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The Tortoise Myth-Busters: Episode 5

Updated: Mar 26

Post-Hibernation Anorexia (PHA)

All-too-often a 'diagnosis' of PHA is arrived at without sufficient understanding of what this actually means, and as such, can distract from discovering or effectively treating the true, underlying causes.

The very first thing to note here is that 'anorexia' as correcty defined is not a specific condition, but a description of a symptom. In this case the usually accepted definition is simply 'an abnormal loss of appetite' or in practice, a refusal to feed. In tortoises, this symptom has no relation whatever to Anorexia nervosa as seen in humans, which is an entirely different thing rooted in psychological or mental health issues. A far better description, and one less likely to cause confusion, is 'innappetance' - an apparent lack of desire to eat. This, of course, can have a great many underlying causes. There is no single cause. When referring to tortoises that have emerged from hibernation (or brumation), however, and then refuse to eat, we can refer to the Tortoise Trust's own records of many hundreds of such cases dating right back to the early 1980's for some clues as to the 'most likely' scenarios to be investigated. Do not make assumptions, however. Investigate every case carefully and with an open mind.

It is important to stress again that 'post hibernation anorexia' directly revolves around a refusal to feed. If a tortoise is feeding, even though there may be other problems or symptoms present, then ipso facto ("by the fact itself") whatever these problems are it cannot be classed as 'post hibernation anorexia'.

Tortoises that refuse to eat invariably have a specific cause that requires identifying. They don't just decide not to eat. Unfortunately, many vets in general practice do not have the necessary degree of experience to diagnose the cause accurately, and so we get non-specific diagnoses such as 'post-hibernation anorexia'. 'vitamin deficiency', 'try a different food' or similar applied to cases where such a conclusion is completely unjustified by the evidence. Even some specialist reptile vets may not have adequate experience with tortoises. That is why we are always so insistent upon working with veterinary surgeons who have extensive experience at treating tortoises specifically.

Let's look at some of the real causes of this symptom in tortoises recently emerged from hibernation:

Inadequate heat and light

Tortoises need adequate basking temperatures and bright light upon emerging from hibernation in order to function correctly. If too cold and/or kept in 'dim' (compared to outdoors) conditions, then desire to feed will be depressed. Tortoises require an adequate basking zone, typically provided by an overhead source of radiant heat that should cover at least as large an area as the body, and preferably, twice that. They also require 'full spectrum' bright light with UV-B content. This is typically best provided for via use of special fluorescent 'full sprectum' tubes with UV-B designed for reptile use. Mediterranean tortoises (Testudo species) need to be able to elevate their body temperatures to around 30-32 Celsius to permit normal activity. These should be available for 12-14 hours per day. If a tortoise does have adequate heat and light, and still refuses to feed, then you can confidently conclude that there is a serious health problem that needs professionally diagnosing and treating. Seek out an experienced tortoise vet. In suitable conditions most tortoises will feed within a day or two, certainly within a week at most. Don't delay beyond that, and meantime gives soaks to encourage drinking. Dehydration at this time is very serious and must be avoided.

Tortoises will often drink voluntarily if offered fresh water like this. Even some frost-blind toroises (though not all) will accept fluid using this method. Drinking is especially critical immediately after emerging from brumation/hibernation.

Poor preparation for hibernation, or too long in hibernation

Common issues here include hibernating an underweight tortoise, a tortoise that is already dehydrated, or a tortoise placed into hibernation too soon after having last eaten. All of these can cause further problems upon emerging. Uric acid levels may be dangerously elevated, and there is an increased risk of bladder 'stones' and urate deposits in other areas or organs. It is critical that any dehydration is dealt with quickly. If the tortoise will not drink voluntarily, then delivering fluids (standard veterinary electrolyte solutions are suitable) via stomach tube is the recommended option, at a rate of 5ml to 35ml daily. This should continue over several days and the precise amount needs to be judged based upon the size of the animal. There are other, more invasive routes for delivering fluid therapies, but except in really extreme cases, we have rarely needed to resort to these, and in any event these procedures can only be carried out by a veterinary professional. In the vast majority of cases we have found oral administration by tube to be very safe and very effective.

It should be stressed that rehydration is, initially, far more important than feeding. Rehydrate first, move on to feeding later. Feeding an already dehydrated tortoise can actually make matters worse (e.g., by inducing dangerously low blood potassium and phosphate levels). This is sometimes known as 'refeeding syndrome' and can be rapidly fatal. Fluids first, always. We would not normally consider feeding until urinary output has been established. If oedema (puffiness, or swelling) is noted, and urination is not present, reduce level and seek expert advice.

An excessive length of time in hibernation can result in a multiplicity of problems that become evident upon emerging. These include (again) elevated urea levels, potentially a very low blood white-cell count than can leave the tortoise susceptible to infections, and generalised 'starvation', low 'energy' reserves (glycogen) and loss of body mass.

Tortoises that have been hibernated incorrectly, for too long, or that have suffered frost damage in hibernation will typically emerge in a very depressed and compromised condition. Urgent supportive treatment is essential if they are to survive.

Blood and urine tests conducted by your vet are an essential guide as to how best to proceed, as these will reveal specific imbalances that require particular formulations to treat.

Blood and urine tests can indicate exactly which types of electrolyte preparations are most suitable, whether other additions such as dextrose are required, or whether medications to reduce uric acid levels are required. However, the most urgent thing is to begin treatment without delay with standard electrolyte fluids, then adjust it in the light of subsequent test results.

Almost all cases require a period of initial supportive fluid therapy to stabilise, followed by (usually) some forced feeding by tube. This will be a long-term requirement so in most cases the keeper will need to learn how to do this. Your vet should be able to teach you the basic technique. Do not be intimidated, as once learned, it is not particularly challenging. For the latter, it is important to go slowly and to only use products suited to tortoises. One product that we have used ourselves many times and found safe and effective is Oxbow Critical Care for Herbivores. Once hydrated, this can be efficiently delivered via a syringe and stomach tube. It very important that the tortoise is not 'overloaded' with excessive force feeding.

Providing fluid therapy to a frost-damaged tortoise.

Note the way in which the head is held, with the mouth held open, and insertion of the

fluid or feeding tube.

The tube should be cut so that it is approximately 3/4 the length of the tortoise. Make sure the cut ends are not sharp or jagged. A larger bore tube is best, as fine bore tubes tend to clog easily. The amount required will depend on the size of the tortoise, but it is vital not to over-feed. If anything, veering slightly in the direction of under-feeding is much safer. Over-feeding, especially in the early phases of treatment can lead to fatalities, as food simply builds up, undigested. Start slowly, and give the digestive tract time to begin working normally. We have found that once every three days is a good initial regime. This can be gradually increased, but only after the tortoise begins to pass faeces. Until then, take it slowly.

As a guide, 10 ml for a 1 kg tortoise every 3 days is about right. You should increase or decrease this proportionally. Note that this is in addition to the continuing fluid intake.

You can also use fully hydrated, mashed commercial tortoise pellets as the basis for a tube-feeding regime. The Testudo Pro-Alpin range is especially suitable. Many normal commercial pellet diets can have dangerously high protein levels and a poor overall balance, so be careful. This is a very different situation from normal feeding, and used carefully in such a role, such products can be both safe and effective. They are quite high in fibre, and although not as easy to tube as Oxbow Critical Care, they can add some much needed variety to a potentially long-term tube feeding regime. With juvenile tortoises in particular, we recommend adding some extra calcium in the form of Nutrobal or Zolcal-D to the tube feeding formula. You can also use a kitchen liquidiser to produce a mash of suitable flowers, and green leaf material to supplement the prepared formulas.

Keep all feeding equipment clean and disinfected. Never share syringes or tubes between different tortoises. Fresh syringes and tubes can be purchased in bulk at low cost from veterinary supply companies.

It is possible that in some cases it will be possible to transition in time from tube feeding to other methods.


Ideal in animals which are not in a serious condition, and where encouragement to take food into the mouth is all that is required. It is frequently highly successful with sight-damaged animals once over the initial stabilisation phase. Technique: simply open tortoises mouth, and place food within. To open a tortoise's mouth efficiently and safely, simply grasp animal firmly behind the ears and jaw with the thumb and second finger of one hand, and firmly force down the lower jaw with the thumb and first finger of the other hand.


Obtain a 5 ml or l0 ml syringe from your veterinary surgeon. Alternatively suitable syringes are often sold in pet stores as baby bird feeders. This method can be used in conjunction with the hand-feeding (above). Technique: open tortoise's mouth manually (as above), and simply syringe small quantities of food onto the tongue to be swallowed naturally.

Syringe feeding. Again note the way in which the head is gently, but firmly held.

Frost damage and frost-induced sight damage

The first thing is to learn to look out for signs that a tortoise could be sight-damaged. In many cases there is additional damage too, often the exposed parts of the limbs may also be affected, and in some cases, brain damage may also be involved. On rare ocassions there may be a red 'flush' on parts of the plastron. This is where a lot of confusion arises, as this is practically indististinguishable from the same symptom but when caused by sepsis. In this case, however, it is a direct consequence of the plastron being exposed to sub-zero conditions (causing subcutaneous bleeding). While the frost-induced 'version' of this symptom will, over time, reduce and the immediate danger is relatively low, if caused by sepsis (that has no direct relevance to PHA whatever), the danger is severe and immediate. Suspected sepsis should always be treated as a veterinary emergency. At the same time, it is worth noting that if contaminated substrates are used around a hibernating/brumating tortoise, this is one potential cause of such infections.

Typical signs of frost damage often include a combination of the following behaviours:

  • Total refusal to eat

  • Immobility

  • Moving in circles

  • Head held at an unusual angle (up or down)

  • Failing to react to visual stimuli

  • Failure to emerge voluntarily from hibernation

These are all good indicators that something is seriously wrong. It is important that any tortoise with these symptoms is seen by a good tortoise vet without delay. The sooner support and treatment is provided the better the long-term prognosis. Sadly, we often find (even as late as June) people contacting us saying “my tortoise has not eaten since coming out of hibernation”. These tortoises should have been detected and treated within days of getting up. Instead, after weeks or months without feeding, they are now not only blind, but severely emaciated and dehydrated in addition.

It is also the case that keepers MUST CHECK HIBERNATING TORTOISES REGULARLY and if they fail to emerge much beyond the usual or expected time MUST INTERVENE. That tortoise may require urgent help. The longer the delay the greater the chance of death or of the tortoise emerging in an emaciated and dehydrated condition.

It is no use trying to ‘tempt’ a sight damage tortoise to eat. They will not respond to that. More active intervention is required, as described above.

It is very difficult to say how long this feeding regime may be necessary. It can be weeks. It can be years. Our co-founder, the late Jill Martin, once maintained a tortoise like this for eight years before it one day, without any prior indication, started to feed for itself. Continue to provide the opportunity for self feeding - you never know. Jill refused to give up on tortoises. So should you. Sometimes, a sudden recovery just happens. It is certainly not hopeless. Many of these tortoises do recover. This may be due to scar tissue on the retinas finally disolving, or some unexpected recovery of the cornea - but it does happen.

There may be very slight, or even no visible evidence of such damage, although if the eye is examined by a specialist vet using an opthalmoscope, bleeding or scar tissue on the retinas or scarring of the lens may be apparent.

These are examples of tortoises with frost-induced eye damage.

This tortoise suffered freezing in hibernation, causing blindness and extensive local tissue damage including the extremeties.

Here, there is damage to the lens and also to the retina, visible as an opaque disk.

A few other cautions when working with sight damaged tortoises. Because they do not move easily, and cannot detect shade, be ultra-careful if giving them outdoor time on hot days. They may just sit there and overheat - possibly with fatal consequences. Make sure this cannot happen. Finally, always keep a close check on their digestive functions and general health. These tortoises are very vulnerable. With good care, however, we believe they can continue to enjoy life and deserve to be given the chance to make a full recovery. We do not recommend hibernating sight damaged tortoises again. We have heard of relapses following this, even if no further freezing takes place. We believe it is safer to over-winter them in future.

As always, prevention is better than cure, and with a careful pre-hibernation preparation, followed by adequate monitoring throughout the period, and then suitable conditions (light and heat) to greet the emerging tortoise, this is a situation that is entirely preventable.

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A. C. Highfield/Tortoise Trust (c) 2024

1,169 views2 comments


Very interesting article. So far, I have been lucky enough with my tortoise when he awakes from hibernation - he is quickly full of beans and raring to go. He hibernates Dec, Jan and Feb and usually I’m afraid I dig him out early March as I feel a good three months is quite enough for him (a Hermann’s). But it is reassuring to know that if he is unusually sluggish, there are several options to try.


Valuable information here - and know from personal experience having helped a sight damaged TGG many years ago to start feeding again. His eyes 10 years on had also improved sight wise.

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