Four-toed hedgehogs (Atelerix albiventris), also known as African pygmy hedgehogs, white-bellied hedgehogs, or central African hedgehogs, are solitary, nocturnal mammals in the family Erinaceidae, order Eulipotyphla, which includes shrews and moles. Hedgehogs are native to dry, open habitats in central and eastern Africa. They are active animals that will travel for miles in search of prey.
Four-toed hedgehogs are often kept as pets. Some US states and municipalities require a permit to keep a hedgehog as a pet, whereas in other parts of the US, having a pet hedgehog is illegal. In addition, a USDA permit is required to breed, transport, sell, or exhibit hedgehogs.
Although similar in appearance to A albiventris, lesser hedgehog tenrecs (Echinops telfairi), often referred to simply as "lesser hedgehogs," are native to Madagascar and are not closely related to hedgehogs. Lesser hedgehog tenrecs are also sometimes kept as pets; however, they are not the topic of this discussion.
Anatomy, Physiology, and Behavior of Four-Toed Hedgehogs
The dorsum of a four-toed hedgehog, also known as the mantle, is covered in a dense coat of partially hollow keratin spines. Each spine is firmly attached within the follicle by a basal bulb. A narrowed portion at the skin surface allows for spines to be held flat against the body or erect in a defensive position. It is difficult to pull a healthy spine from the follicle. The mantle has a thin, mostly hairless epidermis and a thick, fibrous dermis with abundant adipose tissue and minimal vascularization. The unique anatomy of the mantle has the potential to affect the pharmacokinetics of injectable drugs administered in this area.
A wary hedgehog will erect the spines and crouch. When a hedgehog is frightened, the panniculus muscle contracts and pulls the loose spiny skin around the entire body. The panniculus is thickened at the rim to form the orbicularis, a purse-string–like muscle that cinches the mantle closed around the hedgehog, forming an intimidating ball of raised spines.
For selected physiological data, see the table .
Physiological Data for Four-Toed Hedgehogs
Average body weight | Male: 400–600 g; Female: 300–400 g |
Lifespan | Average 4–6 yr |
Body temperature | 35.4–37.0°C (95.7–98.6°F) |
Adult dental formula | 2 (I 3/2:C 1/1:P 3/2:M 3/3) = 36 (variations have been noted) |
GI transit time | Approx. 8 h |
Heart rate | 170–250 bpm |
Respiratory rate | 18–90 bpm |
Age at sexual maturity | 2–3 mo |
Reproductive lifespan | Male: throughout life Female: 2–3 yr |
Gestation | 34–37 d |
Litter size | 3–4 (range 1–9) |
Birth weight | 10–18 g |
Age when eyes open | 14–18 d |
Deciduous teeth eruption | Begins on day 18; all deciduous teeth erupted by 9 wk |
Permanent teeth eruption | Begins at 7–9 wk |
Age at weaning | 5–6 wk (start eating solids at 3 wk) |
Four-toed hedgehogs have brachydont teeth. The first incisor in each quadrant is large and projects forward, and there is a gap between the maxillary first incisors in which the mandibular incisors sit when the jaw is closed. The molars are relatively flattened with multiple cusps. Hedgehogs have a simple stomach and a vomiting reflex.
The male has a conspicuous prepuce that opens midabdomen. There is no scrotal sac; the testes move freely between the abdomen and a para-anal recess and can be palpated in reproductively active males.
The female urogenital opening is a few millimeters cranial to the anus. The uterus is bicornuate, with dramatically curled horns, a single cervix, and no uterine body. Hedgehogs are polyestrous and breed throughout the year in captivity. Ovulation is believed to be induced, and sterile matings with pseudopregnancy can occur.
Hedgehogs are born with closed eyes and ears and without hair. At birth, babies have spines that are covered by a membrane that dries up and disappears within the first few hours of life.
Hedgehogs easily dig, climb, swim, and run. Although they have sensitive olfaction and hearing, their eyesight is poor.
This four-toed hedgehog has just self-anointed after being introduced to a novel object or smell. In self-anointing, the hedgehog licks, bites, or holds the novel material in its mouth, creates a frothy saliva, and applies the saliva mixture to its spines with its long tongue. Note the foamy saliva on the spines. This hedgehog has adopted a defensive posture characterized by a contracted frontodorsalis muscle, partially covering the face with the crown.
Courtesy of Dr. Grayson Doss.
While foraging, hedgehogs make a variety of snuffling noises. When agitated, they make a loud hissing sound interrupted by coughlike and puffing sounds. Hedgehogs in intense distress might scream.
With patience, most hedgehogs learn to accept handling. Hedgehogs rarely bite.
Hedgehogs engage in a unique behavior called self-anointing, or anting. This behavior can be elicited by a variety of substances, particularly those with a strong odor. The hedgehog licks, bites, or holds the material in its mouth, creates a frothy saliva, and applies the saliva mixture to its spines with its long tongue (see ). The purpose of this behavior is unknown.
For More Information
Doss G, Carpenter JW. African pygmy hedgehogs. In: Quesenberry KE, Orcutt CJ, Mans C, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery. 4th ed. Saunders; 2021:401-415.
Doss G, Carpenter JW. Hedgehogs. In: Carpenter JW, Harms CA, eds. Carpenter's Exotic Animal Formulary. 6th ed. Saunders; 2023:511-529.
