Scientific Papers

Peer Reviewed Papers
Ian H. Mendenhall, Dolyce Low, Erica Sena Neves, Ali Anwar, Serena Oh, Yvonne C.F. Su, Gavin J.D. Smith


Cross-species transmission can often lead to deleterious effects in incidental hosts. Parvoviruses have a wide host range and primarily infect members of the order Carnivora. Here we describe juvenile common palm civet cats (Paradoxurus musangus) that were brought to the Singapore zoo and fell ill while quarantined. The tissues of two individual civets that died tested PCR-positive for parvovirus infection.
Phylogenetic analysis revealed this parvovirus strain falls in a basal position to a clade of CPV that have infected dogs in China and Uruguay, suggesting cross-species transmission from domestic to wild animals. Our analysis further identified these viruses as genotype CPV-2a that is enzootic in carnivores.
The ubiquity of virus infection in multiple tissues suggests this virus is pathogenic to civet cats. Here we document the cross-species transmission from domestic dogs and cats to wild civet populations, highlighting the vulnerability of wildlife to infectious agents in companion animals.
Ali Anwar Ahmad, Praveena Jayarajah, Gwen Wong Yee Han, Serena Jocelyn Oh Wai Yin, Abdullah Rasedee


Currently, there are no complete parameters established for serum biochemistry andhematology for the determination of health status of rescued common palm civets (Paradoxurushermaphroditus).
In this study, blood samples were obtained from 18 adults and 15 juvenilecivets caught on Singapore Main Island. Significant age-related differences (P<0.05) were notedin the hemoglobin, erythrocyte count, packed cell volume (PCV), total serum protein andglobulin concentration in the adult civets showing higher values compared with the juvenilecivets.
The mean corpuscular volume (MCV), the alkaline phosphatase (ALP) and the phosphorusconcentrations were significantly higher (P<0.05) in juveniles compared with adult civets.
Chia-Da Hsu, Yaoprapa Mathura


In January 2016, a 20-year-old female oriental small-clawed otter (Aonyx cinereus) from Night Safari in Singapore was euthanized and diagnosed with a thyroid gland carcinoma. Postmortem examination and histology also revealed metastasis to the regional lymph nodes andsevere visceral pentastomiasis.
Grossly, the lymph nodes were infested, and encapsulation wasobserved on the visceral serosal surface. Histopathologically, the lymph nodes were encysted bya thick fibrous connective capsule with minimal inflammatory response. Pentastomiasis has beenpreviously reported in the smooth coated otter (Lutrogale perspicillata) in Malaysia.
This report is the first case of severe visceral pentastomiasis in an oriental small-clawed otter with functionalthyroid carcinoma.
Ali Anwar Ahmad, Sofeah Samsuddin, Serena Jocelyn Wai Yin Oh, Pedro Martinez-Perez, Abdullah Rasedee


The Sunda pangolin (Manis javanica) population in Southeast Asia faces threats such as poaching and deforestation. Health assessments of rescued individuals including physical examination and blood work are crucial for clinicians to determine the health status of these animals.
The establishments of reference intervals of hematology and serum biochemistry are important for identifying clinical abnormalities. The objectives of our study were to establish blood reference intervals for Sunda pangolins, to determine if there are age and sex related differences in hematology and serum biochemistry, and to compare our results with those of aprevious study on confiscated Sunda pangolins in Thailand.
Fifty-eight Sunda pangolins were rescued between January 2011 and December 2015. The hematology and serum biochemistry results of 51 clinically normal Sunda pangolins were selected for the establishment of the blood reference intervals. No sex related differences were noted in this study. Age-related differences were observed, in which adult Sunda pangolins had a significantly higher mean corpuscularvolume than juveniles, and juvenile Sunda pangolins had significantly higher red blood cell counts and hemoglobin levels than those of the adults (P<0.05).
Age-related differences were also noted in several serum biochemistry parameters: alkaline phosphatase (ALP) was significantly higher in juveniles, and total protein was significantly higher in adult Sunda pangolins. Compared to a previous study the white blood cell counts, neutrophil counts, and ALP were higher, and the lymphocyte counts were lower in the present study.
Ali Anwar Ahmad, Shangari Sekar, Pei Yee Oh, Sofeah Samsuddin


The Sunda pangolin (Manis javanica) faces threat of extinction due to illegaltrafficking of its scales for the purpose of traditional medicine in the Asian region. Ex-situ captive breeding and reintroduction programs have been identified to be a key effort in the conservationof the species. The establishment of blood parameters for captive Sunda pangolins are vital toassess the health in these animals during health assessments.
The objective of this study is to establish blood parameters for captive Sunda pangolins and compare the blood parameters withthe established blood reference ranges for rescued wild Sunda pangolins in Singapore. Bloodparameters for hematology and serum biochemistry were established from 13 clinically normalcaptive Sunda pangolins.
Male captive Sunda pangolins were found to have significantly (P<0.05) higher potassium compared to the female captive Sunda pangolins. Captive Sunda pangolins were found to have significantly (P<0.05) lower white blood cell count (WBC), neutrophil counts, alaninephosphatase (ALP) and phosphorus and significantly (P<0.05) higher PCV, TP, globulin and bloodurea nitrogen (BUN) when compared with rescued wild Sunda pangolins from the previous study.
Ali Anwar Ahmad, Norsham Abd Wahab, Clara Wenjing Yeo, Serena Jocelyn Wai Yin Oh, Hui Cheng Chen


Forty rescued common palm civets were anesthetized. Twenty animals received intramuscular injections of alfaxalone 5 mg/kg and medetomidine 0.05 mg/kg (A-M group),whereas twenty animals received 5 mg/kg of tiletamine and zolazepam (T-Z group). The A-M group was reversed with atipamazole 0.25 mg/kg.
There were no significant differences in the time from anesthetic injection to induction and intubation between the A-M and T-Z groups. The time from the injection of reversal in the A-M group and the time from cessation of isoflurane in the T-Z group to extubation, first response to recovery and ambulation were longer (P<0.05) in the T-Zgroup.
The T-Z group recorded lower (P<0.05) rectal temperatures compared to the A-M group. This study showed that both drug combinations can be used effectively for the immobilizationof civets. The A-M combination provided better anesthetic depth, but with higher incidence ofbradycardia and hypoxemia. The recovery time was reduced significantly as atipamezole was used as a reversal agent in the A-M combination.
Yirui Heng, Charlene Yen-Feng Yeong, Shin Min Chong, Abraham Mathew


Three eastern bongos (Tragelaphus eurycerus isaaci) presented acutely withhemorrhagic diarrhea at the Singapore Zoo, thought to be caused by a mouldy batch of hay. Repeated fecal tests were negative of parasites and common gastrointestinal bacteria includingsalmonella and campylobacter.
The diarrhea resolved for all individuals after a week of leafonlydiet. However, 2 individuals developed signs of colic. Both animals were anesthetized for examination including blood tests and imaging studies. The findings were consistent of gastrointestinal ileus and a possible impaction.
With intensive treatment involving repeated sedations for fluid therapy administration and treatments for gastrointestinal impaction, one individual eventually made a full recovery, but the other individual died due to septic peritonitis secondary to a rupture in the spiral colon. Persistent supportive therapy may be vital in treating severe gastrointestinal disease in this species.
Shin Min Chong, Pei Yee Oh, Delia Chua, Shangari D/O Sekar, Chia-Da Hsu


Two free-ranging female Sunda colugos (Sunda flying lemur; Galeopterus variegates) were found dead in Singapore in November 2018 and February 2019.

Septicemia and mastitis werediagnosed in both animals on postmortem examination.Infectious diseases have not previouslybeen established as a cause of death in wild Sundacolugos.

Mark Rusli


Several species of hornbills are known to develop dorsal air sacs after hatching, which present as a pocket of air undertheir skin. These increase in size as the chicks grow, and gradually disappear as the chicks develop feathers. However, this feature is not well-described, nor do we know the extent it occurs in Bucerotids.

Here, it is reported in a clutch of hand-reared Von der Decken’s hornbills (Tockus deckeni) (n = 5) at Jurong Bird Park, Singapore. Air sacs were not presentat hatch, but developed within 24 h, increasing in size until about 10 days of age. They gradually recede from this age and are not always inflated, disappearing at about 16 days of age when the chick has considerable feather growth.

The functions of this unique feature are largely unclear, but it is thought to be mostly related to thermoregulation. Further research is required to determine this, possibly using captive specimens from zoological institutions as it is more difficult to collect data from wild birds.

John Sha Chih Mun, Beverly Xue Yi Ting, Jeslyn Ho Li Jun, Subash Chandran, Azmi Amzah, Serena Oh Wai Yin


Considerable variability in dietary and digestive strategies exists across primate taxa. The Singapore Zoo houses a diverse collection of primate species and their diets are formulated with consideration for their natural diets. We evaluated five species of primates with different diets managed by providing differen tproportions of fruits/vegetables and leaves to replicate their natural diet compositions.

We examinedthe typical proportion of foods provided and consumed by the different species, and compared the nutrients consumed from the respective food types provided. We found that the primates consumed proportions of the two food types provided consistent with the quantities provided.

However, allspecies consumed a higher proportion of fruits/vegetables to leaves than was provided. Species with more folivorous diets often consumed all fruits/vegetables provided to them, but species with more frugivorous diets did not, and supplemented their diets with leaves. More folivorous species obtained the majority of their nutrition from the leaf component of their diet whereas more frugivorous primates obtained relatively equal proportions from both food types.

Nutrient selection in preferred food items was not strongly exhibited but the primates generally preferred food items with higher protein and non-structural carbohydrate (NSC) content; species with more folivorous diets preferred leaf items with higher protein–fibre ratio while the converse applied to species with more frugivorous diets. Dietary fibre consumption levels for all species were relatively high; and NSC consumption levels forspecies with more folivorous diets were close to the recommended upper limits for foregut fermenters.

Although current diets provided for these primate species are appropriate, adjustments should be made to refine the proportions and compositions of major food types provided to ensure nutritional goals are met while minimising food wastage. Diets for primates with different dietary specialisations should be customized whenever possible, within the constraints of practical captive management.

Shangzhe Xie, Todd J. McWhorter


It is currently unknown if current guidelines for collecting and interpreting blood corticosteronein flying birds can be extrapolated to penguins. It is also difficult to collect blood quickly without causing stress to a penguin. Therefore, immunoreactive fecal glucocorticoid metabolites (FGCMs) maybe the most practical and minimally invasive way of monitoring the stress levels of penguins.

This study investigated the reliability of FGCMs for monitoring stress levels in captive Humboldt Penguins (Spheniscus humboldti) at Jurong Bird Park, Singapore. Humboldt Penguin feces were randomly sampled and pooled from the exhibit for 2 months. The penguins were restrained and transported on three separate occasions to simulate stressful events. The feces were analyzed using an enzyme immunoassayto measure corticosterone levels.

There were significant increases lasting 3 to 7 days in the FGCM levels after a stressful event. This method was then used to test whether accelerometer vests used for behavior quantification caused stress responses in these birds. There was no significant difference in FGCMs between time periods with and without the accelerometer vests. The results indicated that FGCMs can be an accurate indication of capture-, restraint-, and transport-related stress in Humboldt Penguins, and that accelerometer vests do not appear to cause stress.

F. Cabana, J. B. Clayton, K. A. I. Nekaris, W. Wirdateti, D. Knights, H. Seedorf


Environment and diet are key factors which shape the microbiome of organisms. There is also adisparity between captive and wild animals of the same species, presumably because of the changein diet. Being able to reverse the microbiome to the wild type is thus particularly important for the reintroduction efforts of Critically Endangered animals.

The Javan slow loris (Nycticebus javanicus) isa suitable model, being kept in the thousands within rescue centres throughout Southeast Asia. Withnext-generation sequencing, we show how a naturalistic diet impacts the gut microbiome of captiveslow lorises (Primates: Nycticebus). A comparison of the microbiome of wild animals with captive animals that had been fed a standard captive or improved diet reveals strong microbiome differences between wild and captive animals; however, diet changes failed to alter the microbiome of captivepopulations significantly. Bifidobacterium was the most abundant genus in wild animals (46.7%) while Bacteroides (11.6%) and Prevotella (18.9%) were the most abundant in captive animals fed the captive and improved diets, respectively.

Correlation analyses of nutrients with microbial taxa suggest important implications in using nutrition to suppress potential pathogens, with soluble fibre and water soluble carbohydrates both being associated with opposing microbiome profiles. The improved diet significantly increased microbe diversity, which exemplifies the importance of high fibre diets; however, wild individuals had lower diversity, which contradicts recent studies.

Detection of methanogens appeared to be dependent on diet and whether the animals were living in captivity or in the wild. This study highlights the potential of nutrition in modulating the microbiome of animals prior to release. Unexpectedly, the results were not as significant as has been suggested in recent studies.

Nerrisa Chao, Thirzaa.C.Loffeld, Kate Mastro Daniel H.A.Willcox, Vicki Guthrie, Madhu Rao


South-east Asia is home to exceptional biodiversity, but threats to vertebrate species are disproportionately high in this region. The IUCN Species Survival Commission Asian Species Action Partnership aims to avert species extinctions.

Strengthening individual and organizational capacity is key to achieving long-term, sustainable conservation impact, and is a core strategic intervention for the Partnership. To look at the needs and opportunities for developing capacity for species conservation in South-east Asia, we undertook a needs assessment with organizations implementing species conservation within this region.

We conducted a review of available training opportunities, mapping them against a list of identified competences needed for species conservation to determine gaps in current training. Our assessments revealed an imbalance in the focus of training opportunities vs the actual competences needed for effective species conservation, and that training opportunities within South-east Asia are limited in number and highly competitive.

These findings corroborate other similar reviews, particularly on capacity gaps in the Global South. We discuss the implications of our review and use the findingsto generate recommendations.

Guillaume Douay, Rina Maguire, Francis Cabana, Melanie Berthet, Zi Teng Lim, Anna Meredith


This study assessed the detection of faecal biomarkers in captive callitrichids affected by Marmoset Wasting Syndrome (MWS), using a commercial coloured chromatographic immunoassay intended forthe detection of calprotectin and lactoferrin in humans affected by inflammatory intestinal diseases.

The test was applied to faecal samples from 77 animals of 11 callitrichid species. Animals were divided into two groups consisting of 23 animals affected by MWS and 54 apparently healthy animals. All samples tested negative for lactoferrin while 64.9 % tested positive for calprotectin. The commercial test exhibited a high sensitivity (95.6%) but a low specificity (48.1%) for calprotectin, indicating poor utility in detecting new cases of MWS in a given population.

A semi-quantitative assessment of thecommercial test revealed a statistically significant difference between affected and non affected animals for calprotectin (25.10/9.53, W=226, P=4.389e-05). Although the use of fecal biomarkers inthe context of wasting syndrome did not seem to be completely conclusive, it would be interesting to investigate further as some trends were noticed in this study.

Trisha Tay Ting Ni, Josephine Kawi, Li Desheng, Huang Yan


The breeding of giant pandas (ailuropoda melanoleuca) in captivity can be a challenge, especially if natural mating is unsuccessful and artificial insemination is the only way to achieve fertilisation.The best chance of successful artificial insemination is when the female is inseminated within 24 hours of ovulation, right after oestrogen levels peak and start declining during her oestrous period.

Hence, determining the exact point at which the female reaches her oestrous peak is crucial. Besides monitoring behavioural and physical changes in the female, urinary oestrogen is a common non invasive biomarker in determining the female’s oestrogen hormone profile. However, urine may be hard to collect in a naturalistic environment when the female is out on display.

Conditioning a female panda to urinate on cue allows for direct urine collection and hence accurate monitoring of oestrogen levels at a consistent rate while ensuring that the sample collected is fresh and clean. This has led to improvement of the oestrogen hormone profile over recent years, allowing for a more accurate determination of the female’s oestrous peak and a better grasp of timing for artificial insemination.

Francis Cabana, Praveena Jayarajah, Pei Yee Oh, Chia-Da Hsu


Feeding primates in zoological institutions is no simple task due to their varying nutritional requirements and complex social organisation. Daily feeding in a zoo enclosure of high quality food items, such as fruits, may encourage food-based dominance within a group, which leads to unequal division of energy and nutrients. This can affect their body condition (as a proxy for weight), with dominant animals tending to be over-conditioned and subordinate individuals under-conditioned.

This is particularly true with large troop primates, such as hamadryas baboons (papio hamadryas). The hamadryas baboon troop at Wildlife Reserves Singapore (WRS) exhibits food-based aggression and also suffers chronic parasite burdens. We aimed to lower the soluble carbohydrates and increase the fibre content of the diet of this troop to decrease food-based aggression with a view to reducing the large range of body conditions and high parasite burden evident within the WRS troop.

We collected 10 mixed-age freshfaecal samples from before and after the diet change and performed a quantitative analysis of worm burden of each sample. We recorded body condition (on a scale of 1 [emaciated] to 5 [obese]) and coat scores (1 [poor quality] to 5 [excellent quality]) for six male baboons and their harems, weekly for four weeks before and four weeks after the diet change.

The diet was changed from one mostly comprising fruit, rice and chicken to one comprising vegetables, pulses and browse. The average body condition of the troop was significantly reduced from 4.2 to 3.7 and the coat condition was significantly increased from 2.9 to 3.5. The average parasite count decreased from 1670 to 610; however, this was not significant. A low soluble carbohydrate and high fibre diet was conducive to healthier body conditions and coat conditions of a P. hamadryas troop, and may also have helped reduce the parasite burden.

Shangzhe Xie, Bohong Cai, Ellen Rasidi, Ching-Chiuan Yen, Chia-da Hsu, Wai Tung Chow, Virginie De Busscher, Li Chieh Hsu


The advent of new technologies in medical imaging and 3D printing in recent years has made customization of surgical tools and implants more accessible, revolutionizing many surgical fields. In many human diseases, these implants have led to superior surgical outcomes and greatly improved patients’ quality of life.

Thus, it is of great interest to apply these technologies to the treatment of animal diseases. In this study, we report the use of computed tomography (CT) and 3D printing for the treatment of a Great Hornbill at Jurong Bird Park that was diagnosed with squamous cell carcinoma of the casque.

A 3D printed prosthesis that perfectly fitted the subject was implanted to replace its resected casque. The subject exhibited natural eating behaviour with no post-operative complications. Using this case as an example, the positive outcomes suggest a great potential in applying these technologies to the treatment of other wildlife diseases.

Shangzhe Xie, Gabrina Shuang-Li Goh, Chia-Da Hsu


An African penguin (Spheniscus demersus) presented with a large peri-cloacalmass. The mass was diagnosed as a pyogranuloma histologically, with multifocal to coalescing inflammatory responses in the subcutis and keratinized simple stratified squamous epithelium overlying the surface.

The patient was prescribed 125 mg/kg oral clavulanic acid/amoxycillin twice a day and 20 mg/kg oral terbinafine once a day for 14 days, but there was no change in the size of the mass 4 days after therapy, so a decision was made to administer 1 mg/kg of intralesional methylprednisolone.

Fourteen days later, the mass resolved with no further recurrence. This case demonstrated that intralesional methylprednisolone used with antibiotic and antifungals was effective in resolving a peri-cloacal pyogranuloma and without any side effects.