Decompression sickness, a condition in whales caused by bubble formation in certain body tissues from dissolved inert gases. It occurs during transition from a high pressure environment to one of lower pressure, resulting in a range of conditions from itching to joint pain, convulsions, and death. A carcass of a stranded Sei Whale, Balaenoptera borealis, found on the shores of southern coast of Peninsular Malaysia was presentedfor postmortem. Investigation results showed that the male Sei Whale, named Si Corner showed pathologic lesions as seen from histology with the formation of fibrosis, emphysema and edema in the lungs and hepatic atrophy which indicated chronic starvation. It believedthat he also suffering from “Barotrauma or decompression sickness” which affected the ear or lungs which lead to unbalanced movement due to changes in air pressure.This may have caused the whale to beach and consequent mortality. The pathologic lesions found give an insight into possible causes of death of beached whales inMalaysia.

The major causes of the decline of the Dugong population along the urban coast of Mersing, Johor includes gill netting, subsistence hunting, habitat loss from extreme weather events that are likely to be exacerbated by climate change, humansettlement, breach of the bots and sea water pollution. In March 2017, a male Dugong dugon, estimated age of 10 to 20 years, wasincidentally found dead near Pulau Tinggi, Mersing, Johor by a fisherman. The entire body was found to have old and new scarsat the anterior part of the abdomen. The right eye was protruded out and bleeding which indicated that the eye was piercedby a sharp object. Necropsy revealed the upper small intestine and the stomach compartments were semi-impacted with a massive helminth burden (more than 1,000 nematodes). Paradujardinia halicoris worms were identified based on morphological characteristics. Zoonotic fungus named Madurella mycetomi were isolated from heart and lung after incubation for 14 days.Histologically, the lung was confirmed to have the presence of big mast cells which formed capsules, indicating presence offungal spores causing systemic mycoses where the macrophages invade and engulf the spores. The shrinkage of myocardium myocyte and myocardium necrosis with mild vasculitis indicates heart failure. Groucott’s stain confirmed Madurella mycetomi infection that induced systemic pulmonary and myocardium mycosis in Dugong dugon.