Small-clawed Otter Research Articles

Assessment of Captive Environment for Oriental Small-Clawed Otters (Aonyx cinereus) in Otter Cafés in Japan.

This study investigates the captive environments of oriental small-clawed otter (OSO; Aonyx cinereus) cafés in Japan, aiming to identify discrepancies with established welfare guidelines. Improved management of these commercial facilities could raise awareness about the difficulties of keeping OSOs as pets and enhance their welfare. Utilizing the role of commercial facilities in public outreach, we consider that the rigorous implementation of proper care practices in these establishments could help mitigate the increasing demand for OSOs domestically and contribute to the conservation of the OSO. In this study, we focused on the critical aspects of the captive environment necessary to maintain the psychological well-being of OSOs and evaluated the captive environments of OSOs housed in animal cafés for OSO welfare using non-invasive methods. Based on zoo husbandry standards, it was found that there were deficiencies in aquatic environments and solitary housing conditions; however, the enrichment tools aligned with the guidelines. The results suggest that deviations from the recommended elements in the environment of OSOs in captivity are associated with a tendency of these OSOs to develop various diseases. It is deemed necessary to amend the regulations governing animal-handling businesses to include welfare criteria, and it is considered essential for each establishment to operate only after ensuring sufficient welfare for the OSOs.

Laterality Handedness When Completing a Tool-Use Task in Asian Small-Clawed Otters (Aonyx cinerea)

Laterality is defined as the occurrence of each cerebral hemisphere having asymmetric control over the different sides of the body, leading to preferences to use one side of the body over the other for various behaviors. Many types of laterality exist, but handedness is the form that is most predominantly assessed. Handedness in animals is of special interest to laterality researchers, as humans were once thought to be the only species that exhibited lateralized hand preferences. The aim of the current study was to determine if Asian small-clawed otters (Aonyx cinerea) exhibit significant paw preferences in behaviors associated with completing a specific tool-use task. Video data of the otters completing the task was analyzed for specific paw interactions with the tool-use apparatus, and the percentage of correct completion of the task was documented for each otter. Overall, no significant population level paw preference was present. However, individual differences in paw preference and differing trends in handedness on each focal behavior was present. The results showed that paw preference (or lack thereof) did affect the tool-use task completion for some otters, and for others, the preference did not seem to have an effect. The main implications of this study are that paw preferences in Asian small-clawed otters are present on an individual level when solving a novel tool-use task.

Laterality Handedness When Completing a Tool-Use Task in Asian Small-Clawed Otters (Aonyx cinerea)

Laterality is defined as the occurrence of each cerebral hemisphere having asymmetric control over the different sides of the body, leading to preferences to use one side of the body over the other for various behaviors. Many types of laterality exist, but handedness is the form that is most predominantly assessed. Handedness in animals is of special interest to laterality researchers, as humans were once thought to be the only species that exhibited lateralized hand preferences. The aim of the current study was to determine if Asian small-clawed otters (Aonyx cinerea) exhibit significant paw preferences in behaviors associated with completing a specific tool-use task. Video data of the otters completing the task was analyzed for specific paw interactions with the tool-use apparatus, and the percentage of correct completion of the task was documented for each otter. Overall, no significant population level paw preference was present. However, individual differences in paw preference and differing trends in handedness on each focal behavior was present. The results showed that paw preference (or lack thereof) did affect the tool-use task completion for some otters, and for others, the preference did not seem to have an effect. The main implications of this study are that paw preferences in Asian small-clawed otters are present on an individual level when solving a novel tool-use task.

Phylogenetics of Asian Small-Clawed Otters (Aonyx cinereus) in West Sumatra.

<b>Background and Objective:</b> The presence of Asian small-clawed otters (<i>Aonyx cinereus</i>) in West Sumatra has been reported from ecological data in the form of footprints and feces, while its genetic information has not been reported yet. This genetic information needs to be reported along with the determination of <i>A. cinereus</i> as a vulnerable species and is experiencing population decline by the International Union for Conservation of Nature (IUCN). This study aimed to determine the phylogenetic relationship of <i>A. cinereus</i> found in West Sumatra with other regions. <b>Materials and Methods:</b> The samples used were <i>A. cinereus</i> stool collected from several wetland locations in West Sumatra. <i>Aonyx cinereus</i> DNA was extracted from stool samples following the QIAamp Fast DNA Stool Mini Kit protocol (Qiagen). Amplification was performed using the CO1 gene. The IQTree was used to provide phylogenetic information on <i>A. cinereus</i> and MEGA 7 was used to determine the uncorrected genetic distance of <i>A. cinereus</i>. <b>Results:</b> <i>Aonyx cinereus</i> clustered to form three sub-clusters namely <i>A. cinereus</i> Sundaland, Laos lineage and unknown lineage. <i>Aonyx cinereus</i> Sundaland consists of <i>A. cinereus</i> West Sumatra and <i>A. cinereus</i> Sarawak, Malaysia which are closely related with a genetic distance of 0.68%. Moreover, compared to <i>A. cinereus</i> from unknown lineage (including Captive Copenhagen Zoo) and Laos lineage, <i>A. cinereus</i> of West Sumatra had a genetic distance of 0.68-1.20 and 4.18%, respectively. <b>Conclusion:</b> Wetland conversion and the role of humans have influenced the obstacle to connectivity among populations that cause genetic variation.

Unveiling the Diverse Mammalian Species of a Tropical Rainforest in Northeast Bangladesh

Tropical rainforest supports an incredible diversity of mammalian species. The forest patches of northeast Bangladesh are considered hotspots for a range of threatened mammals. However, the transboundary Lathitila reserve forest in Moulvibazar district of northeast Bangladesh remained largely unexplored. We assessed the diversity of medium- and small-sized mammals using camera-trapping, and distance sampling, which was supplemented by sign survey and interviews. We recorded a total of 38 species of mammals belonging to 9 orders and 22 families. The Carnivora (34%) contained the highest number of mammals followed by Rodentia (21%), Primates (18%), Chiroptera (10%), and Artiodactyla (5%). Thirty seven percent of the recorded species were rare, followed by very common (26%), occasional (24%) and common (13%). Of these, 45% were categorized as threatened in the updated national Red List of IUCN Bangladesh. The remarkable species that we recorded are the Critically Endangered Asian elephant (Elephas maximus), Western hoolock gibbon (Hoolock hoolock), Chinese pangolin (Manis pentadactyla), Phayre’s leaf monkey (Trachypithecus phayrei), Northern pig-tailed macaque (Macaca leonina), and Bengal slow loris (Nycticebus bengalensis). The Endangered Fishing cat (Prionailurus viverrinus), and Asian small-clawed otter (Aonyx cinerea) were also recorded. The principal threats to the Lathitila forest are the habitat degradation, habitat fragmentation, human disturbance, illegal wood extraction, and wildlife poaching. This study highlights the conservation importance of this least-known forest, thereby protection measures are urgently needed to conserve its diverse mammalian fauna. Bangladesh J. Zool. 51(2): 135-154, 2023

Recent record of Eurasian Otter Lutra lutra (Linnaeus, 1758) (Mammalia: Carnivora: Mustellidae) from Kerala part of the Western Ghats, India and an insight into the behaviour and habitat preferences

We report a recent record of the elusive Eurasian Otter Lutra lutra from Kerala, through a direct observation in the higher reaches of the Chinnar Wildlife Sanctuary within the Western Ghats, southern India. Field observation involved the sighting of two Eurasian Otters in a rocky-torrential stream in March 2020. The otters displayed a hyperactive foraging behaviour, searching among submerged rocks and crevices, followed by occasional dives. They seemed particularly interested in areas where water rushed with force, avoiding locations with low water flow or shallow pools. The observation site, at 1,275 m altitude in Chinnar Wildlife Sanctuary, located in the Western Ghats of Kerala region, featured wet evergreen vegetation, transitional sholas (stunted evergreen forests), and riparian patches along a stream characterised by rapid water flow, boulders, and fallen trees. This habitat, as observed by others, was also indicative of Asian Small-clawed Otter Aonyx cinereus suitability, suggesting potential resource partitioning between the two otter species. This discovery challenges previous assumptions about the preferred habitat of Eurasian Otters in the Western Ghats and emphasizes the need for comprehensive research on the taxonomy, distribution, population status, and behaviour of these possibly sympatric species of otters, the Asian Small-clawed Otter and the Eurasian Otter. Such studies are crucial for the conservation of both these species, which face threats from habitat loss, sand mining, hunting, and population decline. Preserving and restoring riparian vegetation in the higher reaches of the Western Ghats is essential for their protection within this biodiversity hotspot.

Assessing effects of landscape modifications and identifying priority areas for two Asian otters in coastal wetlands

Conserving species inhabiting areas overlapped with human settlements is more challenging than usual as anthropogenic impacts need to be accounted for when management plans are formulated. This study aims to identify conservation priority areas for two otter species and evaluate the impact of land-use changes on conservation management in the coastal wetlands of southern Thailand. We conducted camera-trap surveys across 283 grids of 25 km2 each between 2016 and 2020. A single-species occupancy model was applied to estimate the occupancy probability of two otter species in relation to landscape characteristics and human factors. Occupancy probabilities were then correlated with anthropogenic threat levels obtained from Bayesian Belief Network to identify conservation management hotspots and conservation importance areas under various scenarios. The Smooth-coated Otter shows a higher occupancy probability in the Andaman, where a larger proportion of less disturbed wetlands remains compared to the Gulf. The Small-clawed Otter, in contrast, has higher occupancy in the Gulf. In the Andaman, the Smooth-coated Otter appears to occupy areas associated with lower human impacts and a higher proportion of natural habitats, while in the Gulf, both otter species have higher occupancy in areas where modifications of natural habitats are more intensive. In total, 1350 km2 were identified as very high conservation management hotspots, with an additional 750 km2 identified as very high conservation importance. The majority of these areas were located along the Andaman coast. However, land-use changes expanded the management hotspot areas to 2025 km2 while reducing conservation importance areas to just 175 km2. Our results emphasize the importance of protecting natural habitats and the urgency of implementing management interventions for otters on the Andaman coast, for the long-term survival of these threatened species.

Assessing habitat selection of the vulnerable Asian small-clawed otters in an anthropized riparian forest of eastern Bangladesh

Assessing habitat selection of the vulnerable Asian small-clawed otters in an anthropized riparian forest of eastern Bangladesh

Biological and Management-Related Predictors of Reproductive Success in North American Ex Situ Asian Small-Clawed Otters (Aonyx cinereus)

The long-term sustainability of ex situ animal populations requires coordination across facilities through cooperative breeding programs. Here, we investigate the reasons for inconsistent reproductive success in the zoo-based North American Asian small-clawed otter (ASCO; Aonyx cinereus) population. Reproductive viability analysis (RVA) was used to identify which characteristics of ASCOs in breeding pairs were most predictive of reproductive success. The RVA identified pair type, contraception history, and age as the most significant predictors of offspring production. The use of deslorelin in males and long-term deslorelin use in females hinder future reproductive potential and should, therefore, be considered carefully in genetically valuable individuals and potential breeders. Moreover, genetically valuable animals should be paired with younger mates, as advancing male and female age decreases the likelihood of success. The lack of reproductive success observed after 1 year of attempted breeding among new pairs provides evidence of potential mate incompatibility, therefore, population managers should consider splitting up pairs that remain unsuccessful over time, because the likelihood of offspring production is low. Lastly, the inclusion of dens and/or caves and pools designed with ample shallow water areas in ASCO habitats may improve breeding success.

The Integrated Effect of Environmental Conditions and Human Presence on the Behaviour of a Pair of Zoo-Housed Asian Small-Clawed Otters

Zoos and aquaria have the ethical responsibility to provide animals under their care with conditions that promote good welfare. This study evaluated the combined influence of human presence and environmental factors on the behaviour of zoo-housed Asian small-clawed otters (Aonyx cinereus). Data collection was conducted on a pair hosted at Pistoia Zoo (Italy). Data were collected from July to September 2020 (over 14 days). We video-recorded the otters’ behaviours, using the continuous focal animal sampling, obtaining 42 h of observation per subject. The otters displayed a wide array of species-specific behaviours. Compared to previous captive studies, the subjects engaged less in locomotion, food-related and affiliative behaviours, and more in vigilance. Human–animal interactions were limited, and mostly elicited neutral or positive responses, except for begging behaviours performed towards caregivers. Time of day and animal identity were the main significant predictors for behaviours. No effects of visitor presence or background noise were detected. Nonetheless, increasing enrichment use could stimulate food-related behaviours, and reduce vigilance and begging. This study confirms the importance of applying an integrated approach to analyse the complexity of otters’ experiences, and provides insights to guide husbandry improvements.

Presence of medium and large sized terrestrial mammals highlights the conservation potential of Patharia Hill Reserve in Bangladesh

Establishing and managing protected areas is a common approach for in situ conservation of wildlife and their habitats, but its effectiveness relies on the magnitude of anthropogenic pressures and their successful mitigation. Bangladesh is a densely populated country, and demand for land and natural resources is accelerated in and around the remaining forests. It is particularly of concern for an important transboundary hill forest, called the Patharia Hill Reserve in the northeastern Bangladesh, which appears to be the last resort for many important forest mammals. We conducted a camera-trap survey for assessing the occurrence of mammals in this tropical forest patch during January 2019 and July 2021. An effort of 2,805 trap-nights yielded 1,986 records of 22 medium and large-sized mammal species. We confirmed the presence of globally ‘Vulnerable’ Fishing Cat, Oriental Small-clawed Otter, Hog Badger, & Northern Pig-tailed Macaque and the globally ‘Endangered’ Phayre’s Langur in this study. Our records include a number of species which are either the first record for the northeastern region or have been detected after several decades. In contrast, we could not detect several large carnivores which were recorded previously in the study site and in the Indian side of Patharia Hill Reserve. This study highlights the conservation value of this poorly known reserve forest, and presents a call for immediate action to maintain its function as a transboundary forest area.

Heartworm (Dirofilaria immitis) in carnivores kept in zoos in Texas, USA: risk perception, practices, and antigen detection

BackgroundDirofilaria immitis is the causative agent of heartworm disease in wild and domestic canids, felids, and mustelids. Recent studies demonstrate that additional families in the order Carnivora are also susceptible to infection. Therefore, the objectives of this study were to (1) better understand current practices surrounding heartworm prevention and diagnostics in zoological facilities located in the state of Texas, USA, and (2) assess archival serum samples of carnivores kept in these facilities for the presence D. immitis antigen and/or antibody.MethodsA questionnaire was completed by veterinarians or veterinary technicians representing 10 zoological facilities across Texas. This questionnaire was designed at the taxonomic family level, encompassing the 12 terrestrial carnivore families Ailuridae, Canidae, Eupleridae, Felidae, Herpestidae, Hyaenidae, Mephitidae, Mustelidae, Prionodontidae, Procyonidae, Ursidae, and Viverridae. The second objective was achieved with the use of archival serum samples made available by six zoo facilities.ResultsRisk perception varied across facilities for every family, including among species belonging to Canidae. All facilities used monthly heartworm prevention in canids and felids, with more variation existing in the other families. The use of diagnostic testing and type and route of administration of preventive varied by facility, with oral ivermectin the most commonly used preventive. A total of 217 archival serum samples, belonging to 211 individual animals encompassing 11 families and 39 species, were tested with a commercial heartworm antigen ELISA test, pre- and post-immune-complex dissociation. A subset of samples was also assessed for the presence of feline anti-heartworm antibodies using a commercial ELISA test. Two animals, both of which were Asian small-clawed otters from the same facility, had antigen detected (0.95%).ConclusionsThis study demonstrates that while the zoo veterinary community is aware of the risk and health impact of heartworm disease in canids and felids, there is still a great deal of uncertainty regarding the risks and ideal strategies for prevention in other carnivore families. The low proportion of antigen detection may serve as a baseline for future prevalence studies across the southern United States, where there is an emerging concern of macrocyclic lactone resistance in heartworm.Graphical

Lingual morphology ofdomesticated Asian small-clawed otters inYogyakarta, Indonesia.

This study aimed toobserve the lingual morphology ofthe domesticated Asian small-clawed otter, Aonyx cinereus (A.cinereus), from Yogyakarta, Indonesia. Six domesticated A.cinereus adults were obtained from alocal otter breeder inYogyakarta, with noregard tosex. The animals were acclimated tothe laboratory for one day, following this, the animals underwent macroscopy identification and scanning electron microscopy (SEM) and light microscopy (LM) analysis. Macroscopically, the tongue ofdomesticated A.cinereus isdivided into three parts: the apex, corpus, and radix. The apex isthe shortest part and can move freely. Amedian groove isbent along the corpus. Typically, the radix contains circumvallate papillae and the epiglottic valleculae. The SEM and LM observations revealed that the lingual morphology ofA.cinereus consisted oftwo types ofpapillae: mechanical papillae (horny filiform, leaf-like filiform, bifid filiform, trifid filiform, elongated leaf-like filiform, triangular filiform and conical papillae) and gustatory papillae (fungiform and circumvallate papillae). The lingual glands consisted ofWeber's glands and von Ebner's glands secreting acid and neutral mucins. Collagen fibres are found inthe lamina propria and muscular layer. Inconclusion, the papillae ofthe Asian short-clawed otter have the same structure asthose ofother Mustelidae family members.

Habitat selection and diet of the Asian small-clawed otter in Karlapat Wildlife Sanctuary, Odisha, India

ABSTRACT Conservation of habitats and flagship species, such as the Asian small-clawed otter, is one of the most effective ways to conserve aquatic biodiversity. The study was conducted at Karlapat wildlife sanctuary, Odisha, India, and aims to determine the habitat and diet preferences of Asian small-clawed otters. Presence-absence of Asian small-clawed otters and associated habitat variables were recorded along 1-km sections of streams and rivers. We used principal component analysis (PCA) and logistic regression to examine habitat variables influencing otter presence along streams and rivers. Diet analysis of Asian small-clawed otters was conducted to calculate the percent frequency of occurrence and score-bulk estimate of each food item in the study area. We found that the presence of Asian small-clawed otters was related to denser canopy, higher shrub cover, and rocky stretches. A logistic regression model showed that Asian small-clawed otters significantly selected for higher canopy cover. Crabs were found to be the most preferred food item (>80%) in the diet of Asian small-clawed otters. These findings shed light on the regional-scale habitat selection and diet of Asian small-clawed otters and indicate important species-habitat relationships, thus providing valuable information for conservation management and land-use planning.

Behavioral analysis of a captive male Bornean orangutan (Pongo pygmaeus) when exposed to environmental changes

Understanding the species-specific behavioral needs of Bornean orangutans (Pongo pygmaeus) has led zoological gardens to focus on creating more natural and stimulating facilities. Studies have documented enhanced welfare through various methods, including environmental enrichment like mixed-species habitats, which could improve animal welfare. This study aimed to evaluate the behavioral adaption following the transfer to a new facility and the possible effects of environmental enrichment on an orangutan in captivity at Aalborg Zoo in Denmark. A newly arrived male was observed for analyzing behavioral changes in the weeks after relocation and introducing two small-clawed Asian otters (Aonyx cinereus) to the facility. Changes in behavior were analyzed using recorded behavior and an ethogram before and after the introduction of the otters. The expression of behaviors associated with stress and individual plasticity was analyzed, and the results indicated a change in the behavioral phenotype in response to the introduction of the otters. The study shows that behaviors associated with stress decreased after the introduction of small-clawed otters, suggesting that it had a positive effect on the behavior of the orangutan.

Identification of three Asian otter species (Aonyx cinereus, Lutra sumatrana, and Lutrogale perspicillata) using a novel noninvasive PCR-RFLP analysis.

Four species of otters occur in tropical Asia, and all face multiple threats to their survival. Studies of distribution and population trends of these otter species in Asia, where they occur sympatrically, are complicated by their elusive nature and difficulties with reliable identification of species in field surveys. In Malaysia, only three species, the smooth-coated otter, Asian small-clawed otter, and hairy-nosed otter have been reliably reported as residents. We designed a replicable and cost-efficient PCR-RFLP protocol to identify these three species. Using published reference sequences of mitochondrial regions, we designed and tested three PCR-RFLP protocols on DNA extracted from reference samples and 33 spraints of wild otters collected along the North Central Selangor Coast of Malaysia. We amplified and sequenced two fragments (450 and 200 bp) of the mt D-loop region and a 300-bp fragment of the mt ND4 gene using primer sets TanaD, TanaD-Mod, and OTR-ND4, respectively. Amplification products were digested with restriction enzymes to generate species-specific RFLP profiles. We analyzed the costs of all three protocols and compared these with the costs of sequencing for species identification. Amplification success was highest for the smallest PCR product, with the TanaD-Mod primer amplifying DNA from all 33 spraints. TanaD and OTR-ND4 primers amplified DNA from 60.6% and 63.6% spraints, respectively. PCR products of TanaD-Mod provided the expected species-specific RFLP profile for 32 (97%) of the spraints. PCR products of OTR-ND4 provided the expected RFLP profile for all 21 samples that amplified, but TanaD produced spurious bands and inconsistent RFLP profiles. The OTR-ND4 primer-enzyme protocol was the least expensive (437 USD) for processing 100 samples, followed by TanaD-Mod (455 USD). We suggest the use of both OTR-ND4 and TanaD-Mod protocols that show potential for highly efficient and reliable species identification from noninvasive genetic sampling of three Asian otter species. We expect our novel noninvasive PCR-RFLP analysis methods to facilitate population monitoring, ecological and behavioral studies on otters in tropical and subtropical Asia.

Taxonomic status of otter species in Nakai-Nam Theun National Park, Lao PDR, based on DNA evidence.

Otter populations are threatened by habitat loss, pollution, conflicts with humans, and illegal wildlife trade to meet the demand for pets, for their fur, and for parts used in traditional medicines. Baseline information on the distribution, population genetic diversity, and connectivity is crucial to inform conservation management decisions; however, reliable data from otter populations in Southeast Asia remain scarce. In this study, we conducted baseline otter fecal DNA surveys based on mitochondrial DNA (mtDNA) to identify species, assess the occurrence, and map the spatial distribution of genetic diversity and evolutionary relationships of otter populations using 1700 bp Cytochrome B - Control Region and mitogenome from Nakai-Nam Theun National Park in the Annamite Mountains of Lao PDR. Of the total 56 samples identified to species, the majority (87.5%) was of the widely distributed Eurasian otter with three haplotypes (Lutra lutra; LLLA01-LLLA03), with a calculated haplotype diversity of 0.600 and a nucleotide diversity of 0.00141 based on mitogenome. The second species was the Asian small-clawed otter with only one haplotype detected (Aonyx cinereus; ACLA01). All Eurasian otter haplotypes were newly characterized and clustered within the strongly supported South-Southeast-North Asian clade of Lutra lutra. Compared with the European clade, the high mtDNA diversity of Lutra lutra in Nakai-Nam Theun National Park potentially reflects long-term demographic stability and lesser degree of population bottleneck during the last glacial maxima (LGM, ~21,000 years ago). The single haplotype detected in Asian small-clawed otters had not been detected in previous genetic studies. Our research is the first otter-specific noninvasive genetic study in Lao PDR and provides baseline insights into the otter population diversity in a regional priority site for biodiversity conservation.

DEVELOPMENT OF A MOBILITY ASSESSMENT SCORE FOR EVALUATION OF THE EFFECTS OF ORAL HYALURONIC ACID ON CLINICAL LAMENESS IN ASIAN SMALL-CLAWED OTTERS (AONYX CINEREA) AND AFRICAN SPOT-NECKED OTTERS (HYDRICTIS MACULICOLIS) UNDER HUMAN CARE.

Oral hyaluronic acid has been shown to reduce inflammation and pain in humans with osteoarthritis. Eight Asian small-clawed otters (Aonyx cinerea) and two African spot-necked otters (Hydrictis maculicolis) with varying degrees of osteoarthritic changes identified on radiographs were selected for a randomized, double-blinded, placebo-controlled clinical trial. Animal husbandry staff completed otter mobility assessment (OMA) questionnaires for each animal prior to study commencement and following either oral hyaluronic acid at a loading dose of 4 mg/kg PO SID for 10 d followed by a maintenance dose of 2 mg/kg PO SID for 20 d, or placebo for 30 d. Four veterinarians with experience assessing otters watched randomized videos of otter gaits and assigned a clinical lameness score. Two additional evaluators watched the videos: an experienced veterinarian in small animal practice and a final-year veterinary student. All evaluators for OMA and clinical lameness score were blinded to treatment group. Radiographs performed prior to, and following, the study were assessed by a board-certified radiologist (Dennison). The OMA questionnaire had high reliability coefficients and correlated strongly with clinical gait scores and radiographic assessment. Although hyaluronic acid appears to be safe for use in otters at the dose described, there was no observed significant effect of hyaluronic acid on clinical lameness scores, OMA scores, or radiographic assessment of the limbs. The development of the OMA questionnaire is a promising tool for evaluating lameness in managed-care otters and may be further validated in future studies investigating therapeutics or incorporated as a component of animal welfare assessment.

NO PROGRESSION OF UROLITHS IN ASIAN SMALL-CLAWED OTTERS (AONYX CINEREUS) FED A NATURALISTIC CRUSTACEAN-BASED DIET FOR 2 YEARS.

Asian small-clawed otters (ASCO; Aonyx cinereus) are a popular species of otter housed in zoological institutions. A common health challenge in this species is the development of uroliths, which may have a dietary origin. Feeding recommendations for ASCO are largely based on the nutrient requirements of domestic carnivore models. Using otter-specific feeding ecology may allow for further refinement of these nutrient recommendations. This study aimed to assess if a naturalistic diet of crustaceans, mollusks, and fish could control the development of uroliths in ASCO. Baseline data were collected on 10 ASCO (five males and five females) of different ages and repeated 2 years after the treatment diet was introduced. Blood and urine parameters, as well as the size of nephroliths based on radiographic images, were recorded. The treatment diet was higher in protein and lower in calcium than the nontreatment diet and did not contain any kibble. During the 2-year treatment trial, blood globulin, glucose, and sodium increased and albumin decreased. Glucosuria and leukocyturia significantly decreased. There were no significant changes in urolith size over the 2 years, and animals without nephroliths at the beginning of the study remained urolith free. The development of nephroliths was significantly reduced during the treatment compared with the year prior. Although interpretation is limited by the methods used, a naturalist diet may have a beneficial impact in the development of uroliths in ASCO.

Dirofilaria immitis in an Asian small-clawed otter (Aonyx cinereus) from southeastern Louisiana, United States.

A single, male Dirofilaria immitis was found in the right ventricle of a captive, 10-month-old female Asian small-clawed otter (Aonyx cinereus) from East Feliciana parish in Louisiana, USA. Molecular analysis was performed for unequivocal species level identification using the cytochrome c oxidase subunit 1 (cox1) region of the mitochondrial DNA and comparing to known D. immitis cox1 sequences available on GenBank to which the specimen had a 99.54-100% pair wise identity. As there is no safe adulticidal treatment for D. immitis in mustelids, chemoprophylaxis using macrocyclic lactones is recommended to prevent infection. Further studies are needed to better characterize D. immitis infection and its propensity to cause disease in the Asian small-clawed otter.