Le souffle équin est une maladie inflammatoire chronique des petites voies respiratoires, très fréquente chez les chevaux gardés à l’intérieur avec de la paille et du foin moisi et poussiéreux. Les signes cliniques peuvent être prévenus par le contrôle de l’environnement et soulagés par l’administration de corticostéroïdes systémiques et inhalés. L’objectif de cette étude était de déceler les effets secondaires présents sur des chevaux atteints de souffle traités à la fluticasone (Flovent 250 μg HFA®, 2000 μg BID, pendant six mois, et puis 2000 μg SID, pendant six autres mois) par le cortisol sérique et la présence d’ulcères gastriques. Cinq chevaux exempts de maladie respiratoire et onze chevaux atteints du souffle ont été gardés à l’intérieur d’une écurie avec du foin moisi et de la paille dans le but de provoquer la maladie chez le groupe atteints du souffle. Une fois les chevaux atteints de souffle devenus symptomatique, ils ont été divisés en deux groupes : un premier groupe traité avec de la fluticasone, nourri avec du foin et gardé sur une litière de paille, et un deuxième groupe non traité nourrie avec de la moulée et gardé sur une litière de ripe, pendant six mois. Par la suite, les deux groupes ont été mis au pâturage. Le cortisol a été mesuré par Immunoessai enzymatique par chimiluminescence (CEIA, Immunolite 1000, Siemmens®) les 12e et 10e jours avant et les 7e, 28e, 80e, 160e, 200e, 250e, 290e et 320e jours après le début du traitement afin de déterminer le degré de suppression du cortisol sérique. On a également fait une suivi de la présence d`ulcères gastriques à l`aide de vidéo endoscopique. La fluticasone inhalée deux fois par jour cause une diminution du cortisol sérique les 28e, 80e et 160e jours, mais elle n’entraîne pas d’effets sur le score des ulcères gastriques. Les pellets de luzerne causent quant à elles, une augmentation du score des ulcères gastrique chez les animaux exempts de maladie respiratoire. / Recurrent Airways Obstruction (RAO) is a small airways inflammatory disease, very common in horses stabled in mouldy-dusty hay and straw environments. The clinical signs are prevented by environmental control, relieved by systemic and inhaled corticosteroids. Our objectives were to determine whether inhaled corticosteroids cause a suppression of cortisol levels and gastric ulceration in RAO horses treated with fluticasone 2000μg (Flovant HFA®) BID for 6 months and 2000μg SID for another 6 months. Five (5) healthy horses were used as controls and eleven (11) RAO affected horses were stabled in a moldy-dusty environment to induce disease exacerbation. Once they were symptomatic, they were divided into two groups, the treated group was kept on hay/straw and the untreated group was fed with pellets food and bedded on wood shavings six months. Afterwards, all horses were pasture for the next 6 months. Serum cortisol was mesured by Immuno-essai enzymatique par chimiluminescence (CEIA, Immunolite 1000®, Siemmens) 12, 10 days before and 7, 28, 80, 160, 200, 250, 290, 320 days after treatment initiation, in order to determine cortisol suppression. Fluticasone administered twice a day reduces blood cortisol levels after 28, 80 and 160 days, but did not cause any change in gastric ulcers. However, pellets slightly increased gastric ulcer scores in healthy horses.

Chez le chien, les thromboses représentent une complication majeure de nombreuses conditions qui sont revues dans ce manuscrit. L’arsenal thérapeutique actuel présente certaines limites: des effets anticoagulants variables d’un patient à l’autre, des hémorragies et une administration par voie sous-cutanée pour l’héparine. Le rivaroxaban est un nouvel anticoagulant oral approuvé pour la prévention et le traitement des thromboses chez l’humain. C’est un inhibiteur direct du facteur Xa. La présente étude a pour objectif d’évaluer les effets hémostatiques du rivaroxaban chez des chiens en santé, en utilisant les tests de coagulation suivants: temps de prothrombine (PT), temps partiel de thromboplastine (aPTT), activité anti-facteur X, génération de thrombine (GT) et thromboélastographie (TEG®). Tout d’abord, l’effet anticoagulant du rivaroxaban a été évalué in vitro : le plasma citraté pauvre en plaquettes provenant de 20 Beagle en santé a été aliquoté et enrichi avec des solutions de rivaroxaban à des concentrations de 0 à 1000 mg/L d’anticoagulant. Une prolongation concentration-dépendante de tous les tests de coagulation a été notée. Les concentrations de 0.024 et 0.053 mg/L diminuent respectivement de 50% la vitesse de propagation de la GT et la densité optique de l’activité anti-facteur X. Ces derniers tests sont les plus sensibles et précis pour détecter l’effet anticoagulant du rivaroxaban. Ensuite, 24 Beagle en santé ont été répartis aléatoirement en 3 groupes (n=8). Chaque groupe a reçu par voie orale un placebo, ou 20 mg de rivaroxaban une ou deux fois à 8h d’intervalle. Quinze échantillons sanguins ont été prélevés pour chaque chien sur 30 heures. Pour tous les tests de coagulation excepté la TEG®, une différence significative a été notée dans les résultats entre les groupes traités et le groupe placebo (p<0.0001). La durée de l’effet anticoagulant du rivaroxaban était de 7.9-18.7h dans le groupe traité une fois; et de 17.5-26.8h dans le groupe traité deux fois. Le pic d’action de l’effet anticoagulant était d’environ 2h. Seul le paramètre R de la TEG® était significativement affecté dans les groupes traités. En conclusion, le rivaroxaban exerce un effet anticoagulant chez le chien à la dose de 2 mg/kg. Une administration biquotidienne semble appropriée pour un effet de 24h. / In dogs, thrombosis is a major complication detected in many conditions. The limits of the current available anticoagulants in veterinary medicine are their variable effects from one patient to another, bleeding complications and subcutaneous injections for heparin administration. Rivaroxaban is a novel oral anticoagulant approved for the prevention and treatment of thrombosis in humans. It is a direct factor Xa inhibitor. The objectives of the study were to determine the haemostatic effects of rivaroxaban in healthy dogs by evaluating the following coagulation assays: prothrombin time (PT), activated partial thromboplastin time (aPTT), anti-factor X activity, thrombin generation (TG) and thromboelastography (TEG®). An in vitro study was conducted: citrated platelet poor plasma from 20 healthy Beagles was aliquoted and mixed with rivaroxaban to obtain solutions ranging from 0 to 1000 mg/L of the anticoagulant. Rivaroxaban exerted a concentration-dependent anticoagulant effect. Rivaroxaban solutions at 0.024 and 0.053 mg/L cause 50% inhibition of the propagation of TG and of the optical density of anti-factor X activity respectively. These assays were the most sensitive to detect the anticoagulant effect of rivaroxaban. Secondly, 24 healthy Beagles were randomly divided in 3 groups (n=8) and received one placebo pill orally, or 20 mg rivaroxaban once or twice at 8h interval. Fifteen citrated blood samples were collected from each dog over 30h. For each coagulation assay except for TEG®, there was a significant difference in assay results between placebo and rivaroxaban groups (p<0.0001). The duration of the rivaroxaban anticoagulant effect was 7.9-18.7h in the group receiving rivaroxaban once, and 17.5-26.8h in the group receiving rivaroxaban twice. The peak of action of rivaroxaban appeared 2h after the dose. Only R parameter of TEG® was significantly affected by rivaroxaban administration. To conclude, rivaroxaban is an efficient anticoagulant in healthy dogs at 2 mg/kg. A twice daily administration seems appropriate to exert a 24h anticoagulation.

Master of Science / Department of Anatomy and Physiology / Daniel C. Marcus / Sensory transduction in the cochlea depends on regulated ion secretion and absorption. Results of whole-organ experiments suggested that Reissner’s membrane may play a role in the control of luminal Cl-. We tested for the presence of Cl- transport pathways in isolated mouse Reissner’s membrane using whole-cell patch clamp recordings and gene transcript analyses using RT-PCR. The current-voltage (I-V) relationship in the presence of symmetrical NMDG-Cl was strongly inward-rectifying at negative voltages, with a small outward current at positive voltages. The inward-rectifying component of the I-V curve had several properties similar to those of the ClC-2 Cl- channel. It was stimulated by extracellular acidity and inhibited by extracellular Cd2+, Zn2+, and intracellular ClC-2 antibody. Channel transcripts expressed in Reissner’s membrane include ClC-2, Slc26a7 and ClC-Ka, but not Cftr, ClC-1, ClCa1, ClCa2, ClCa3, ClCa4, Slc26a9, ClC-Kb, Best1, Best2, Best3 or the beta-subunit of ClC-K, barttin. ClC-2 is the only molecularly-identified channel present that is a strong inward rectifier. This thesis incorporates the publication by K.X. Kim and D.C. Marcus, Inward-rectifier chloride currents in Reissner’s membrane epithelial cells. Biochem. Biophys. Res. Commun. 394 (2010) 434-438, with permission of the publisher Elsevier, and is the first report of conductive Cl- transport in epithelial cells of Reissner’s membrane and is consistent with an important role in endolymph anion homeostasis.

Master of Science / Department of Clinical Sciences / Luciana Bergamasco / As public concern for food animal welfare increases, the need for objective pain assessment and methods to alleviate pain associated with production practices such as castration gains attention. The aims of this study were (i) to evaluate the physiological response to pain induced by castration in calves and (ii) to elucidate age-related differences in pain response of calves subjected to different castration methods. Seventy six Holstein bull calves were blocked by age (≤ 6 weeks and ≥ 6 months) and randomly assigned to one of four treatment groups: control (n = 20), castration by banding (n = 18), cut and clamp surgical castration (n = 20), and cut and pull surgical castration (n = 18). Measurements included electroencephalogram, heart rate variability, infrared thermography, electrodermal activity, and concentrations of serum cortisol, and plasma substance P prior to, during, and following castration. Electroencephalogram recordings showed desynchronization for all treatments, consistent with increased arousal; yet the magnitude of desynchronization was greatest for 6-month-old calves castrated by cut and clamp. Additionally, older calves in the cut and pull group showed greater desynchronization than younger calves in the same group. Based on the heart rate variability analysis, 6-month-old calves in the control or cut and pull castration groups showed greater sympathetic tone than younger calves in the same treatment groups. Overall, younger calves showed lower electrodermal activity than older calves. Regardless of treatment, concentrations of cortisol and plasma substance P were greater in 6-month-old calves relative to their younger counterparts. In summary, neurohormonal and electroencephalographic stress responses of calves to castration were age-specific. Castration by cut and clamp showed the most pronounced stress response in 6-month-old calves.

Master of Science / Department of Diagnostic Medicine and Pathobiology / Juergen A. Richt / Influenza A virus is an important respiratory pathogen with the potential to affect both humans and animals, thereby creating the conditions for public health disasters, especially during pandemic episodes. At present, two primary strategies to combat influenza are vaccination and antiviral drugs. Since influenza viruses mutate rapidly and constantly via antigenic drift and shift, vaccines can become quickly outdated; and resistance to antiviral drugs can readily result. Interferon alpha (IFN-[alpha]) plays an important role as a first line of innate antiviral immunity. To investigate the antiviral potential of exogenously applied IFN-[alpha] on the replication of different subtypes of influenza A viruses, three subtypes of influenza A virus, i.e. swine H3N2, pandemic H1N1 and avian H9N2 were chosen. Their replication kinetics in the presence of Alferon N (human Interferon alpha) on human epithelium (A549) cells and swine testis (ST) cells was evaluated. In these tests of the three subtypes of influenza A viruses, it was found that the replication ability of all three viruses was inhibited when ST cells were treated with Alferon for four hours before infection. The ability of Alferon to inhibit influenza A viruses replication was found to be dose-dependent. Similar results were obtained when A549 cells were used; however, pretreatment of A549 cells with Alferon for more than 16 hours was necessary before infection. Furthermore, the expression of some ISGs (Interferon stimulated genes) between ST and A549 cells was also investigated. The differences in response of the ISGs between the two cell lines provided an explanation of the disparity towards exogenous interferon treatment. In summary, these results demonstrated that Alferon N has the ability to inhibit replication of different subtypes of influenza A viruses in cell cultures. This study provides a foundation for future in vivo studies using exogenous IFN-[alpha] treatment as an alternative approach to combat influenza A virus infection.

Doctor of Philosophy / Department of Animal Science and Industry / Chris Reinhardt / Dan Thomson / Bovine Respiratory Disease Complex (BRDC) is the most common and costly disease in feedlot cattle in North America. Annual economic losses are estimated to be US$1 billion due to mortality, reduced performance, and treatment costs. The disease is a multifactorial syndrome caused by a combination of environmental factors, management practices, animal susceptibility, and viral and bacterial pathogens. The objectives of this dissertation were to evaluate two injectable antimicrobials for the treatment and control of BRDC in feedlot cattle, investigation of factors associated with BRDC mortality and morbidity, and to develop control charts based on statistical process control (SPC) principles to monitor cattle mortality rates. Two multi-site prospective studies were conducted to evaluate the comparative efficacy of the administration of gamithromycin and tulathromycin for the treatment and control of BRDC. A total of 2,529 animals were enrolled at two commercial feedlot locations to evaluate the efficacy of the antimicrobials to control BRDC. Morbidity due to BRDC was higher (P = 0.03) among calves receiving gamithromycin compared with those receiving tulathromycin; however, treatments were considered bioequivalent (P < 0.05) for BRDC mortality, case fatality rate and re-treatment rate. Final BW, ADG, DMI and F:G, were similar (P<0.05) between the groups of calves receiving gamithromycin and tulathromycin. For the evaluation of treatment efficacy, a total of 1,049 calves were enrolled in the study. Re-treatment rate was higher among animals treated with gamithromycin compared with those treated with tulathromycin. Treatments were bioequivalent (P < 0.05) for case fatality rate, final BW, and ADG. To evaluate factors associated with BRDC, a retrospective study was conducted to analyze BRDC mortality and morbidity associated with initial body weight, rectal temperature, and castration and dehorning (tipping) at processing. Calves with lighter weights and fever at processing were at greater risk of mortality and morbidity due to BRDC. Also, bulls castrated at processing were at higher risk of developing BRDC. Finally, we developed control charts based on SPC principles to monitor and identify “normal” and special cases of variation of mortality rate. In feedlot cattle, monitoring lots of cattle through SPC principles can be used as a powerful tool for continuous improvement.

Master of Science / Department of Clinical Sciences / Daniel U. Thomson / Bovine Respiratory Disease (BRD) continues to be one of the largest animal health concerns in the cattle industry. BRD is a multifaceted group of pathogens, both viral and bacterial, that take advantage of an immune compromised calf to cause disease. This study took aim at comparing metaphylactic treatments for BRD in both the feedlot and pasture setting. In the feedlot study, heifers (n=579, 403.7 ± 27.4 lbs) from Southwest Texas were identified as being high risk for BRD and shipped to the Clayton Livestock Research Center in Clayton, NM. Cattle were randomly allocated within truck load lots into 18 to 20 head treatment pens (30 pens; 3 treatments; 10 reps). Cattle were given one of three metaphylactic treatments based on the randomly assigned treatment for their pen within a replicate. The three antibiotic treatments administered at initial processing were: 1) Tulathromycin (2.5 mg/kg), 2) Tilmicosin (13.3 mg/kg), and 3) Gamithromycin (6.0 mg/kg). Cattle were fed a typical commercial starter diet for the first 56-60 d with a step-up ration change at day 28. At the end of the feeding period, pens were weighed and body weights recorded. Dry Matter Intake, morbidity, and mortality were recorded by CLRC personnel daily. Cattle administered tulathromycin had higher daily gains than cattle administered gamithromycin by 0.29 lbs/d (P<.01) and tended (P=0.09) have higher daily gains than cattle that received tilmicosin by 0.18 lbs/d. Tulathromycin treated cattle tended (P = 0.12) to have improved feed efficiency compared to gamithromycin treated cattle. Cattle that received tulathromycin (5.2%) had lower morbidity rates (P < .02) than tilmicosin (14.6%) and gamithromycin (12.79%) treated cattle. There were no treatment differences in dry matter intake or mortality in cattle. For the wheat pasture study, heifers (n=120, 393.2 ± 28.6 lbs) from the same origin and risk were shipped to the CLRC and processed before being trailed to a nearby wheat pasture. Cattle were randomly assigned into three treatment groups (3 treatments, 40 reps), and were given one of three metaphylactic treatments. The three antibiotic treatments administered at initial processing were: 1) Tulathromycin (2.5 mg/kg), 2) Tilmicosin (13.3 mg/kg), and 3) Gamithromycin (6.0 mg/kg). Cattle were allowed to graze on wheat for 54 days with free-choice Hi-Pro mineral mixed with Lasalocid, an ionophore. After 54 days on wheat pasture, the cattle were trailed back to the CLRC facilities and final individual weights were recorded. Morbidity and mortality were recorded daily by CLRC personnel. No differences were identified for ADG (P=0.98), morbidity (P=0.46) or mortality (P=0.36) among the three treatment groups.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / T. G. Nagaraja / Escherichia coli O157:H7 and over 380 non-O157 serotypes of Shiga toxin producing E. coli (STEC) are human food-borne pathogens that inhabit the hindgut of ruminants and are shed in the feces, which subsequently contaminate food products. Recent epidemiological data have shown that six non-O157 STEC (O26, O103, O111, O121, O45 and O145) account for majority of human STEC infections. Fecal shedding of STEC is influenced by a number of factors, including diets, supplements, and feed additives, because of their potential to alter hindgut ecosystem. Not much is known about the fecal shedding of non-O157 STEC in cattle because of lack of standardized detection methods. Fecal shedding of E. coli O157:H7 was studied to determine the effects of supplemental urea, monensin, an ionophore, and ractopamine, a beta-agonist. Cattle fed monensin at 44 mg/kg of feed had lower (P = 0.05) fecal O157:H7 prevalence than cattle fed 33 mg/kg. Supplemental urea (0.35 or 0.70% of the diet) and inclusion of ractopamine at 200 mg/animal/day had no effect on fecal shedding of E. coli O157:H7. In an experimental inoculation study, inclusion of corn starch to a distiller’s grains (DG)-supplemented diet had no effect on fecal shedding of E. coli O157 suggesting that either the decreased starch content in the DG-supplemented diet is not a factor in the increased shedding of E. coli O157:H7 or inclusion of pure starch in the diet may not have achieved our intended goal to have starch flow into the hindgut similar to that of corn grain. A multiplex PCR to detect O26, O45, O103, O111, O121, O145, and O157 was designed and applicability to detect the seven serogroups in cattle feces was evaluated. A multiplex PCR, designed to detect E. coli O104, feces showed presence of O104 in cattle feces (20.6%), but the isolated strains did not carry genes characteristic of the virulent strain responsible for the 2011 food-borne outbreak in Germany. Two preharvest interventions, a siderophore receptor and porin proteins-based vaccine and a Lactobacillus acidophilus-based direct-fed microbial, intended to control E. coli O157, had no effect on fecal shedding of O26 assessed by culture-based or PCR-based method.

Master of Public Health / Department of Diagnostic Medicine/Pathobiology / Douglas Powell / Outbreaks of human illness have been linked to visiting settings with animal contact throughout developed countries. These outbreaks demonstrate that although contact with animals in public settings can provide educational and entertainment opportunities, the potential to spread disease exists if risk-reduction tools are not implemented, proper hygiene measures aren’t practiced, and precautions are not taken and reinforced. This thesis is divided into two parts. Part one is an observational study of hand hygiene tool availability and recommendations; frequency of risky behavior; and, handwashing attempts by visitors in Kansas and Missouri, U.S., petting zoos. Part two delineates best practices for organizing events where human-animal interactions are encouraged, in hopes it will lower the risk of zoonotic disease transmission. Handwashing signs and hand hygiene stations were available at the exit of animal-contact areas in 10/13 and 8/13 petting zoos respectively. Risky behaviors were observed being performed at all petting zoos by at least one visitor. Frequently observed behaviors were: children (10/13 petting zoos) and adults (9/13 petting zoos) touching hands to face within animal-contact areas; animals licking children’s and adults’ hands (7/13 and 4/13 petting zoos, respectively); and children and adults drinking within animal-contact areas (5/13 petting zoos each). Of 574 visitors observed for hand hygiene when exiting animal-contact areas, 37% (n=214) of individuals attempted some type of hand hygiene, with male adults, female adults, and children attempting at similar rates (32%, 40%, and 37% respectively). Visitors performed hand hygiene more often when a staff member was present within or at the exit to the animal-contact area (136/231, 59%) than when no staff member was present (78/343, 23%; P < 0.001, OR = 4.863, 95% CI = 3.380–6.998), and in petting zoos where animal contact occurred over a fence (188/460, 40.9%) as opposed to visitors entering an animals’ yard for contact (26/114, 22.8%; P < 0.001, OR = 2.339, 95% CI = 1.454–3.763). Inconsistencies existed in tool availability, signage, and supervision of animal- contact. Risk communication was poor, with few petting zoos outlining risks associated with animal-contact, or providing recommendations for precautions to be taken to reduce these risks. Recommendations made in the second part of this thesis were based on these observations, recent publications, and the suggestions of many health agencies. It focuses on what event planners can do to design and plan a safer event, and what staff working at the event should be aware of in order to inform visitors and lower the risk of zoonotic disease transmission. Part two discusses two primary tools to reduce risk of zoonotic disease transmission: sanitation and awareness of risk behaviors. Keeping facilities, animals, and visitors clean, and informing visitors of risky behaviors to avoid, while reinforcing positive messages within the animal- contact area, can lower the risk of zoonotic infection. Included with the second part, is a checklist (see appendix A) designed for visitors to assess whether an event that encourages human-animal interaction poses a high or low risk. By identifying possible risk factors, teachers and parents will be able to make an informed decision about the safety of the human-animal encounter.

Master of Science / Department of Clinical Sciences / Daniel U. Thomson / Bovine respiratory disease (BRDC) is a multifaceted disease that causes considerable economic loss in both the beef and dairy industry. However, because there may be lingering effects of BRDC in the dairy industry, the full economic costs of the disease may not be realized. These lingering effects may include an increased departure from the herd, decreased milk production, and decreased reproductive performance. All of these outcomes are affected by multiple variables, but proper statistical modeling can control for many of the different influences. Few studies have attempted to look at the long term effects of calfhood BRDC but consistent associations have not been identified. The objective of this observational, retrospective study was to determine the association between calfhood BRDC prior to 120 d of age and departure from the herd, milk production, and reproductive performance. The association between the occurrence of BRDC with departure from the herd prior to first calving depended on the birth year, but for 5 of the 6 years, animals that contracted BRDC were 1.62 to 4.98 times more likely to leave the herd than animals that did not contract BRDC. In addition, animals that contracted BRDC were also 1.28 times more likely to leave the herd between first and second calving than animals that did not contract BRDC. Furthermore, the age at BRDC occurrence was associated with departure from the herd. Animals that contracted BRDC pre-weaning were 2.62 times more likely to leave the herd prior to first calving than animals that contracted BRDC post-weaning. However, age of BRDC occurrence was not significantly associated with departure from the herd between first and second calving. The occurrence of BRDC during the first 120 d of life was associated with a 233 kg decrease in lactation-one production, but was not significantly associated with production in subsequent lactations. Finally, calfhood BRDC was not significantly associated with a decreased reproductive performance measured by calving interval. In conclusion, calfhood BRDC negatively impacts productivity both prior to and after first calving.