African Pygmy Hedgehogs or Four-toed hedgehogs are unique, nocturnal mammals related to shrews and moles. As of December 5, 2015, African Pygmy Hedgehogs have been removed from the restricted wildlife list in Arizona, and can be legally kept as pets. Legal restrictions vary from state; be sure to check with your local laws before pursuing ownership.
BEHAVIOR
One of the African Pygmy Hedgehog’s defining physical traits is its quills. Quills are modified hairs that cover most of hedgehog’s body. When rolled into a ball, these quills protect hedgehog’s undersides from predators or perceived threats. Contrary to popular belief, hedgehogs do not ‘throw’ or ‘shoot’ their quills, however just like normal fur they shed and regrow them.
Hedgehogs are best kept singly where tolerance of handling can vary amongst individuals. To encourage your hedgehog to become more accustomed to being handled and interacting, it is best to allow hedgehogs to unroll on their own and have slow deliberate movements. Offering treats at this time may help to associate you with positivity. Most hedgehogs do not enjoy being petted and respond by rolling tightly into a ball.
Another interesting behavior that hedgehogs exhibit when an interesting smelling object is found is called self-anointing. Self-anointing occurs when hedgehogs salivate excessively or foam after encountering an interesting smelling object and chew on that object. The mixture of their saliva and that object is then smeared over the hedgehog’s body. Many studies exist for why hedgehogs perform and suggest that this behavior may be linked to scent camouflage, communication, to smearing toxic substances to protect from predators.
DIET
Hedgehogs are omnivores, consuming plants and insects. Despite popular belief, it is best to not feed cat food as a staple diet to hedgehogs. Cat diets are high in fats and animal proteins and lack an important component of insects called chitin. Chitin helps compose the exoskeleton of insects and is thought to act like fiber in the diet and promote digestive health. Hedgehogs are best fed 3-4 teaspoons of a diet consisting of insectivore kibble such as Mazuri Insectivore Diet. The diet can be supplemented with root vegetables and occasional insects like crickets and meal worms. Avoid high sugar foods, raw meats, and all dairy products. Hedgehogs are prone to obesity; make sure to measure your hedgehog’s food and consult your exotics veterinarian for any concerns regarding weight and health.
HOUSING
Hedgehogs need to be housed in a solid bottom cage that measures 5 sq. ft. Do not house them on wire bottomed cages as they will damage their feet and possibly fracture limbs. Paper based bedding, aspen wood shavings, or felt can be used for the bottom. In the wild, hedgehogs spend most of their time foraging for insects and roots. To replicate this in captivity, provide a solid, appropriately sized wheel for exercise in the enclosure. Most hedgehogs use their wheels regularly and often defecate on them. Open spaces can be stressful for hedgehogs, so provide them with several hiding opportunities like PVC tubes or boxes. Water should be available at all times either by using a water bottle and a ceramic dish.
HANDLING
Most hedgehogs are uncomfortable being picked up and can make picking them up uncomfortable for their owners. It is best to pick up your hedgehog with two hands. Gloves or a folded towel are best to protect against the quills. Allow your hedgehog to unroll itself on its own terms. Never attempt to unroll a hedgehog. Gentle, patient, and consistent handling will help to create a more social hedgehog.
COMMON ILLNESSES
Skin problems: Mites are somewhat common with hedgehogs and cause flaky skin, raggedy ear edges, and quills that fall out very easily. Fungus/ringworm can cause similar symptoms as well. Both mites and fungal problems can be treated so if poor skin health symptoms are noted they should be seen by a veterinarian.
Wobbly Hedgehog Syndrome is caused by a degenerative neuropathy in the spine. It causes hedgehogs to first appear wobbly like they are stumbling or falling over as they walk. Unfortunately it is progressive with no known treatment and eventually causes paralysis and death.
Cancer is very common in African Pygmy Hedgehogs and it is suspected that there is a genetic component to some of the many types of cancers that hedgehogs get. There can be lumps and bumps that arise in many areas of the body including internally, on the jaw, in the skin, and commonly the reproductive tract.
Cancer in Hedgehogs
Hedgehogs unfortunately are highly prone to cancer, especially as they age, with one study reporting over two-thirds of hedgehogs over the age of 3 having cancer. Cancer has been reported in many areas of the body, but is commonly found in the mouth, skin, and female reproductive system. Tumors are often malignant and can carry a poor prognosis, especially without treatment. Early identification will allow for optimal treatments to be implemented and improve long-term prognosis. We recommend yearly exams for all hedgehogs, and as they age it can be helpful to have them seen more frequently to identify any issues early on. Due to their personalities, hedgehogs may require sedation in order to facilitate a complete physical exam. This allows better evaluation of the face, mouth, and palpation of the belly, as well as allowing for blood draws or radiographs to be obtained if needed. It is important to monitor your hedgehog closely for any changes in attitude, appetite, or activity levels, as any small changes can indicate underlying problems.
ORAL TUMORS
Squamous cell carcinoma is a common cancer found in the mouth in hedgehogs. Symptoms include swelling of the mouth or jaw, tooth loss, decreased appetite, bleeding, and a bad smell or discharge from the mouth. These tumors can be challenging to remove fully due to their location, but other treatments can be implemented to help with discomfort and help slow growth of the tumor. Because hedgehogs are prone to dental disease, they can also have excessive growth and inflammation of the gums that look similar to tumors, so it is important to take biopsy samples of the tissue to identify what is going on. These tumors will continue to grow so careful monitoring of quality of life is imperative. 
SKIN TUMORS
Tumors on the skin are frequently seen on the soft haired belly area, but can be seen anywhere on the body including under the quills, on the limbs, or around the face. These tumors often grow rapidly and can break open causing bleeding as well as become infected. Most tumors are easily removed from the skin when they are small in size. Unfortunately many of these tumors are aggressive and can spread to other areas of the body. If you see a bump on your hedgehog, don’t wait until it gets big to get it checked! Surgical removal generally has a good outcome.
REPRODUCTIVE ORGAN TUMORS
A recent study of hedgehog diseases noted that uterine tumors were the most common lesion found. Female hedgehogs affected by reproductive cancers (in the uterus or ovaries) can show non-specific signs initially of weight loss or decreased appetite and activity. Many present with bloody discharge from the urogenital region, which often looks like blood in the urine. Prolapse of the tissue out of the vulva is a serious complication of advanced disease. Treatment requires spaying to resolve the primary issue, and some patients need other supportive care treatments prior to pursuing surgery to make sure they are good anesthetic candidates. Most of the time, spaying is curative for this disease.
Wobbly Hedgehog Syndrome
Wobbly Hedgehog Syndrome (WHS) is a degenerative neurologic condition that can occur in African Pygmy Hedgehogs (aka Four-toed hedgehogs). The cause is unknown, but is believed to be genetic.
This condition causes demyelination, where the protective coating of nerve cells experience damage. This causes ataxia (difficulty walking, stumbling), paralysis, and weight loss in hedgehogs. There is an evident “wobble” when the hedgehog tries to stand still. Signs usually occurs around 2-3 years of age, but can happen at any age. Both males and females can be affected with equal frequency. Death commonly occurs 18-24 months after onset of clinical signs.
There are other causes of neurological signs, like ataxia, that can cause suspicion of WHS. Brain or spinal cord diseases, vestibular (inner ear) problems, malnutrition, tumors, toxins, trauma, or other conditions can all be investigated as possible causes. Diagnostics like radiographs (x-rays) and bloodwork can be done to help rule out some of these conditions. However, WHS can only be definitively diagnosed after death via histopathology (looking at tissues under a microscope) of nervous tissue (brain and spinal cord).
Treatment for WHS is supportive care; helping the hedgehog remain upright using towels, making food and water easier to access or hand feeding, and cleaning after the hedgehog as soiled itself. There is no cure for WHS. Prognosis is grave and euthanasia is recommended when quality of life is poor.
References
Hoppes, S., DVM,DABVP (Avian). (2016). Common Diseases in Hedgehogs. Retrieved from https://www.vin.com. Southwest Veterinary Symposium, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA
Axelson, R., DVM (2011) Wobbly Hedgehog Syndrome. Retrieved from https://vcahospitals.com/know-your-pet/wobbly-hedgehog-syndrome
Hedgehogs and Salmonella Typhimurium Infection in People
Like all pets, hedgehogs can carry bacteria and viruses that can make people sick. Recently a number of cases of Salmonella Typhimurium in people have been linked to exposure to pet hedgehogs. This is a bacteria that hedgehogs can carry in their intestines without showing any signs of illness. Symptoms in people include diarrhea, fever, and stomach cramps. Severe cases require hospitalization and can be fatal. Risks of illness are higher in children under the age of 5, the elderly, and immunocompromised persons. If you feel ill, contact your physician and inform them you have a pet hedgehog.
To protect yourself from infection we recommend practicing good hygiene. Always wash your hands thoroughly after handling your pet or its cage furnishings. Avoid touching your face or mouth while handling your pet. Keep your hedgehog away from your face. Do not kiss your hedgehog. Do not eat, drink, or smoke while handling your hedgehog. Keep pet hedgehogs out of the kitchen or anywhere food is prepared or consumed.
For more information on human Salmonella exposure from pet hedgehogs visit the Centers for Disease Control’s website at https://www.cdc.gov/salmonella/typhimurium-01-19/index.html.
