SEROEPIZOOTIOLOGICAL SURVEY FOR SELECTED VIRAL INFECTIONS IN CAPTIVE ASIATIC LIONS (PANTHERA LEO PERSICA) FROM WESTERN INDIA

CASE-CONTROL STUDY OF THE FREQUENCY AND ETIOLOGY OF ATAXIA IN ASIATIC LIONS (PANTHERA LEO PERSICA) BETWEEN 2002 AND 2020

The Asiatic lion (Panthera leo persica) is an endangered species with a slowly increasing captive and wild population. Several zoos from within the European Association of Zoos and Aquaria Ex Situ Program reported Asiatic lions with neurological signs such as (progressive) ataxia, and stargazing. The aim of this study was to evaluate the frequency (prevalence and incidence) and etiology of these clinical signs within the captive Asiatic lion population. The medical history of 74 Asiatic lions (36 healthy and 38 affected) was retrieved and reviewed for blood tests (biochemical, hematological, and retinol), diagnostic imaging (MRI and CT scans) and postmortem examinations. The data of the affected lions was compared with those of healthy lions. Between 2002 and 2020, the prevalence of ataxia ranged from 0.6% in 2004 to 13.0% in 2020. The incidence of ataxia was variable per year between 2002 and 2020 and ranged between 0 and 40%. Besides ataxia, stiffness and lameness were the most described signs in this study. Blood results showed lower total protein, ALT and creatinine, and higher phosphate in lions with neurological signs. Moreover, neurologically affected lions showed a significant lower blood retinol than the control lions (0.59-0.81 µmol/L). The most important finding in diagnostic imaging and necropsy included caudal fossa hyperostosis and cerebellar herniation. These abnormalities are similar as found in African lions (Panthera leo) with calvarial hyperostosis syndrome associated with vitamin A deficiency. Leucomyelopathy, syringomyelia (in one case combined with cerebellar herniation) and incidental mineralization of the dura mater were also described. A possible congenital/hereditary component should not be excluded.

Long live the king: chromosome-level assembly of the lion (Panthera leo) using linked-read, Hi-C, and long-read data

BACKGROUND

The lion (Panthera leo) is one of the most popular and iconic feline species on the planet, yet in spite of its popularity, the last century has seen massive declines for lion populations worldwide. Genomic resources for endangered species represent an important way forward for the field of conservation, enabling high-resolution studies of demography, disease, and population dynamics. Here, we present a chromosome-level assembly from a captive African lion from the Exotic Feline Rescue Center (Center Point, IN) as a resource for current and subsequent genetic work of the sole social species of the Panthera clade.

RESULTS

Our assembly is composed of 10x Genomics Chromium data, Dovetail Hi-C, and Oxford Nanopore long-read data. Synteny is highly conserved between the lion, other Panthera genomes, and the domestic cat. We find variability in the length of runs of homozygosity across lion genomes, indicating contrasting histories of recent and possibly intense inbreeding and bottleneck events. Demographic analyses reveal similar ancient histories across all individuals during the Pleistocene except the Asiatic lion, which shows a more rapid decline in population size. We show a substantial influence on the reference genome choice in the inference of demographic history and heterozygosity.

CONCLUSIONS

We demonstrate that the choice of reference genome is important when comparing heterozygosity estimates across species and those inferred from different references should not be compared to each other. In addition, estimates of heterozygosity or the amount or length of runs of homozygosity should not be taken as reflective of a species, as these can differ substantially among individuals. This high-quality genome will greatly aid in the continuing research and conservation efforts for the lion, which is rapidly moving towards becoming a species in danger of extinction.

Assessing the health risks of reintroduction: The example of the Amur leopard, Panthera pardus orientalis

Translocation of wildlife as a means of reintroducing or reinforcing threatened populations is an important conservation tool but carries health risks for the translocated animals and their progeny, as well as wildlife, domestic animals and humans in the release area. Disease risk analyses (DRA) are used to identify, prioritize and design mitigation strategies to address these threats. Here, we use a DRA undertaken for Amur leopards (Panthera pardus orientalis) to illustrate how specific methodology can optimize mitigation strategy design. A literature review identified a total of 98 infectious hazards and 28 non-infectious hazards. Separate analyses were undertaken for disease risks in leopards from hazards of source origin (captive zoo collections and the transit pathway to the Russian Far East), or of destination origin (in breeding enclosures and wider release areas); and for disease risks in other wildlife, domesticated species or humans, similarly from hazards of source or destination origin. Hazards were assessed and ranked as priority 1, priority 2, priority 3 or low priority in each of the defined scenarios. In addition, we undertook a generic assessment of stress on individual leopards. We use three examples to illustrate the process: Chlamydophila felis, canine distemper virus (CDV) and feline immunodeficiency virus (FIV). We found that many potentially expensive screening procedures could be performed prior to export of leopards, putting the onus of responsibility onto the zoo sector, for which access to diagnostic testing facilities is likely to be optimal. We discuss how our methods highlighted significant data gaps relating to pathogen prevalence in the Russian Far East and likely future unpredictability, in particular with respect to CDV. There was emphasis at all stages on record keeping, meticulous planning, design, staff training and enclosure management, which are relatively financially inexpensive. Actions to minimize stress featured at all time points in the strategy and also focussed on planning, design and management.

EVALUATION OF TWO CANINE DISTEMPER VIRUS VACCINES IN CAPTIVE TIGERS (PANTHERA TIGRIS)

Canine distemper virus (CDV) has caused clinical disease and death in nondomestic felids in both captive settings and in the wild. Outbreaks resulting in high mortality rates in tigers (Panthera tigris) have prompted some zoos to vaccinate tigers for CDV. In this study, six tigers received a recombinant canarypox-vectored CDV vaccine (1 ml s.c.) and were revaccinated with 3 ml s.c. (mean) 39 days later. Blood collection for CDV antibody detection via serum neutralization was performed on (mean) days 0, 26, and 66 post-initial vaccination. No tigers had detectable antibodies at days 0 or 26, and only two tigers had low (16 and 32) antibody titers at day 66. Eight additional tigers received a live, attenuated CDV vaccine (1 ml s.c.) on day 0 and were revaccinated with 1 ml s.c. (mean) 171 days later. Blood collection for CDV antibody detection via serum neutralization was performed on (mean) days 0, 26, 171, and 196. Seven of eight tigers receiving the live, attenuated vaccine had no detectable titers prior to vaccination, but all animals had titers of >128 (range 128-1,024) at day 26. At 171 days, all tigers still had detectable titers (geometric mean 69.8, range 16-256), and at 196 days (2 wk post-revaccination) all but two showed an increase to >128 (range 32-512). To determine safety, an additional 41 tigers were vaccinated with 2 ml of a recombinant vaccine containing only CDV components, and an additional 38 tigers received 1 ml of the live, attenuated vaccine, administered either subcutaneously or intramuscularly; no serious adverse effects were noted. Although both vaccines appear safe, the live, attenuated vaccine produced a stronger and more consistent serologic response in tigers.

Canine distemper spillover in domestic dogs from urban wildlife

Canine distemper virus (CDV) causes a major disease of domestic dogs that develops as a serious systemic infection in unvaccinated or improperly vaccinated dogs. Domesticated dogs are the main reservoir of CDV, a multihost pathogen. This virus of the genus Morbillivirus in the family Paramyxoviridae occurs in other carnivorous species including all members of the Canidae and Mustelidae families and in some members of the Procyonidae, Hyaenidae, Ursidae, and Viverridae families. Canine distemper also has been reported in the Felidae family and marine mammals. The spread and incidences of CDV epidemics in dogs and wildlife here and worldwide are increasing.

Canine distemper in Siberian tiger cubs from Zagreb ZOO: case report

Canine distemper is a contagious, potentially lethal disease of mainly domestic and wild canids, but also of many other mammalian species including large felids. In February 2004, two Siberian tiger (Panthera tigris altaica) cubs at the age of six months died at the Zagreb ZOO. The animals were presented for necropsy with two days history of severe digestive disorders, characterized mainly by haemathemesis. Dissections revealed catarrhal to pseudomembranous gastroenteritis (depending on the animal) accompanied with haemorrhagic oedema of the lungs. Necrotic tonsillitis and disseminated depletion of the lymphocytes were the most prominent histological findings in both examined animals, while intranuclear and intracytoplasmatic inclusion bodies were found in the samples of the tongues and intestines. Representative portions of the livers, intestines, tonsils and lymph nodes were submitted for bacteriological and mycological analysis. The presence ofClostridiumspp.,Campylobacter coliandEscherichia coliwas detected in gut samples, coli-like bacteria were found in samples of liver, tonsils and lymph nodes, whileCandidasp. was found in the gut and pharynx samples. Toxicological analysis excluded anticoagulant and organophosphorous intoxication as the cause of death. Immunohistochemical analysis was positive for canine distemper virus. Based on all this, epizootiological, clinical and additional findings, canine distemper was recognized as the cause of the observed condition in these animals.