A better understanding of semen characteristics and resilience to freezing temperatures is necessary before developing assisted reproductive techniques and systematic biobanking for the Sunda clouded leopard. The objective of this study was to evaluate for the first time the semen and sperm quality (in fresh and frozen samples) of two captive Sunda clouded leopards in Malaysia. A total of 17 examinations of the reproductive tract (using ultrasonography) and electro-ejaculations were performed on the two leopards over a 2-year period. Samples obtained from Leopard 1 (8 years old) varied in terms of volume (402 ± 92 µL), pH (7.9 ± 0.9), sperm motility (54.5 ± 24.2%), sperm concentration (122.4 ± 84.7 × 10⁶ sperm/mL), normal morphology (23.9 ± 12.3%), and viability (55.2 ± 18.2%). Midpiece defects represented the most common structural abnormality followed by abnormal tail and head defects. Samples from Leopard 2 (11 year old with abnormal testicular tissue) were of lesser quality. Two frozen semen samples from Leopard 1 were thawed and examined for acrosome integrity. Post-thawed samples contained <10% of motile spermatozoa but almost 50% of abnormal acrosomes. The present results emphasized the high incidence of structurally-abnormal spermatozoa, similar to the mainland clouded leopard. Post-thaw evaluations showed that the few surviving spermatozoa could potentially be used for in vitro fertilization or sperm injection. However, more individuals must be studied to validate those first findings that are exciting but still preliminary.

In this study, we provide a comprehensive genomic analysis of population structure, genetic diversity, and load across the four Asian elephant (Elephas maximus) subspecies using whole-genome sequencing data of 81 wild-born individuals, with most of them currently living under human care. Our results reveal striking contrast in inbreeding: the Bornean subspecies (E.m. borneensis) exhibits the highest level of inbreeding, with ∼65% of its genome in runs of homozygosity (ROH), and the lowest genome-wide heterozygosity (∼46 heterozygous sites per 100 kb). The Sumatran subspecies (E.m. sumatranus) shows intermediate levels of inbreeding (35% ROH) and heterozygosity (∼101 sites per 100 kb), while the mainland and Sri Lankan subspecies (E.m indicus and E.m. maximus) display similarly low inbreeding (∼10% to 11% ROH) and high heterozygosity (∼130 to 134 sites per 100 kb). Notably, when correcting for ROH coverage, heterozygosity levels are comparable across all four subspecies (∼136 to 155 sites per 100 kb), indicating that differences in genetic diversity are primarily driven by loss of heterozygosity within ROHs due to inbreeding. Genetic load remains relatively low in all subspecies, especially in highly conserved genomic regions. The high genetic diversity observed in the island-dwelling E.m. maximus subspecies likely reflects historical gene flow linked to intensive human-mediated elephant trade, raising questions about its taxonomic status. Given its high inbreeding, E.m. borneensis represents the highest conservation priority, with genetic rescue as a potential management strategy. This study highlights the urgent need for focused conservation efforts and further genomic research to safeguard the unique genetic diversity and long-term viability of Asian elephants.

Elephant Endotheliotropic Herpesvirus (EEHV) is a leading cause of fatal hemorrhagic disease in juvenile Asian elephants and represents a significant concern for elephant conservation. However, information on the epidemiology of EEHV in Bornean elephants (Elephas maximus borneensis) remains limited. This study investigated the prevalence and subtype distribution of EEHV in wild and captive Bornean elephants in Sabah, Malaysia, using samples collected during conservation management activities including rescue operations, translocation, GPS collaring, necropsies and routine veterinary examinations between 2009 and 2026. A total of 240 samples, comprising 100 whole-blood and 140 tissue samples from 110 elephants, were analyzed by conventional polymerase chain reaction (cPCR) targeting EEHV1 and EEHV4. EEHV DNA was detected in 6.4% (7/110) of elephants. Most positive cases were identified post-mortem, indicating a possible association of EEHV infection with mortality. EEHV1 was the only subtype detected, and sequence analysis showed close similarity to previously reported EEHV1A cases from Sabah. No EEHV4 was detected. Although no significant associations were observed between EEHV detection and population type, age group, sex, or sampling location, the detection of EEHV in both wild and captive elephants indicates that the virus is circulating in this endangered population. These findings provide baseline epidemiological data and support the need for continued surveillance and strengthened diagnostic capacity to inform EEHV management and conservation strategies in Sabah.