Christian Walzer

USE OF POPULATION VIABILITY ANALYSIS TO IDENTIFY MANAGEMENT PRIORITIES AND SUCCESS IN REINTRODUCING PRZEWALSKI'S HORSES TO SOUTHWESTERN MONGOLIA

Abstract The Przewalskis horse (Equus caballus przewalskii) became extinct in the wild in the 1960s. Since 1997, captive-bred horses have been released into the Gobi-B Strictly Protected Area (SPA) in southwestern Mongolia, and successful reproduction in the wild started in 1999. In 2002, the population formed 3 harem groups and 1 bachelor group (total 38) in the wild, and 3 harem groups (24) awaited release in summer 2003 within acclimatization enclosures, totaling 62 individuals. We used the stochastic population simulation model VORTEX to (1) identify key variables and their threshold values in population dynamics, (2) predict extinction risk, and (3) optimize project management and release regime by comparing model parameters with our population data. Maximum age of reproduction, foal mortality, and fecundity rates were key factors in population dynamics, while number of released animals, release interval, and duration of supplementation played lesser roles. The severity level of natural catastrophes had the greatest influence on extinction risk and population size according to VORTEX. Assuming a maximum reproductive age of 16 years, an initial population of >140 horses is necessary to achieve a 95% probability of survival over 100 years under the low-severity level of catastrophes scenario. The corresponding extinction risk for high-severity level of catastrophes is 37%, even for initial population sizes >500. The low natural growth rate of the Przewalskis horse may have been the essential prerequisite for extinction in this remote area of Mongolia. However, uncertainty of results was high and limits the predictive value of the model. Comparisons between model parameters with observed population characteristics over the past 10 years reveal some discrepancies that may require readjustment of the model if present trends continue. While our model currently underestimates reproductive rate and foal survival, adult mortality tends to be higher than estimated in the model. We believe that adult survival can be improved in the wild and that the reintroduction program has a realistic chance of success. We stress the importance of an intensive monitoring program of the Przewalskis horse population and consecutive modeling exercises to reevaluate success of this reintroduction program.

IDIOPATHIC ACUTE ONSET MYELOPATHY IN CHEETAH (ACINONYX JUBATUS) CUBS

Abstract Numerous cases of ataxia, hind limb paresis, and paralysis have occurred in cheetah (Acinonyx jubatus) cubs over the past 10 yr within the European Endangered Species Program population, including 12 in mainland Europe, two in the British Isles, one in Namibia, and one in Dubai. The condition is the most important medical factor limiting European cheetah population growth. Eight cubs at the Salzburg Zoo, Austria, were affected. They demonstrated upper motor neuron lesions when alive and bilateral, symmetrical myelin degeneration of the spinal cord on necropsy. Ballooning of myelin sheaths surrounded mostly preserved axons, and no spheroids, characteristic of acute axonal degeneration, were found. Myelin loss markedly exceeded axonal degeneration. The syndromes etiology is unclear, although viral, bacterial, parasitic, genetic, nutritional–metabolic, toxic, and physical causes have been considered.

PATHOLOGIC FINDINGS IN REINTRODUCED PRZEWALSKI'S HORSES (EQUUS CABALLUS PRZEWALSKII) IN SOUTHWESTERN MONGOLIA

Abstract The Przewalskis horse (Equus caballus przewalskii) was extinct in the wild by the mid 1960s. The species has survived because of captive breeding only. The Takhin Tal reintroduction project is run by the International Takhi Group; it is one of two projects reintroducing horses to the wild in Mongolia. In 1997 the first harem group was released. The first foals were successfully raised in the wild in 1999. Currently, 63 Przewalskis horses live in Takhin Tal. Little information exists on causes of mortality before the implementation of a disease-monitoring program in 1998. Since 1999, all dead horses recovered (n = 28) have been examined and samples collected and submitted for further investigation. Equine piroplasmosis, a tick-transmitted disease caused by Babesia caballi or Theileria equi, is endemic in Takhin Tal and was identified as the cause of death of four stallions and one stillborn foal. In December 2000, wolf predation was implicated in the loss of several Przewalskis horses. However, thorough clinical, pathologic, and bacteriologic investigations performed on dead and surviving horses of this group revealed lesions compatible with strangles. The extreme Mongolian winter of 2000–2001 is thought to have most probably weakened the horses, making them more susceptible to opportunistic infection and subsequent wolf predation. Other occasional causes of death since 1999 were trauma, exhaustion, wasting, urolithiasis, pneumonia, abortion, and stillbirth. The pathologic examination of the Przewalskis horses did not result in a definitive diagnosis in each case. Several disease factors were found to be important in the initial phase of the reintroduction, which could potentially jeopardize the establishment of a self-sustaining population.

Seasonal changes in liver size in edible dormice (Glis glis): non-invasive measurements using ultrasonography

We used non-invasive ultrasonography to investigate seasonal changes in liver size of an obligate hibernator; the edible dormouse (Glis glis). We repeatedly measured liver size in dormice at two study sites, (1) an enclosure-housed colony and (2) a free-ranging population. We observed a significant increase in transverse liver size throughout the active season; however, this effect was most pronounced in animals with low body mass early in the active season. Ultrasonography imaging revealed that the content of fat in the liver (distributed in an unexpected pattern of discrete focal areas) visibly increased at the end of the active season both in the field and enclosure. Thus, the observed increase in liver size of dormice seems mainly related to fat accumulation. We found no principal differences in the time courses of transversal liver size between the two study sites. Our results support the view that non-invasive ultrasonography is an accurate method to study internal organ sizes, such as liver, in the laboratory and in the field.

EVALUATION OF LONG-TERM SEDATION IN CHEETAH (ACINONYX JUBATUS) WITH PERPHENAZINE ENANTHATE AND ZUCLOPENTHIXOL ACETATE

Abstract Two long-acting neuroleptics were used to tranquilize nine captive cheetahs (Acinonyx jubatus). Perphenazine enanthate (3.0 mg/kg) and zuclopenthixol acetate (0.6 mg/kg) were each administered to separate groups of three cheetahs in a double blind trial. Both products were administered together to a third group of three animals at the same dosages. Behavioral effect, duration of effect, and possible side effects were observed by a predefined protocol. Under standardized holding conditions, the cheetahs were observed 5 days before drug administration and 14 days after administration. Daily activity was defined and statistically evaluated by a U-test. A significant reduction of activity was observed after administration in all three trials. Zuclopenthixol acetate at 0.6 mg/kg alone and in combination with perphenazine enanthate caused inappetence, ataxia, extra pyramidal reactions, akathisia, and prolapse of the third eyelid. Zuclopenthixol acetate should not be used in cheetahs. Perphenazine enanthate did not cause inappetence, reduced appetite, or any of the previously mentioned side effects when used alone. It produced satisfactory tranquilization and is suitable and safe for cheetahs at 3.0 mg/kg. This dosage should be varied depending on health, age, and temperament of the individual cheetah.

Health screening of free-ranging European brown hares (Lepus europaeus) on the German North-Sea island Pellworm.

BackgroundA sudden decline of the European brown hare (Lepus europaeus) population in one of the best hunting districts for small game species in northern Germany, the German North-Sea island Pellworm, in the years 2007/08 following marked habitat changes led to the implementation of a thorough health assessment program of the population. 110 animals were collected during the normal hunting season in the years 2010 and 2011. A post-mortem examination and histopathological investigation was performed on all animals. Additionally, routine bacteriology of the small intestine and parasitology were carried out. Sera of hares were tested for European Brown Hare Syndrome (EBHS) by enzyme linked immunosorbent assay, and for Treponema sp. by indirect immunofluorescent test. Additional testing was performed when deemed necessary.ResultsThe most striking result was a shift in the intestinal bacterial flora towards Gram-negative Enterobacteriaceae with a predominance of either Escherichia coli, or Aeromonas sp., or a high-grade double-infection with these two pathogens with subsequent catarrhal enteritis. Additionally, a marked coccidiosis, and varying infestations with the nematode Trichostrongylus retortaeformis were found. The sero-prevalence for EBHS was 78.1%, and for Treponema 43.9%.ConclusionsThe shift and decrease in diversity of the intestinal flora was the main and most consistent result found. In the authors’ opinion the change of the habitat combined with other stressors increased the animals’ sensitivity to ubiquitous bacterial species and parasites which usually would not have such fatal effects.

Acute Die-off of Chamois (Rupicapra rupicapra) in the Eastern Austrian Alps due to Bacterial Bronchopneumonia with Pasteurellaceae

Abstract Monitoring circulating pathogens in wildlife populations is important in evaluating causes and sources of disease as well as understanding transmission between wild and domestic animals. In spring 2010, a sudden die-off in a chamois (Rupicapra rupicapra) population sharing habitat with livestock occurred in northeastern Austria. Nineteen animals were submitted for examination. Necropsy and pathohistologic and bacteriologic results yielded lesions associated with Pasteurellaceae species. Additional testing included enterobacterial repetitive intergenic consensus and random amplification of polymorphic DNA PCR analysis to evaluate the circulating strains. The isolated strains were most closely related to Mannheimia glucosida and Bibersteinia trehalosi. Reports of mass mortalities in chamois due to pneumonia have been reported previously in the northern Alpine area of Italy. To the authors knowledge, this is the first report of acute mortality due to strains of Mannheimia and Bibersteinia in Austrian chamois.

Verocytotoxin-producing Escherichia coli in chamois (Rupicapra rupicapra) and cattle in Austria.

We assessed the prevalence of verotoxigenic Escherichia coli (VTEC) in chamois (Rupicapra rupicapra) and livestock grazing on a mountain pasture in Austria during June–August 2009. We detected VTEC throughout the sampling period in high numbers in cattle as well as in chamois, leading to the assumption that the degree of contamination of the environment is high. This is the first report of pathogenic E. coli identified in chamois, implicating chamois as a new potential reservoir of these zoonotic pathogens. Because the study area also serves recreational purposes, there is a risk of humans acquiring infection via direct or indirect contact.

A Simple Field Method for Spinal Cord Removal Demonstrated in the Cheetah (Acinonyx Jubatus)

Removal of the spinal cord is considered time consuming and difficult. A delay in the necropsy procedure, especially in the central nervous system, can result in significant tissue autolysis and subsequent diagnostic difficulties. In the field, where many necropsies are performed, suitable electric saws are mostly unavailable. A technically simple and rapid method for spinal cord removal, requiring only a straightforward tool, has been devised. No necropsy-induced structural damage has been noted on histopathologic examination.