Spinal disease in a captive population of Panthera species: Review of 86 cases (2003-2021)

This retrospective study aimed to characterize and determine the prevalence of spinal disease in nondomestic felids within a sanctuary population. A review of 304 postmortem examination reports in Panthera species from 2003 to 2021 revealed that 86/304 (28%) were diagnosed with spinal disease. Spinal lesions were categorized according to pathologic process: degenerative (78/86, 91%), developmental (8/86, 9%), inflammatory (6/86, 7%), or neoplastic (8/86, 9%). Degenerative lesions included intervertebral disk disease (IVDD; 66/78, 85%), spondylosis without concurrent IVDD (4/78, 5%), and idiopathic (noncompressive) degenerative myelopathies (8/78, 10%). Fourteen individuals had lesions in more than 1 category. Developmental cases were vertebral (4/8) or spinal cord (3/8) malformations or both (1/8). Inflammatory lesions included meningitis (4/6) and meningomyelitis (2/6). Neoplasia included vertebral multiple myeloma (4/8) and others (4/8). IVDD often involved multiple disks but primarily affected the cervical (41/66, 62%) and thoracic spine (32/66, 48%). A multivariate binary logistic model predicted the diagnosis of IVDD at postmortem examination, where odds of being affected were highest for males, lions (Panthera leo), and geriatric age group (>14 years). The spinal lesions documented in this study provide insight into high-risk signalment categories and predominant associated lesions affecting captive Panthera populations. Specifically, spinal disease, especially cervical IVDD, is common among Panthera species, and lions, males, and older felids are at increased risk.

Neuropil Variation in the Prefrontal, Motor, and Visual Cortex of Six Felids

INTRODUCTION

Felids have evolved a specialized suite of morphological adaptations for obligate carnivory. Although the musculoskeletal anatomy of the Felidae has been studied extensively, the comparative neuroanatomy of felids is relatively unexplored. Little is known about how variation in the cerebral anatomy of felids relates to species-specific differences in sociality, hunting strategy, or activity patterns.

METHODS

We quantitatively analyzed neuropil variation in the prefrontal, primary motor, and primary visual cortices of six species of Felidae (Panthera leo, Panthera uncia, Panthera tigris, Panthera leopardus, Acinonyx jubatus, Felis sylvestris domesticus) to investigate relationships with brain size, neuronal cell parameters, and select behavioral and ecological factors. Neuropil is the dense, intricate network of axons, dendrites, and synapses in the brain, playing a critical role in information processing and communication between neurons.

RESULTS

There were significant species and regional differences in neuropil proportions, with African lion, cheetah, and tiger having more neuropil in all three cortical regions in comparison to the other species. Based on regression analyses, we find that the increased neuropil fraction in the prefrontal cortex supports social and behavioral flexibility, while in the primary motor cortex, this facilitates the neural activity needed for hunting movements. Greater neuropil fraction in the primary visual cortex may contribute to visual requirements associated with diel activity patterns.

CONCLUSION

These results provide a cross-species comparison of neuropil fraction variation in the Felidae, particularly the understudied Panthera, and provide evidence for convergence of the neuroanatomy of Panthera and cheetahs.

Mortality associated with SARS-CoV-2 in nondomestic felids

Between September and November 2021, 5 snow leopards (Panthera uncia) and 1 lion (Panthera leo) were naturally infected with severe acute respiratory coronavirus 2 (SARS-CoV-2) and developed progressive respiratory disease that resulted in death. Severe acute respiratory syndrome coronavirus 2 sequencing identified the delta variant in all cases sequenced, which was the predominant human variant at that time. The time between initial clinical signs and death ranged from 3 to 45 days. Gross lesions in all 6 cats included nasal turbinate hyperemia with purulent discharge and marked pulmonary edema. Ulcerative tracheitis and bronchitis were noted in 4 cases. Histologically, there was necrotizing and ulcerative rhinotracheitis and bronchitis with fibrinocellular exudates and fibrinosuppurative to pyogranulomatous bronchopneumonia. The 4 cats that survived longer than 8 days had fungal abscesses. Concurrent bacteria were noted in 4 cases, including those with more acute disease courses. Severe acute respiratory syndrome coronavirus 2 was detected by in situ hybridization using probes against SARS-CoV-2 spike and nucleocapsid genes and by immunohistochemistry. Viral nucleic acid and protein were variably localized to mucosal and glandular epithelial cells, pneumocytes, macrophages, and fibrinocellular debris. Based on established criteria, SARS-CoV-2 was considered a contributing cause of death in all 6 cats. While mild clinical infections are more common, these findings suggest that some SARS-CoV-2 variants may cause more severe disease and that snow leopards may be more severely affected than other felids.

Anthropogenic Transmission of SARS-CoV-2 from Humans to Lions, Singapore, 2021

In Singapore, 10 captive lions tested positive for SARS-CoV-2 by real-time PCR. Genomic analyses of nanopore sequencing confirmed human-to-animal transmission of the SARS-CoV-2 Delta variant. Viral genomes from the lions and zookeeper shared a unique spike protein substitution, S:A1016V. Widespread SARS-CoV-2 transmission among humans can increase the likelihood of anthroponosis.

Getting to the Meat of It: The Effects of a Captive Diet upon the Skull Morphology of the Lion and Tiger

Zoo animals are crucial for conserving and potentially re-introducing species to the wild, yet it is known that the morphology of captive animals differs from that of wild animals. It is important to know how and why zoo and wild animal morphology differs to better care for captive animals and enhance their survival in reintroductions, and to understand how plasticity may influence morphology, which is supposedly indicative of evolutionary relationships. Using museum collections, we took 56 morphological measurements of skulls and mandibles from 617 captive and wild lions and tigers, reflecting each species' recent historical range. Linear morphometrics were used to identify differences in size and shape. Skull size does not differ between captive and wild lions and tigers, but skull and mandible shape does. Differences occur in regions associated with biting, indicating that diet has influenced forces acting upon the skull and mandible. The diets of captive big cats used in this study predominantly consisted of whole or partial carcasses, which closely resemble the mechanical properties of wild diets. Thus, we speculate that the additional impacts of killing, manipulating and consuming large prey in the wild have driven differentiation between captive and wild big cats.

The Effects of Onychectomy (Declawing) on Antebrachial Myology across the Full Body Size Range of Exotic Species of Felidae

While people are familiar with the practice of declawing domestic cats, "onychectomy", as it is also known, is also performed on non-domesticated species, including pantherines, to prolong their use for entertainment purposes. Although the surgery (the partial or complete removal of the distal phalanx) has clear osteological implications, its myological effects have never been studied. As the mass of an animal increases cubically as a product of its volume, while the areas of its paws only increase as a square, larger felids have higher foot pressures and, therefore, the surgery may have particularly substantial functional effects on larger cats. In this study, we evaluate the forearms of clawed and declawed non-domestic felid specimens that spanned the body size range of the whole family to evaluate the effects of onychectomy on muscle fiber architecture. We found that the deep digital flexors (the muscles most directly affected by onychectomy) of declawed felids are significantly lighter (~73%) and less powerful (46-66%) than those of non-declawed felids, while other muscles do not make up for these reductions. Thus, onychectomy has a substantial effect on the myological capabilities of cats, and because these deficiencies are not compensated for in biomechanically disadvantaged larger felids, it probably has even more functionally devastating consequences for these species.

A morphological analysis of carnivoran ossicles from Rancho La Brea

The morphology of the mammalian middle ear-including the size, shape, and stiffness of individual ossicles-controls their vibrational response to sound and, is closely related to an animal's auditory capabilities. While the relationship between middle ear morphology and hearing frequency has been explored in living carnivorans, the size and shape of ossicles in fossil carnivorans have been sparsely documented. In this study, we present the first morphological data on four iconic carnivoran taxa from the Rancho La Brea Tar Pits: Smilodon fatalis, Panthera atrox, Canis dirus, and Arctodus simus. These data are contextualized with samples of extant felids, canids, and ursids to determine the extent to which the ossicles of these iconic fossil taxa resemble their living relatives. Six, five, and seven linear measurements were taken from the malleus, incus, and stapes, respectively. Comparisons of geometric means reveal that the ossicles of fossil canids and felids are similar in size to living analogs, but those of A. simus are significantly larger than those of any living ursid. Further, principal components analyses demonstrate close morphological affinities between fossil and extant taxa within canids and felids, and again, a greater disparity between fossil and extant ursids. Canids and ursids occupy distinct regions of the morphospace, yet both overlap the morphological range spanned by felids. While some elements-for example, the stapes-require further specimens to facilitate more nuanced interpretations of variation, our findings underscore the need for concerted efforts towards identifying and preserving these bones within fossil assemblages.

Exploring innovative problem-solving in African lions (Panthera leo) and snow leopards (Panthera uncia)

Cognitive ability is likely linked to adaptive ability; animals use cognition to innovate and problem-solve in their physical and social environments. We investigated innovative problem-solving in two species of high conservation importance: African lions (Panthera leo; n = 6) and snow leopards (Panthera uncia; n = 9). We designed a custom multi-access puzzle box (MAB) to present a simple and effective behavioral test for the cats to explore. We measured Repeated Innovation, Persistence, Success, Contact Latency, and the Exploration Diversity of individuals interacting with the MAB. Of the six African lions, three (50%) solved one door to the box, one solved two doors (16.67%), and one solved three doors (16.67%). Of the nine snow leopards, one solved one door (11.11%), three solved two doors (33.33%), and none solved all three doors (0%). Persistence was a significant predictor of Success in African lions and snow leopards; more Persistent individuals were more likely to open a door. We also observed significant individual variation in Persistence for both species, but only snow leopards also exhibited differences in Contact Latency and Exploration Diversity. These results suggest individuals vary in their problem-solving approaches. Our findings support both species as successful, repeated innovators. Carnivores face ecological and social challenges and, presumably, benefit from cognitive abilities facilitating the successful navigation of these challenges in captivity and the wild.

Sylvatic Canine Morbillivirus in Captive Panthera Highlights Viral Promiscuity and the Need for Better Prevention Strategies

Canine Distemper Virus (CDV) is a multi-host morbillivirus that infects virtually all Carnivora and a few non-human primates. Here we describe a CDV outbreak in an exotic felid rescue center that led to the death of eight felids in the genus Panthera. Similar to domestic dogs and in contrast to previously described CDV cases in Panthera, severe pneumonia was the primary lesion and no viral antigens or CDV-like lesions were detected in the central nervous system. Four tigers succumbed to opportunistic infections. Viral hemagglutinin (H)-gene sequence was up to 99% similar to strains circulating contemporaneously in regional wildlife. CDV lesions in raccoons and skunk were primarily encephalitis. A few affected felids had at least one previous vaccination for CDV, while most felids at the center were vaccinated during the outbreak. Panthera sharing a fence or enclosure with infected conspecifics had significantly higher chances of getting sick or dying, suggesting tiger-tiger spread was more likely than recurrent spillover. Prior vaccination was incomplete and likely not protective. This outbreak highlights the need for further understanding of CDV epidemiology for species conservation and public health.

Taxonomic Distribution of Neoplasia Among Non-Domestic Felid Species Under Managed Care

As evidenced by numerous case reports from zoos, neoplasia in felids is common, but most reports are limited to Panthera species in North America or Europe. In order to obtain a wider epidemiologic understanding of neoplasia distribution, necropsy records at seven facilities (USA, Mexico, Colombia, Peru, and Brazil) were evaluated. In contrast to others, this study population (195 cases, 16 species), included many non-Panthera felids. Overall neoplasia prevalence was 28.2% (55/195). Panthera species had a higher prevalence of neoplasia than non-Panthera species (52.5%; vs. 13.0%). Lions (66.7%), jaguars (55.0%), and tigers (31.3%) had the highest species-specific prevalence of neoplasia. Neoplasms in Panthera species were more frequently malignant than in non-Panthera (86.1% vs. 55.6%). The systems most commonly affected were the reproductive, hematolymphoid, and respiratory. The range of management conditions and more varied genetic backgrounds support a robust taxonomic pattern and suggest that the reported propensity for neoplasia in jaguars may have a genetic basis at a taxonomic level higher than species, as lions and tigers also have high prevalence. Given the high prevalence of neoplasia and high likelihood of malignancy, routine medical exams in all nondomestic felids, but Panthera species in particular, should include thorough assessments of any clinical signs of neoplasia.

Molecular screening indicates high prevalence and mixed infections of Hepatozoon parasites in wild felines from South Africa

Genetic diversity within partial 18S rRNA sequences from Hepatozoon protozoan parasites from wild felines in South Africa was assessed and compared with data from domestic cats to assess patterns of host specificity. Lions, leopards, servals, a caracal and an African wildcat were all positive for parasites of the Hepatozoon felis-complex. However, haplotypes were not species-specific, and potential mixed infections were widespread. Additional genetic markers are needed to untangle the extremely complex situation of these parasites in both domestic cats and wild felines in South Africa.

REVIEW OF CANINE DISTEMPER VACCINATION USE AND SAFETY IN NORTH AMERICAN CAPTIVE LARGE FELIDS (PANTHERA SPP.) FROM 2000 TO 2017

Data on canine distemper virus (CDV) vaccination were collected on 812 large felids (351 tigers, Panthera tigris; 220 lions, Panthera leo; 143 snow leopards, Panthera uncia; 50 leopards, Panthera pardus; and 48 jaguars, Panthera onca) from 48 institutions to assess vaccine use and safety. The documented individual vaccination events with multiple products numbered 2,846. Canarypox-vectored CDV vaccines were the most commonly used vaccines (96.3% of all vaccinations) and the Purevax^® Ferret Distemper (PFD) vaccine was the most commonly used canarypox-vectored vaccine (91.0% of all vaccinations). Modified live virus (MLV) CDV vaccines were used for 3.7% of all vaccinations, and only in tigers, lions, and snow leopards. Adverse effects were reported after 0.5% (13 of 2,740) of the canarypox-vectored vaccinations and after 2.9% (3 of 104) of the MLV CDV vaccinations. This low complication rate suggests large felids may not be as sensitive to adverse effects of MLV CDV vaccines as other exotic carnivores. Serological data were available from 159 individuals (69 tigers, 31 lions, 31 snow leopards, 22 jaguars, and 6 Amur leopards, Panthera pardus orientalis) vaccinated with the PFD vaccine, and 66.0% of vaccinates seroconverted (defined as acquiring a titer ≥1: 24) at some point postvaccination: 24.3% after one vaccination, 55.8% after two vaccinations, 54.3% after three vaccinations, and 79.2% after four or more vaccinations. Among animals exhibiting seroconversion after the initial PFD vaccinations, 88.9% still had titers ≥12 mo and ≥24 mo after the last vaccination, and 87.5% had titers ≥1: 24 at ≥36 mo after the last vaccination. The study was unable to assess fully the safety of vaccination with either canarypox-vectored or MLV CDV vaccines during gestation because of the small number of animals vaccinated while pregnant (n = 6, all vaccinated with PFD).

Aminoacyl tRNA synthetases as potential drug targets of the Panthera pathogen Babesia

Background

A century ago, pantheras were abundant across Asia. Illegal hunting and trading along with loss of habitat have resulted in the designation of Panthera as a genus of endangered species. In addition to the onslaught from humans, pantheras are also susceptible to outbreaks of several infectious diseases, including babesiosis. The latter is a hemoprotozoan disease whose causative agents are the eukaryotic parasites of the apicomplexan genus Babesia. Babesiosis affects a varied range of animals including humans (Homo sapiens), bovines (e.g. Bos taurus), pantheras (e.g. Panthera tigris, P. leo, P. pardus) and equines. Babesia spp. are transmitted by the tick vector Ixodes scapularis or ticks of domestic animals, namely Rhipicephalus (Boophilus) microplus and R. (B.) decoloratus. At the level of protein translation within these organisms, the conserved aminoacyl tRNA synthetase (aaRS) family offers an opportunity to identify the sequence and structural differences in the host (Panthera) and parasites (Babesia spp.) in order to exploit these for drug targeting Babesia spp.

Methods

Using computational tools we investigated the genomes of Babesia spp. and Panthera tigris so as to annotate their aaRSs. The sequences were analysed and their subcellular localizations were predicted using Target P1.1, SignalP 3.0, TMHMM v.2.0 and Deeploc 1.0 web servers. Structure-based analysis of the aaRSs from P. tigris and its protozoan pathogens Babesia spp. was performed using Phyre2 and chimera.

Results

We identified 33 (B. bovis), 34 (B. microti), 33 (B. bigemina) and 33 (P. tigris) aaRSs in these respective organisms. Poor sequence identity (~ 20–50%) between aaRSs from Babesia spp. and P. tigris was observed and this merits future experiments to validate new drug targets against Babesia spp.

Conclusions

Overall this work provides a foundation for experimental investigation of druggable aaRSs from Babesia sp. in an effort to control Babesiosis in Panthera.

Big cats as a model system for the study of the evolution of intelligence

Currently, carnivores, and felids in particular, are vastly underrepresented in cognitive literature, despite being an ideal model system for tests of social and ecological intelligence hypotheses. Within Felidae, big cats (Panthera) are uniquely suited to studies investigating the evolutionary links between social, ecological, and cognitive complexity. Intelligence likely did not evolve in a unitary way but instead evolved as the result of mutually reinforcing feedback loops within the physical and social environments. The domain-specific social intelligence hypothesis proposes that social complexity drives only the evolution of cognitive abilities adapted only to social domains. The domain-general hypothesis proposes that the unique demands of social life serve as a bootstrap for the evolution of superior general cognition. Big cats are one of the few systems in which we can directly address conflicting predictions of the domain-general and domain-specific hypothesis by comparing cognition among closely related species that face roughly equivalent ecological complexity but vary considerably in social complexity.

Oral health correlates of captivity

The predominant diet fed to captive carnivores in North America consists of ground meat formulated to provide full nutritional requirements. However, this ground meat diet completely lacks the mechanical properties (i.e., toughness and hardness) of the foods these animals would consume in the wild. The goal of this study is to evaluate the effect of captivity on oral health by comparing the prevalence of periodontal disease and dental calculus accumulation in wild and captive lions and tigers (Panthera leo and Panthera tigris), and to also correlate oral health with cranial morphology in these specimens. To achieve this, 34 adult lion and 29 adult tiger skulls were scored for the presence and extent of dental calculus and periodontal disease. These oral health scores were also compared to cranial deformations examined in a previous study. We found that the occurrence and severity of calculus buildup and periodontal disease was significantly higher in captive felids compared to their wild counterparts. Further, higher calculus accumulation occurred on the posterior teeth when compared to the anterior teeth, while an opposite trend for periodontal disease was observed. We also found a significant correlation between oral health and cranial morphology of lions and tigers. The results suggest that food mechanical properties are significant factors contributing to oral health in felids.

The complete mitochondrial genome structure of the jaguar (Panthera onca)

The jaguar (Panthera onca) is the largest felid in the Western hemisphere, and the only member of the Panthera genus in the New World. The jaguar inhabits most countries within Central and South America, and is considered near threatened by the International Union for the Conservation of Nature. This study represents the first sequence of the entire jaguar mitogenome, which was the only Panthera mitogenome that had not been sequenced. The jaguar mitogenome is 17,049 bases and possesses the same molecular structure as other felid mitogenomes. Bayesian inference (BI) and maximum likelihood (ML) were used to determine the phylogenetic placement of the jaguar within the Panthera genus. Both BI and ML analyses revealed the jaguar to be sister to the tiger/leopard/snow leopard clade.

'Mystery big cats' in the Peruvian Amazon: morphometrics solve a cryptozoological mystery

Two big cat skulls procured from hunters of Yanachaga National Park, Peru, were reported as those of cats informally dubbed the 'striped tiger' and 'anomalous jaguar'. Observations suggested that both skulls were distinct from those of jaguars, associated descriptions of integument did not conform to this species, and it has been implied that both represent members of one or two novel species. We sought to resolve the identity of the skulls using morphometrics. DNA could not be retrieved since both had been boiled as part of the defleshing process. We took 36 cranial and 13 mandibular measurements and added them to a database incorporating nearly 300 specimens of over 30 felid species. Linear discriminant analysis resolved both specimens as part of Panthera onca with high probabilities for cranial and mandibular datasets. Furthermore, the specimens exhibit characters typical of jaguars. If the descriptions of their patterning and pigmentation are accurate, we assume that both individuals were aberrant.