Made available in DSpace on 2014-08-13T14:50:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-22Bitstream added on 2014-08-13T18:01:17Z : No. of bitstreams: 1 000725296_20150101.pdf: 109418 bytes, checksum: cebf9f97c8e08074ee65a1e7f67f9863 (MD5) Bitstreams deleted on 2015-01-05T11:00:50Z: 000725296_20150101.pdf,Bitstream added on 2015-01-05T11:01:48Z : No. of bitstreams: 1 000725296.pdf: 956123 bytes, checksum: 50d72cefdb85fffba1d5001620776c3f (MD5) / Este estudo foi realizado para caracterizar os achados dermatológicos, oftalmológicos e morfológicos da pele de cavalos com Astenia Dérmica Regional Hereditária Equina (HERDA) e padronizar um ensaio de “High Resolution Melting” (HRM), para determinar a ocorrência de heterozigotos. As avaliações e a padronização do HRM foram realizadas em cinco cavalos afetados (GA) e cinco não afetados (GC). Adicionalmente, cinco animais heterozigotos (GH) foram utilizados para padronizar o HRM. A ocorrência de heterozigotos foi determinada em 690 animais. Diversas regiões da pele foram mensuradas com cutímetro no GA e GC. Biópsias de pele foram submetidas aos exames histopatológico e ultraestrutural. Avaliação histopatológica foi realizada por dois patologistas. O exame oftalmológico incluiu, além das avaliações rotineiras, aferição dos diâmetros da córnea, paquimetria e biometria. Foi extraído DNA do sangue colhido do GA, GC, GH e de 690 cavalos e o HRM foi validado. Observou-se menor espessura de pele no GA. A sensibilidade e especificidade do diagnóstico histopatológico da pele dependeram do avaliador e da região, respectivamente. Foram observados menor espessura e maior curvatura e diâmetros da córnea no GA. O HRM apresentou elevadas acurácia e precisão. A frequência de heterozigotos foi de 4,7%. Apesar do padrão regional dos sinais dermatológicos, a diminuição da espessura da pele não é regional. Para o diagnóstico histopatológico, recomenda-se realizar biópsia de pele no pescoço, garupa ou dorso. A relevância clínica dos achados oftalmológicos deve ser investigada. O ensaio de HRM padronizado será útil na seleção dos acasalamentos, visando minimizar a ocorrência da doença / The present study was conducted to characterize the dermatological, ophthalmological, and morphological findings from horses affected with Hereditary Equine Regional Dermal Asthenia (HERDA) and to standardize a High Resolution Melting (HRM) genotyping assay to determine the frequency of carriers. The evaluations and HRM standardization were performed in five affected (AG) and five non-affected (CG) horses. Additionally, five heterozygous (HG) horses were used to HRM standardization. The frequency of carriers was determined in 690 horses. Several skin regions of both groups were measured with a cutimeter Skin biopsies were submitted to histopathological and ultrastructural evaluations. Histopathological evaluation was performed by two pathologists. Ophthalmology included, besides the routine evaluations, corneal diameters measurement, pachymetry, and biometry. HRM was validated using purified DNA from blood samples of the AG, CG, HG and 690 horses. Skin thickness decrease was observed in the AG. Histopathological sensitivity and specificity to diagnose HERDA was dependent on the evaluator and region, respectively. HERDA horses exhibited decreased corneal thickness and increased corneal curvature and corneal diameters. The HRM assay resulted in high accuracy and precision. The estimated carrier frequency was 4.7%. Despite of the regional pattern of the dermatological signs, the decrease of skin thickness from HERDA horses is not regional. Skin samples of the neck, croup or back are recommended to diagnose HERDA. The relevance of the ocular findings should be further investigated. The standardized HRM assay will be useful in the management of breeding programs to minimize the occurrence of this disease

Orientador: Alexandre Secorun Borges / Banca: Carlos Alberto Hussni / Banca: João Pessoa Araújo Junior / Banca: Luiz Claudio Nogueira Mendes / Banca: Paulo Henrique Jorge da Cunha / Resumo: Este estudo foi realizado para caracterizar os achados dermatológicos, oftalmológicos e morfológicos da pele de cavalos com Astenia Dérmica Regional Hereditária Equina (HERDA) e padronizar um ensaio de "High Resolution Melting" (HRM), para determinar a ocorrência de heterozigotos. As avaliações e a padronização do HRM foram realizadas em cinco cavalos afetados (GA) e cinco não afetados (GC). Adicionalmente, cinco animais heterozigotos (GH) foram utilizados para padronizar o HRM. A ocorrência de heterozigotos foi determinada em 690 animais. Diversas regiões da pele foram mensuradas com cutímetro no GA e GC. Biópsias de pele foram submetidas aos exames histopatológico e ultraestrutural. Avaliação histopatológica foi realizada por dois patologistas. O exame oftalmológico incluiu, além das avaliações rotineiras, aferição dos diâmetros da córnea, paquimetria e biometria. Foi extraído DNA do sangue colhido do GA, GC, GH e de 690 cavalos e o HRM foi validado. Observou-se menor espessura de pele no GA. A sensibilidade e especificidade do diagnóstico histopatológico da pele dependeram do avaliador e da região, respectivamente. Foram observados menor espessura e maior curvatura e diâmetros da córnea no GA. O HRM apresentou elevadas acurácia e precisão. A frequência de heterozigotos foi de 4,7%. Apesar do padrão regional dos sinais dermatológicos, a diminuição da espessura da pele não é regional. Para o diagnóstico histopatológico, recomenda-se realizar biópsia de pele no pescoço, garupa ou dorso. A relevância clínica dos achados oftalmológicos deve ser investigada. O ensaio de HRM padronizado será útil na seleção dos acasalamentos, visando minimizar a ocorrência da doença / Abstract: The present study was conducted to characterize the dermatological, ophthalmological, and morphological findings from horses affected with Hereditary Equine Regional Dermal Asthenia (HERDA) and to standardize a High Resolution Melting (HRM) genotyping assay to determine the frequency of carriers. The evaluations and HRM standardization were performed in five affected (AG) and five non-affected (CG) horses. Additionally, five heterozygous (HG) horses were used to HRM standardization. The frequency of carriers was determined in 690 horses. Several skin regions of both groups were measured with a cutimeter Skin biopsies were submitted to histopathological and ultrastructural evaluations. Histopathological evaluation was performed by two pathologists. Ophthalmology included, besides the routine evaluations, corneal diameters measurement, pachymetry, and biometry. HRM was validated using purified DNA from blood samples of the AG, CG, HG and 690 horses. Skin thickness decrease was observed in the AG. Histopathological sensitivity and specificity to diagnose HERDA was dependent on the evaluator and region, respectively. HERDA horses exhibited decreased corneal thickness and increased corneal curvature and corneal diameters. The HRM assay resulted in high accuracy and precision. The estimated carrier frequency was 4.7%. Despite of the regional pattern of the dermatological signs, the decrease of skin thickness from HERDA horses is not regional. Skin samples of the neck, croup or back are recommended to diagnose HERDA. The relevance of the ocular findings should be further investigated. The standardized HRM assay will be useful in the management of breeding programs to minimize the occurrence of this disease / Doutor

MA / African horsesickness is a disease endemic in Sub Saharan Africa affecting horses, a non-native species, which are extremely susceptible to this disease. Both the ‘dunkop’ form (with its dramatic high fever, laboured breathing, frothy nasal discharge and sudden death) and the ‘dikkop’ form (with its swollen head and eyes and bleeding in the membranes of the mouth and eyes) have been visited upon equine populations and their human owners in successive epidemics through the earliest colonial settlement until recent times. This thesis traces the development of veterinary science in South Africa and the effect it had on the changing ideas surrounding African horsesickness. It explores not only the veterinary progress in the country but also the impact of the progress on African horsesickness as other diseases received attention. The discussion traces the disease from one of the major epidemics ever encountered in the country, in the mid nineteenth century, to the beginning of the development of veterinary services in South Africa when little was known about African horsesickness. It illustrates the implications of a country's struggle with animal disease, the reasons for a lack of knowledge and the ramifications of the Onderstepoort Veterinary Institute’s interventions. This thesis shows that African horsesickness not only had an impact on the veterinary developments of the country but was also indirectly involved in the South African War, 1899-1902. It demonstrates the impact of disease during wartime while illustrating the importance of horses during such difficult times. Thus, this thesis draws on works on animal diseases and on social history to explore not only the effect African horsesickness had historically on equines, but the effects it had more broadly on southern African society. This study is intended to bring insight into the social history of the disease itself: how it was experienced by livestock owners and also how settler and indigenous efforts were turned towards combating this dramatic disease.

M. Tech. / Purpose: Trigger points in the paraspinal muscles are commonly associated with lameness or stiffness in horses, and unless they are “released”, muscle power and flexibility are impaired and athletic performance is reduced (Rogers, Fischer, Pontinen, and Janssens, 1996). The aim of this study was to determine the immediate and the prolonged effects of Sacroiliac mobilization on spot tenderness within the Erector spinae muscles of performance horses. Method: Horses from a selected stable yard underwent a screening process under the supervision of a qualified Chiropractor and Veterinarian to identify horses suitable for the study. Thirty horses were selected for the study based on the inclusion and exclusion criteria. The sample was divided into two groups of fifteen horses. The experiment group received mobilization therapy for SI joint restrictions, while the control group did not receive any treatment intervention. Procedure: Horses received an initial treatment and two follow ups, totaling three treatments. The first follow up treatment was two days after the initial and the second was four days post initial treatment. During these treatment sessions, trigger points in the Erector spinae muscles were located in each horse and algometer measurements were taken. Sacroiliac restrictions were then identified using motion palpation and passive range of motion as indicators. The researcher performed a mobilization technique on the Sacroiliac joints of horses in the experiment group only, and thereafter both groups were reassessed two minutes later, via an algometer, for spot tenderness within the same trigger points. The Sacroiliac restrictions and trigger points were re-assessed without treatment two weeks later. Conclusion: The results indicated that low-velocity Sacroiliac mobilization was effective in increasing the pain-pressure tolerance within the Erector spinae muscles of performance horses immediately and over the treatment period of two weeks.

Potomac Horse Fever (PHF) is a disease of great concern to many horse owners in the Potomac River area of Maryland and Virginia. It is caused by a rickettsia, Ehrlichia risticii. The involvement of an arthropod vector has been suspected because of the seasonal epidemiology of the disease. This research was an attempt to identify and evaluate potential arthropod vectors. A seasonal activity study of biting arthropods attacking horses in endemic areas of Maryland and Virginia identified five potential vectors: (1) Simulium jenningsi (Diptera: Simuliidae), (2) Stomoxys calcitrans (Diptera: Muscidae), (3) Culicoides obsoletus (Diptera: Ceratopogonidae), (4) C. variipennis, and (5) Dermacentor variabilis (Acari: Ixodidae). These five arthropod species were given status as potential vectors because they were collected feeding on horses just prior to and throughout the PHF season. Simulium jenningsi and D. variabilis have the closest seasonal association with the occurrence of PHF as presented in this study. D. variabilis was determined to have the greatest potential due to its reported association with other rickettsial diseases. A series of laboratory and field studies were designed to examine the potential role of D. variabilis in the transmission of E. risticii. We first attempted to transmit E. risticii by feeding adult D. variabilis collected from an endemic farm on susceptible horses. Other laboratory studies included mouse to horse and mouse to mouse transmission attempts using ticks fed on mice inoculated with E. risticii. A serological survey of 105 trapped field rodents (host of immature D. variabilis) on endemic farms in Maryland showed all specimens collected to be negative for PHF antibodies. These studies and others gave no indication of D. variabilis's involvement in the transmission of the disease in nature. The other species mentioned above were not examined. / Ph. D.

African horse sickness (AHS) is a non-contagious viral disease transmitted by an arthropod vector and is endemic to sub-Saharan Africa. The disease affects all equine species, but is more severe in horses and other equid species not native to Africa. Vaccination is the only demonstrated means of its prevention. The horse-owning public provides much anecdotal evidence of prophylactic strategies, such as repellents, stabling, alternate hosts, traps, paraffin, blankets, smoke or fans. The present study investigated the relationship of these strategies to the incidence of AHS, and evaluated alternate hosts, wind speed and repellents on the activity of males and females of the different Culicoides species.. Cypermethrin and citronella-containing repellents repelled the most female midges. Sheep and cattle offer an alternate blood meal to gravid and nulliparous female midges. Fans are very effective in keeping midges away from horses. Methods are summarised for the horse owner to implement in addition to vaccination to prevent AHS. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

African horse sickness virus causes a non-contagious, infectious disease of equids. It is epizootic to sub-Saharan Africa and parts of the Middle East. The epizootics caused by the virus have caused widespread devastation amongst equids worldwide. Fortunately no epizootic has lasted more than 5 years outside of sub- Saharan Africa. It is vectored by species of Culicoides midges (Diptera: Ceratopogonidae) and most importantly by the two Avarita species of C. imicola Keiffer and C. bolitinos Meiswinkel. The literature pertaining to the study and research of the virus, the disease and the vectors is reviewed. Models allowing prediction of future possible outbreaks as well as details of control strategies and findings of researchers are presented and discussed. The virus needs a long term reservoir host in which to overwinter and various theories are discussed. Control measures in South Africa are suggested so that outbreaks of the disease can be reduced. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermarizburg, 2008.

A naturally occurring disease involving hyperplasia of the thyroid gland and a consistent pattern of musculoskeletal deformities of newborn foals in western Canada was first described in 1981. This disease was an important cause of foal mortality and, therefore, reproductive loss throughout western Canada during the 1990s and has since been recognized in western Ontario and the northwestern United States. A series of investigations were conducted to describe, characterize, and attempt to determine the pathogenesis and cause of this syndrome. Affected foals were typically born after a long gestation (x = 360 days, range = 340 to 400 days), were diagnosed as hypothyroid based on a poor response to the administration of thyroid-stimulating hormone, and had various musculoskeletal lesions of which mandibular prognathism, flexural deformities and rupture of tendons of the limbs, and incomplete ossification of the carpal and tarsal bones were present most commonly. In spite of the normal to long gestation, foals had signs of immaturity, were usually weak and unable to stand, became septic, and died or were euthanatised. Similar histories, clinical findings, and lesions were present in surgically created hypothyroid foals that were thyroidectomized in utero at about 210 days gestation. These findings supported the conclusion that foals which naturally developed these lesions were also hypothyroid in utero and that all the lesions present in affected foals were the result of the hypothyroidism and not of an underlying concurrent disease process. A case-control study was conducted to identify risk factors for naturally occurring congenital hypothyroidism. Information from congenitally hypothyroid foals concerning foal and dam signalment, farm environment, and dam management was compared with that from normal foals. Pregnant mares fed greenfeed, not supplemented with mineral, that left their "home farm" during gestation, or grazed irrigated pasture, had a 13.1 (<i>P</i>=0.0068), 5.6 (<i>P</i>=0.0472), 4.3 (<i>P</i>=0.0076) and approximately 15.3 (<i>P</i>=0.0245) times greater odds, respectively, of producing a congenitally hypothyroid foal than mares not exposed to these factors. Greenfeed often contains high levels of nitrate (NO₃^-) which is known to impair thyroid gland function. In light of this, forage samples from participating farms were analysed for nitrate levels. The odds of one or more congenitally hypothyroid foal being born on a farm feeding forage with at least a trace of nitrate was 8.0 times greater (<i>P</i>=0.0873) than the odds of the disease occurring a farm that fed forage free of nitrate. Further, the odds of a mare producing an affected foal when fed forage containing at least a trace of nitrate was 5.9 times greater (<i>P</i>=0.0007) than a mare fed nitrate-free forage.This study suggests that congenital hypothyroidism in foals may result from diets containing nitrate or low in iodine being fed to pregnant mares. These results need to be confirmed through further field investigations and controlled experiments. However, if they are accurate, there is cause for concern that other livestock raised in areas where congenitally hypothyroid foals occur may be exposed to the same dietary risk factors and may suffer similar disease.

House flies (Musca domestica L.) are common pests affecting horses and their owners. Control of house flies in stable yards is currently based on the use of pesticides. However, the development of resistance by these flies to most pesticide groups has motivated horse owners to seek alternative methods of fly control. An entomopathogenic fungus, Beauveria bassiana (Bb) and an entomopathogenic bacterium, Bacillus thuringiensis var. israelensis (Bti) are two biological agents known to have activity against house flies. The broad objective of this study was to evaluate the effect of these two biological control agents on house flies in an equine environment. Using a structured questionnaire, presented in Chapter 2, thirty horse owners in KwaZulu-Natal were asked about the nuisance value of house flies, their current control measures, the potential market for biocontrol agents against house flies, and each owner’s perception of biocontrol methods. The horse owners were using three methods of house fly control namely, physical, chemical and biological. Most horse owners (97%) wanted access to effective biocontrol agents for control of house flies. Most horse owners (80%) stabled their horses at night, some or all of the time. The resultant manure piles in the stable yard were considered to be the primary cause of house fly problems. About 64% of the horse owners were dissatisfied with the currently available methods of controlling house flies in this situation. Chapter 3 covers two observational trials in which varying doses of Bacillus thuringiensis var. israelensis (Bti) were fed to horses, in order to identify a baseline dosage to give to horses in order to adequately control house fly populations growing in horse manure. The bacterium Bti, grown on wheat bran, was fed to six miniature horses at doses of 0, 0.125, 0.25, 0.5, 0.75, and 1.0 g per meal in Trial 3a, and at 0, 0.5, 1, 2, 4 and 8 g per meal in Trial 3b. Faeces were collected three times a week for 11 weeks and placed in incubation trays to allow the number of emerging adult house flies and closed pupae to be counted. In Trial 3a, there was a significant reduction in the number of closed pupae with an increase in Bti in the feed. The regression equation suggests that there will be 3.1 times as many closed pupae in the faeces when horses are fed 1 g of Bti in their feed, than when horses are fed no Bti. This dosage is the minimum baseline dosage for future trials. v Using manure from horses dosed in Trials 3a and 3b, the survival of the bacterium through the gut of horses was evaluated using a standard isolation technique. The growth of Bt colonies on the manure after the Bt isolation technique showed that some of the bacterial cells survived transition through the digestive tract of the horse. This study was qualitative in nature and did not attempt to quantify the level of Bti spore survival. These two observations suggest that Bacillus thuringiensis var. israelensis has the potential to be used as a biocontrol agent, applied via horse feed, for the control of house flies in stable yards. Future clinical trials, with appropriate replication, should be conducted using 1 g Bti/meal as the lowest test dosage. The objective of Chapter 4 was to determine whether spraying Bti or Bb on to horse manure is effective in the control of house flies. Over a six week period, two spraying trials were conducted in which increasing doses of Bb and Bti were sprayed on to 500 g samples of horse manure. Counts of house fly pupae and adults were taken. The doses of Bb and Bti tested were 0, 1, 2, 4 g in Trial 4a, and 0, 4, 8 and 12 g in Trial 4b. The research reported in Chapter 4 was characterized by the unexpectedly high levels of biological variation in egg, larvae and pupae numbers that were found in samples of horse manure, taken from the same skip two days apart. The statistical design of the two trials conducted was inadequate to cope with the high level of variation about treatment means for fly and larval counts. However, despite the lack of significant differences between treatment means, there is observational evidence that suggests that both Bb and Bti do have an effect on house fly survival. A simplified statistical model, which compared the number of hatched house flies on untreated manure, with the number on manure treated with any level of Bb (1 to 4 g /250 ml water), found a significant reduction in the number of hatched flies on treated manure. There was no significant corresponding reduction in the number of closed pupae, which suggests that Bb acts primarily before the larva pupates. The optimal dose of Bb and Bti to be sprayed on to manure could not be determined because of the high variation about treatment means. It is suggested that, in future trials similar dosages for Bb could be tested, but that higher dosages of Bti (starting at 2 g/250 ml water) should be used. Trial periods should be extended and replication increased dramatically to reduce variation about treatment means. Transformation of data before analysis may also be necessary to equalize variation about treatment means. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

Dissertation (PhD(Agric))--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: This study was carried out to investigate whether environmental and/or genetic factors had an effect on the incidence of epistaxis related to exercise-induced pulmonary haemorrhage among racehorses in Southern Africa. A further aim was to estimate the heritability of liability to epistaxis in the Southern African Thoroughbred population. For the purpose of the environmental study, the data covering the period 1986-2001 and involving a total of778 532-race runs, were analysed. This included the following race start information: date of race (day/month/year), age, sex, breeder, trainer, distance, jockey, state of going, weight carried, centre of racing and altitude. The genetic part of the data was two-fold in nature and included firstly the analysis of all horses that suffered epistaxis whilst racing in Southern Africa from 1986 to 2001 and involving 1118 individual bleeders. The second genetic analysis included the same Southern African population plus those Southern African horses exported to Mauritius and then being recorded as bleeders in that country (1252 bleeders in total). Pedigree data covering the period 1960-1986 was used as required to calculate the incidence of bleeding amongst ancestors of the post 1986 era. Only pedigrees of horses that raced were included in this study as it was not possible to predict whether non-runners would have bled had they raced. Consequently all non-runners and also those that raced overseas in countries where bleeding occurrence was not recorded were excluded. Veterinarians employed by the Jockey Club suspended officially recorded horses that showed epistaxis as demonstrated by frank bleeding from the nostrils after racing. Oncourse endoscopy is not employed as a routine on any of the Southern African racetracks. In the environmental study epistaxis was identified in 1 287 race starts (0.165%). Epistaxis related to exercise-induced pulmonary haemorrhage was significantly (p<0.001) associated with altitude, age, race year, month and the day of racing. More horses demonstrated epistaxis at sea level than at altitude, between the months of May - October than the rest of the year, in older horses than in horses less than three-years old, after 1995 than between the years 1986 and 1995, and on Fridays and Sundays than on any other week day. No association could be established between epistaxis and breeder, trainer, distance, jockey, state of going, sex and weight carried. The heritability of liability method as described by Falconer (1989) was used to estimate the relative importance of heredity and environment. For the period investigated, the population incidence for epistaxis in Southern African horses was 2.1%. The estimation of heritability ofliability showed that first-degree relatives had a figure of 55.4%. The heritability of second- and third degree relatives were 41.3% and 30.4% respectively. The data investigated depicts horses that bled almost exclusively on race days as only a small percentage (- 5%) was reported as having bled during exercise. Accordingly, the full extent of epistaxis amongst racing Thoroughbreds in Southern Africa is difficult to gauge. Pedigree and race run data from Thoroughbreds racing in Southern Africa, covering the period 1986-2002 (63 146) horses in pedigree data-set and 778 532 race runs, were further analysed in order to study genetic and environmental factors affecting the incidence of epistaxis as associated with EIPH (exercise-induced pulmonary haemorrhage). As fixed effects for the model, variables that were tested significantly in a preliminary data analyses, were included. Various combinations of such variables namely age, weight, altitude, sex, month and going were tested. Fixed effects that were included in the fmal model were gender, going and altitude. The heritability estimates from a logit transformed analysis for epistaxis fitting both the animal and sire generalized mixed models were 0.23 and 0.40 respectively, which indicated that epistaxis as associated with EIPH in the Southern African Thoroughbred sires has a strong genetic basis. Genetic trends indicating an increase in epistaxis were also found. It is concluded that the frequency of epistaxis related to pulmonary haemorrhage is associated with altitude, winter and spring months and the horse's age. It is suggested that racing at a lower altitude may increase the probability of exercise-induced pulmonary haemorrhage. It is clear that epistaxis in the racing Thoroughbred has a strong genetic basis. It is further suggested that horses showing frank bleeding from the nostrils after racing or exercise, be suspended and not used for breeding purposes. This would result in relatively fast progress being made towards eradicating this costly scourge of the modem Thoroughbred racehorse. Affected stallions and those racing whilst being treated with furosemide, should be barred from breeding and not be considered as future sires. Estimated breeding values for epistaxis should be used as a tool for selecting against it and be considered in breeding programmes to decrease the incidence thereof. / AFRIKAANSE OPSOMMING: 'n GENETIESE ANALISE VAN DIE VOORKOMS VAN LONGBLOEDING IN DIE SUID-AFRIKAANSE RENPERD: Die doel met hierdie studie was om vas te stelof omgewings- of genetiese faktore enige invloed op die voorkoms van longbloeding in die Suid-Afrikaanse renperd het. 'n Verdere doelstelling was om die oorerflikheid op die onderliggende verspreiding van longbloeding in die Suid-Afrikaanse Volbloedpopulasie te bepaal. Vir die omgewingstudie is data wat oor die periode 1986-2001 strek en wat 'n totaal van 778 532 wedren-deelnames ingesluit het, statisties ondersoek. Die data het die volgende inligting ingesluit: datum van deelname, ouderdom, geslag, teler, afrigter, afstand van wedren, jokkie, toestand van baanoppervlakte, gewig gedra, sentrum waar deelname plaasgevind het en die hoogte bo seespieël van die sentrum. Die studie van die genetiese aspekte het eerstens 'n analise van al die perde wat longbloeding tydens 'n wedren in Suider-Afrika gedurende die jare 1986-2002 ondervind het (I118 perde), en tweedens dieselfde populasie perde, plus die Suiderlike-Afrikaanse perde wat uitgevoer is na Mauritius en bloeding daar ondervind het, (1252 perde), ingesluit. Ter aanvulling is uitgebreide stamboomdata van voorouers gedurende 1960-1986 gebruik om die voorkoms van longbloeding tydens die post 1986 tydvak te bepaal. Slegs stambome van renperde wat aktief aan renne deelgeneem het, is in die data ingesluit aangesien dit nie moontlik was om te voorspel of 'n perd wat nooit aan wedrenne deelgeneem het nie, longbloeding sou ondervind indien dit wel deelgeneem het. Dus is alle renperde wat nooit aan wedrenne deelgeneem het, asook daardie perde wat in die buiteland deelgeneem en waar longbloeding nie aangeteken word nie, uitgesluit. Alle perde wat bloeding van die neus na wedrenne getoon het, is deur veeartse in diens van die Jokkie Klub van Suid-Afrika ondersoek, as 'n bloeier aangeteken en van verdere deelname aan wedrenne geskors. Endoskopie word op geen van die Suid- Afrikaanse renbane as 'n standaard praktyk na wedrenne uitgevoer nie. Longbloeding het in 1 287 perde of gedurende 0.165% van alle wedrenne plaasgevind. Longbloeding soos geassossieer met EIPH, (exercise-induced pulmonary haemorrhage), is betekenisvol (p<0.001) met hoogte bo seespieël, ouderdom, dag van deelname, maand, en jaar verbind. Meer perde het longbloeding by seevlak in vergelyking met hoër vlakke bo seespieël ondervind, tussen die maande Mei-Oktober as die res van die jaar, in perde ouer as drie-jaar, na 1995 as tussen die jare 1986-1995, op Vrydae en Sondae as enige ander dag van die week. en meer by reuns as by merries of hingste. Geen verwantskap kon tussen bloeding en teler, afrigter, afstand, jokkie, toestand van baan, geslag en gewig gedra, gevind word nie. Die oorerflikheid op die onderliggende verspreiding vir longbloeding soos omskryf deur Falconer (1989), is gebruik om die relatiewe belangrikheid van oorerflikheid en omgewing te bepaal. Vir die periode bestudeer, was die voorkoms van longbloeding in die Suid-Afrikaanse renperd 2.1%. Die oorerflikheid van longbloeding was 55.4% vir eerste-graadse verwantes. By tweede-graadse verwantes was die ooretlikheid 41.3% en by derde-graadse verwantes 30.4%. Die data wat ondersoek is, was bykans uitsluitlik die van perde wat tydens wedrenne gebloei het en slegs 'n baie klein persentasie (~ 5%) was aangeteken as perde wat tydens oefening gebloei het. Dus is die volle omvang van longbloeding in Suider-Afrikaanse Volbloedperde moeilik om akkuraat te bepaal. Die stamboom- en wedrendata van Suid-Afrikaanse Volbloedperde is verder ontleed in 'n poging om die genetiese en omgewingsfaktore se invloed op die voorkoms van longbloeding, soos geassosieer met EIPH te bepaal. As vaste effekte vir die model is veranderlikes wat betekenisvol gevind was, ingesluit. Verskeie kombinasies van hierdie veranderlikes soos ouderdom, gewig, hoogte bo seespieël, geslag, maand en toestand van die baan is ingesluit. Die vaste effekte wat in die finale model ingesluit is, was geslag, toestand van die baan en hoogte bo seespieël. Die beraamde oorerflikheid verkry vanaf 'n "logit" getransformeerde analise vir longbloeding wat beide die diere- en vader- gemengde model gepas het, was onderskeidelik 0.23 en 0.40, wat 'n aanduidending is dat longbloeding, soos geassosieer met ElPH, 'n sterk genetiese grondslag het. Genetiese tendense het ook gedui op 'n toename in die voorkoms van longbloeding, veraloor die laaste vyf jaar van die studie. Samevattend is die bevinding dat die frekwensie van longbloeding 'n betekenisvolle verwantskap toon met hoogte bo seespieël, winter en lente maande en die perd se ouderdom. Dit word voorgestel dat renperde wat deelneem aan wedrenne by laer vlakke van hoogte bo seespieël, meer onderhewig aan longbloeding sal wees. Uit die resultate verkry is dit duidelik dat longbloeding 'n genetiese grondslag het. Dit word voorgestel dat perde wat fisiese simptome van neusbloeding na of gedurende wedrenne toon, geskors word van verdere deelname en ook nie toegelaat word om mee te teel nie. Hierdie maatreëls behoort aanleiding te gee dat relatief vinnige vordering gemaak sal word in die strewe om hierdie ongewenste sindroom in die moderne Volbloed te verminder. Aangetaste hingste, asook die wat aan wedrenne deelgeneem het terwyl hul behandeling ontvang met furosemide, moet nie toegelaat word om te teel en nie as toekomstige teelhingste oorweeg word nie. Die waarde van voorspelde teelwaardes vir longbloeding moet nie onderskat word in seleksie daarteen nie en moet in teelprogamme om die voorkoms daarvan te verminder, oorweeg word.