From 1994 to 2002, 39 strandings (44 individuals) of Kogia sp. were recorded along the Taiwan coast. In this study, eight carcasses of stranded Kogia sp., including seven K. sima and one K. breviceps (six live-stranded and two dead-stranded; two calves, two juveniles and four adults), collected from 1998 to 2002 were examined. We collected blood, blowhole, and feces samples in rehabilitated cases. Detailed measurements and examinations were made in all carcasses, and skeletal elements were gathered. We collected samples for molecular biology, contaminant analyses, pathology, microbiology, and stomach contents. The pathologic records are as follows:
Case 1 (KH98-5): A male Kogia sima calf, 121.5cm and 25kg, was found live stranded and died after a 20-day rehabilitation. We observed lung consolidation, and pulmonary congestion, edema, and aspiratory pneumonia were noted in pathological examination.
Case 2 (IL00-2): A juvenile male Kogia sima, 160cm in length, was found live stranded and died after six days of rehabilitation. Blood-like ascites, rectum flatulence, kidney hemorrhage and pulmonary congestion were observed.
Case 3 (ML00-4): A female Kogia breviseps calf, 143cm in length, was beached alive and died the next day. Gross findings included blood-like pericardial fluid, lung reddening, widespread nodules on left lung surface, stomach ulceration and yellowish liver. Hemopericardium, multifocal pulmonary necrosis, fatty liver and pulmonary congestion were recorded in the pathological report.
Case 4 (TN00-3): An adult female Kogia sima, 220cm in length, was found live stranded and died after a five-day rehabilitation. We noted nematode infestation in the stomach, flatulence, lung emphysema, a 5cm fetus in the left uterine horn, and a corpus luteum on the left ovary with no corpus albicans. The pathological record included heavy Anisakis sp. infestation of the stomach and mild gastritis.
Case 5 (TP02-11): A male adult Kogia sima, 245cm in length, was found dead stranded. The necropsy revealed several round wounds near the genital cleft, parasitic infestations of the stomach, frontal sinus and blubber, stomach ulceration, lung consolidation and thoracic subdural hemorrhage. We recorded Anisakis sp. and trematode infestations of the stomach, Crassicauda sp. infestation of frontal sinus, Cysticercus sp. infestation in blubber, myocardiac lysis, basophilic inclusion of cerebrum, mild calcification and RBC infiltration of spinal dura mater, pulmonary edema, fatty liver, pulmonary, renal and hepatic congestion on the pathologic examination.
Case 6 (TP02-12): A male adult Kogia sima, 215.5cm in length, was found live stranded and died on the beach. The necropsy revealed parasitic infestation of GI tract and blubber, lung consolidation, stomach ulceration, and diffuse cerebral hemorrhagic lesion. We observed Anisakis sp. and trematode infestations of the stomach, stomach ulceration, renal, hepatic and CNS congestion, pulmonary edema, dura mater hemorrhage of the cerebrum, Cysticercus sp infestation of blubber and fatty liver were observed in pathologic examination.
Case 7 (TY02-4): A male adult Kogia sima, 222cm and 147.8kg, was found freshly dead on the beach. Gross findings included parasitic infestation of the stomach, stomach ulceration, lung consolidation and cerebral hemorrhagic lesion. Cysticercus spp. infestation of blubber, Anisakis spp. and trematode infestation of stomach, myocardiac lysis, pulmonary, hepatic and CNS congestion, stomach ulceration, pulmonary edema, interstitial pneumonia, fatty liver, cerebrum and cerebellum hemorrhages were recorded on pathologic examination.
Case 8 (KH01-1): A juvenile male Kogia sima, estimated 180cm in length, was found beached alive and died after a five-day rehabilitation. On necropsy, we found that the heart was rounded with an extremely distended right side, 500c.c clear-colored liquid in the abdominal cavity, nutmeg liver, parasitic infestation of the stomach, stomach flatulence and ulceration, and widespread nodules on the lung surface and the colon had a brownish pseudomembrane covering. On microscopic examination, we found myocardiac lysis, pulmonary and hepatic congestion, multifocal caseous necrosis and edema in the lung, fibrinous-hemorrhagic colitis, penis arteriosclerosis, and central lobular necrosis of liver.
Three of four adults, one of two juveniles and one of two calves Kogia sp. in the study were all characterized by cardiomyopathy. The microscopic examination revealed myocardiac lysis and degeneration with unknown causes in these whales. Cetaceans, in particular the highly sensitive Kogia, when under stress from disease, trauma, and/or stranding may release excess catecholamines into the circulation, which produce myocardial necrosis. This endogenous myocardial injury may contribute to the high mortality rate of stranded cetaceans. Heighten levels of serum glucose, ALT, AST, LDH, and creatinine in the six above-mentioned live-stranded whales indicated the initial stages of catecholamine-induced myocardial necrosis. The significantly increased levels of CPK and AST in the serum and the complications noted in cases three and eight were caused by subsequent extensive myocardial necrosis and hemorrhage throughout the epicardium and myocardium. Animals that suffer from cardiomyopathy usually have some complications, including central lobular necrosis of the liver, pulmonary and hepatic congestion, pulmonary edema, ascites, and excessive vasoconstriction, as was observed in case three, five, six, seven, and eight. The heart rupture in case three, a calf, may reveal a congenital disease, though the cause is still pending. There was no predilection for the cardiomyopathy according to sex. The electrocardiogram was useful in diagnosing cardiac diseases in all live-stranded Kogia. Early treatment with appropriate drugs to block the stimulatory effects of catecholamines, reduce cardiac work, improve oxygen supply to myocardial cells, counteract ionic shifts and lessen stress levels may reduce the severity of myocardial necrosis in stranded Kogia. Potential treatment, such as several types of diuretics, vasodilators and positive inotropic agents in stranded Kogia should be investigated to improve the rehabilitation success rate of these animals.
Pulmonary diseases were noted in all cases. Pulmonary congestion and edema were the most common findings and may be caused by cardiac failure and/or inhalation of seawater. Interstitial pneumonia and multifocal pulmonary necrosis might be produced by pathogen infection.
Crassicauda sp. was only found in the frontal sinus of case five. Five of eight cases had nematode Anisakis sp. in their first and second stomachs. Undetermined trematodes were found in the pyloric stomachs of three of the eight cases. Three cases harbored Phyllobothrium sp. in their blubber. Crassicauda sp. infestation in the frontal sinus may induce tympanic cavity and VIII cranial nerve degeneration. Anisakis sp. infestation was confirmed as one of the causes of GI tract ulceration. No clinical signs or pathological changes were found in Phyllobothrium sp. infestation cases.
In case five, we noted extracellular round basophilic inclusions with estimated 30µm in diameter in cerebrum. This situation was never seen before in other cetaceans, except in a finless porpoise (Neophocaena phocaenoides) and a Risso's dolphin (Grampus griseus) stranded in Taiwan. This case suggests neuronal storage disease and needs further study.