Master of Science / Department of Clinical Sciences / James K. Roush / Hydrocodone and tramadol are opioid analgesics. No studies have been performed to evaluate the clinical efficacy or pharmacokinetics of hydrocodone/acetaminophen and tramadol in a heterogenous population of dogs. The efficacy of tramadol in dogs has been questioned based on previous pharmacokinetic data. The objectives of this study were to evaluate the analgesic effects of hydrocodone/acetaminophen and tramadol measured by a success/failure model and to determine the pharmacokinetic profile of each drug following the second oral drug dose administration. Fifty client-owned dogs presenting for routine tibial plateau leveling osteotomy were randomized to receive either oral hydrocodone/acetaminophen or tramadol in the postoperative period. A blinded investigator using a modified Glasgow Composite Measure Pain Scale scored each animal. Treatment failures were recorded and compared statistically for differences between the two groups. Blood sampling for pharmacokinetic analysis was initiated after the second oral dose. Mean [plus or minus] SE dose of hydrocodone/acetaminophen administered was 0.5 [plus or minus] 0.04 mg/kg and 16.6 [plus or minus] 1.41 mg/kg for hydrocodone and acetaminophen, respectively. Mean [plus or minus] SE dose of tramadol administered was 5.91[plus or minus] 0.61 mg/kg. The terminal half life, maximal serum concentration (Cmax) and time to maximal serum concentration (Tmax) for tramadol were approximately 1.56 hours, 155.6 ng/mL and 3.90 hours, respectively. Plasma concentrations of the active metabolite O-desmethyltramadol (M1) were low. For hydrocodone, the Cmax and Tmax were approximately 7.90 ng/mL and 3.47 hours, respectively. Plasma concentrations of hydromorphone were low after oral hydrocodone administration. Eighteen of 48 (37.5%) dogs required additional rescue analgesic therapy. This included 10 dogs in hydrocodone group and 8 dogs in the tramadol group (p=0.628). In a group of postoperative patients, no difference in pain scoring could be detected in hydrocodone/acetaminophen and tramadol groups. The pharmacokinetics of tramadol and metabolites were similar to previous studies. Wide variations existed in tramadol drug concentrations and the effects of tramadol are likely independent of the μ-opioid receptor. There is poor metabolism of hydrocodone to hydromorphone in dogs, however, efficacy may be achieved through hydrocodone. The analgesic efficacy of tramadol, 5-7 mg/kg PO q 8 h, and hydrocodone, 0.5 mg/kg PO q 8 h, should be assessed further prior to widespread use in canine postoperative patients.

Master of Science / Department of Anatomy and Physiology / Lei Wang / Jishu Shi / Interleukin-1 beta (IL-1β) is an important mediator of inflammatory response, and the elevated expression of IL-1β is correlated with tumor growth and metastasis. Epithelial-mesenchymal transition (EMT) is a reversible transition between epithelial phenotype and mesenchymal phenotype. Usually, EMT can be identified by its unique morphology change and expression of EMT markers. In our study, we have found after treated HCT-116, a colon cancer cell line, and human primary colon cancer cells with IL-1β, cells began to display mesenchymal phenotype with highly down-regulated E-cadherin expression and up-regulated ZEB factors expression. For colon cancer cells, sphere formation assay in serum free medium (SFM) with the presence of growth factors is used to identify cancer stem cell population. We have shown that IL-1β can induce colon cancer stem cell proliferation and express stem cell markers (Bmi1, Nanog, and Nestin). In addition, besides the stem cell markers, we also found ZEB factors were highly up-regulated in spheroid cells as well. We silenced Zeb1 expression and investigated the effect of IL-1β on shZeb1 HCT-116 cells. The results indicated Zeb1 knockdown not only inhibited IL-1β-induced EMT but also reduced proliferation of spheroid cells and inhibited Bmi1 expression. Therefore, ZEB factors must play an important role in both EMT process and cancer stem cell development. From our data, we conclude that IL-1β promotes epithelial-mesenchymal transition and a stem cell phenotype in colon cancer via ZEB factors.

Master of Science / Department of Clinical Sciences / Greg Grauer / A urinary tract infection (UTI) is defined as a temporary or permanent breach in host defense mechanisms that allows microbes to adhere, multiply, and persist within the urinary tract. Development of a UTI is multi-factorial with bacterial number and virulence and the health status of the patient (normal urogenital tract anatomy and physiology and systemic immunocompetence) playing important roles in determining the outcome. A UTI can involve a single site, such as the renal pelvis, ureter, bladder, urethra, prostate or vagina, or can include multiple sites. Infection of any portion of the urinary tract may increase the likelihood of infection in other locations. Diagnosis of a UTI incorporates findings from the history, physical examination, complete urinalysis, and urine culture. Proper classification and localization of the UTI are important when formulating a treatment regime as well as evaluating treatment success and failure. Most UTI can be successfully managed with appropriate antibiotic treatment; however, bacterial resistance and compromised host defense mechanisms can result in persistent or recurrent infections. In patients with recurrent UTI, identification of underlying predisposing conditions will often improve treatment success. In patients where underlying causes cannot be identified or treated, therapies designed to prevent recurrent UTI may be employed. Proanthrocyanidins found in cranberry juice inhibit E. coli attachment to human uroepithelial cells, impairing bacterial adherence and colonization. These characteristics have encouraged widespread usage of cranberry extract as a prevention strategy for woman predisposed to urinary tract infections. E. coli is a common cause of canine urinary tract infection. Current treatment emphasizes eradication of established infection rather than infection prevention, but increased antibiotic resistance necessitates strategies to prevent infection. We hypothesized that purified cranberry extract (CE) inhibits bacterial adhesion to canine uroepithelial cells. The results of our study show that CE supplementation can reduce adhesion of uropathogenic E. coli to canine uroepithelium and suggests one mechanism by which CE might improve urinary tract health.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Daniel U. Thomson / The widespread use of beta adrenergic agonists in beef cattle production has been adopted by the beef industry in recent years to improve weight gain and feed efficiency at the end of the feeding period. During this feeding period, anecdotal reports of increased mortality during the timeframe in which beta agonists were being fed to cattle was also reported, and confirmed in epidemiologic studies. Additionally, adverse animal welfare events at abattoirs in cattle fed beta adrenergic agonists were reported in August 2013. The objectives of this dissertation were to investigate physiologic and management factors that may be associated with adverse effects of the use of beta adrenergic agonists in cattle. Two studies were conducted, one to establish normal Holter monitor registration values and evaluate the electrocardiographic effects of zilpaterol and ractopamine hydrochloride on finishing steers, and one to develop a model to investigate the physiologic effects of forced exercises in finished cattle, which was hypothesized to be a possible factor in reported adverse cattle welfare events in August 2013. Thirty steers were enrolled to evaluate the effect of ractopamine, zilpaterol or negative control on arrythmia and mean heart rate at 4 different time periods during a 28 day feeding period. Cattle fed ractopamine and zilpaterol had increased heart rate (P < 0.05) but no differences in arrythmia rates were found. Forty steers were enrolled in a study at a commercial feeding facility to develop a model for fatigue in cattle forced to run 1,540 m compared to control cattle walked 1,540 m. Blood lactate, cortisol, rectal temperature, heart rate was increased (P < 0.05), blood pH decreased (P < 0.01) and to have reduced locomotion, as measured by pedometers, during the 48 hour period following handling compared to controls. Additionally cattle that were fatter and forced to run had increased lactate (P =0.057) and lower blood pH (P < 0.01) than thinner cohorts. Cattle handling method is a factor in the health and welfare of cattle and the continued adoption of low stress handling methods throughout the beef industry should be pursued.

Master of Science / Department of Clinical Sciences / Michael W. Sanderson / Escherichia coli O157:H7 has emerged as a significant human food-borne pathogen over the past two decades. While cattle have been identified as the major reservoir of the pathogen, the dynamics of shedding are still largely unknown. The role immunosuppression may play on fecal shedding in cattle is explored. The first study determined whether immunosuppression induced by dexamethasone injections affects the level and duration of fecal shedding of E. coli O157. Six one week old Holstein bull calves were injected intramuscularly with dexamethasone and orally inoculated with 109 CFU of a mixture of three nalidixic-acid resistant strains of E. coli O157. Another five one week old Holstein bull calves, only inoculated with the E. coli O157, served as controls. All calves were necropsied and samples from the gastrointestinal tract were cultured. Dexamethasone treated calves shed at higher levels on days four and seven post-inoculation, but not thereafter. The data from this study suggest that there may be a time dependent correlation between dexamethasone immunosuppression and the concentration of E. coli O157 an animal will shed in the feces and that transient immunosuppression does not result in prolonged shedding of E. coli O157. The goal of the second study was to determine whether calves immunosuppressed by persistent infection with bovine viral diarrhea virus (BVDV) will shed E. coli O157 at a higher level and for a longer duration than a normal animal. Nine six to eight week old calves persistently infected with non-cytopathic BVDV and eight normal calves obtained from separate cow-calf operations were orally inoculated with 109 CFU of a mixture five nalidixic-acid resistant strains of E. coli O157. All calves were necropsied and samples from the gastrointestinal tract cultured. There was no statistical difference in the concentration of E. coli O157 shed or the duration of shedding between the persistently infected BVDV calves and the control calves throughout the length of the study. The data suggest that immunosuppression caused by persistent infection with non-cytopathic BVDV infection does not play a role in the level or duration of shedding of E. coli O157:H7 in calves.

Master of Science / Department of Clinical Sciences / Walter C. Renberg / Objective: To measure strain in vivo in the calcanean tendon during trotting in canines, and to compare to strain present after tibiotarsal immobilization. Animals: 6 canines Procedures: A Differential Variable Reluctance Transducer[superscript]TM (DVRT®) strain gauge was surgically implanted on the common gastrocnemius tendon. Surface EMG, % strain, and ground reaction forces were measured prior to intervention and after immobilization. Peak vertical force (Fz), vertical impulse, initial, maximum and final strain, and peak-to-peak EMG amplitude were recorded. Data was analyzed using repeated measures analysis of variance and paired t-tests (p[equal to or less than]0.05). Results: Timing of strain data correlated closely to the hind limb footstrike and EMG activity in all dogs. Maximum tendon strain occurred simultaneous with peak Fz. Continued muscle contraction was evident after immobilization. There was no statistical difference in maximum strain after immobilization compared to normal motion. Minimum strain, both at the beginning and end of the strain curve, was significantly decreased with the immobilized state compared to non-immobilized joints. Conclusions and Clinical Relevance: Tibiotarsal immobilization did not eliminate calcaneal tendon strain during weight bearing. Decreased isometric muscle contraction during swing phase of the gait would account for smaller minimum strain in immobilized joints. Immobilization is frequently applied after Achilles tendon rupture to alleviate strain and force on the sutured repair, with possible complications due to the immobilization method. Direct correlation of strain with tendon force was not made in this study. This would be an important factor before adjusting current treatment recommendations.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Daniel U. Thomson / Escherichia coli O157:H7 is responsible for over 70,000 cases of human illness every year in the United States. Most cases occur in children under the age of five, the elderly, or other immune-compromised people. A small percentage of these cases will develop a life threatening complication, hemolytic uremic syndrome. Cattle are the reservoir host for E. coli O157:H7 and serve as the main source of contamination of meat products and other food sources. The beef cattle industry is diverse with producers caring for as few as one to as many as thousands of cattle. The first objective of this research was to examine three major production systems (conventional, organic, and natural) in the U.S. and the published performance effects of the various technologies used in each system. The second objective was to determine if a newly licensed E. coli O157:H7 SRP® (SRP) vaccine administered to cows pre-partum could achieve successful passive transfer in their offspring. The third objective was to determine if colostrum obtained from SRP vaccinated heifers could protect against an oral challenge with an E. coli K99+ strain. The fourth objective was to examine the shedding characteristics, health, and performance effects of calves born to SRP-vaccinated cows that also receive SRP vaccination themselves. The technologies used in conventional beef cattle production resulted in significant improvements in health and performance of beef cattle. Vaccinating cows pre-partum with SRP resulted in passive transfer in calves consuming their colostrum. Calves that achieved successful passive transfer shed less E. coli K99+ and had improved fecal consistency compared to placebo. When calves were vaccinated with SRP at branding, weaning, and arrival to the feedyard there was no difference in fecal E. coli O157:H7 shedding on arrival to the feedyard or at harvest. Vaccinating calves with SRP had no effects on performance or health outcomes. Vaccinating cattle with SRP may provide protection against other pathogenic E. coli strains and warrants further investigation. The timing of vaccination appears to be an important consideration in order to ensure maximum vaccine efficacy.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Derek A. Mosier / The bovine respiratory disease complex (BRDC) is a major concern for cattle producers in the United States and worldwide. One of the most costly and deadly components of BRDC is bovine pneumonic pasteurellosis (BPP) caused by Mannheimia haemolytica. The initial pulmonary inflammation associated with BPP is a characteristic serofibrinous exudation into the lung, which is believed to be induced by M. haemolytica virulence factors such as lipopolysaccharide (LPS) and leukotoxin (LKT) and host cytokines and chemokines such as tumor necrosis factor – α, interleukin – 1β, and interleukin – 8. However, these pulmonary changes often occur before virulence factors or cytokines are substantial components of the pulmonary microenvironment. Other proinflammatory molecules such as substance P (SP) may be involved in the pathogenesis of the peracute serofibrinous exudation of BPP. SP is an 11 amino acid long neuropeptide that is a neurotransmitter of pain that can be released from sensory nerves into tissues to cause neurogenic inflammation. Neurogenic inflammation is characterized by serofibrinous exudation and leukocyte activation. SP-like immunoreactivity was present in the airways, alveolar septa, macrophages, endothelium, and peribronchial nerves in both pneumonic and normal bovine lung; however, SP-like immunoreactivity was increased in pneumonic compared to normal bovine lung due to increased immunoreactivity in macrophages. SP and the combination of SP with histamine and LPS increased the permeability of a calf pulmonary arterial endothelial cell line to Evans blue dye labeled albumin by 12.34%, 13.57%, and 22.03%, respectively compared to a cell control. Similarly, SP and the combination of SP and histamine increased the monolayer permeability of a bovine adrenal gland capillary endothelium by 8.27% and 16.69% compared to a cell control. The increase in permeability was due to endothelial cell shape change and the formation of intercellular gaps rather than cell death. However, SP does not increase the surface expression of the β2 integrin CD18 (the M. haemolytica LKT receptor) on bovine neutrophils nor does it increase LKT-induced leukocytotoxicity of bovine peripheral blood leukocytes. These findings indicate that SP may be a contributor to BPP in association with other cytokines.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / David G. Renter / Bradley J. White / The objective of my research was to generate novel information concerning the epidemiology, diagnosis and prevention of bovine respiratory disease complex (BRDC), a common pre-weaning and post-weaning beef calf disease. To reach my objective, I conducted three prospective field trials within post-weaned calf populations, and one retrospective study of pre-weaned calves utilizing survey data. I evaluated differences in behavior, health and performance in calves receiving multiple component health programs. Calves in a minimally invasive program, which included primarily non-injectable products, displayed less aversion to initial product administration but experienced higher BRDC morbidity (P = 0.02) and poorer performance (P = 0.04) compared to calves in a more invasive (all injectable products) program. Secondly, in a study of Mannheimia haemolytica inoculated calves, I found that no parameter included in physical examinations, or common blood component evaluations could discern health from disease. However, disease recognition was aided by the measurement of the number of steps taken by a calf in a 24 hour period. None of the parameters that were evaluated predicted the severity of lung pathology. Thirdly, I conducted a study in post-weaned feeder calves that determined prevalence estimates for Mollicutes in general, and Mycoplasma bovis specifically, and their respective associations with health and performance. Nasal Mollicutes prevalence was high on arrival, and differences in calf performance were associated with (P < 0.01) nasal prevalence. More than half of the calves seroconverted to M. bovis; calves not seroconverting gained more weight (0.49 kg/head/day) during the study than those calves that did seroconvert (0.35 kg/head/day). Finally, I conducted a retrospective analysis of national U. S. cow-calf survey data to identify herd level management practices associated with pre-weaned calf BRDC. I found feeding antibiotics to pre-weaned calves, importing cattle, the number of outside visitors, economic purpose of the cow-calf operation, and breeding management of the herd were associated with herd-level pre-weaning BRDC rates. My research projects generated unique information concerning the epidemiology of important pathogens, differences among preventive health programs, objective BRDC diagnostic parameters, and pre-weaning BRDC risk factors. These research studies reinforce the complexity of BRDC and demonstrate the pathogen, animal and management factors affecting BRDC risk in pre- and post-weaned beef calves.

Master of Public Health / Public Health Interdepartmental Program / Manuel Moro / Activities of a state public health veterinarian.