A retrospective study of mortality in Eurasian lynx (Lynx lynx) in UK zoos

Liver and Let Die? A Retrospective Analysis of Secretarybird Mortality in European Zoos

The secretarybird (Sagittarius serpentarius) is a threatened African raptor species, and as such requires conservation attention. While the species is managed under a European Association of Zoos and Aquaria (EAZA) Ex-situ Programme (EEP), no studies of mortality are currently available. A retrospective mortality project was therefore conducted to identify the most common causes of death in captive secretarybirds, with a view to informing management decisions. Data were collected by requesting the postmortem reports from zoos where secretarybirds had died and combining this with the existing data recorded in the Zoological Information Management System. Overall, 167 birds were recorded as having died within the EEP population, of which post-mortem information was available for 51 (30.54%) individuals. Trauma was the most common cause of death identified (22 birds, 13.17%), with infection appearing as the second most prevalent cause (15 birds, 8.98%). One incidental finding at postmortem was that many (9) birds showed evidence of liver damage, with reports of bacterial hepatitis, staphylococcal infection, lesions, and dark coloration. Further research into liver complications and diet composition for secretarybirds may therefore have value in reducing mortality. Similarly, investigating strategies to reduce trauma caused by other enclosure occupants or conspecifics may have value in lengthening lifespans for this endangered species.

MORTALITY AND MORBIDITY REVIEW IN THE UNITED KINGDOM EX SITU POPULATION OF EUROPEAN WILDCATS (FELIS SILVESTRIS) BETWEEN 2000 AND 2021

The Scottish population of the European wildcat (Felis silvestris), the only remaining native felid species in the United Kingdom, is critically endangered and was declared functionally extinct by the International Union for Conservation of Nature in 2019. This retrospective study investigated the causes of morbidity and mortality reported in the United Kingdom captive wildcat population from 01 January 2000 to 31 December 2021. The aim was to assess the health and welfare of ex situ wildcats and, by making recommendations for management based on study findings, contribute to the sustainability of the population under managed care. Younger wildcats accounted for 85.7% of all morbidity cases (kittens, 7/77; young adults, 59/77), and the gastrointestinal (67.5% [52/77]), musculoskeletal (10.4% [8/77]), and integumentary (5.2% [4/77]) systems were most affected. Mortality was primarily associated with disease of the gastrointestinal (13.5% [12/89]), respiratory (13.5% [12/89]), neurological (5.6% [5/89]), and renal (5.6% [5/89]) systems. One quarter of all the histopathology examinations reported gastritis with associated Helicobacter-like organisms, often combined with pancreatitis or cholangiohepatitis. Neonates represented 25% (22/89) of all deaths, a high percentage compared with that of previous reviews in other nondomestic felids.

A SYSTEMATIC REVIEW OF RETROSPECTIVE MORBIDITY AND MORTALITY STUDIES ON CAPTIVE WILDLIFE SPECIES

Zoological institutions manage animals for conservation, education, entertainment, and research purposes. Zoological staff have a responsibility to safeguard the welfare of animals in their care. Retrospective morbidity and/or mortality studies (MMSs) can be useful tools to highlight common diseases in captive wildlife populations. There is currently no standardized methodology for conducting MMSs. Variation in the methodology of MMSs, particularly the categorization of diseases, can make comparisons between studies challenging and may limit the applicability of the results. A Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) compliant systematic review was performed, which identified 67 MMSs describing 146 species of captive wildlife. These MMSs are becoming more common and were predominantly performed on mammals (76/146). Prospective authors are encouraged to perform MMSs on amphibians, birds, reptiles, fish, and invertebrates. The studied animals were mostly managed at institutions in the United States of America (28/67, 41.2%) and Europe (14/67, 20.9%). Classifying individuals into age groups facilitates the identification of disease trends within age classes. Only 22/67 (32.8%) studies cited justification for their age classification; classifications should be based on a referenced source on the breeding biology of the studied species. There is variation in the body systems used by authors and into which system a disease is categorized, which makes study comparisons challenging. Diseases were predominantly categorized by etiology and body system (28/77, 36.4%). Because of its ubiquity, the use of the categorization system employed by the pathology module of the Zoological Information Management System is recommended as a useful standard. This system is imperfect, and amendments to it are suggested. The results and recommendations of this study were discussed with a panel of zoo and wildlife experts; guidelines have been formulated for prospective authors aiming to conduct MMSs in captive wildlife.

A RETROSPECTIVE STUDY OF NEOPLASIA IN NONDOMESTIC FELIDS IN HUMAN CARE, WITH A COMPARATIVE LITERATURE REVIEW

This retrospective study of neoplasia in nondomestic felids in human care presents the cases diagnosed at Northwest ZooPath (NWZP), Monroe, Washington, from 1998 to 2017 in conjunction with a scoping literature review. The 554 neoplasms identified in 20 species in the NWZP archive were combined with the 984 neoplasms identified in those same species in the published literature. Some of the cases identified in the literature were from the NWZP archive. Based on this review, mammary adenocarcinoma (183/1,483, 12.3%), lymphoma (89/1,483, 6.0%), squamous cell carcinoma (85/1,483, 5.7%), pheochromocytoma (57/1,483, 3.8%), and thyroid adenoma (57/1,483, 3.8%) are the most frequently reported neoplasms in nondomestic felids in human care. Apparent species predilections for neoplasia include mammary adenocarcinoma in tigers, jaguars, lions, and jungle cats; lymphoma in lions and tigers; squamous cell carcinoma in snow leopards; pheochromocytoma in clouded leopards; ovarian adenocarcinoma in jaguars; cholangiocarcinoma in lions and tigers; multiple myeloma in tigers; bronchoalveolar adenocarcinoma in cougars and lions; hemangiosarcoma, hepatocellular carcinoma, and gastrointestinal adenocarcinoma in lions; mesothelioma in clouded leopards, lions, and tigers; myelolipoma and cutaneous mast cell tumor in cheetahs; soft tissue sarcomas in tigers; and transitional cell carcinoma of the urinary bladder in fishing cats.

Anatomical variations and pathological changes in the hearts of free-ranging Eurasian lynx (Lynx lynx) in Finland

The Eurasian lynx (Lynx lynx) despite the wide distribution has fragmented populations with possibly decreased genetic variability. Reports from Central Europe have raised cardiac health as possible risk factor for lynx populations. The knowledge on normal anatomic variations of lynx heart is crucial to assess emerging pathological or hereditary disorders. The aim of this study was to give a detailed description of the cardiac anatomy and circulation of the Eurasian lynx and to report the cardiac health of the lynx in Finland. The cardiac anatomy and pathology were studied post mortem from 63 legally hunted lynx. In general, the cardiac anatomy of Eurasian lynx corresponded with that described for other felids. In the ventricles, varying number of thin ventricular bands was a common feature and their histological appearance was characterized by a fibromuscular pattern. The size of the heart varied between males and females, but the relative size was similar to that described for most domesticated carnivores. No marked pathologic lesions were observed in the lynx hearts. Fibrosis was observed in 56% of the hearts, but it was focal and mild in degree and unlikely to affect cardiac function or to have clinical significance. In conclusion, the cardiac health of the Finnish Eurasian lynx population is good with no signs of heritable cardiac disorders. Furthermore, we were able to give a detailed anatomic description of the lynx heart, which can serve as a reference for further epidemiological investigations on cardiac diseases in lynx populations.

A retrospective study of mortality in Eurasian lynx (Lynx lynx) in UK zoos

IUCN currently classifies the Eurasian lynx (Lynx lynx) as “Least Concern,” however, across its six to nine subspecies, some isolated populations are classified as “Endangered” or “Critically Endangered.” Despite this and the species’ relative ubiquity in European zoos, a retrospective mortality study of a captive population has not previously been performed. By analyzing necropsy reports, animal records, and the European studbook, we were able to ascertain a cause of death for 38 (73%) of the 52 recorded lynx deaths in UK zoos during the study period (January 1, 2000 to November 1, 2015). “Culling” as part of population management was the most common cause of death (21%) followed by neoplastic (16%), circulatory (11%), neurological (11%), and genitourinary (11%) disease. “Geriatric” individuals accounted for 62% of lynx to die within the study period, 23% were “neonates” and 15% “adults.” Neoplasia, circulatory disease, and culling were the leading causes of death in each of these age categories, respectively. Excluding “culls” and “neonates,” the mean age at death was 18.81 ± 0.42 years, consistent with existing data. Squamous cell carcinoma was reported in three individuals (8%) and suspected idiopathic epilepsy in four individuals (11%), warranting further investigation. Intraspecific killing (3%) and neonatal mortality, excluding culls, (14%) were reported with lower prevalence than expected based on previous studies of similar species. The lack of data available and high incidence of culling of individuals with a high inbreeding coefficient highlights the need for improved record‐keeping and consultation with the studbook coordinator, respectively.