A quick note here: this section applies to African Pigmy hedgehogs, rather
than European hedgehogs (which do hibernate, primarily between January and
March).

A common concern is whether or not pet hedgehogs can, or should hibernate --
especially as winter starts to arrive.  The answer to the first part -- can
they? -- is yes.  The answer to the second part -- should they? -- is NO!

Our pet hedgehogs are African in origin.  They have adapted to the much
warmer climate, and have generally lost the ability to tolerate hibernation.
While they can still go into hibernation, when they get too cold, and they do
have the ability to Aestivate (similar to hibernation, but to survive very
hot, dry periods), their chances of surviving either for more than a brief
period are virtually nonexistant.  In effect the hibernation ability is
almost vestigal, and aestivation is almost as dangerous for an animal which
is not prepared for it.

As pets, hedgehogs do not stock up on food, nor put on the necessary extra
body fat (at least in the right manner) needed to get through hibernation.  A
pet that is allowed to even suffer semi-hibernation extensively can suffer
long term effects (becomming very weak and sick), and those that do end up in
full hibernation will rarely survive beyond 1-2 days in this state, if at
all.

Now that we've made it clear that they shouldn't be allowed to hibernate (or
even go into semi-hibernation, what are the signs to look for, and how do you
prevent it from happening?  The good news is that if caught in time, the
effects are reversable.  If the temperature where they are kept drops too low
(below about 20 degrees C or 68 degrees F), they can start preparing for
hibernation and will certainly go into hibernation for brief periods, if the
temperature drops much below this -- at least until the temperature returns
to a comfortable level.

If your hedgehog seems to be sleeping too soundly, and you are worried, any
kind of movement to his or her bed will usually earn you at least a brief
spate of unhappy snuffling.  If this happens, then you can probably assume
you've just disturbed a sleepy hedgehog, or at least he's not in full
hibernation.  If this and nudging at him don't have any effect, and he's been
in quite a cool (for a hedgehog) temperature, he may have slipped into the
beginnings of hibernation, and should be gently (and slowly) warmed up, which
should let him awaken, and come back to full activity.

Hedgehogs will also tend to slow down and get somewhat grumpy if they are
kept at a temperature that's too cool for their liking.  If you're finding
that your previously energetic hedgehog is acting a bit slow and grumpy, and
cool weather has started to arrive, then you may want to take steps to warm
up your hedgehog [5.2], [7.3].

One of the most common signs of a hedgehog being too cold (semi-hibernation),
is being very unsteady on its feet.  Wobbly hedgehogs, or ones showing signs
of problems in their hindquarters are almost always due to being too cold.
There are some other causes for this type of symptom, as well (see [9.5] on
Wobbly Hedgehogs), but of the cases I've heard of over 99% are from being
cold.

Another sign that a hedgehog that is too cool is its going off its food.  If
your hedgehog isn't eating, and is walking a bit funny, it may be because he
is a bit cool.

    The first thing to do is to check to see if the animal is warm enough.
    Feel its legs and belly.  If these feel chilled the animal needs to be
    immediately warmed up.  A chilled hedgehog will walk as if it is drunk.
    A variety of methods can be used to warm them.  The one that I use is
    to put the animal in the cut off sleeve of a sweatshirt.  I then put
    it in a box (I actually have an 8 litre cooler that I use) with a jar 
    of hot water.  Close the lid of the box (or put the lid on loosely to 
    allow for air in the cooler).  They usually warm up in about an hour
    or so.  When I put the animal back in its own cage, I make sure I give
    it a sleeve to keep warm in.  Some animals are more prone to chills
    than others.
    -- Linda Wheatley

In general, the likelihood of hibernation happening is quite low, so if your
hedgehog isn't making its home in the refrigerator, and you don't like living
in subarctic conditions indoors, you probably shouldn't worry.  That having
been said, I have heard of several instances of it happening (briefly, and
all fully recovered when warmed up), so some caution is worthwhile.

Recently, another cause of hibernation, or more commonly, partial hibernation
has shown up.  It appears that hedgehogs are quite sensitive to the short
daylight hours, or even low light, as can happen during the winter months.
If your hedgehog is warm enough, but still shows indications of wanting to
hibernate, try leaving a light on to extend the `length of the day' for him.
I've seen this help with my own hedgehogs, and my thanks to both Dawn Wrobel
and Sharon Massena for bringing it to my attention.

Beyond even the light issue, it appears that some `lines' of pet hedgehogs
may be more prone to hibernation, or rather trying to hibernate than others.
In some cases, you may need to be very diligent to ensure your little friend
doesn't drift off into a one-way winter's nap on you.  Details on this,
assumed, genetic link are very sketchy as yet.

Also a worry is the chance of pet hedgehogs going into aestivation.  This is
similar to hibernation, but is done when things get too warm.  In their
natural habitat, this is to let the hedgehog wait things out until cooler
and/or damper weather returns.  Pet hedgehogs can slip into this state,
especially in light of heatwaves in recent years in North America.  The
problems and side effects of aestivation are largely the same as for
hibernation.

Remember, keep your hedgie warm!