Biochemical and physiological observations in meerkats (Suricata suricatta) at two zoos during a dietary transition to a diet designed for insectivores

Pathology and causes of death in captive meerkats (Suricata suricatta)

BACKGROUND

Meerkats (Suricata suricatta) are endemic carnivores of southern Africa and, although currently listed as "least concern" by the International Union for Conservation of Nature (IUCN) red list, there is evidence of a significant decrease in wild populations mainly attributed to effects of climate change. Little is known about diseases associated with mortality in captive meerkats.

AIM

To characterise macroscopic and microscopic lesions that accounted for the death or euthanasia in a series of captive meerkats.

MATERIAL AND METHODS

Eight captive meerkats submitted for post-mortem examination between 2018 and 2022.

RESULTS

Three animals died unexpectedly without clinical signs, 2 exhibited neurological signs, 2 collapsed after con-specific fighting and 1 showed gastrointestinal signs. Common pathological findings of this study that may be related to the death of captive meerkats included foreign bodies (trichobezoars or plastic materials) within the alimentary tract, traumatic penetrating injuries or starvation associated with abnormal social behaviours (bullying and con-specific attacks), verminous pneumonia and systemic atherosclerosis. Common incidental findings included pulmonary edema and congestion, cholesterol granulomas, pulmonary adenomas and vertebral spondylosis.

CONCLUSIONS

Non-infectious diseases outreach infectious diseases as causes of mortality in captive meerkats including, foreign bodies within the alimentary tract, con-specific attacks and systemic atherosclerosis, which is described for the first time. These data should raise concern about appropriate husbandry (e.g. environmental enrichment, cleaning of facilities and diet formulation) by zookeepers and emphasise the need for further study of meerkat mortality in both captive and wild populations.

PRELIMINARY CHARACTERIZATION OF DILATED CARDIOMYOPATHY IN A CAPTIVE POPULATION OF BANDED MONGOOSES (MUNGOS MUNGO)

Between 2006 and 2015, a high incidence of dilated cardiomyopathy (DCM) was diagnosed in a captive population of banded mongooses (Mungos mungo) at Chester Zoo, United Kingdom. The aim of this study was to characterize DCM in these mongooses in order to raise awareness of this condition and help inform management and clinical decisions. Prospective clinical assessments, including echocardiography, radiography, and cardiac biomarkers, were carried out in four mongooses remaining in the collection. Radiographs from 15 mature mongooses were reviewed and cardiac size and metrics assessed. Ten postmortem reports and the histologic sections from nine of these cases were reviewed for cardiac lesions. Echocardiographic findings were consistent with a diagnosis of preclinical DCM in one out of the four cases assessed, and it was considered equivocal in a second case. Taurine levels were within normal limits for domestic carnivores. Radiographs in seven mongooses showed right-sided or generalized cardiomegaly. The width of the heart in intercostal spaces and vertebral-tracheal angle on the lateral view were the most-discriminatory radiographic variables for diagnosis of cardiac disease. At necropsy, there was gross pathological evidence consistent with DCM in seven out of 10 mongooses examined. Histopathologically, mild multifocal fibrosis and rare intermyofiber edema were observed. This study provides preliminary evidence that DCM occurs in captive banded mongoose, but etiology and wider prevalence need to be determined.

Group size and visitor numbers predict faecal glucocorticoid concentrations in zoo meerkats

Measures of physiological stress in zoo animals can give important insights into how they are affected by aspects of their captive environment. We analysed the factors influencing variation in glucocorticoid metabolites in faeces (fGCs) from zoo meerkats as a proxy for blood cortisol concentration, high levels of which are associated with a stress response. Levels of fGCs in captive meerkats declined with increasing group size. In the wild, very small groups of meerkats are at a higher risk of predation, while in larger groups, there is increased competition for resources. Indeed, group sizes in captivity resemble those seen in unstable coalitions in the wild, which may represent a stressful condition and predispose meerkats to chronic stress, even in the absence of natural predators. Individuals in large enclosures showed lower levels of stress, but meerkat density had no effect on the stress measures. In contrast with data from wild meerkats, neither sex, age nor dominance status predicted stress levels, which may reflect less food stress owing to more equal access to resources in captivity versus wild. The median number of visitors at the enclosure was positively correlated with fGC concentrations on the following day, with variation in the visitor numbers having the opposite effect. Our results are consistent with the hypothesis that there is an optimum group size which minimizes physiological stress in meerkats, and that zoo meerkats at most risk of physiological stress are those kept in small groups and small enclosures and are exposed to consistently high numbers of visitors.

Acute pancreatitis in slender-tailed meerkats (Suricata suricatta)

Four adult, full-sibling slender-tailed meerkats (Suricata suricatta) were diagnosed with acute pancreatitis. The incident case presented with lethargy, anorexia, abdominal guarding, and a cranial abdominal mass. Serum was grossly lipemic, with elevated cholesterol and triglyceride concentrations and increased amylase and lipase activity. An exploratory laparotomy confirmed chylous peritonitis and included excision of a saponified spleno-duodenal mass, a partial pancreatectomy, and a splenectomy. Histopathology revealed severe, multifocal, subacute necrotizing and granulomatous pancreatitis. Within 13 days of the incident case, the second meerkat was identified with essentially identical clinical, surgical, and histologic findings. During subsequent physical examinations of apparently unaffected cohorts (n=12), physical and hematologic findings suggestive of pancreatitis were identified in the two remaining siblings of the first two cases. The definitive cause for these four cases is undetermined; however, common risk factors identified were obesity and hyperlipidemia, a change to a higher-fat diet, and genetic predisposition. To assess its usefulness in the diagnosis of meerkat pancreatitis, serum canine and feline pancreatic lipase immunoreactivity (cPLI and fPLI) concentrations were measured in serum samples (n=61) from two unrelated meerkat populations. Although these assays are highly sensitive and specific for the diagnosis of pancreatitis in domestic carnivores, similar correlation was not apparent for meerkats. In addition, hyperlipidemia was inconsistently present in many meerkats, with no apparent correlation to the development of clinical illness. Based on these observations, sensitive and specific diagnostic tests for pancreatitis in meerkats are currently unavailable.