No description available.

No description available.

Doctor of Philosophy / The aim of this research was to describe the epidemiology of musculoskeletal (MS) injuries in two- and three-year-old Thoroughbred racehorses. A 27 month longitudinal study commencing in May 2000 was conducted. The study convenience sampled 14 trainers with facilities at metropolitan and provincial racetracks in New South Wales, Australia. In the 2000/01 and 2001/02 racing season, 323 and 128 two-year-olds, respectively, were enrolled in the study. The 451 Thoroughbred horses contributed, 1, 272 preparations and 78, 154 training days to the study. Of the 323 horses enrolled in the 2000/01 racing season, 219 contributed three-year-old data to the study. During the study period 8%, of training days had missing training data and 3% of the 1, 986 starts in the races or barrier trials were incorrectly recorded. The rate of incorrect entries varied with both study month and trainer. Similarly, the rate of training days with missing data varied between trainers and with study month. Four hundred and twenty-eight MS injuries were recorded in association with 395 preparations in 248 two- and three-year-old Thoroughbred racehorses. The IR for all categories of MS injuries, except for tendon and ligament injuries, were higher in twoyear- olds than three-year-olds, although the differences were only significant for shin soreness. Seventy-eight percent of horses enrolled in the study started, in a barrier trial or race, within one year on entering the study. After accounting for other confounders, horses that had sustained a MS injury were 0.50 times less likely to start, in a race or trial, race than those that did not sustain an injury. Seventy percent of horses returned to training after their first MS injury, and the cumulative percentage of these horses that had recovered within six months of the initial MS injury was 55%. After adjusting for clustering at the level of the trainer, the analysis showed that horses that exercised at a gallop pace ≥ 890 m/minute (but had not started in a race) prior to the onset of MS injury, were 2.14 times more likely to recover than horses whose maximum speed, prior to the onset of the first MS injury, was less than 890 m/minute. Similarly, horses that had started in a race or barrier trial were 4.01 times more likely to recover than horses whose maximum speed was less than 890 m/minute. 8 Training days were grouped into units referred to as preparations. A preparation began on the day that the horse was enrolled in the study, or when a horse returned to training after an absence of more than seven days from the stable. The preparation continued until the horse was lost to follow-up or left the stable for a period of more than seven consecutive days. Univariable and multivariable analytical methods were used to examine the association between a range of independent variables and four preparationlevel measures of performance: (i) the duration of preparations, (ii) length of time from the beginning of the preparation until the first start in a race or barrier trial, (iii) length of time from the first start until the end of the preparation and (iv) rate of starts in races or barrier trials. After adjusting for confounders, younger horses tended to have shorter preparations, took longer to start in a race or barrier trial, had a shorter interval from the first start to the end of the preparation and fewer starts per 100 training days. MS injury was not conditionally associated with any of the outcomes considered in this chapter. Multivariate statistical models were used to explore risk factors for MS injuries. The results suggest that MS injuries involving structures in the lower forelimb (carpus to fetlock inclusive) could be reduced by limiting exposure to high-speed exercise. This supports the proposition that training injuries are caused by the accumulation of micro damage. The results suggest there are a number of other factors that vary at the trainer level that may be risk factors for injuries, in particular joint injuries. These include unmeasured variables such as the rate of increase in distance galloped at high-speed, conformation of the horse, skill of the riders and farrier and veterinary involvement.

Thesis (Ph. D.)--Michigan State University. Comparative Medicine and Integrative Biology, 2008. / Title from PDF t.p. (Mar. 27, 2009). Includes bibliographical references. Also issued in print.

Radiographic examination of Thoroughbred racehorses at the time of the yearling sales is common practice in South Africa. Although it is generally accepted that yearlings will have some radiographic changes, there is only one study that estimated the prevalence of these changes in Thoroughbred racehorse yearlings in South Africa. Furniss et al reported on the occurrence of radiographic abnormalities over a one-year period (Furniss 2011). Furniss et al. study differs from other studies in that there was a higher prevalence of palmar metacarpophalangeal and plantar metatarsophalangeal osteochondral fragments and a lower prevalence of pedal osteitis, dorsal osteochondral fragmentation of the metatarsophalangeal joint, distal metacarpal saggital ridge changes, ulnar carpal bone lucencies, carpal osteophytes, distal intertarsal and tarsometatarsal joint changes, tarsal osteochondrosis lesions and stifle osteochondrosis lesions was found. This study will further assist practitioners to identify joints where the most prevalent changes are likely to occur. Our objective was to describe the prevalence and distribution of radiographic changes in the metacarpophalangeal joint, metatarsophalangeal joint, carpi, tarsi, stifle and fore digits of racing Thoroughbred yearlings in South Africa when examined as part of a pre-purchase examination during the Annual National Yearling Sales extending from 2008 through 2010. Thoroughbred racehorse yearlings were subjected to radiographic evaluation including the digit (n= 566 ), metacarpophalangeal joint (n=566 ), metatarsophalangeal joint (n= 566), carpi (n= 566), tarsi (n= 566) and stifle (n=566 ). The radiographic changes were categorised by location and type of change present for each series. The digit Where informal comparisons with previously published data can be made, similar changes of pedal osteitis were recorded in this study, with a total percentage of 6.7%. There was an 8.7% prevalence of inversion of the third pedal bone. Other studies describing radiographic changes in Thoroughbred racehorse yearlings did not investigate inversion of the third pedal bone, therefore results cannot be compared. The metacarpophalangeal and metatarsophalangeal joints with proximal The metacarpophalangeal and metatarsophalangeal joints with proximal sesamoid bones The prevalence of dorsoproximal phalanx one fragmentation (1.2%) of metacarpophalangeal joints were similar compared to other studies. Osteochondral fragmentation of proximal plantar phalanx one (6%) was 8.5 times more prevalent when compared to proximal palmar phalanx one (0.7%). The latter prevalence is in agreement with similar studies. There were low incidences of subchondral cyst-like lesions seen in distal third metacarpus (0.4%), distal third metatarsus (0.2%) and proximal first phalanx, similar to other studies. The most common change recorded on the dorsal aspect of distal third metacarpus and metatarsus was a well-defined semi-circular notch (dorsal aspect of distal third metacarpus 20.3%; dorsal aspect of distal third metatarsus 27%) similar to other studies. Our study showed a higher prevalence of lucencies present at dorsal aspect of distal third metacarpus (8.5%) and metatarsus (4.2%) compared to other studies. There was a marked lower prevalence in the current study of flat distal palmar third metacarpal condyles (6%). Prevalence of palmar and plantar third metacarpal and metatarsal supracondylar lysis were markedly higher in the present study. Slight palmar and plantar third metacarpus and metatarsus supracondylar lysis was seen in 19.3% of the horses. Moderate to extreme palmar and plantar third metacarpus and metatarsus supracondylar lysis were present in 10.2% of the horses. The carpi There was a higher prevalence of dorsomedial carpal disease in our study population (11.3%) and prevalence of carpal osseous cyst-like lesions such as a circular lucency in ulnar carpal bone was lower (14%). A markedly higher prevalence of 4.2% in carpal osteochondral fragmentation was found. The tarsi Osteochondrosis of the tarsocrural joint showed a similar prevalence (13.4 %). Degenerative joint disease of tarsometatarsal joint had a higher prevalence (36%) than the centrodistal (distal intertarsal) joint (20.3%). There was also a higher incidence of degenerative joint disease in tarsometatarsal joint (36%). The stifle In the current study, osteochondrosis of the stifle had a similar prevalence (3.6%) when compared to other studies. 6 Conclusion In South Africa Thoroughbred racehorse yearlings, radiographic changes most commonly involved the metacarpo- and metatarsophalangeal joints, carpi and tarsi. This study revealed markedly higher prevalence of palmar and plantar third metacarpal and metatarsal supracondylar lysis (slight 19.3% and moderate to extreme 10.2%), carpal osteochondral fragmentation (4.2%) and degenerative joint disease in tarsometatarsal joint (36%). Establishment of normal prevalence and distribution of radiographic changes in South Africa Thoroughbred yearlings will allow for comparison with populations of young horses worldwide. Knowledge of the normal prevalence will assist veterinarians to identify joints in which radiographic changes are most likely to occur. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Companion Animal Clinical Studies / unrestricted

Horses have been domesticated for thousands of years. Through selection practices horses have been separated into groups that pass on desired traits. We have viewed what the breeders have done at the genotypic level to accomplish their breeds. By using a relatively new technique, DNA fingerprinting, Thoroughbred inbreeding and eight other breeds (Standardbreds, Quarter horses, American Saddlebreds, National Show Horses, Arabians, Morgans, Mustangs and Belgians) have been studied. The probes CAC5 and YNZ 132 gave the best probability (ranging from 1.9x10⁻¹⁰ to 4.8x10⁻¹⁵) that two unrelated individuals would not have the same DNA fingerprint out of the probes screened. The level of inbreeding in Thoroughbreds has been estimated by comparing the number of bands shared among these animals to a quasi-natural population (Mustang) and a theoretically known genetic relationship (a sire and his offspring). Using the probes CAC5 and YNZ 132 Thoroughbreds share 20% more bands than the Mustang and 30-50% less than the sire and offspring. To compare the nine breeds, blood from ten horses from nine different breeds was mixed and DNA fingerprinted. Each lane on the autoradiograph therefore represents one breed. The two probes produced data with a rank correlation of .75 (Kendall's tau) (Ostle,B., 1963). Selection practices have been divided into, narrow selection regimes (where one or two traits have been selected for) and broad selection regimes (where numerous traits have been selected for). The amount of bands shared between the breeds was calculated and applied to a computer program named Gendiv (Gentzbittel and Nicolas, 1989,1991). Three consensus trees were derived showing that the narrow selection regime breeds, Thoroughbreds and Standardbreds, were the most genetically distanced from broad selection regime breeds, Mustangs and Morgans. / Master of Science

Thirteen Thoroughbred farms in Virginia provided 260 horses for the study of growth patterns of horses from birth to July of the yearling year. Measurements included heart girth, wither and hip height, body length, chest width, knee to ground length, cannon bone circumference and body weight, as estimated by heart girth. Quadratic regression equations, adjusted for the effects of farm, sex and month were developed to describe the growth of foals. Foals born in January-February were smallest overall at birth, 30 and 90 d-of-age (P< .01) May-June foals were largest at birth. Differences in wither height, body length and body weight of foals born in May-June vs in January-February at 30 d-of-age, were 1.7, 3.8 cm and 21.6 kg, respectively; At 90 d-of-age, differences were 1.6, 4.9 cm and 13.3 kg, respectively. Differences in size due to birth month were apparent up to 270 d-of-age. May-June foals exhibited the fastest initial growth rate. Colts were intermittently larger than fillies subsequent to 150 d-of-age. In January of the yearling year, birth mouch influenced all measurements (P< .01). Foals born in January to March were larger than foals born in April to June. In July of the yearling year, differences were identified less often and actual differences in size were smaller than in January. Average differences in heart girth and wither height of foals born in January to March compared to foals born in April to June were 8.4 and 5.1 cm in January and 5.2 and 3.6 cm in July of the yearling year. Foals born in April to June displayed larger gains during the first 7 mo of their yearling year than did early-born foals. Correlation coefficients between measures of foals up to 400 d-of-age decreased or remained the same. Thus, growth in various proportions was asynchronous. Regression coefficients that described the resemblance between wither heights of parents and offspring increased with age and were highest in July of the yearling year. Offspring-midparent regression coefficients of 1982 foals increased from .50 ±.18 at 30 d-of-age to .78 ±.14 at 400 d-of-age. The regression coefficient in July was .84 ±.15. / Ph. D.

This dissertation is the product of two behaviour studies and an in vitro fermentation trial. Both behaviour studies were conducted at the Ashburton Racehorse-Training Centre in Ashburton, near Pietermaritzburg in KwaZulu- Natal. The first behaviour study evaluated differences in behaviours obtained through feeding either twice or four times daily. This trial showed (P<O.OO1) that horses fed twice a day spend a greater proportion of their day in stereotypic or vice-like behaviours. Horses eating four times a day ate less hay (P<O.OO1) and more concentrate (P<O.05) than horses being fed twice a day. Horses in both yards ate more hay (P<O.05) when exercise intensity was increased. Defecation frequency was higher on days when exercise intensity was high (P<O.05) and in the yard where horses were fed four times per day (P<O.O1). Faecal weight was greater (P<O.05), horses lay down more frequently (P<O.05), spent more time eating concentrate (P<O.OO1) and less time eating hay (P<O.OO1) when horses were fed four times per day. Fillies spent more time (P<O.05) eating hay than geldings. The second behaviour study was conducted within one yard only and considered the effects of changes in management strategies on the incidence of stereotypic behaviour. The results did not indicate that changes in management related to exercise intensity would have an effect on behaviours exhibited. However this trial did demonstrate that a reduction in feed intake on days when exercise is reduced will reduce the incidence of stereotypic behaviours. Horses reduced the time spent eating hay when exercise was reduced except that when feeding frequency was reduced in conjunction with reduced exercise, more time was then spent eating hay (P<O.OO1). It was found that fillies spent more time licking surfaces (P<O.OO1) and weaving (P<O.O1) than geldings, which were more aggressive (P<O.OO1) and ate more bedding (P<O.05) than the fillies. All the horses were more alert (P<O.OO1) on days of moderate exercise except when feed was reduced in conjunction with reduced exercise, so that horses were less alert (P<O.OO1) and more time resting (P<O.OO1). The in vitro study was conducted at the department of Animal and Poultry Science at the University of KwaZulu-Natal, Pietermaritzburg. This was a dilution trial, using different ratios of maize and Eragrostis curvula. It was shown that as the proportion of maize in the ration was increased so the digestibility and the degradability of the ration increased (P<O.OO1). It was also shown that the adapted two stage digestion techniques described by Tilley & Terry (1963) had lower supernatant pH levels than the samples that underwent microbial digestion only. This was accounted for by a problem with the methodology. The trial had hoped to show a dramatic decrease in pH and increased rates of gas production when the maize portion of the sample was increased. From the results established during this trial it is clear that application exists in the adoption of this method in in vitro feed analysis in the horse industry.· The behaviour studies significantly linked the incidence of stereotypic behaviour to feeding and nutritional management in racehorses. Some explanations of the noted behaviours can be elucidated through the development of in vitro protocols, where hindgut pH, degradability and fermentation of different ration mixtures elicit responses in physical terms. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Upper airway endoscopy at rest has been the diagnostic method of choice for diagnosing equine upper respiratory tract (URT) disease since its development in the 1970´s. The development of high-speed treadmill endoscopy (HSTE) improved the sensitivity of URT endoscopy by allowing the examiner to observe the horse’s nasopharynx and larynx during exercise. However, the level of exertion achieved during HSTE may not always represent that achieved during normal exercise as surface, rider, tack, and environmental variables are altered. Recently, the development of dynamic overground endoscopy (DOE) has addressed some of those shortcomings. A retrospective study was undertaken to describe the upper airway abnormalities detected during DOE in horses presenting with poor performance and/or abnormal respiratory noise in South Africa. Patient records of Thoroughbred racehorses undergoing DOE from November 2011 to August 2012 by the Onderstepoort Veterinary Academic Hospital were reviewed. Data collected included signalment, primary complaint, distance exercised, maximum speed attained, and dynamic airway abnormalities detected. XIII A second study was carried out to evaluate agreement within and among examiners of three grading systems for laryngeal function at exercise. The grading systems assessed were an existing system for grading axial deviation of aryepiglottic folds (ADAF), a modified system for grading recurrent laryngeal neuropathy (RLN) at exercise, and a proposed system for grading vocal cord collapse (VCC). For investigation of intra-observer variability, recordings were watched by two of the investigators at the same time, on two different occasions, in real time, slow motion, and at frame-by-frame speed. To evaluate inter-observer variability, recordings were watched by four investigators on one occasion, as described for investigation of intra-observer variability, and scoring sheets completed. Kappa agreement was calculated for both intra- and inter-observer sessions. Fifty-two horses that underwent DOE for investigation of poor performance and/or abnormal respiratory noise were identified. The main abnormalities detected included dorsal displacement of the soft palate (DDSP) (13/52 horses, 25%); recurrent laryngeal neuropathy (RLN) (17/52 horses, 33%); axial deviation of the aryepiglottic folds (ADAF) (21/52 horses, 40%) and vocal cord collapse (VCC) (18/52 horses, 35%). A total of 40 horses presented one or more abnormalities of the URT (77%). Fifteen horses (29%) had a single abnormality, and 25 horses (48%) had multiple abnormalities. Results at frame-by-frame speed from the intra-observer evaluations for all the conditions showed substantial agreement for RLN by both observers (K = 74 - 80). Intra-observer evaluations for VCC were moderate to substantial (K 53 – 63). ADAF was the most difficult URT abnormality to assess for both observers, and agreement within observers was only fair to moderate (K = 36 - 52). Inter-observer evaluations for RLN showed substantial to moderate agreement (K = 62). Inter-observer evaluations for VCC showed moderate agreement (K = 47 – 54), and inter-observer evaluations for ADAF showed only slight to fair agreement and were the lowest for all the conditions (K = 14 – 22). This study showed that DOE is a useful technique for providing valuable information about disease of the URT. Finding multiple abnormalities in 48% of horses examined using DOE suggests that DOE may be indicated even for those horses with an obvious abnormality found during resting endoscopy. The intra-observer evaluations showed that RLN had higher agreement values than those for ADAF and VCC at all speeds, and that ADAF had lower agreement values than those for VCC and RLN at all speeds. Inter-observer agreement was less than intra-observer agreement, presumably because more observers were involved in the inter-observer assessment. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Companion Animal Clinical Studies / unrestricted

This dissertation describes the epidemiological investigation and management of the first outbreak of Contagious Equine Metritis (CEM) reported in South Africa. In addition, the subsequent implementation of a nationwide quantitative polymerase chain reaction (qPCR)- based stallion screening programme and traceback of exposed animals to define the spread of CEM in South Africa is described. The first South African outbreak of CEM caused by the bacterium, Taylorella equigenitalis was reported on the 9th May 2011 to the World Health Organisation for Animal Health (OIE). The outbreak was recognized subsequent to the importation of a young Warmblood stallion from Germany. The outbreak initially appeared confined to a single index property (focus property), an equine breeding facility in Midrand, Gauteng, South Africa with a single confirmed case of transmission involving the index stallion and a Thoroughbred mare. The initial response was rapidly instituted following the suspicion of T. equigenitalis on the index property. This included an inspection of the index property and its records. A riskclassification of in-contact animals allocated them to “high,” “moderate” or “low”-risk categories. The classification was dependent on the temporal relationship of their presence on the index property relative to the period of residence of the index cases. After T. equigenitalis infection was confirmed from both index cases, the breeding facility was placed under state– administered quarantine and all exposed mares and the index cases were transferred to a quarantine facility. The animals were re-tested by genital swabbing for bacterial culture following a standard protocol according to internationally-accepted practice (OIE Terrestrial Manual on Contagious Equine Metritis). Additional duplicate swabs were obtained for real time qPCR. None of the mares were shown to be positive on either bacterial culture or qPCR. All animals were however treated according to an accepted protocol for T. equigenitalis infection (Luddy and Kutzler, 2010, UK Horseracing Betting Levy Board (HBLB) Code of Practice, 2011). All stallions that had been present on the index property and undergone semen collection on the same day as the index stallion were classified as “moderate risk” and were similarlytested. This identified two additional T. equigenitalis-positive stallions, which were confirmed on bacterial culture (World Organization for Health (OIE) Manual of Diagnostic Tests and Vaccines for Terrestrial Animals (Chapter 2.5.1, Contagious Equine Metritis version adopted 20/10/2011) and which were subsequently quarantined and successfully treated. Following recognition of this outbreak, the Department of Agriculture, Forestry and Fisheries (DAFF) in consultation with the Equine Research Centre (ERC) of the Faculty of Veterinary Science at the University of Pretoria promulgated a nationwide qPCR-based screening programme that aimed to establish the prevalence and distribution of T. equigenitalis in South Africa. This required certification of all South African stallions used for breeding either by natural cover or assisted reproductive techniques. The compliance for certification was based on submission of two sets of genital swabs that both tested negative for T. equigenitalis on qPCR-testing. The process was coordinated by a web-based platform (http://wto the prescribed World Organisation for Health (OIE) method (Terrestrial Manual on Contagious Equine Metritis). All stallions apart from one could be linked to the index property. As of 31st October 2013, two additional T. equigenitalis-positive females have been identified, following a traceback of all identified potentially-exposed mares and their offspring that was instituted in September 2012. An “exposed mare” was defined as a mare that had been bred, either by natural breeding or assisted breeding techniques to the index stallion or any other T. equigenitalis-positive stallion. These mares were distributed across five provinces of South Africa at the time the traceback was initiated. During the nationwide traceback, a subpopulation focus was identified when 24 of the 33 resident stallions at the South African Lipizzaner Centre, Midrand, Gauteng tested positive for T. equigenitalis. Six of these stallions had visited the index property for semen collection over the course of several years prior to the arrival of the index stallion. This suggested the possible albeit undetected presence of T. equigenitalis on these premises prior to the arrival of the first reported index case. We strongly suspected that there may have been undetected CEM incursions into South Africa in the past. The index case in this outbreak may either have introduced a new infection or was infected by a pre-existing source of infection subsequent to his arrival. It is hoped that future strain-typing of the isolates from the positive cases identified during this intervention will further clarify this scenario. The use of qPCR-based screening proved to be a highly specific and sensitive method for detecting T. equigenitalis and helped to define the distribution and prevalence of T. equigenitalis in breeding stallions and exposed mares in South Africa. In addition, this method had significant practical advantages with respect to the associated costs, turn-around times and in-the-field application when compared with bacterial culture. The institution of a web-based platform from which the national screening programme was launched and coordinated proved to be indispensable in managing stakeholder access and information availability. To date, 31st October 2013, a total of 39 horses (36 males and 3 females) have been identified as T. equigenitalis-positive and have all subsequently been successfully treated. © Universityww.cemsa.co.za) As of 31st October 2013, an additional 33 carrier stallions have been identified by this screening programme. Of these stallions, 23 have been confirmed on bacteriology according to the prescribed World Organisation for Health (OIE) method (Terrestrial Manual on Contagious Equine Metritis). All stallions apart from one could be linked to the index property. As of 31st October 2013, two additional T. equigenitalis-positive females have been identified, following a traceback of all identified potentially-exposed mares and their offspring that was instituted in September 2012. An “exposed mare” was defined as a mare that had been bred, either by natural breeding or assisted breeding techniques to the index stallion or any other T. equigenitalis-positive stallion. These mares were distributed across five provinces of South Africa at the time the traceback was initiated. During the nationwide traceback, a subpopulation focus was identified when 24 of the 33 resident stallions at the South African Lipizzaner Centre, Midrand, Gauteng tested positive for T. equigenitalis. Six of these stallions had visited the index property for semen collection over the course of several years prior to the arrival of the index stallion. This suggested the possible albeit undetected presence of T. equigenitalis on these premises prior to the arrival of the first reported index case. We strongly suspected that there may have been undetected CEM incursions into South Africa in the past. The index case in this outbreak may either have introduced a new infection or was infected by a pre-existing source of infection subsequent to his arrival. It is hoped that future strain-typing of the isolates from the positive cases identified during this intervention will further clarify this scenario. The use of qPCR-based screening proved to be a highly specific and sensitive method for detecting T. equigenitalis and helped to define the distribution and prevalence of T. equigenitalis in breeding stallions and exposed mares in South Africa. In addition, this method had significant practical advantages with respect to the associated costs, turn-around times and in-the-field application when compared with bacterial culture. The institution of a web-based platform from which the national screening programme was launched and coordinated proved to be indispensable in managing stakeholder access and information availability. To date, 31st October 2013, a total of 39 horses (36 males and 3 females) have been identified as T. equigenitalis-positive and have all subsequently been successfully treated. / Dissertation (MMedVet)--University of Pretoria, 2013. / gm2014 / Production Animal Studies / unrestricted