Ultrasonic imaging and sonographic digital analysis of the heart, liver, stomach, kidneys and urinary bladder in Philippine tarsiers (Tarsius syrichta Linn.)

The Philippine tarsier (Tarsius syrichta Linn.) possesses various distinctive characteristics and habitats that make it an ideal subject of both scientific research and popular curiosity. At present, there is little available scientific data on the anatomy and physiology of this endangered species. The purpose of this study was to describe the ultrasonographic features and determine the echogenicity of the heart, liver, stomach, kidneys and urinary bladder according to sex, age and source of Philippine tarsiers. The examination was done using a veterinary ultrasound machine equipped with a 7.5 MHz linear-array scanner. Eight apparently healthy Philippine tarsiers, 4 males and 4 females with 2 juvenile and 2 adults for each sex, were examined. Three tarsiers were caught from the wild while 5 tarsiers were captive-bred. After examination, the ultrasonograms obtained were analyzed and digital analysis was conducted to obtain echo mean values to compare the echogenicity of the different organs. The heart appeared as an anechoic, rapidly contracting ovoid structure. Wild tarsiers had higher heart rate than captive-bred tarsiers. Adults and wild tarsiers had larger heart size than corresponding juvenile and captive bred tarsiers. Histogram analysis of the heart chamber showed that female and wild tarsiers had higher echo mean values than male and captive-bred tarsiers, respectively. The liver appeared homogenously hypoechoic with some anechoic areas. Hepatic dimensions showed larger size in adults, females and wild tarsiers compared to juveniles, females and captive-bred tarsiers, respectively. The liver parenchyma of the adult tarsiers, female tarsiers and wild tarsiers had higher echo mean values than juvenile tarsiers, male tarsiers and captive-bred tarsiers, respectively. The stomach had anechoic lumen with hyperochoic wall. The size of the stomach was related to the age of the tarsier, adults having larger dimensions than the juveniles. Higher echo mean values of the stomach were observed among adults, females and wild tarsiers compared to juveniles, females and captive-bred tarsiers, respectively. The kidneys appeared as a bean-shaped with anechoic renal medulla, hypoechoic renal cortex, hyperechoic renal pelvis and a thin hyperechoic renal capsule. The dimensions of the kidneys showed larger size in adults, females and wild trasiers compared to juveniles, males and captive-bred tarsiers, respectively. The echoegenicity of the renal structures showed that the renal pelvis had the highest echo mean values, followed by the renal cortex and renal medulla. In all eight tarsiers, histogram analysis showed that the liver was less echogenic than the kidney. The urinary bladder had anechoic lumen with defined hypoechoic walls. The dimensions of the urinary bladder showed a larger size among adults, females and wild tarsiers compared to juveniles, males and captive-bred tarsiers, respectively. Comparison of the echo mean values showed that the urinary bladder lumen of juveniles, females and wild tarsiers were more echoegenic than adults, males and captive-bred, respectively. The results of the study could be used as baseline data for the ultrasound features of the heart and different abdominal organs, which could be used for diagnosis of diseases and disorders of these organs in Philippine tarsiers.