Comparative Radiographic Mapping of the Skeletal System of Male and Female Savannah Monitor Lizard (Veranus Exanthematicus)

Abstract

The aim of this study is to establish the radiographic mapping of the skeletal system of the male and female Savannah Monitor lizards  since there is a dearth of information on them. Radiographs of various parts of the skeletal system of a male and female monitor lizards  were taken and their measured anatomic parts were compared. The Lizards were hand-captured and anesthetized with atropine sulfate  (0.02 mg/kg), chlorpromazine (10mg/kg), and ketamine (15 mg/kg) for restaint and positioning for x-ray exposures. Using a portable X- ray machine, radiographs were obtained with the following exposure settings: for the body, KVP = 75, MA = 50, and mAs = 10; for the tail,  KVP = 70, MA = 50, and mAs = 10. With the lizards on sternal recumbency, the radiographs of head to caudal abdomen including the limbs  and tail were obtained. The number of vertebral bones, snout-totail length, vertebral length, horizontal and vertical rib lengths, and  appendage lengths were obtained and images analyzed. The male lizard weighed 1.4 kg with a body length of 102 cm, while the female weighed 1.7 kg and had a body length of 105 cm. Comparison of the skeletal measurements revealed that both lizards had similar  dimensions in terms of snout-to-tail length and the number of cervical, thoracic, and lumbar vertebrae. However, the female had more  coccygeal vertebrae (45) compared to the male (43). Additionally, the female had longer horizontal ribs (6 cm vs. 4 cm) and vertical ribs (3 cm vs. 2 cm) compared to the male. In conclusion, the female monitor lizard exhibited greater body length, body weight, and rib  dimensions, likely due to being older than the male as there is very little difference in rate of growth of both sexes when young.