Decode the Lactate Dehydrogenase Isoenzyme Profiles in Ten Stranded Cetaceans
From 2002 to 2004, there were 140 stranding events along the Taiwan coast and 36% were live-stranded. To get more comprehension of the meaning of lactate dehydrogenase (LDH) isoenzymes in cetaceans, in this study, we compare the LDH profiles of ten stranded cetaceans. The ten cases included one Globicephala macrorhynchus, one Pseudorca crassidens, one Tursiops aduncus, one Tursiops truncatus, two Stenella attenuate, and four Steno bredanensis (2 calves, 5 juveniles and 3 adults; 6 males and 4 females). Physical evaluation, complete blood examination, blowhole, gastric fluid and feces sampling were performed altogether. Separating LDH isoenzymes by electrophoresis in ten animals was all done by the same laboratory (Union Clinical Laboratory, Taipei, Taiwan). Necropsy was carried out in all carcasses. The brief descriptions of these cases were listed below:
Case 1 (IL02-3): A juvenile male Steno bredanensis, 200 cm and 91 kg, was found live stranded and released after 68-day rehabilitation. The dolphin was unable to swim on its own in the first week. Anemia, dehydration, malnutrition, evidence of severe gastrointestinal infection and gastric ulcer, pulmonary edema, bronchitis and/or pneumonia were noted. A deep wound bite of right abdomen by cookie-cutter shark was found and drained.
Case 2 (TN03-8): A juvenile female Globicephala macrorhynchus, 335 cm and 400 kg, was beached alive and died after 24-day rehabilitation. The major sign was the severe respiratory problem with red, sandy discharge gushed from the blowhole. WBC was normal. Dehydration, malnutrition with hypoalbuminemia, elevated hepatic index, and unbalanced electrolytes were noted. Under necropsy, parasitic obstruction of bile duct was reported.
Case 3 (TP03-5): A juvenile female Stenella attenuata, 208 cm and 80 kg, was found live stranded and released by local government at the same day. Clinical findings included severe dehydration, malnutrition, eosinopenia, lymphopenia, declined serum protein, hypoglobulinemia, and serum iron, elevation of AST, ALT, and conjugated bilirubin, hypernatremia, and hyperchloremia.
Case 4 (ML03-1): A juvenile male Stenella attenuata, 198 cm and 50 kg, was found live stranded. Unbalance, malnutrition and weakness were observed and died after 5-day rehabilitation. Blood work revealed mild lymphopenia and monocytopenia, declined serum protein, globulin and triglyceride, elevated indirect bilirubin and serum iron, and unbalanced electrolytes. Necropsy revealed pulmonary edema, multifocal pulmonary necrosis of the apical side and a large, white abscess at the right lung near the diaphragm. Large amount of foreign body, ulceration and Anisakis sp. were found in the first and second stomachs.
Case 5 (KL03-3): A juvenile male Steno bredanensis, 170cm and 60 kg, was beached alive and released after 38-day rehabilitation. He was found restranded alive and unbalanced on the next day of release. Mild neutrophilia, dehydration, malnutrition, unbalanced electrolytes, elevated AST and ALT and declined globulin were noted.
Case 6 (TY03-2): A calf female Pseudorca crassidens, 212cm and 300kg, was found live stranded and died after 11-day rehabilitation. Exam demonstrated lymphocytosis, monocytosis, neutropenia, anemia, dehydration, malnutrition, unbalanced electrolytes, and elevated hepatic index. Necropsy revealed acute pneumonia.
Case 7 (TP04-1): Three Steno bredanensis was found swimming into Tanshui River. Two dolphins were captured and released after 24-day observation. One of the two dolphins was an adult male, 220 cm and 80 kg estimated. Mild neutrophilia and unbalanced electrolytes were noted.
Case 8 (TP04-2): Three Steno bredanensis was found swimming into Tanshui River. Two dolphins were captured and released after 24-day observation. The individual accompanied case 7 was an adult female, 220 cm and 80 kg estimated. Neutrophilia, elevated platelets and AST, low serum protein, and unbalanced electrolytes were noted.
Case 9 (HC04-1): A calf male Tursiops aduncus, 210 cm and 80 kg, was beached alive and died after 6-day rehabilitation. Lymphopenia, severe dehydration, malnutrition, and declined serum calcium and iron were noted. Severe, diffuse pneumonia and mild swelling of mesenteric lymph nodes were reported under necropsy.
Case 10 (PE04-1): An adult female Tursiops truncatus, 252 cm and 220 kg, was found live stranded and died 15 hours later. A deeply injured wound of dolphin's fluke was noted. Blood examination indicated monocytosis, eosinopenia, significantly elevated AST and ALT, elevated direct bilirubin, severe malnutrition, and unbalanced electrolytes. There was very little evidence that the dolphin had eaten before stranding.
In many species of mammals, the enzyme LDH is found in the cells of almost all body tissues. The elevated serum LDH level is revealed cell injury in tissues containing LDH, including heart, red blood cells, lungs, kidneys, muscles, brain, and livers. In the ten studied cetaceans, all the serum level of total LDH significantly surpasses the upper limit of normal ranges* (Figure 1). Thus we further analyze the five LDH isoenzymes (labeled LDH-1 through LDH-5) for the ten stranded Delphinidae and compare them with classic patterns of elevated LDH isoenzymes in certain diseases of human beings.
Generally, LDH-1 is found mainly in the heart; LDH-2 is primarily associated with reticuloendothelial system. In human beings, levels of LDH-2 are usually higher than those of the other isoenzymes. And an LDH-1 level higher than that of LDH-2 is indicative of a heart attack or injury. In the ten cases, all the LDH-1/LDH-2 ratios were normal. LDH-3 is found in the lungs and certain tumors; elevations of LDH-2 and LDH-3 indicate lung injury and/or disease. Among five isoenzymes in the ten stranded cetaceans, the LDH-3 level is the highest or second. Comparing with the records of physical, laboratory, and pathologic examination, pneumonia and/or other pulmonary diseases were dominated in ten stranded animals. Elevations of LDH-4 and LDH-5 indicate muscle and/or liver disease. Many cases had elevations of hepatic values, serum bilirubin, and CK, but only two dolphins (case 3 and 10) had significant rises in LDH-4 and LDH-5 which demonstrated both muscle and liver injuries. However, in the other eight cases with suspected hepatopathy, the LDH-4 and LDH-5 did not go correspondently with the results of biochemistry (Figure 2). On the other hand, the rises of all LDH isoenzymes at the same time (the levels of total LDH were 18150 U/L in case 3 and 6402 U/L in case10) indicated injury to multiple organs. In this situation, it was difficult to do differential diagnosis. In case 5, all the examinations were obtained after restranding. The levels of his isoenzymes expressed as percent of total LDH (621 U/L) were 17.8%, 31.2%, 35.3%, 13.0%, and 2.8% (from LDH-1 to LDH-5). Comparing with the normal profiles in human, the isoenzyme profile in case 5 was close to normal for stranded cetaceans with elevation of LDH-3. By analyzing LDH isoenzymes with complete blood profiles, the LDH isoenzymes may provide diagnostic values for the early phase of rehabilitation. The normal baseline of LDH isoenzymes for cetaceans is needed more data accumulation and further experiments to verify.
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Figure 1. Peak serum LDH level for ten stranded Delphinidae in three groups. horizontal lines denote the upper limits of normal range (538 U/L for group SaSbT, 505 U/L for group Gm, and 370 U/L for group Pc). SaSbT = Stenella attenuata, Steno bredanensis, and Tursiops sp.; Gm = Globicephala macrorhynchus; Pc = Pseudorca crassidens.
Figure 2. Peak serum LDH isoenzyme level for eight stranded Delphindae (excluded case 3 and 10). Numbers 1 to 5 represent LDH isoenzymes 1 to 5.
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