In this thesis I examine the population ecology of wild horses (Equus caballus) in the Australian Alps. Wild horses were first introduced into the Alps over 150 years ago. Paradoxically, they are a feral animal impacting on the environment, but are also a cultural icon. Managing wild horse populations is contentious and needs to be founded on knowledge of their population ecology. This is the first study of its kind in the Australian Alps and therefore has a broad focus. Four general areas were addressed: distribution, estimation of abundance and density, population dynamics and the influence of brumby-running. The study was conducted between 1999 and 2002 inclusive in the Australian Alps national parks, which form a contiguous protected area in south-eastern Australia from the Australian Capital Territory (ACT) in the north, through New South Wales (NSW) and into Victoria in the south. The current distribution of wild horses in the Australian Alps national parks is patchy. There are five major discrete populations in NSW and Victoria with the northern most population in Kosciuszko National Park (NSW) bordering on the ACT. A review of published material and oral history reveals historic influences on distribution. The presence of each population is associated with introductions by people. The distribution of some populations expanded after introductions and many have fluctuated over time. Distributions have been contained or reduced through control by people, natural events such as snow and drought and by geographical barriers. Park managers eliminated a population of wild horses in the ACT in the 1980s. Distributions have expanded in areas without active management (notably northern Kosciuszko National Park) and are likely to continue expanding under a policy of no management. In February and March 2001, abundance and density of wild horses were estimated by helicopter aerial survey in areas where the mapping showed horses to occur. This was the first time that these parameters have been estimated empirically. I compared three different aerial survey techniques (strip, mark-recapture and line transect) based on relative accuracy and precision and found that line transect analysis gave the highest, most precise estimate. Given that aerial surveys usually underestimate abundance, this method was also likely to be the most accurate. Mark-recapture over a 50m wide strip gave a similar result but lacked precision. Strip and mark-recapture techniques performed poorly over 200m strips because animals were missed. Numbers observed dropped off dramatically beyond the 50m strip. Line transect analysis (for both observers combined) gave an estimate of 5010 (+/- 1408SE) horses while mark recapture over 50 metres gave an estimate of 4915 (+/-2733SE). These estimates correspond to a density of 1.8 horses km-2 over the area surveyed (2789km2). The results suggest that aerial surveys of large mammals using a wide strip width (200m) and mark recapture analysis may seriously underestimate population density. The population dynamics and demography of wild horses were estimated at three sites, Big Boggy, Cowombat and Currango, every spring and autumn over 3 years. The sites were spread widely across the Alps with the aim of obtaining a broad understanding of population dynamics. The survey used Pollock�s robust design and natural markings were used to identify individuals. There was a seasonal spring peak in population size at Big Boggy with no clear seasonal trend at the other two sites. Mean wild horse densities determined at Big Boggy (2.01km-2) and Currango (2.13km-2) were not significantly (p<0.5) different to the density calculated in the aerial survey, whereas density was significantly higher at Cowombat (6.4 km-2). Census techniques were of limited use in estimating annual population growth rate because of low precision. Demographic analysis showed that none of the populations were increasing at the maximum intrinsic rate (l = 1.2), and the Big Boggy and Cowombat populations may be stable (l = 1.0/yr). There was an apparent trend of food limitation across the sites. Body condition was positively related (p<0.01) to pasture biomass. The Currango population was increasing (l = 0.09) associated with higher recruitment, body condition and pasture biomass than in the other two populations studied. The Cowombat population had the lowest annual finite rate of increase (l = 1.03), and horses at this site were in the poorest condition and pasture biomass was lowest. The Big Boggy population was intermediate between the two. Annual adult survival was constant in all populations at 0.91. Survival in the first three years of life was more variable with the average at each site ranging from 0.63/yr to 0.76/yr. An average of 0.26 female foals was born per adult female per year. Sensitivity analysis showed that population growth rate is most sensitive to changes in adult survival, followed by fecundity and then survival in the first three years of life. The dynamics observed at each site was representative of the demography of wild horses in other parts of the world and is typical for large mammalian herbivores. Brumby-running is a form of harvesting that is currently being used to control wild horses in the Alpine National Park (Victoria) and is soon to be trialled in Kosciuszko National Park (NSW). The effectiveness of brumby-running has not been assessed prior to this study. Data collected by the Alpine Brumby Management Association and predictive modelling were used to examine the influence of brumby-running on the wild horse population in Alpine National Park. Brumby-runners remove about 200 horses per year with a preference for young animals and adult females. More horses are caught in autumn (61/yr) and least in summer (30/yr) (p<0.05). Brumby-runners do not appear (p>0.05) to target horses in poor condition. One skilled brumby-runner caught an average of 1.16 horses/day, while his companions caught an average of 0.55 horses/day. Brumby-runners show behaviour analogous to social carnivores. Predictive modelling suggests that brumby-runners could suppress the population of wild horses in Alpine National Park similar to the effects of predators, or human harvesting of other large mammals. Selecting young animals in the harvest reduces the impact of harvesting on the population compared to unselective harvesting, while selecting adult females increases the predicted impact. There are several management recommendations based on the findings of this thesis that address concerns for both environmental impact and the cultural value of wild horses. The distribution of wild horses should not be allowed to expand further, and the size of the wild horse population should be prevented from increasing further. Other management recommendations that are more complex involve reducing some populations so that the level of environmental impact they are causing is acceptable. This requires a definition of �acceptable impact.� Finally managers should consider eradicating smaller populations.

Population-level dynamics are affected by temporal variation in individual vital rates of survival and reproduction, which are in turn influenced by habitat-specific processes. Variation in habitat quality within a population’s range can drive movement of individuals between different areas, and so there may be a relationship between variation in vital rates and spatial heterogeneity in population growth (λ). I investigated this relationship for the feral horses (Equus ferus caballus) of Sable Island, Nova Scotia, Canada, from 2008−2010. The horses (n = 484 in September 2010) form a closed population that is free from human interference and predation. I analyzed annual population growth using age-structured projection matrix models parameterized with survival and fertility data collected from almost every female (98.7% of females). I found some evidence of temporal variation in growth during the two years I studied the population (λ2008−2009 = 1.065, λ2009−2010 = 1.117). Age structure appears to have converged to a stable age distribution, suggesting this growth rate has been sustained in the years leading up to the end of my study. Variation in vital rates of adult fertility and foal survival made the largest contribution to annual variation in population growth. Future growth is predicted to be most influenced by proportional changes in adult survival, which remained relatively unchanged between 2008 and 2010. The population can be stratified into three spatially distinct subunits found across a west−east longitudinal gradient of water resources (access to permanent ponds vs. ephemeral water sources and holes dug in sand). I assessed the existence of source-sink dynamics to determine if individual movements between subunits could explain spatial heterogeneity in population growth. I found that spatial heterogeneity in growth appears to be most influenced by immigration and emigration events between subunits. Evidence suggests that current growth of the overall Sable Island horse population is made possible by individual emigration from more productive into less productive subunits; in particular, a source presented in the west of the island where permanent water ponds are located.

Thèse de doctorat : Physiologie et biologie des organismes, populations, interactions : Strasbourg 1 : 2007. / Texte en français et en anglais. Titre provenant de l'écran-titre. Bibliogr. p. 219-239.

African horse sickness (AHS) was reported in the south-western Khomas Region, central Namibia (22° 24.063´ S, 17° 01.791´ E; 23° 32.617´ S, 15° 53.870´ E), contrary to expectations that the arid conditions in the area would limit its occurrence. This prompted investigation into the occurrence of AHS in horses, a possible reservoir animal, the Hartmann’s mountain zebra (Equus zebra. hartmannae) and the occurrence of the Culicoides midge vector (Diptera: Ceratopogonidae) of the disease in the area. Questionnaires were used to explore the geographic characteristics of the study area, the occurrence of an expected AHS virus reservoir animal, E. z. hartmannae and AHS in horses in the study area. According to the questionnaire, rainfall patterns seem to follow topography of the area, where the north-east formed the higher rainfall (420 mm/a) high-ground and the south-western formed the lower rainfall (120 mm/a) pediment zone in the south-west. Cases of AHS occurred mostly in mid-rainfall zones. E. z. hartmannae were present throughout the area. They migrated from the southwest towards the north-eastern high-grounds during droughts, presumably along ephemeral river beds. E. z. hartmannae were sampled for blood and tissues and analysed for evidence of African Horse Sickness Virus (AHSV) infection by indirect ELISA, RT-PCR and virus isolation techniques. All useable samples tested positive for anti-AHSV antibodies. Viral RNA was demonstrated in 26% of all the zebra sampled. No viable viruses were isolated from these samples, however further research is required, as difficult sampling conditions may have yielded false-negatives. From 6 July to 21 September 2009, Culicoides midges were collected during the dry winter season in suction UV-light traps installed at five selected sites along a rainfall gradient. In 38 collections, a total of 9091 Culicoides individuals, representing 25 species were collected. The dominance of the proven vector of AHSV, Culicoides imicola Kieffer, varied in dominance from 94% near Windhoek with high altitude and relatively higher annual rainfall, to 12% at the site situated farthest southwest, with the lowest altitude and annual rainfall. From what was observed of the occurrence of AHS in horses, E. z. hartmannae and the distribution and abundance of the AHSV vector (Culicoides spp.), it was concluded that AHS can be maintained in the south-western Khomas Region even in the lowest mean annual rainfall zones. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012

African horse sickness (AHS) was reported in the south-western Khomas Region, central Namibia (22° 24.063´ S, 17° 01.791´ E; 23° 32.617´ S, 15° 53.870´ E), contrary to expectations that the arid conditions in the area would limit its occurrence. This prompted investigation into the occurrence of AHS in horses, a possible reservoir animal, the Hartmann’s mountain zebra (Equus zebra. hartmannae) and the occurrence of the Culicoides midge vector (Diptera: Ceratopogonidae) of the disease in the area. Questionnaires were used to explore the geographic characteristics of the study area, the occurrence of an expected AHS virus reservoir animal, E. z. hartmannae and AHS in horses in the study area. According to the questionnaire, rainfall patterns seem to follow topography of the area, where the north-east formed the higher rainfall (420 mm/a) high-ground and the south-western formed the lower rainfall (120 mm/a) pediment zone in the south-west. Cases of AHS occurred mostly in mid-rainfall zones. E. z. hartmannae were present throughout the area. They migrated from the southwest towards the north-eastern high-grounds during droughts, presumably along ephemeral river beds. E. z. hartmannae were sampled for blood and tissues and analysed for evidence of African Horse Sickness Virus (AHSV) infection by indirect ELISA, RT-PCR and virus isolation techniques. All useable samples tested positive for anti-AHSV antibodies. Viral RNA was demonstrated in 26% of all the zebra sampled. No viable viruses were isolated from these samples, however further research is required, as difficult sampling conditions may have yielded false-negatives. From 6 July to 21 September 2009, Culicoides midges were collected during the dry winter season in suction UV-light traps installed at five selected sites along a rainfall gradient. In 38 collections, a total of 9091 Culicoides individuals, representing 25 species were collected. The dominance of the proven vector of AHSV, Culicoides imicola Kieffer, varied in dominance from 94% near Windhoek with high altitude and relatively higher annual rainfall, to 12% at the site situated farthest southwest, with the lowest altitude and annual rainfall. From what was observed of the occurrence of AHS in horses, E. z. hartmannae and the distribution and abundance of the AHSV vector (Culicoides spp.), it was concluded that AHS can be maintained in the south-western Khomas Region even in the lowest mean annual rainfall zones. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2012

A tonometria é de extrema importância durante o exame oftálmico, pois auxilia no diagnóstico e no acompanhamento do glaucoma e de inflamações intraoculares. No entanto, os valores da pressão intraocular podem sofrer influência do momento do dia em que o exame é realizado. Objetivou-se avaliar a pressão intraocular (PIO) com tonômetro de rebote em equinos hígidos da raça Crioula em diferentes horários do dia. Foram avaliados ambos os olhos de 25 cavalos da raça Crioula, machos ou fêmeas, subdivididos em três categorias de diferentes idades designadas por GI: nove animais (3-5 anos de idade), GII: oito animais (6-8 anos de idade) e GIII: oito animais (9-16 anos de idade). Previamente à tonometria foram realizados teste lacrimal de Schirmer, biomicroscopia com lâmpada de fenda, prova da fluoresceína e oftalmoscopia indireta em todos os equinos. Num mesmo dia foram realizadas sete aferições da PIO (às 6, 9, 12, 15, 18, 21 e 24 horas). A avaliação estatística utilizou o teste T de Student quando haviam dois grupos de comparações, e o teste de análise de variância (ANOVA) para as variáveis PIO, horário de aferição (tempo) e categoria de idade. O valor médio da pressão intraocular obtido foi de 28,4±3,7 mmHg considerando todos os animais avaliados. Os valores médios da pressão intraocular para os equinos de GI, GII e GIII foram 29,2±3,5 mmHg, 28,4±4,3 mmHg e 27,7±3,2 mmHg, respectivamente. Não houve diferença estatisticamente significativa entre os olhos direito e esquerdo (p= 0,257), nem entre sexos (p= 0,284). Quando comparadas as idades, a PIO média foi significativamente maior nos indivíduos jovens (p= 0,012). Não houve diferença estatisticamente significativa entre os diferentes horários do dia (p= 0,560). Os valores da PIO aferidos com o tonômetro de rebote em equinos da raça Crioula sofreram influência da idade. Os valores da pressão intraocular média obtidos com tonômetro de rebote em equinos hígidos não variaram em diferentes horários ao longo do dia. / The tonometry is extremely important during ophthalmic examination, because assists in the diagnosis and follow-up of glaucoma and intraocular inflammation. However, intraocular pressure values may be influenced by the moment of the day it is measured. The objective was to evaluate the intraocular pressure (IOP) with Rebound Tonometer in healthy horses of the Crioula breed at different times of the day. Twenty five horses, male or female, were divided into three groups by age: Group I: nine horses (3-5 years old), Group II: eight horses (6-8 years old), and Group III: eight horses (9-16 years old). Ophthalmic examination was performed previously by Schirmer Tear Test, slit lamp biomicroscopy, fluorescein test and indirect ophthalmoscopy in all horses. Seven measurements of intraocular pressure were assessed on the same day (at 6, 9, 12, 15, 18, 21 and 24 hours).The Student’s T Test statistical analysis was used when there was two groups of comparisons, and the Analysis of Variance (ANOVA) was used for variables IOP, measurement time and age category. The average value of intraocular pressure was 28.4 ± 3.7 mmHg considering all the animals evaluated. The mean intraocular pressure for groups I, II and III were 29.2 ± 3.5 mmHg, 28.4 ± 4.3 mmHg and 27.7 ± 3.2 mmHg, respectively. There was no statistically significant difference between right and left eyes (p = 0.257), nor between genders (p = 0.284). When compared to the ages, the average IOP was significantly higher in young animals (p = 0.012). There was no statistically significant result between the different times of the day (p = 0.560). The IOP values measured with rebound tonometer in Crioula horses were influenced by age. The average intraocular pressure values obtained with rebound tonometer in healthy horses did not change with time of day.

A tonometria é de extrema importância durante o exame oftálmico, pois auxilia no diagnóstico e no acompanhamento do glaucoma e de inflamações intraoculares. No entanto, os valores da pressão intraocular podem sofrer influência do momento do dia em que o exame é realizado. Objetivou-se avaliar a pressão intraocular (PIO) com tonômetro de rebote em equinos hígidos da raça Crioula em diferentes horários do dia. Foram avaliados ambos os olhos de 25 cavalos da raça Crioula, machos ou fêmeas, subdivididos em três categorias de diferentes idades designadas por GI: nove animais (3-5 anos de idade), GII: oito animais (6-8 anos de idade) e GIII: oito animais (9-16 anos de idade). Previamente à tonometria foram realizados teste lacrimal de Schirmer, biomicroscopia com lâmpada de fenda, prova da fluoresceína e oftalmoscopia indireta em todos os equinos. Num mesmo dia foram realizadas sete aferições da PIO (às 6, 9, 12, 15, 18, 21 e 24 horas). A avaliação estatística utilizou o teste T de Student quando haviam dois grupos de comparações, e o teste de análise de variância (ANOVA) para as variáveis PIO, horário de aferição (tempo) e categoria de idade. O valor médio da pressão intraocular obtido foi de 28,4±3,7 mmHg considerando todos os animais avaliados. Os valores médios da pressão intraocular para os equinos de GI, GII e GIII foram 29,2±3,5 mmHg, 28,4±4,3 mmHg e 27,7±3,2 mmHg, respectivamente. Não houve diferença estatisticamente significativa entre os olhos direito e esquerdo (p= 0,257), nem entre sexos (p= 0,284). Quando comparadas as idades, a PIO média foi significativamente maior nos indivíduos jovens (p= 0,012). Não houve diferença estatisticamente significativa entre os diferentes horários do dia (p= 0,560). Os valores da PIO aferidos com o tonômetro de rebote em equinos da raça Crioula sofreram influência da idade. Os valores da pressão intraocular média obtidos com tonômetro de rebote em equinos hígidos não variaram em diferentes horários ao longo do dia. / The tonometry is extremely important during ophthalmic examination, because assists in the diagnosis and follow-up of glaucoma and intraocular inflammation. However, intraocular pressure values may be influenced by the moment of the day it is measured. The objective was to evaluate the intraocular pressure (IOP) with Rebound Tonometer in healthy horses of the Crioula breed at different times of the day. Twenty five horses, male or female, were divided into three groups by age: Group I: nine horses (3-5 years old), Group II: eight horses (6-8 years old), and Group III: eight horses (9-16 years old). Ophthalmic examination was performed previously by Schirmer Tear Test, slit lamp biomicroscopy, fluorescein test and indirect ophthalmoscopy in all horses. Seven measurements of intraocular pressure were assessed on the same day (at 6, 9, 12, 15, 18, 21 and 24 hours).The Student’s T Test statistical analysis was used when there was two groups of comparisons, and the Analysis of Variance (ANOVA) was used for variables IOP, measurement time and age category. The average value of intraocular pressure was 28.4 ± 3.7 mmHg considering all the animals evaluated. The mean intraocular pressure for groups I, II and III were 29.2 ± 3.5 mmHg, 28.4 ± 4.3 mmHg and 27.7 ± 3.2 mmHg, respectively. There was no statistically significant difference between right and left eyes (p = 0.257), nor between genders (p = 0.284). When compared to the ages, the average IOP was significantly higher in young animals (p = 0.012). There was no statistically significant result between the different times of the day (p = 0.560). The IOP values measured with rebound tonometer in Crioula horses were influenced by age. The average intraocular pressure values obtained with rebound tonometer in healthy horses did not change with time of day.

In 2010, Simon Estok observed that, "the most immediate question ecocriticism can ask is about how our assumptions about animals affect the natural environment". In this thesis, I respond to this challenge by generating a sustained conversation between the hitherto surprisingly distinct fields of animal studies and ecocriticism. I do this by formulating a new critical concept, that of the geomorphic animal, which I use to show how literary representations of animals often expose the many complex ways in which they constitute space rather than simply inhabiting it. This, in turn, should make them central to future ecocritical readings. I focus on two periods, medieval and modern; the broad historical and generic scope of this thesis is intended to demonstrate the conceptual validity and robustness of geomorphic readings. Chapter One shows how concerns with death and symbiosis are expressed through the earth-bound activities of the geomorphic animals of the Exeter Book riddles. Chapter Two examines geomorphic whales in texts deriving from two related traditions: the Book of Jonah and the Physiologus. Chapters Three and Four focus on modern theatre, which affords distinctive ways of articulating the spatial implications of geomorphism. Chapter Three discusses the literary representation of museums and zoos in terms of the interpretative complexities generated by staging and spectacle. Chapter Four, focusing on mediation, discusses the interplay between animals, viewpoints and place in theatre, also taking into account particular issues arising from the adaptation of plays into films. This argument paves the way to addressing the geomorphic depiction of marginalised humans and human groups, suggesting the critical potential of geomorphism as a means of furthering feminist and post-colonialist aims.

A tonometria é de extrema importância durante o exame oftálmico, pois auxilia no diagnóstico e no acompanhamento do glaucoma e de inflamações intraoculares. No entanto, os valores da pressão intraocular podem sofrer influência do momento do dia em que o exame é realizado. Objetivou-se avaliar a pressão intraocular (PIO) com tonômetro de rebote em equinos hígidos da raça Crioula em diferentes horários do dia. Foram avaliados ambos os olhos de 25 cavalos da raça Crioula, machos ou fêmeas, subdivididos em três categorias de diferentes idades designadas por GI: nove animais (3-5 anos de idade), GII: oito animais (6-8 anos de idade) e GIII: oito animais (9-16 anos de idade). Previamente à tonometria foram realizados teste lacrimal de Schirmer, biomicroscopia com lâmpada de fenda, prova da fluoresceína e oftalmoscopia indireta em todos os equinos. Num mesmo dia foram realizadas sete aferições da PIO (às 6, 9, 12, 15, 18, 21 e 24 horas). A avaliação estatística utilizou o teste T de Student quando haviam dois grupos de comparações, e o teste de análise de variância (ANOVA) para as variáveis PIO, horário de aferição (tempo) e categoria de idade. O valor médio da pressão intraocular obtido foi de 28,4±3,7 mmHg considerando todos os animais avaliados. Os valores médios da pressão intraocular para os equinos de GI, GII e GIII foram 29,2±3,5 mmHg, 28,4±4,3 mmHg e 27,7±3,2 mmHg, respectivamente. Não houve diferença estatisticamente significativa entre os olhos direito e esquerdo (p= 0,257), nem entre sexos (p= 0,284). Quando comparadas as idades, a PIO média foi significativamente maior nos indivíduos jovens (p= 0,012). Não houve diferença estatisticamente significativa entre os diferentes horários do dia (p= 0,560). Os valores da PIO aferidos com o tonômetro de rebote em equinos da raça Crioula sofreram influência da idade. Os valores da pressão intraocular média obtidos com tonômetro de rebote em equinos hígidos não variaram em diferentes horários ao longo do dia. / The tonometry is extremely important during ophthalmic examination, because assists in the diagnosis and follow-up of glaucoma and intraocular inflammation. However, intraocular pressure values may be influenced by the moment of the day it is measured. The objective was to evaluate the intraocular pressure (IOP) with Rebound Tonometer in healthy horses of the Crioula breed at different times of the day. Twenty five horses, male or female, were divided into three groups by age: Group I: nine horses (3-5 years old), Group II: eight horses (6-8 years old), and Group III: eight horses (9-16 years old). Ophthalmic examination was performed previously by Schirmer Tear Test, slit lamp biomicroscopy, fluorescein test and indirect ophthalmoscopy in all horses. Seven measurements of intraocular pressure were assessed on the same day (at 6, 9, 12, 15, 18, 21 and 24 hours).The Student’s T Test statistical analysis was used when there was two groups of comparisons, and the Analysis of Variance (ANOVA) was used for variables IOP, measurement time and age category. The average value of intraocular pressure was 28.4 ± 3.7 mmHg considering all the animals evaluated. The mean intraocular pressure for groups I, II and III were 29.2 ± 3.5 mmHg, 28.4 ± 4.3 mmHg and 27.7 ± 3.2 mmHg, respectively. There was no statistically significant difference between right and left eyes (p = 0.257), nor between genders (p = 0.284). When compared to the ages, the average IOP was significantly higher in young animals (p = 0.012). There was no statistically significant result between the different times of the day (p = 0.560). The IOP values measured with rebound tonometer in Crioula horses were influenced by age. The average intraocular pressure values obtained with rebound tonometer in healthy horses did not change with time of day.

The Cape Mountain Zebra (CMZ) has been described as one of the most vulnerable mammals in the Republic of South Africa with current populations existing in isolated units. In recent years, South African conservation officials have noted the appearance of tumour like growths, similar to equine sarcoids, in some of these populations. The possibility that the existing populations, numbering around 1 500 animals in total, arose from a very small gene pool is very real, considering that in the early 1970’s there were only 35 breeding animals in the Mountain Zebra National Park. A genetic component to the susceptibility to sarcoid tumour development has been identified in horses. Researchers have found an association between susceptibility to sarcoid and certain heritable cell-surface proteins called major histocompatibility antigens. Studies have reported the possibility of high levels of inbreeding in CMZ in the Bontebok National Park (BNP). The non-territorial social organisation of mountain zebras allows the population to increase to a high density within a relatively short period of time. These observations, coupled with the fact that there are no confirmed reports of sarcoids in the relatively outbred Burchell’s zebra population in the Kruger National Park and the Hartmann’s mountain zebra populations in Namibia, strongly support the hypothesis that a correlation exists between inbreeding in zebra populations and expression of sarcoids. The small number of CMZ in BNP with an apparent high prevalence of suspected sarcoid tumours made this an ideal population to capture, identify and to study the skin tumour. The entire population of CMZ in the BNP was observed and sampled. A total of 15 CMZ was present in the Park at the time of the study. The individual animals were darted from a helicopter using M99, Azaperone and Hyalase after which a ground team moved in and covered their eyes and ears. Each animal was thoroughly examined for the presence of any tumours; the distribution was recorded on a body chart and sizes and appearance were recorded. Anatomical location on the body was divided into head and neck, ventral abdomen and limbs. Biopsies were taken from all of the zebras with sarcoid-like growths. The sarcoids were either surgically excised or a representative biopsy was taken by means of 6mm biopsy punches. The samples were collected in 10% buffered formalin for histological examination. The prevalence of sarcoid in CMZ in BNP was 53%. Of the affected animals, 50% had multiple tumours. The main predilection sites were on the trunk, followed by the limbs and then the head and neck. The severity of the lesions in one stallion was so extreme that it warranted euthanasia. The verrucous type, followed by much lower percentages of the fibroblastic and nodular types, dominated the clinical appearance. Lastly, the sarcoids examined showed either all or some of the typical epidermal and dermal histological features of equine sarcoid. A total of 7 of the affected CMZ were treated using four different methods. The sarcoids were surgically excised (n = 2), treated with intra-lesional 5-fluorouracil (n = 2), autogenous vaccine (n = 2) or autogenous vaccine combined with 5-fluorouracil (n =1). The zebras were immobilised for examination 18 months later. One animal that had been treated with intralesional 5-fluorouracil only had large numbers of verrucous and fibroblastic sarcoids. Her condition was so severe that she had to be euthanased. No signs of sarcoids could be found anywhere on the remaining 6 treated CMZ. This study confirmed that the growths in the CMZ in BNP population are indeed sarcoids and that many of them exhibit an aggressive nature. Sarcoid tumours is a disease that is considered multifactorial in aetiology and therefore other parameters such as immune status of tumour-affected populations and associated environmental variables warrant further investigation. / Dissertation (MSc (CACS))--University of Pretoria, 2006. / Companion Animal Clinical Studies / unrestricted