A hedgehog is any of the spiny mammals of the subfamily Erinaceinae, which is in order Erinaceomorpha. There are seventeen species of hedgehog in fivegenera, found through parts of Europe, Asia, Africa and New Zealand (by introduction). There are no hedgehogs native to Australia, and no living species native to the Americas. Hedgehogs share distant ancestry with shrews (family Soricidae), with gymnures possibly being the intermediate link, and have changed little over the last 15 million years. Like many of the first mammals they have adapted to a nocturnal, insectivorous way of life. Hedgehogs' spiny protection resembles that of the unrelated rodent porcupines and monotreme echidnas.
Although traditionally classified in the now abandoned order Insectivora, hedgehogs are not exclusively insectivores but are almost omnivorous. Hedgehogs feed oninsects, snails, frogs and toads, snakes, bird eggs, carrion, mushrooms, grass roots, berries, melons and watermelons. Berries constitute a major part of an Afghan hedgehog's diet in early spring after hibernation.
Hedgehogs suffer many diseases common to humans. These include cancer, fatty liver disease and cardiovascular disease.
Cancer is very common in hedgehogs. The most common is squamous cell carcinoma. Squamous cell spreads quickly from the bone to the organs in hedgehogs, unlike in humans. Surgery to remove the tumors is rare because it would result in removing too much bone structure.
Fatty liver disease is believed by many to be caused by bad diet. Hedgehogs will eagerly eat foods that are high in fat and sugar. Having a metabolism adapted for low-fat, protein-rich insects, this leads to common problems of obesity. Fatty liver disease is one sign, heart disease is another.
Hedgehogs uncommonly transmit a characteristic fungal skin infection to human handlers as well as other hedgehogs. This ringworm or dermatophytosis infection is caused by Trichophyton erinacei, which