There are 2 varieties of hedgehogs, African and European.  African hedgehogs are commonly kept as pets here in the United States.  They are very hardy as long as they are cared for properly.

General biology

Hedgehogs weigh from 250-700 grams with a life expectancy of 5-8 years in captivity.  Hedgehogs are nocturnal (active at night) but will emerge from their next during the day occasionally.  When frightened, they contract their strong longitudinal muscles running along their chest and abdomen.  This causes them to roll up into a tight ball.  Frightened hedgehogs may also puff up, spit and emit high pitched hissing sounds.  Hedgehogs have a peculiar behavioral called self anointing.  This can be seen when hedgehogs are introduced to unfamiliar objects.  They will lick the new object over and over, salivate excessively and create a frothy saliva.  They then rub this saliva on their skin and spines (quills).  The purpose to this ritual is unknown.  Maturity occurs at 6-8 months of age.  However, be careful because they can breed as early as 8-9 weeks of age.  Offspring can be born at anytime of the year.  Gestation is 34-37 days.  Pregnancy detection is difficult and usually required weekly weight checks.  All other hedgehogs should be removed from the cage when pups are born.

General husbandry

Hedgehogs are insectivores.  Their natural diet consists of insects, worms, snails, and perhaps small vertebrates (mammals) and fruit.  Their are various hedgehog formulated foods on the market now.  In the past, hedgehogs have been maintained on dry kitten, cat, dog or ferret food.  However, the commercial hedgehog foods are better.  Also, the hedgehog should be given insects, earthworms, mealworms, and occasional fruits and vegetables.  It is also nice to occasionally feed small pinkie mice (newborn mice).  Hedgehogs are prone to being overweight.  Check with your local veterinarian regarding your hedgehog's diet.

Cages should be smooth walled enclosures because hedgehogs can climb very well.  Wire flooring is not recommended because it can cause toe and or leg injuries.  A hiding box or nest should also be provided.  Bedding material can be shredded newspaper (unprinted), pelleted bedding material or processed bedding material.  Do not use cedar shavings, cat litter or soil.  Bedding material should be changed frequently.  The cage should provide lots of room for your hedgehog to run around in order to get exercise.  An exercise wheel is a good exercise tool for your hedgehog and most hedgehogs will use them regularly (at night).  A little known fact is that hedgehogs like to swim and swim very well.  You can have supervised swimming sessions for your hedgehog.  Just use a shallow pan with warm water and place your hedgehog in the water.

Hedgehogs are solitary animals.  They do not need to be with other hedgehogs unless it's for breeding.  Males typically fight over females so there should be only one male in a group of females if you have several hedgehogs.  However, females can also fight and inflict serious damage on cage mates.

Low temperatures induce hibernation.  High cage temperatures can cause heat stress and/or sluggishness.  The recommended cage/environmental temperature should be between 75 and 85 degrees Fahrenheit.

Your hedgehog should have annual physicals and bloodwork done by your veterinarian in order to assure it's health and longevity.

Common diseases of hedgehogs:

Skin diseases

A hedgehog's skin should not be flaky or dried.  Heavy flaking, ear margin crusts, quill loss or hair loss, scabs, redness and/or swollen paws are all signs of a skin problem.  The most common cause of skin disease in hedgehogs is SARCOPTID MANGE mite.  This parasite lives and breeds on the hedgehog's skin.  It can be transmitted to other hedgehogs by direct contact, but not to other pets in the house.  Mites are diagnosed by taking skin samples and looking at the sample under a microscope to find the mites.  Mites are easily treated and most hedgehogs respond quite favorably to treatment.  The cage should also be cleaned thoroughly and even new cage furniture should be bought.

Skin tumors can also occur in hedgehogs, as well as abscesses and papillomas.  Fungal skin diseases (ringworm) has also been reported in  hedgehogs.  In fungal diseases, the owner may notice crusts around the base of the spines.  Fungal disease may be secondary to a skin bacterial infection, traumatic wounds, etc.  Thus, the primary skin disease should be treated as well in order to obtain successful treatment of the fungal disease.

Neoplasia (Cancer)

Unfortunately, hedgehogs commonly get tumors in many different organs.  Tumors are more commonly seen in hedgehogs over 3 years of age.  They can have vague signs such as lethargy, inappetance and weight loss.  Of course, these signs can be seen with other diseases, thus your veterinarian may have to do extensive tests in order to figure out what is wrong with your hedgehog.

Parasites

Internal parasites, such as gastrointestinal parasites, have been found in hedgehogs.  Various parasites that a hedgehog can have are nematodes, protozoa, cestodes, coccidia, cryptosporidium, and giardia.  Fecal analysis of your hedgehog's feces will help to identify which parasite, if any, your hedgehog has.  Treatment would then ensue depending on the parasite found.

Hedgehogs can also have external parasite, just like cats and dogs.  Fleas can easily be found on hedgehogs that live in areas with high flea populations.  Ask your veterinarian about how hedgehogs are treated if fleas are found.  Again, skin mites (Choriptes) is a common mite found on hedgehogs (see "skin disease" above).

Respiratory disease

Hedgehogs can have lung/respiratory infections from such bacteria as Bordetella, Pasteurella, Corynebacterium and Mycobacterium.  Your hedgehog may show nasal discharge, sneezing and problems with breathing (dyspnea).  Your veterinarian may want to run bloodwork, do radiographs (x-rays) of the chest and culture of respiratory secretions.  Treatment will depend on the test results.

Trauma

Hedgehogs kept in cages with wire cage flooring can often have toe and limb trauma.  However, hedgehogs may also fight amongst themselves and sustain trauma that way.  Seek veterinary care for your hedgehog if any lacerations, puncture wounds, cuts, and/or bruises are seen on your pet.  Many times, hedgehogs will need antibiotics and daily cleaning of the affected area(s).

Summary

If you feed your pet hedgehog the correct meal, keep your hedgehog in the correct cage, and have annual physicals done on your hedgehog, you should enjoy many long and happy years with your pet hedgehog.  They make wonderful, small companions, and have wonderful personalities.  Ask your veterinarian if he or she sees hedgehogs.  If he or she does, set up a visit with him/her and your hedgehog for a check-up.  If your veterinarian does not see exotic animals, ask him/her if they can refer you to someone who can see your hedgehog.  Should you have an emergency, you should already have this information on hand, rather than scrambling to find someone immediately during a stressful emergency.  We hope some of this information will help you better understand your hedgehog so that you will both enjoy each other's company.