Veterinary Medicine and Surgery electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Veterinary Medicine and Surgery. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Locoregional techniques for dogs undergoing tibial plateau leveling osteotomy : a literature review, anesthesiologist survey, and future directions(University of Missouri--Columbia, 2023) Parker, Lindsay Allison; Torres, BryanOver the past several decades there have been significant advancements in our understanding and ability to provide effective analgesia to animals undergoing elective orthopedic surgery through methods that can help us minimize the risk of adverse effects. In dogs, one of the most common elective orthopedic surgeries performed on the pelvic limb is the tibial plateau levelling osteotomy (TPLO) for the treatment of cranial cruciate ligament disease (CCLD). While historically the lumbosacral epidural has been considered the primary method of locoregional therapy for dogs undergoing TPLO, the development of peripheral nerve blocks has been a rapidly growing area of veterinary research. An in-depth knowledge of the pain cycle and ways to intervene in nociception is an immense area of interest in both the human and veterinary worlds. This thesis examines the pain cycle and how protective pain becomes pathologic, along with an exploration of the various pharmaceuticals and locoregional techniques that can be utilized for the lumbosacral epidural, peripheral nerve block, and the peri-incisional infiltration technique. Additional information about locoregional analgesic preferences is gleaned through a survey-based study of board-certified veterinary anesthesiologists. This study demonstrated that newer graduates prefer the use of bupivacaine-dexmedetomidine for peripheral nerve blocks in dogs undergoing TPLO and that analgesic decision-making in the clinical setting is multi-factorial. Overall, this research demonstrates that while significant advancements have occurred in the veterinary anesthesia and analgesia, further research into the effectiveness of various techniques as well as the clinical application of these methods is needed.Item Prolonged survival in 58 dogs with thyroid carcinoma treated with radioactive iodine as sole therapy(University of Missouri--Columbia, 2023) Cowan, Caitlin Marie; Donnelly, LindsayTreatment of thyroid carcinomas in people and dogs often involves multimodal therapy, including radioactive iodine (I-131). The objective of this study is to describe outcomes associated with I-131 as sole therapy in dogs with thyroid carcinoma. Retrospective review of medical records from a single institution (2004-2021) of dogs treated with intravenous I-131 was performed. Dogs were included if they had macroscopic thyroid carcinoma, received I-131 as a sole treatment and follow up information was available. Fifty-eight client owned dogs met inclusion criteria. 10/58 (17 percent) had non-neck tumor location. 21/52 (40 percent) dogs with known thyroid status were hyperthyroid prior to treatment. 16/51 (28 percent) of dogs had stage IV disease. Maximal responses were recorded in 49 (84 percent) of dogs; of these, objective responses were available in 20 (41 percent) and subjective responses were available in 29 (59 percent) of dogs. The overall response rate of dogs with recorded responses was 65 percent including 8 (16 percent) of dogs achieving a complete remission and 24 (49 percent) of dogs achieving a partial response (PR). Stable disease (SD) was documented in 14 (28 percent) of the population and progressive disease was noted in 3 (6 percent) of dogs. Hyperthyroidism resolved in all dogs. Of 50 evaluable dogs, 30 (60 percent) progressed. The median progression free interval (PFI) was estimated to be 614 days (range 30-2213). The median survival time (MST) was estimated to be 629 days (range 30-2213); 7 dogs were alive and censored. Dogs with distant metastasis (stage IV) at the time of diagnosis had significantly shorter MST (385 days) when compared to dogs of lower stage (p = 0.0021). No survival difference was identified based on thyroid hormone status or tumor location. Minimal toxicity was observed. This cohort uniquely demonstrates the value of I-131 as a sole therapy in dogs with thyroid carcinoma. Despite advanced disease in many cases, PFI and MST were prolonged.Item Neonatal beef calf morbidity and mortality in Missouri(University of Missouri--Columbia, 2022) Rivero, Luis A; Adkins, PamelaNeonatal morbidity and mortality are major causes of economic loss for US beef cattle producers. The Missouri cattle industry represents 19 percent of the total agriculture sales in the state and is valued at 1.6 billion dollars. It is estimated that calf sales can account for up to 55 percent of a farm's gross cash income which highlights the economic importance of calf health to producers. The overarching aim of this body of work was to characterize morbidity and mortality of neonatal beef calves with a focus on bacteremia. An additional goal was to determine if any prognostic factors could be identified that may indicate a calf is likely to survive a critical illness. This body of work is comprised of two studies, one retrospective study on necropsy findings in neonatal beef calves presented to the University of Missouri's Veterinary Medical Diagnostic Laboratory and one prospective study conducted on critically ill neonatal beef calves presented to the University of Missouri's Food Animal Clinic. The objective of the retrospective study was to describe lesions and abnormal test results among neonatal beef calves presented to a veterinary diagnostic laboratory. Overall, 1,060 reports were reviewed and inclusion criteria were bovine, 2 to 21 days of age, and of a non-dairy breed. Statistical analysis was performed to compare age, system affected, and pathologic agent types in addition to interactions between each system affected. A total of 95 cases met the inclusion criteria. Median age of enrolled calves was 9 days (range: 2 to 21). A total of 252 lesions were identified with a median of 3 lesions/calf (range: 0 to 7) and 2 different body systems involved/calf (range, 0 to 5). The most common disorders were classified as digestive (42.1 percent [106/252]), respiratory (12.7 percent [32/252]), and multisystemic (11.1 percent [28/252]). With respect to age and system affected, calves with neurologic lesions were significantly younger (mean age: 5.1 days) than calves with digestive lesions (mean age: 9.6 days). For the prospective study, the study objectives were to determine the prevalence of bacteremia in neonatal beef calves, identify factors predictive of bacteremia, and identify factors associated with survival. A total of 27 calves were enrolled in the study. Median age of calves was 7 days (range, 1 to 21). Diarrhea was the most common presenting complaint and was present in 26 percent (13/50) of calves. Most calf deaths occurred either during hospitalization or by 2 weeks after discharge. A lower prevalence of bacteremia (17 percent) was found in this study compared to previous reports. In this study, no bacteremic calves survived. Hypothermia, hypercapnia, and hyperfibrinogenemia were associated with decrease likelihood of survival. The results of this thesis suggest that calves submitted to a veterinary diagnostic laboratory have a high prevalence of infectious diseases, mainly digestive, respiratory and multisystemic in origin. In addition, critically ill calves are more likely to die during hospitalization or in the first 2 weeks after discharge and that hypothermia, hypercapnia, and hyperfibrinogenemia were associated with decreased likelihood of survival. These findings could help guide producers and veterinarians when assessing factors contributing to neonatal beef calf loss and establishing prognosis for critically ill calves.Item Diagnosis of aerodigestive disorders in dogs utilizing videofluoroscopic swallow study(University of Missouri--Columbia, 2022) Howard, Jennifer Lynn; Reinero, CarolAn aerodigestive disease (AeroD) is a disorder pathologically linking the respiratory and alimentary tracts. Dogs having respiratory signs without dysphagia, vomiting, or regurgitation typically lack diagnostics identifying comorbid alimentary disease. Videofluoroscopic swallow study (VFSS) identifies defects in swallowing, pathologic reflux, and aspiration. We hypothesized dogs with respiratory/no alimentary disease (RESP) would have significantly more abnormal VFSS metrics versus healthy controls (CON). We hypothesized RESP dogs with parenchymal disease would have more reflux and higher penetration-aspiration score (PAS) than those with airway disease. Forty-five client owned dogs with respiratory disease (RESP) and 15 hospital staff owned dogs (CON) were evaluated. Prospectively, all dogs underwent VFSS. RESP dogs had advanced respiratory diagnostics. Eight subjective and three objective VFSS metrics (pharyngeal constriction ratio, PCR; PAS; and esophageal transit time, ETT) were assessed. Fishers Exact test compared differences between groups (presence or absence of VFSS abnormalities). PCR and PAS were compared via Mann-Whitney Rank Sum test (p[less than]0.05 significant). Results revealed subjective VFSS abnormalities in 34/45 (75 percent) RESP and 2/15 (13 percent) CON dogs, with RESP dogs significantly more likely to have VFSS abnormalities (p = 0.006). There was no significant difference in PCR between groups. RESP dogs were more likely to have pathologic PAS than CON (p = 0.027). RESP dogs with airway disease had higher PAS than CON (p = 0.011) but not RESP dogs with parenchymal disease (p = 0.246). Overall, seventy-five percent of RESP dogs had VFSS abnormalities, underscoring that AeroDs are common.Item Relative HER2 protein expression in normal canine tissue and canine osteosarcoma(University of Missouri--Columbia, 2022) Reich, Sessaly; Bryan, JeffreyDevelopment of HER2-targeted immunotherapy in canine osteosarcoma (OSA) is underway, yet HER2 expression in normal and neoplastic canine tissue has not yet been defined. This study's objective was to evaluate the relative HER2 protein expression in canine osteosarcoma tissue, normal canine tissue, and a HER2-overexpressing human cancer cell line. Flash frozen tumor tissue donated from 24 dogs with spontaneouslyoccurring OSA tumors, 2 normal colon samples, cell pellets from 2 OSA cell lines (Abrams, HMPOS) and a HER2-overexpressing human cell line were available for protein extraction and HER2 immunoblotting. Formalin-fixed tissue suitable for H and E staining and HER2 immunostaining was available for 6 normal colon and 18 OSA (13 primary tumors, 5 metastases) canine samples. None of the 26 OSA tumors showed relative HER2 blot band intensity equal to or greater than those of controls. Four of 5 OSA metastases and all 13 OSA primary tumors showed some degree of HER2 immunostaining, predominantly weak and cytoplasmic. Only a subset of spontaneously occurring canine osteosarcoma tumors express HER2 in a relevant manner for treatment with anti-HER2 immunotherapy, and not in a membranous pattern to justify surface-targeted therapies.