Post Hibernation Anorexia (PHA) in Tortoises

Post hibernation anorexia (PHA) is a very common problem in pet tortoises at this time of the year, and can be frustrating to treat. Prevention is much preferable to treatment, and with the correct husbandry, dietary practices and hibernation preparation, this is easily achievable.

Sadly, post hibernation problems recur each year. Many pet tortoises are still kept by owners who are ignorant of their requirements regarding heat and UVb light provision, and the fact that many tortoises can cope with poor husbandry for relatively long periods before showing clinical signs can mask the problem.

What is post hibernation anorexia (PHA)?

PHA is when a tortoise fails to eat in the days and weeks following waking from hibernation. It is not a disease in itself, merely a descriptive term that reflects underlying disease(s).

Why does PHA happen?

The main reasons for PHA occurring are:

1. The tortoise was not fit enough to hibernate in the first place.
2. The hibernation was inadequately set up or poorly monitored.
3. The hibernation lasted too long.

A veterinarian treating a case of PHA must first play detective to find out the previous husbandry practices, diet and health problems of the tortoise, and ascertain the precise hibernation set up the owner was using.

Tortoises are particularly vulnerable during the post hibernation period. When they wake they are usually very weak and have a low white blood cell count, meaning they are susceptible to infection. They also have a high urea level, due to the accumulation of metabolic toxins. This is exacerbated if the tortoise is dehydrated or has had a very long hibernation period. The combination of a high white blood cell count and a high urea level means that if anything else goes wrong, there is very little time available to diagnose and treat the problem.

The problem is made worse in countries with an unnatural climate, such as the UK. In the wild, most tortoises have a long summer to prepare them for a short winter, and therefore a short hibernation period. In countries like the UK, tortoises have a short summer to prepare for a long hibernation period. It is very important therefore to artificially control the duration of hibernation, or else the tortoise may be fatally weakened and unable to recover organ function properly.

The recommended maximum length for a hibernation is 3 months for a healthy adult tortoise, so most of them will need waking toward the end of January, and kept inside a warm enclosure until the summer.

The owner responsibilities

When a tortoise wakes from hibernation, the owner should carefully check for clinical signs such as sunken eyes (suggests dehydration) or wounds to the limbs (usually due to bites from rodents when tortoises have been hibernated outside). If any problems are suspected, veterinary help should be sought immediately.

If all seems well, tortoises should be bathed daily in shallow warm water and housed in an indoor enclosure, kept at 22 to 25 degrees centigrade, with both a basking lamp and a UVb light provided.

A healthy tortoise should start to eat and urinate within a week. If this does not occur, veterinary attention is required. The owner must closely monitor appetite, thirst, urination, defaecation and activity for at least three weeks post hibernation. If the tortoise fails to urinate within 6 weeks of waking, the prognosis is very poor sadly.


1. Excessive duration of hibernation period

Basically, those longer than 3 months. This occurs in tortoises left outside for the winter.

2. Low white blood cell count

This can sometimes have been present before hibernation. Stress and seasonal changes in reproductive hormones can play a role. The tortoise will be immunosuppressed on waking and if warmed too quickly, disease causing microorganisms will multiply and cause infections such as runny nose syndrome.

3. Disease or injury during hibernation

Rat bites and frost damage are two common injuries that occur during hibernation. Blindness can also occur, which is sometimes overlooked.

4. Poor post hibernation management

This includes failing to rehydrate the tortoise by bathing etc, not realizing the hibernation was over and inadequate food or heat provision.

5. Undetected long term diseases

Health problems have often developed over a very long period, with hibernation being the final straw which pushes the tortoise over the edge. Examples of diseases affecting tortoises are mycotic (fungal) infections, viral infections, kidney failure, egg retention, liver disease, disease of the digestive tract and eye problems.

Treating PHA can be very frustrating for the veterinarian. It is much preferable to do all you can to stop it from occurring in the first place. Good vets will suggest a pre hibernation consultation for the following season, where long term husbandry and care can be discussed.
Dr Matthew Homfray is one of the veterinary pet experts at Our dedicated community of caring pet experts are waiting to offer you advice, second opinions and support.
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