Hibernation can cause health problems for tortoises, particularly when done without due care. Weight loss, unthriftiness and poor appetite are common post-hibernation complaints. A good system put in place to care for your tortoise before, during and after hibernation, can help to prevent these problems. As well as keep your tortoise happy and healthy through his slower months.
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Should I hibernate my tortoise?
Before even considering how to prepare your chelonian for hibernation, it’s important to be sure that it’s relevant for him. Not all species of tortoise need to hibernate, those that do include Hermann’s, Horsfield, and Mediterranean spur-thighed tortoises, although there are others. Get familiar with your species and contact your veterinarian if you have any doubts. Species isn’t the only thing we have to bear in mind, however, and tortoises that are unwell, debilitated or very young should also not be hibernated. They won’t be strong enough to tolerate it.
Preparation for hibernation begins many months in advance, storing up reserves. So any ill-health needs catching early to give your tortoise the best chance of getting into condition to hibernate. Normally, hibernation is started from a minimum of two years old but can be as late as 4. Younger tortoises will hibernate for a shorter time than their more mature counterparts; often only six weeks as opposed to two or three months.
Tortoises that aren’t being hibernated also need careful attention. They need to be kept active, fed and maintained in an appropriately temperature-controlled environment.
When you’re happy that your tortoise can and should hibernate, you need to consider how to safely get him through it. Please don’t hesitate to contact your veterinarian if you have any doubts. One of the main things we want to avoid is a hibernation period that’s too long. So don’t let him hibernate too soon, aim for November onwards. Your tortoise will pick up on shortening day lengths and cooler weather, indicating that it’s time to start slowing down. It’s a good idea to get him booked in for a general health check early on (think spring or summertime). This is to allow subtle signs of illness to be picked up and any relevant tests to be done. This will give him the best chance of getting in the best condition to go into hibernation as healthy as possible.
If your tortoise is in good health, and the time is right, you can start the hibernation process. As he notices the change in daylength and temperature, your tortoise’s appetite will decrease and you should reduce his feeds. Then, at least two weeks before he goes into hibernation, feeding should be stopped completely. The aim is to get his gut as empty as possible to avoid the gut contents from spoiling and causing him to become unwell. This can take longer in larger tortoises. Water is kept available and daily baths can be used to help to both empty the gut and maintain a full bladder. The bladder is an essential source of water during hibernation – he shouldn’t be going into hibernation with an empty bladder.
The ambient temperature should be reduced each week to gradually cool your tortoise and encourage hibernation. This can be done through allowing time outside in a protected environment during the daytime, before being brought in to a cool place at night. Or by appropriately reducing the temperature of his vivarium or enclosure. The preparatory process takes several weeks. During the last week before hibernation the tortoise may not need to be bathed, but should again be weighed before he is allowed to hibernate completely.
The hibernation process
There are various methods of hibernation, including natural hibernation (where he is allowed to bury outside, although this is hard to control and fraught with problems such as potential for frostbite and wildlife attacks) and artificial hibernation (where he is maintained in a protected, temperature-controlled environment and monitored).
Owing to the problems with natural hibernation, artificial hibernation and specifically fridge hibernation is a sensible option. Fridge hibernation involves placing the tortoise in a plastic container base of appropriate size to allow space for some warm substrate like moss for burrowing, before storing it inside the refrigerator at a temperature of around 5 degrees Celsius. The tortoise should be checked regularly. As well as weighed weekly to monitor for any drop in weight that could indicate a problem (a drop of around 1% of bodyweight per month can be expected and tolerated). Any sign of urination is a concern and the tortoise should be woken immediately to prevent dehydration.
It can be a good idea to contact your vets to enquire whether they offer facilities for hibernating tortoises. Because some will have dedicated chillers for just this purpose. Specialised chillers can be set up correctly to allow careful temperature control, regular weight checks, and careful monitoring of their hibernating patients for any abnormal signs indicating that the tortoise needs additional care or to be woken up.
Hibernation isn’t always straightforward. Attacks from predators, overly low temperatures (below 2 degrees Celsius), abnormal respiration, urination, exposure to frost, and dropping weight are potential complications of hibernation that require your tortoise to be roused. Care also needs to be taken right into the post-hibernation period. Tortoises should be allowed to wake slowly, and be thoroughly checked over for any signs of ill health. The tortoise should be placed back in its normal environment and activity encouraged. Rehydration is essential and requires careful regular bathing to help promote drinking and flush out any accumulated waste; food can be offered the day after emergence. If you notice any sign of persistent inappetence, breathing difficulty or low body weight, contact your veterinarian for advice as soon as possible. This is to make sure he hasn’t suffered any adverse effects from hibernation.