Anatomy of the Hind Limb Skeleton of the Chinchilla ( Chinchilla lanigera )

Cevik-Demirkan A. , V. Ozdemir, I. Turkmenoglu, I. Demirkan: Anatomy of the Hind Limb Skeleton of the Chinchilla (Chinchilla lanigera). Acta Vet. Brno 2007, 76: 501-507. This study aimed to document the detailed features of the hind limb bones in chinchillas (Chinchilla lanigera). Twenty chinchillas (10 females and 10 males) were used. Animals were euthanized and X-ray of appendicular skeleton of pelvis was taken immediately. Then the bones were macerated. The iliac wing was considerably long and the gluteal line formed a distinct crista. The sacropelvic surface (facies sacropelvina) was not observed, however, the iliac tuberosity (tuberositas iliaca) was evident. While the average distance between the midacetabulum and the tuber coxae (ventral iliac spine) was 33.58 mm in males and 31.34 mm in females, the average distance between the midacetabulum and the ischial tuberosity was 15.09 mm in males and 17.18 mm in females (statistically non-significant). The caput ossis femoris was bent to medial at an average of 60 degrees angle. The differences in both the width and length of the obturator foramen between males and females were statistically significant (p III > I > II (from the largest to the smallest) and the fifth metatarsal bone shaped a small bone. The comparative lengths of the other metatarsal bones were II > III > I > IV (from the longest to the shortest). Three phalanges bones were notable. The proximal phalanx was the biggest of all. Chinchilla, ossa membri pelvini, anatomy Chinchillas are perhaps the best known for their incredibly soft, thick and luxurious fur, and they are becoming more popular as pets (http://exoticpets.about.com). Chinchilla means “little chinta” a name given by the Indian tribes in their area. Their scientific name is Chinchilla lanigera, which means long-tailed chinchilla. Their class is Mammalian (Mammals), their order Rodentia (Rodents), and their family is called the Chinchillidae (Chinchillas and Visachas) (Erencin 1977; http://members.aol.com; Kurschner 1992). One may describe this animal as similar to squirrel with big ears or having a rabbit’s body with mouse-like ears and squirrel’s tail (http://members.aol.com). They are closely related to the porcupine and the guinea pig (http://www.vets.org). In the posterior limb of rodents, in general, the proximal or girdle portion comprises the paired coxal bones, that are united ventrally at the pelvic symphysis, thus forming the pelvic girdle (Craigie 1969). The hip or pelvic girdle consists of three bones (ilium, ischium, pubis) that meet and fuse with each other at the socket (the acetabulum) for the hip joint. The long, blade-like ilium extends cranially and dorsally from the acetabulum to articulate with the sacrum (Walker and Homberger 1998). The ischium extends backward from the acetabulum, its axis continuing that of the ilium (Craigie 1969). The pubis is the ventro-caudal portion of the coxae, and joined to its counterpart by the pubic symphysis (McLaughlin and Chiasson 1990). The distal portion of the posterior limb, like that of the anterior, comprises the supports of the free extremity and is divisible into proximal, middle, and distal segments (Craigie 1969). The proximal segment contains a single element, the femur; it is the largest bone of the thigh, and its head articulates with ACTA VET. BRNO 2007, 76: 501-507; doi:10.2754/avb200776040501 Address for correspondence: Aysun Cevik Demirkan Departmant of Anatomy Faculty of Veterinary Medicine Afyonkarahisar Kocatepe University Afyonkarahisar, 03200-Turkey Phone: +90272 2149309 Fax: +90272 2281349 E-mail: aysuncevik@yahoo.com http://www.vfu. cz/acta-vet/actavet.htm the acetabulum (McLaughlin and Chiasson 1990; Walker and Homberger 1998). The middle segment contains two elements, tibia and fibula; tibia is the largest shin bone of the leg, and fibula is the slender, splint like bone fused to the upper lateral half of the tibia (Craigie 1969; McLaughlin and Chiasson 1990). The distal segment contains six tarsals, four metatarsals, three phalanges in each digit, and pedal sesamoid bones (McLaughlin and Chiasson 1990). Macro-anatomy of the skeletal systems of wild rodents such as the otter (Dinc et al. 1999), badger (Ozdemir and Karan 2001), marten (Atalar and Ozdemir 2002) and porcupine (Yilmaz et al. 1999) have been exclusively studied, however, the skeletal systems of chinchillas have not been investigated in detail. Therefore, the aim of this study was to investigate the ossa membri pelvini of the skeletal system and to compare them with other rodents in order to contribute to current knowledge in this field. Materials and Methods A total of 20 (10 males and 10 females) apparently healthy adult chinchillas (Chinchilla lanigera) aged 2.5 3 years obtained from the Centre for Experimental Medicine, Research and Application, Afyon Kocatepe University, Turkey were included in the study. The live body mass of males and females varied from 550 g to 600 g and 450 g to 500 g, respectively. Animals were euthanized by the methods of Flecknell et al. (1980) and Poore et al. (1997) and X-ray of pelvic girdle and limb (D/V position at 57 kV, 3.20 mAs, 4.92 ms) was taken as soon as possible (Philips CR). Then, pelvic girdle and hind limb was separated from carcases. For maceration, materials were bathed in % 3 potassium hydroxide (KOH, Merck) at 40 °C for 2 days. Later, debris was removed under running tap water. Bones, completely free from smell and fatty tissues, were kept in 10% H2O2 solution for 24 h, then washed under running water and dried at room temperature (Tasbas and Tecirlioglu 1965). Bones were measured by a digital compass. For statistical analysis, independent sample test was applied. Significance level was set at p < 0.05. The photographs were taken using a digital camera (Sony DSC F-717) and drawings of bones were achieved using computer software (Photoshop). For terminology, Nomina Anatomica Veterinaria, the 5th ed. (2005) was considered.