contaminants. On the same subject, never use slug pellets or other garden chemicals anywhere near tortoises.

IS YOUR TORTOISE FIT TO HIBERNATE?

Many people are surprised when we ask this question, not as the first frosts are beginning to make their presence felt, but as early as mid-August, when the days may still be bright and hot! We ask in mid-August because, as far as your tortoise is concerned, this is when it reaches a classic ‘go-no-go’ situation as far as its biological clock is concerned. Leaving the decision on hibernation until September, October or November is simply too late. If a tortoise is not fit to hibernate by the end of August, then it is not going to be fit in October. In order to survive hibernation in good condition, tortoises need to have built up sufficient reserves of body fat; this in turn stores vitamins and water. Without fat, vitamins and water tortoises die of starvation or dehydration. Adequate reserves of body fat are vital to tortoises in hibernation; they live off these reserves, and if the reserves run out too soon then the animal’s body will begin to use up the fat contained within the muscles and internal organs, eventually these too will become exhausted. At this point the tortoise will simply die in hibernation.
 
Check:

BOTH EYES: for signs of swelling, inflammation or discharge. If there is a problem, consult a veterinary surgeon with extensive experience of treating reptile patients.

THE NOSE: For signs of discharge; a persistently runny nose requires urgent veterinary investigation. Tortoises with this symptom must also be isolated from contact with others, as some varieties of RNS (‘Runny Nose Syndrome’) are highly infectious. The presence of excess mucus also encourages bacterial growth, and hence places the tortoise in additional danger from diseases such as necrotic stomatitis.

THE TAIL: For inflammation or internal infection; tortoises with cloacitis ‘leak’ from the tail and smell strongly. Any signs of abnormality should be investigated by a veterinary surgeon. It will help if you take a fresh sample of cloacal excretion for a veterinarian to examine under the microscope.
LEGS: Look for any unusual lumps or swellings; abscesses are common in reptiles and if left untreated can result in loss of limb or even death. Report any unusual findings to a competent veterinary surgeon who may want to X-ray the affected part.

EARS: The membranes covering the inner ear should be either flat or slightly concave; ear abscesses are very common and can have fatal consequences if treatment is not obtained. The ear scales, the tympanic membranes, are the two large ‘scales’ just behind the jaw-bone.

INSIDE THE MOUTH: Look for any sign of abnormality; necrotic stomatitis or ‘mouth-rot’ is a highly contagious disease of captive reptiles. It is characterised by the appearance of a yellow ‘cheesy’ substance in the mouth, or by a deep red-purple tinge, or by the appearance of small blood-spots. Sometimes all three symptoms are present. Expert veterinary treatment is called for as a matter of urgency if the animal is to be saved.

These basic checks form your essential pre-hibernation examination. Provided your tortoise is up to weight and no other abnormalities can be detected, then you may begin preparation for hibernation. The golden rule, however, at all times is IF IN DOUBT SEEK EXPERT ADVICE. Our experience is that owners who fail to act promptly when problems occur usually end up, sooner or later, with a dead tortoise. One final, and critically important point before we actually deal with how to hibernate your tortoise. Very many tortoises die each year because owners attempt to hibernate them while they still contain undigested food matter within their gastro-intestinal system. It is natural for tortoises to gradually reduce their food intake as fall approaches (this is one reason why, if they are underweight in August, they will certainly not have put on any extra weight by October). A tortoise’s digestive system is governed to a great extent by temperature, but generally speaking, when the animal’s biological processes are slowing down it takes between 4-6 weeks for the food last consumed to pass completely through the gastro-intestinal tract. In other words, do not attempt to hibernate any tortoise if it has eaten within the last month to six weeks. Delay hibernation rather than allow a tortoise to hibernate while the possibility of undigested food matter within the intestine remains.

Tortoises which are hibernated with food still remaining inside are unlikely to survive in good health. The food decays, produces large quantities of gas and causing tympanic colic which brings about asphyxiation due to internal pressure on the lungs. This error of husbandry is also responsible for a number of serious, and usually fatal, bacterial infections inside the tortoise.

HIBERNATION CONDITIONS

The two biggest killers of captive tortoises are:

Attempting to hibernate unfit specimens and
Failure to provide adequate protection during hibernation.

Hopefully you have taken note of the advice given on fitness for hibernation and so will avoid this problem. Even fit tortoises can die in hibernation if the conditions to which they are subjected are biologically incorrect; essentially this means:
 
· Keeping the tortoise dry and well insulated in properly prepared accommodation (unless otherwise noted for certain species).
· Making absolutely certain that temperatures are stable, and within safe tolerances, i.e. neither too hot nor too cold.

In practice the first is more easily accomplished. We will deal with both accommodation and conditions separately, and in some detail.

ACCOMMODATION

Our recommendations are for an outer box or carton made from either wood or substantial cardboard. The inside of this should be lined with blocks or chippings of polystyrene, of the sort used in house insulation or packaging. Alternatively, tightly packed shredded paper can be used.

Select a second, (this time much smaller) box. Ideally this box should accommodate the tortoise fairly tightly, whilst still allowing for a couple of inches of insulating material all around the animal. We are sometimes asked why two individual boxes are necessary. To answer this question one has only to monitor carefully the behaviour of a hibernating tortoise. A tortoise in hibernation does not stay in one place, but attempts to move, and it either digs deeper into its box, or climbs to the surface. If it is allowed unrestrained movement, there is a grave danger that it may burrow through the protective insulating layers and come into contact with the walls of the hibernation box. Here it is virtually unprotected, and could very easily freeze to death. Our sanctuary hospital is often full of frozen tortoises in the spring, due to precisely this error on the part of owners. It is all rather sad and unnecessary, as the problem is so easily avoided with a little care.

CONDITIONS

The critical factor here is TEMPERATURE. Temperature is absolutely critical to a successful and healthy hibernation. Insulation merely slows down the rate of heat exchange, it does not prevent it altogether. Thus, no matter how well you insulate, if you subject your tortoise’s hibernation box to sub-zero temperatures for an extended period it will still get too cold. Similarly, if you allow your tortoise’s hibernation box to get too warm for too long it will begin to use up valuable fat and energy reserves, and may even wake up early.
 
These critical temperatures are:

MAXIMUM = 50 °F or l0 °C
MINIMUM = 32 °F or 0 °C (Freezing Point)

ALWAYS USE A THERMOMETER – IT SAVES LIVES!!

Under no circumstances whatsoever should a hibernating tortoise be subjected to prolonged exposure to temperatures higher or lower than these. Failure to appreciate the importance of this invariably leads to death and injury in hibernation. Blindness due to the eyes quite literally freezing solid is a particularly unpleasant consequence of allowing temperatures to fall too low.

The easiest way to check temperatures is to obtain a maximum-minimum reading greenhouse thermometer from any garden or hardware store. Check it at regular intervals, hourly if necessary in very cold spells. If sustained low or high temperatures are noted, temporarily move the tortoises into a more suitable place until temperatures stabilise to a satisfactory level again. Today, some excellent electronic thermometers are available with built-in alarms if the temperature goes outside pre-set points. These are truly excellent, and can make a major contribution to hibernation safety.

An ideal temperature for hibernation is 5 °C, or 40 °F. At this temperature tortoises remain safely asleep, but are in no danger of freezing.

Incidentally, it is important to point out that the advice that a hibernating tortoise should never be disturbed is completely invalid. It has absolutely no basis in biological or veterinary science, and should be ignored. You cannot possibly harm a hibernating tortoise simply by handling it.

We routinely handle our tortoises during hibernation to conduct checks on weight. Provided the animals are carefully replaced in their protective insulation, this is an excellent method of checking on their general condition. A tortoise which is losing weight to the extent that it is approaching the danger line should be taken out of hibernation and artificially sustained for the remainder of the winter. Most healthy adult tortoises lose about l% of their body weight each month in hibernation. This is very easy to calculate. A l600 g tortoise put into hibernation in October will lose about l6 g every month. After 5 months hibernation it will probably weight l600 minus 5 x l6 = 80, i.e. l520 g.

While tortoises must not be put into hibernation with a stomach containing food matter, their bladders should contain water. Therefore tortoises should be encouraged to drink before hibernation, even though they are not allowed to feed.

If, when checking a hibernating tortoise you notice that it has urinated, get it up immediately do not put it back. Recent evidence leads us to believe that should this occur, the animal is in grave danger of death from sudden, acute dehydration. If this action does occur, begin re-hydration immediately, and over-winter for the remaining hibernation period. We are undertaking further research into this phenomena, but early results indicate that the problem is most likely to occur towards the end of the hibernation period, or in spells of unusually mild weather where the temperature rises above 10 °C or 50 °F. Check the tortoise regularly at such times.

OVER-WINTERING OR NON-HIBERNATING

Sometimes, either for specific health reasons or because the animal is of a tropical variety, hibernation may not be possible. Where this is the case, the objective must be to keep the animal alert, feeding and in good general condition throughout the winter period. Provided that temperatures are adequate, and that both food and light are also available in sufficient quantity and quality, over-wintering tortoises is not particularly difficult. Suitable accommodation must be provided. Can we please stress that no matter how warm it is, an ordinary room in a house will not by itself keep a tortoise feeding and in good health. A very special combination of background heat, localised radiated heat, and high intensity illumination is absolutely essential. The tortoise requires this ‘spot’ or radiant heat source to thermoregulate properly and to maintain its own body temperature (when measured in the cloaca) at around 2-3 °C above that of the surrounding area (it does this by heat absorption, rather like a dark coloured stone absorbs a great deal of heat from the sun). You cannot keep a tortoise feeding adequately by background heat alone, so please do not try. At night the tortoise can be removed from its daytime accommodation and placed in a warm box situated next to a radiator to sleep. Again, it is important not to let it get too cold, certainly never below about 45 °F. In the morning replace it in its heated area for the day. Tortoises need approximately l4 hours of adequate heat and light per day in order to feed properly and remain in good health. Your task, as owner, is to provide them with an artificial summer.

You can help your tortoise considerably by providing a dietary vitamin and mineral supplement such as “Vionate”, or “Herptivite” (Rep-Cal) regularly, this is particularly important when overwintering, as it contains vitamin D3 which is usually synthesised from sunlight. Vionate and Herptivite are excellent all round products which are particularly well suited to reptiles. It is obtainable through some pet shops, veterinary surgeons, or from the address on the back page.

Hatchling tortoises should definitely be given Herptivite on a regular basis, not so much for its vitamin content as for its mineral ingredients. Additional calcium is also required, to reach a correct Ca:P ratio of around 6 parts calcium to 1 part phosphorous. These minerals are essential to proper bone and shell development. Avoid all foods which have a strongly negative Ca:P balance such as peas or beans, cabbage, spinach, bok choy, or chard. Hatchlings can be hibernated if their health and weight is good. A hibernation of about 6 to l0 weeks is satisfactory. Extended hibernations should never be attempted.

This is perhaps an appropriate point to remark on vitamin injections. Unless the tortoise is suffering from a specific vitamin deficiency disease, injections are not recommended, and often cause potentially fatal damage. Certainly we do not approve of ‘routine’ vitamin injections before hibernation. If a tortoise is truly vitamin-deficient at this point – and this is extremely unlikely if it has been given a reasonable diet – then do not hibernate it. Injections will not cure the problem. Far better to build up vitamin and mineral stores gradually by providing a well balanced diet. Genuine cases of acute vitamin deficiency in tortoises are actually quite rare; it is usually only found in those which have been subjected to an extremely poor diet over a very long period or where the tortoise is otherwise ill. We suggest, therefore, that you do not have your tortoise injected with vitamins, which it almost certainly does not need. Vitamin injections in any case do not help tortoises to survive hibernation. This is accomplished by good husbandry alone. One final point. Dehydration is a particular problem of over-wintering, and should be avoided by providing your tortoise with a daily opportunity to drink. For details on how tortoises can best be encouraged to drink see the next section.

WAKING UP

As the average mean ambient temperature begins to approach the critical l0 °C or 50 °F point, a tortoise’s metabolism will begin to reactivate in readiness for waking. Certain complex chemical and biological processes are initiated as the animal prepares to emerge into the spring sunshine. Upon first emerging from hibernation a tortoise is depleted in strength, has a low White Blood Cell (WBC) count, and is very vulnerable to infection. Unless it receives adequate quantities of heat and light it will simply ‘not get going properly’, and instead of starting to regain weight and strength lost during hibernation, may well refuse to eat, and begin to decline. This condition in its most serious form is known as POST HIBERNATION ANOREXIA, and has been the subject of some intense veterinary research over the past few years. How to deal with it is discussed in the next section. Hopefully you will have followed our previous instructions, and your tortoise will emerge in good condition. As the temperature rises listen carefully to the hibernating box – you should begin to hear the first sounds of movement.

At this point, rather than follow tradition and wait for your tortoise to emerge from its hibernating box itself, you should remove the hibernating box from its winter quarters and warm it up by placing it near a heater, and allow it to warm gradually. After a few hours remove the tortoise from its box and place it in a warm, bright environment. Repeat the pre-hibernation health checks, then offer the tortoise a drink as soon as it is fully awake. Provided the temperature is correct, this should only take a matter of an hour or two.

Many people experience problems in getting tortoises to drink – in fact almost all tortoises will drink provided water is offered in a suitable manner. We recommend placing the entire tortoise in a sink, bath tub, or large container suitable to the size of the tortoise, such as a cat litter pan filled with about l” of very slightly warm water – less in the case of very small tortoises, a little more for giant specimens. Simply offering a small dish of water to the tortoise is not likely to stimulate a good drinking response, but actually placing it in water is usually successful.

The importance of getting the tortoise to drink cannot be overstated. Indeed, this is essential as during hibernation the kidneys in particular accumulate large quantities of dangerous toxins. These must be ‘flushed out’ as quickly as possible, or the tortoise may begin to suffer from poisoning. It will certainly feel ill and remain disinclined to eat.

Drinking is, at this stage, far more important than feeding. Both dehydration and the presence in the body of toxins dictate that every effort must be made to encourage drinking first, feeding later. The tortoise must also be kept warm as described previously- it is absolutely vital that such temperatures are maintained in order to speed up activation of the tortoise’s digestive system. As the tortoise awakes certain biological changes take place; one of the most important of these is the release into the bloodstream of a chemical called glycogen, which has been stored in the liver. This provides extra energy to give the tortoise an initial ‘boost’. Feeding must take place before this is exhausted, or the animal will begin to decline. The glycogen level can be artificially boosted by providing water with glucose in solution daily – about 2 teaspoons per 250 ml dilution, at about l0-20 ml per day for an average sized animal. The use of Pedialyte™ is also successful. Do not continue this therapy indefinitely, or dangerously high blood-sugar levels may be attained.

All tortoises should very definitely feed within ONE WEEK of emerging from hibernation. If they do not there is either;

A health problem, or
A husbandry problem.

If your tortoise is not feeding by itself within one week of waking up, take the steps described in the next chapter, and if this does not produce results within a further three days, do not delay any longer – consult a veterinary surgeon who has particular experience of reptile husbandry, physiology and treatment. Seek the underlying cause of the problem, and do not be satisfied with non-specific ‘vitamin injection’ therapy. There is always a logical and very good reason for a tortoise persistently refusing to eat, and generalised vitamin deficiencies are highly unlikely to be responsible. Good diagnostic techniques, combined with an understanding of reptile metabolism and function, will invariably produce a satisfactory answer. Out of literally thousands of tortoises we have seen over the years with feeding problems, from ancient Galapagos giants to tiny newly hatched babies, we have never yet seen one suffering from anything which a general non-specific ‘vitamin injection’ would correct. It is highly unlikely, to say the least, that yours is the exception. Whatever you do, please do not delay. A tortoise which refuses to feed after a week or more of correct temperatures has a problem. It is your responsibility to find out what the problem is and to deal with it effectively.