This thesis describes the development, optimisation and use of assays to measure equine herpes virus-specific proliferative and cytotoxic Tlymphocyte (CTL) responses in the blood of horses. Equine T cell blast cells stimulated from peripheral blood mononuclear cells (PBMC) with pokeweed mitogen were found to perform best as targets for CTL in "Cr release assays. CTL induced in vitro with an abortigenic strain of EHV-1 (EHV-1/Ab4) were shown to be antigen specific, genetically restricted and predominantly of the CD4' CD8+ phenotype. Cross-reactive CTL were induced in vitro with live EHV-4 virus, which killed EHV-1 infected blast cells. A proportion of EHV-1 induced CTL were shown to be directed against the immediate early gene products. A proliferative LDA was used to determine whether the frequency of precursor T cells detected before challenge with EHV-1 correlated with immune status. The precursor frequency of antigen-specific T cells increased in 3 out of 4 horses after infection. However, there was no correlation between precursor frequency and outcome of infection. A LDA was developed and used to evaluate the precursor frequencies of EHV-1 and EHV-4 induced CTL after infection with these viruses. Pre-infection CTLp frequencies in susceptible animals were < 1/150,000. CTLp frequencies in animals which were immune to EHV-1 were between 1/10,000 and 1/20,000. To my knowledge this is the first report of the use of LDA techniques in the horse. The development and use of CTL LDA assays have provided new information on CTL responses in horses after EHV-1 and EHV-4 infection.

Several case reports of Clostridium perjringens involvement in equine enteric disease have not identified the prevalence and statistical association of these bacteria with foal diarrhoea. Each of five methods which favoured the recovery of C. perjringens in different physiological states were chosen to improve the sensitivity of isolation in a survey of foal diarrhoea for C. perjringens and other pathogens. C. perjringens was significantly associated with foal diarrhoea (isolated from 57% of 421 scouring anjmals but from only 33% of 222 controls; odds ratio 7.4; p < 0.001 by multivariate analysis); it was also associated with fatal diarrhoea (odds ratio 2.7; p=0.047). Rotavirus, Cryptosporidium sp. and large numbers of Strongyloides westeri were the only other pathogens associated with diarrhoea although they were less prevalent than C. perjringens; Salmonella sp. was the only other pathogen associated with fatal diarrhoea. Enterotoxin production was detected by reverse passive latex agglutination test (RPLA) amongst isolates of C. perjringens from scouring and healthy foals. The enterotoxin gene from an equine strain was cloned and its sequence was essentially identical to that published for a human isolate. Less than 5% of C. perjringen isolated from scouring foals and 0.5% from controls were positive for the enterotoxin gene by polymerase chain reaction (PCR) (odds ratio 19.1; p<0.005). Presence of the enterotoxin gene was confirmed in representative isolates with a gene probe of chromosomal DNA and PCR product as well as neutralisation of cytotoxicity by antitoxin. Enterotoxigenicity of half ofRPLA positive isolates could not be confirmed in this way. Enterotoxigenic C. perfringens were a probable cause of foal diarrhoea. However, a greater proportion of the disease was associated with nonenterotoxigenic . perjringens. There is now a need to identify molecular differences between non-enterotoxigenic C. perjringens strains from scouring and healthy foals which might be associated with pathogenicity.

Master of Science / Department of Animal Sciences and Industry / James M. Lattimer / A study was conducted in a Latin rectangle to determine the impact of stressors on immune function in yearling horses. After 51 d of supplementation with either block 1, a molasses block containing 14.30% fat or block 2, a molasses block containing 7.58% fat, horses were subjected to three forms of stress. Blood samples were collected 6 h pre-stress and at h 1, 6, 12, 24, 48, 72, 96, and 168 post stress. Nasopharyngeal flush (NPF) was conducted 6 h pre-stressor and h 12 and 72 post-stressor. Blood was analyzed for fatty acids, various hematological parameters, cytokines, PGE₂, and cortisol. Nasopharyngeal flush samples were analyzed for IgA. Composition of molasses blocks were found to be inconsistent with documented formulation and n-6:n-3 ratios were found to be similar between blocks. Therefore, main effect of hour was evaluated. White blood cells were elevated (P < 0.01) above baseline at subsequent sampling times and platelet count was elevated (P = 0.01) at h 1, 6, 24, 48, and 96 h post-stressor compared to baseline. Lymphocyte concentrations were reduced (P < 0.01) at h 1 compared to baseline but were elevated above baseline by h 6 (P < 0.01). Neutrophil concentrations were elevated (P < 0.01) at h 1 and 6 compared to baseline. Nasal mucosal IgA concentrations had a tendency (P < 0.07) to be greater at h 12 relative to baseline. Serum cortisol dropped to concentrations below baseline (P < 0.01) at h 1 and 6 but increased above baseline by h 12 (P < 0.01). It appears that stressors applied were sufficient to induce mild changes in several of the hematological parameters evaluated but an overall more profound effect may have been displayed if stressors were more profound or prolonged. A second experiment was conducted to evaluate fermentation characteristics and aerobic stability of whole-plant corn silage after inoculation with three different bacterial inoculants. Treatments consisted of Lactobacillus plantarum and Lactobacillus buchneri (LPB), L. plantarum, L. buchneri, and Lactobacillus diolivorans (LPBD), and L. diolivorans (LD). Silages were sampled on d 0, 14, 39, and 90. Propionate was elevated in silages inoculated with LPBD on d 39 and d 90 compared to other treatments (P < 0.03). 1, 2-propanediol was elevated (P < 0.01) in silages inoculated with LPB and LPBD on d 39 and d 90 compared to CON and LD silages. An effect of sampling day (P < 0.05) was detected for DM, aNDF, ADF, ash, starch, pH, total VFA, acetate, propionate, lactate, ethanol, and 1,2-propanediol. When silages sampled on d 14, 39, and 90 were subjected to an aerobic stability test, only treatment differences were detected (P < 0.05) for lactate: acetate and 1-propanol. Sampling day differences were detected (P < 0.05) for pH, total VFA, acetate, propionate, butyrate, lactate:acetate, 1-propanol, and 1, 2-propanediol. Overall, results suggest that epiphytic microflora populations largely dominated the ensiling process as indicated by the relative similarities in silages throughout the trial.

Made available in DSpace on 2014-06-11T19:29:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-31Bitstream added on 2014-06-13T20:19:21Z : No. of bitstreams: 1 araujo_ghm_me_botfmvz.pdf: 252944 bytes, checksum: 8bfe64297ba80536cb087534254b2f9b (MD5) / Estudos sobre a luteólise os fatores que a influenciam foram conduzidos em diferentes espécies de interesse econômico, recentemente, verificou-se a influência do LH sobre a luteólise ocorrida nas espécies suína e bovina, mostrando sua função nestas espécies. Este trabalho foi desenvolvido com o objetivo de se avaliar o efeito do LH sobre as concentrações plasmáticas de progesterona durante a luteólise induzida com dinoprost, usou diferentes tratamentos superovulatórios como modelos que simularam ambientes com concentrações plasmáticas de LH distintas. Sete éguas foram divididas e utilizadas uma vez em cada um dos seguintes 4 grupos: Grupo 01 (n=6): controle que recebeu a aplicação de 5 mg de dinoprost, IM no 7° dia após a ovulação (dia 0); Grupo 02 (n=7): recebeu aplicação de 5 mg de dinoprost no dia 0 e EPE doses constantes (25mg/IM/b.i.d.) do dia 0 até o dia 3; Grupo 03 (n=7): recebeu aplicação de 5 mg de dinoprost no dia 0 e EPE doses decrescentes (40 mg/IM. no dia 0, 35 mg/IM/b.i.d. no dia 1, 30 mg/IM/b.i.d no dia 2; e, no dia 3, 25 mg/IM/b.i.d); Grupo 04 (n=5): FSH purificado eqüino (eFSH), aplicação de 5 mg de dinoprost no dia 0 e eFSH (12,5 mg/IM/b.i.d.) até o dia 3. As coletas de sangue foram realizadas dia -1 ao dia 3 dos tratamentos para as dosagens hormonais de progesterona (P4) e LH por radioimunoensaio. No dia -1 não foi observada qualquer diferença entre os grupos, indicando iguais condições dos grupos no momento do início dos tratamentos. A luteólise (P4<1ng/mL) foi alcançada em todos os grupos em até 48 horas (dia 2) após o início dos tratamentos. Sendo observada diferenças nos valores plasmáticos de LH desde da primeira aplicação do EPE ou eFSH. / Researches has been conduced about luteolysis and other factors that affect in some away the lifespan of the corpus luteum in different species, recently, has been shown the effect of the LH on the luteolysis in swine and bovine specie, demonstrating its function in this species. The aim of the present study was to evaluate the effect of the LH concentrations on the progesterone levels during the induced luteolysis with dinoprost, using as a model for different LH concentrations environments the superovulatory treatment with EPE and purified equine FSH. Seven mares were divided and utilized once in all 4 groups: Group 01 (n=6): control, 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0); Group 02 (n=7): 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0) and EPE in constant doses till day 3; Group 03 (n=7): 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0) and EPE in decreased doses (40 mg/IM in day 0, 35 mg/IM/b.i.d. in day 1, 30 mg/IM/b.i.d. in day 2, and, 25 mg/IM/b.i.d. in day 3); Group 04 (n=5): equine purified FSH, 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0) and 12.5 mg/IM/b.i.d. of eFSH until day 3. The blood samples have been taken from the day -1 to day 3 daily with the objective of evaluated LH and progesterone levels. In the day -1, no differences were observed on hormones dosages among the groups, indicating the same conditions for all groups before the treatments. The luteolysis (P4<1ng/mL) was reached in all groups until 48 hours (day 2) after the beginning of the treatments. Differences were found among the plasmatic values of LH since the first treatment of EPE or eFSH. Differences were observed in P4 levels after day 2 with 0.61 ± 0.10a ng/mL in Group 01; 0.28 ± 0.09b ng/mL in Group 02; 0.25 ± 0.23b ng/mL in Group 03; and, 0.45 ± 0.42ab ng/mL in Group 04...(Complete abstract click electronic access below)

Orientador: Cezinande de Meira / Banca: Marco Antonio Alvarenga / Banca: Rubens Paes de Arruda / Resumo: Estudos sobre a luteólise os fatores que a influenciam foram conduzidos em diferentes espécies de interesse econômico, recentemente, verificou-se a influência do LH sobre a luteólise ocorrida nas espécies suína e bovina, mostrando sua função nestas espécies. Este trabalho foi desenvolvido com o objetivo de se avaliar o efeito do LH sobre as concentrações plasmáticas de progesterona durante a luteólise induzida com dinoprost, usou diferentes tratamentos superovulatórios como modelos que simularam ambientes com concentrações plasmáticas de LH distintas. Sete éguas foram divididas e utilizadas uma vez em cada um dos seguintes 4 grupos: Grupo 01 (n=6): controle que recebeu a aplicação de 5 mg de dinoprost, IM no 7° dia após a ovulação (dia 0); Grupo 02 (n=7): recebeu aplicação de 5 mg de dinoprost no dia 0 e EPE doses constantes (25mg/IM/b.i.d.) do dia 0 até o dia 3; Grupo 03 (n=7): recebeu aplicação de 5 mg de dinoprost no dia 0 e EPE doses decrescentes (40 mg/IM. no dia 0, 35 mg/IM/b.i.d. no dia 1, 30 mg/IM/b.i.d no dia 2; e, no dia 3, 25 mg/IM/b.i.d); Grupo 04 (n=5): FSH purificado eqüino (eFSH), aplicação de 5 mg de dinoprost no dia 0 e eFSH (12,5 mg/IM/b.i.d.) até o dia 3. As coletas de sangue foram realizadas dia -1 ao dia 3 dos tratamentos para as dosagens hormonais de progesterona (P4) e LH por radioimunoensaio. No dia -1 não foi observada qualquer diferença entre os grupos, indicando iguais condições dos grupos no momento do início dos tratamentos. A luteólise (P4<1ng/mL) foi alcançada em todos os grupos em até 48 horas (dia 2) após o início dos tratamentos. Sendo observada diferenças nos valores plasmáticos de LH desde da primeira aplicação do EPE ou eFSH. / Abstract: Researches has been conduced about luteolysis and other factors that affect in some away the lifespan of the corpus luteum in different species, recently, has been shown the effect of the LH on the luteolysis in swine and bovine specie, demonstrating its function in this species. The aim of the present study was to evaluate the effect of the LH concentrations on the progesterone levels during the induced luteolysis with dinoprost, using as a model for different LH concentrations environments the superovulatory treatment with EPE and purified equine FSH. Seven mares were divided and utilized once in all 4 groups: Group 01 (n=6): control, 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0); Group 02 (n=7): 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0) and EPE in constant doses till day 3; Group 03 (n=7): 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0) and EPE in decreased doses (40 mg/IM in day 0, 35 mg/IM/b.i.d. in day 1, 30 mg/IM/b.i.d. in day 2, and, 25 mg/IM/b.i.d. in day 3); Group 04 (n=5): equine purified FSH, 5 mg of dinoprost, IM in the seventh day after the ovulation (day 0) and 12.5 mg/IM/b.i.d. of eFSH until day 3. The blood samples have been taken from the day -1 to day 3 daily with the objective of evaluated LH and progesterone levels. In the day -1, no differences were observed on hormones dosages among the groups, indicating the same conditions for all groups before the treatments. The luteolysis (P4<1ng/mL) was reached in all groups until 48 hours (day 2) after the beginning of the treatments. Differences were found among the plasmatic values of LH since the first treatment of EPE or eFSH. Differences were observed in P4 levels after day 2 with 0.61 ± 0.10a ng/mL in Group 01; 0.28 ± 0.09b ng/mL in Group 02; 0.25 ± 0.23b ng/mL in Group 03; and, 0.45 ± 0.42ab ng/mL in Group 04...(Complete abstract click electronic access below) / Mestre

Fat supplementation is a common practice to increase caloric intake in the performance horse. The effects of fat on fiber digestibility is unknown. Understanding of digestibility in the equine digestive tract is limited by sampling technique. While cecal and ileal cannulations have previously been utilized to determine equine nutrient digestibility and gastrointestinal physiology, the current research has been limited to singular portions of the equine digestive tract. The objectives of this dissertation were to determine the effects of dietary fat supplementation on nutrient digestibility and blood insulin, glucose, and fatty acid concentrations using dual cannulated ponies. The first step to this objective was establishment of a dual cannulated pony herd for research. This study resulted in a post-operation survival rate of 63%. Five of the dual cannulated ponies were fed hay and pelleted alfalfa and supplemented with vegetable oil at 0, 5, 10, or 15 % of total diet. Ileal, cecal, fecal, and blood samples were taken with blood samples analyzed for glucose, insulin and fatty acids. There was a treatment by time effect (P < 0.1) for apparent ileal and cecal fat digestibility and apparent cecal digestibility of crude protein. Apparent total tract digestibility of NDF, ADF and fat was affected by time (P < 0.1). Adding fat increased (P < 0.1) apparent total tract digestibility of fat. At 0 h post feeding apparent total tract digestibility of protein was greatest (P < 0.1) compared to other time periods. Plasma concentration of insulin increased (P < 0.1) over time. Ponies consuming 0 % fat diet had increased C14:0 compared to 5, 10, and 15 % diet. Adding fat at 5, 10, and 15 % of the diet increased C18:2 n-6 when the ponies were fed 0 % fat. Further research using a dual cannulated equine research herd is needed to more completely understand digestibility of other components of the equine diet.

The aim of this study was to determine whether three acupuncture treatments affected thoroughbred racehorses in training. Heart rate variability (HRV) at rest and stride parameters (SP) during a 600m gallop were measured. Needles were inserted for 20 minutes into pre-selected acupuncture points in the treatment horses while those in the non-treatment group were haltered. The delta values (post-treatment minus pre-treatment) of the groups were compared. There were no significant changes (p < 0.05) in the HRV indicators. The treatment group showed (delta median of treatment vs. non-treatment group) that the parasympathetic (PNS) indicators shifted towards inhibition of the vagal system (RMSSD = - 2.19 vs. 1.47; HF = - 37.19 vs. 19.42; SD1 = - 1.56 vs. 1.04). The delta medians of indicators associated with the combined effect of the PNS and sympathetic nervous system (SDNN = 4.39 vs. - 4.00; LF = 179.48 vs. - 397.26; SD2 = 8.55 vs. - 7.48); cardiac autonomic balance (LF/HF = 0.26 vs. - 0.32; LF norm = 14.23 vs. - 0.80; HF norm = - 4.78 vs. 3.54) and heart rate measures (Mean HR = 3.96 vs. - 3.00; Mean RR = - 169.72 vs. 107.54) showed a shift in opposite directions. The SP results showed a significant increase in maximum stride count (p = 0.004). The delta medians showed a shift in opposite directions i.e., average stride length (-0.06 vs. 0.05), average stride count (0.31 vs. -0.26), maximum stride count (0.84 vs. -5.70), maximum speed (1.30 vs. -0.80) and stride length at maximum speed (0.13 vs. -0.01). Thus, the non-treatment group seemed to perform better and were calmer, suggesting that a withdrawal period may be appropriate following acupuncture treatments. / Dissertation (MSc (Veterinary Sciences))--University of Pretoria, 2021. / AgriSETA bursary / Companion Animal Clinical Studies / MSc (Veterinary Sciences) / Unrestricted

Hyperelastosis Cutis (HC) is an autosomal recessive disorder in Quarter Horses. Homozygous (Hr/Hr) horses are affected with fragile, hyperextensible skin that sloughs and scars easily following minor trauma. Heterozygous (N/Hr) horses appear normal, but carry one copy of the gene. Objectives were to determine inbreeding coefficients of affected (Hr/Hr), carrier (N/Hr), and normal (N/N) Quarter Horses, compared to Thoroughbreds, and evaluate economic effects of HC within the cutting horse industry. Of the top cutting horses from 1985 through 2006, 35 were confirmed carriers by either DNA analysis or production of affected offspring. Although 23% of the earnings from the leading 100 lifetime earning sires ($388 million) were attributed to 12 carrier sires, average offspring earnings of carrier sires were not significantly different from normal sires. The increase in dollars is due to the number of earning offspring produced by carriers, highlighting the need for DNA testing and appropriate breeding selections.

In six, healthy, adult horses, the origin of the left internal carotid artery was isolated via a modified hyovertebrotomy approach. Normograde blood flow was occluded by placement of a tourniquet on the artery near its origin. Lumenal access was gained through placement of a distally directed introducer sheath and retrograde blood flow from the cerebral arterial circle was confirmed. An 8.5 mm diameter detachable latex balloon loaded onto a carrier catheter and placed within a guiding catheter was introduced into the internal carotid artery through the introducer sheath and advanced to the target occlusion site (the proximal curve of the sigmoid flexure of the internal carotid artery). The balloon was inflated with 0.5 ml of a radiopaque solution. Correct placement and inflation of the balloon were confirmed by intraoperative radiography. The balloon was then released and the guiding and carrier catheters withdrawn. Immediate embolization of the distal internal carotid artery was determined by lack of retrograde blood flow through the introducer sheath. The introducer sheath was withdrawn from the vessel and the proximal tourniquet was replaced with two ligatures. Horses were euthanized on day 30 and detailed gross and histopathologic examinations were performed. The balloons were easily placed into the target site and produced immediate occlusion of retrograde flow from the cerebral arterial circle. All balloons remained inflated in their original position throughout the study period. Mature thrombus formation and absence of clinically significant inflammation were consistent findings in all occluded internal carotid arteries at gross necropsy and histologic examination. / Master of Science

Feeding a fat-containing diet to the exercising horse is a facile way to increase energy density without risking the complications associated with hydrolyzable carbohydrates. Fat adaptation may also result in increases in the utilization of free fatty acids for fuel during exercise and sparing of muscle glycogen. Phosphatidylcholine, the main component of lecithins, can influence muscle contraction and improve endurance capacity during exercise. When it is combined with corn oil in a total mixed ration, soy lecithin is both highly digestible and palatable to horses. Our objectives in this study were to compare the effects of incremental exercise and isocaloric control (CON), corn oil (CO), and a soy lecithin/corn oil (LE) diets on plasma free fatty acids (FFA), cholesterol, glycerol, triglyceride (TG), lactate, and glucose. Also three different statistical models were compared for goodness of fit to the lactate curve. Plasma lactate and glucose both increased slowly early in the incremental exercise test (IET), then increased rapidly as the work intensity increased. Both decreased during recovery. No effects of IET or diet were found for either of these variables. Plasma TG was unchanged during exercise, but increased rapidly during recovery. Plasma FFA decreased from resting early in the IET then remained steady throughout the remainder of exercise. During recovery a rapid increase was exhibited. Plasma glycerol was constant during exercise, but increased during recovery. Plasma cholesterol did not change during exercise or recovery. Diet affected plasma FFA. Plasma FFA were lower for the CO and LE diets than the CON diet during the IET. Plasma glycerol was lower for the CO diet than the CON diet during the IET, with the LE diet intermediate between the two. Plasma cholesterol was higher for the CO and LE diets than the CON diet during the IET. A segmented model and an exponential model were found to have a good fit to the lactate curve. A point of inflection for a rapid increase in plasma lactate during incremental exercise was discovered. When this model was applied to diet, no differences in lactate threshold were found between the diets. Some criteria for fat adaptation were met, namely diet affected plasma FFA, glycerol, and cholesterol. However diet did not affect plasma TG, lactate, or glucose. This indicates that the rate of fatty acid oxidation was increased following fat adaptation, but it did not affect the rate of glucose oxidation and glycolysis during exercise. A lactate threshold for the equine can be obtained using a broken line model. Further studies using this approach are needed to establish its correlation with performance. / Master of Science