Doctor of Philosophy / Department of Physics / Dean A. Zollman / In this study we explored students' transfer of learning in the X-ray medical imaging context, including the X-ray-based computer-assisted tomography (or CAT). For this purpose we have conducted a series of clinical and teaching interviews. The investigation was a part of a bigger research effort to design teaching-learning materials for pre-medical students who are completing their algebra-based physics course. Our students brought to the discussion pieces of knowledge transferred from very different sources such as their own X-ray experiences, previous learning and the mass media. This transfer seems to result in more or less firm mental models, although often not internally consistent or coherent. Based on our research on pre-med students' models of X-rays we designed a hands-on lab using semi-transparent Lego bricks to model CAT scans. Without "surgery" (i.e. without intrusion into the Lego "body") students determined the shape of an object, which was built out of opaque and translucent Lego bricks and hidden from view. A source of light and a detector were provided upon request. Using a learning cycle format, we introduced CAT scans after students successfully have completed this task. By comparing students' ideas before and after teaching interview with the groups of 2 or 3 participants, we have investigated transfer of learning from basic physics and everyday experience to a complex medical technology and how their peer interactions trigger and facilitate this process. During the last phase of our research we also introduced a CAT-scan simulation problem into our teaching interview routine and compared students' perception of this simulation and their perception of the hands-on activity.

The detection of predators by prey species is crucial in order to escape the threat posed by a predator. In mammals, the olfactory sensory system is commonly used to detect odors emitted by predators, and to determine how threatening the situation actually is. However, knowledge about this ability is still sparse and in some cases conflicting. The aim of the present study was therefore to assess whether CD-1 mice (Mus musculus) show behaviors such as avoidance, anxiety and/or decreased activity when exposed to any of the three odorants: cat bladder urine, horse voided urine or a fruity odor (N-pentyl acetate), with a blank solvent as an alternative in a two-compartment test arena. I found no significant differences between avoidance (the time that the mice spent in the different compartments), anxiety (the numbers of fecal pellets dropped by the mice), or the overall activity (the number of switches between the two compartments), when the mice were exposed to the three different odors. The fact that the cat urine derived from the bladder of the cat may explain the lack of avoidance responses, since bladder urine might not contain the same chemical components as voided urine. Bladder urine might therefore also lack the chemical components that signal “predator” to the mice. In conclusion, mice do not respond differently to the odor of cat bladder urine than to horse voided urine or to the fruity odor of N-pentyl acetate.

Expression of foreign proteins in host organisms usually results in the development of insoluble, inactive proteins. Further, these proteins have a tendency to form aggregates termed inclusion bodies. However, the formation of inclusion bodies can be avoided by fusing the gene encoding the foreign protein to a highly soluble protein. In this report Sterol Carrier Protein-2 (SCP-2) is reviewed as a possible solubility tag. The experiment was carried out by fusing SCP-2 to one of two i nsoluble proteins, Green fluorescent protein (GFP) or a form of chloramphenicol acetyl transferase (CAT∆9). The protein fusion was then inserted into the vector pET-15b, transformed in Escherichia coli and the yield of actively expressed protein was measured. The results obtained from this study, as evaluated by PageBlue staining and  Western blot, are indicating that SCP-2 does not improve the solubility of GFP or CAT∆9. Nonetheless, the solubility of GFP has earlier been increased by fusing it to the solubility tag maltose-binding protein (MBP).  Producing more soluble forms of CAT∆9  have also been tested but without success. Therefore the conclusion drawn from this experiment is that SCP-2 does not work as a solubility tag, however more research must be performed to conclude this with certainty.

Zielstellung: Die Verwendung von Computertomographie und Magnetresonanzto-mographie zur Diagnostik von pathologischen Weichteilveränderungen, wie Läsionen der Speicheldrüsen, wird empfohlen. Diese begründet sich in Ihrer hohen Bildauflö-sung und dem guten Bildkontrast. Nach unserem Wissen gibt es aktuell keine publi-zierte Literatur, welche sich mit der CT- oder MRT-Anatomie der Speicheldrüsen der Katze beschäftigt. Ziel der vorliegenden Arbeit war es daher, Schnittbildmerkmale der Speicheldrüsen zu definieren und Landmarken für eine sichere Identifikation zu be-schreiben. Material und Methoden: Es wurden zwei Gruppen von Katzen untersucht. Die pros-pektiv untersuchten Tiere bestanden aus 16 Katzen, welche aus Gründen euthana-siert wurden, die nicht in Zusammenhang mit der Studie standen. Diese erfuhren ein CT (1 mm Schichtdicke) und 0,5 Tesla MRT (T2W, T2W SPIR, PDW, T1W) des Kop-fes. Im retrospektiven Anteil der Studie wurden CT-Untersuchungen (0,8-1 mm Schichtdicke) von 25 Katzen und MRT-Untersuchungen (T2W, T1W vor und nach Kontrastmittelgabe) von 21 Katzen verwendet. Diese Untersuchungen wurden zwi-schen 2005 und 2013 in unserer Klinik angefertigt. Dabei konnten keine Pathologien in Zusammenhang mit den Speicheldrüsen festgestellt werden. Alle Speicheldrüsen wurden bezüglich Identifizierbarkeit, Abgrenzbarkeit, Größe und Signalverhalten un-tersucht. Wenn vorhanden, wurden anatomische Landmarken die Speicheldrüsen umgebend notiert. Zusammenfassung 80 Ergebnisse: 94,3% der Glandulae parotidae, 90,7% der Glandulae mandibulares und 96,8% der Glandulae zygomaticae konnten mit dem CT identifiziert werden. Beim MRT waren es 94,1% der Glandulae parotidae, 99,2 % der Glandulae mandibulares, 88,9% der Glandulae zygomaticae und 51,4 % der Glandulae buccalis ventralis. In beiden Gruppen konnten keine der restlichen kleinen Speicheldrüsen identifiziert werden, dies galt für beide Schnittbildverfahren. Als hilfreiche anatomi-sche Landmarken konnten der äußere Gehörgang, der M. masseter, der M. pterygo-ideus medialis und der Bulbus oculi herangezogen werden. Die medianen Dichtewer-te lagen für die Glandula parotis, die Glandula mandibularis und die Glandula zygo-matica bei 65 HU, 62 HU und 57 HU. Die Parotis war überwiegend dezent hyperin-tens zur Muskulatur und hypointens zum Fett. Die Mandibularis, Zygomatica, und Glandula buccalis ventralis stellten sich hauptsächlich hyperintens zur Muskulatur und hypointens zu Fettgewebe dar. Dieses Signalverhalten war für T1W, T2W und T2W SPIR (fettunterdrückt) gewichtete Sequenzen gleich. Die Größe war für beide Gruppen und Modalitäten vergleichbar und lag bei circa 17 x 6 mm (gemessen von lateral nach medial und von dorsal nach ventral) bei der Glandula parotis, 8 x 17 mm bei der Glandula mandibularis, 10 x 7 mm bei der Glandula zygomatica und bei der Glandula buccalis ventralis 3 x 10 mm. Schlussfolgerungen: Landmarken und Aussagen über die Signalintensität bezie-hungsweise Dichte und die Größe der Glandula parotis, Glandula mandibularis, Glandula zygomatica und der Glandula buccalis ventralis konnten erhoben werden. Die mangelhafte Identifizierbarkeit der restlichen kleinen Speicheldrüsen, im Ver-gleich zu den oben genannten, kann vor allem mit dem unzureichenden Weichteil-kontrast zum umliegenden Gewebe im CT und der niedrigen Auflösung des Nieder-feld-MRTs erklärt werden. Neuere MRT-Techniken können detailliertere Bilder er-zeugen und so eine Beschreibung der kleinen Speicheldrüsen ermöglichen. / Objective: Due to their high resolution and useful contrast resolution, CT and MRI are recommended methods for diagnosing pathological changes of soft tissues such as lesions of the salivary glands. To our knowledge, no studies about the CT or MR anatomy of the feline salivary glands have been published yet. The aim of the study was to define anatomical characteristics of the salivary glands in cross-sectional im-ages and to describe landmarks for a reliable identification. Materials and methods: Two groups of cats where examined. In a prospective trial, 16 cats, euthanized for reasons unrelated to the study, underwent a head CT (1 mm slice thickness) and 0.5 Tesla MRI scans (T2W, T2W SPIR, PDW, T1W). In a retro-spective trial, the CT scans (0.8-1 mm slice thickness) of 25 cats and the MR scans (T2W, T1W, pre- and post-contrast) of 21 cats were used. These scans were per-formed at our clinic between 2005 and 2013. No signs of salivary-gland-related pa-thologies were visible. All images were reviewed with respect to the following criteria: the presence, delineation and size of the salivary glands as well as the signal intensi-ty. Anatomical landmarks surrounding the glands were also recorded. Results: 94.3% of the parotid glands, 90.7% of the mandibular glands and 96.8% of the zygomatic glands could be delineated using CT. With MRI, 94.1% of the parotid Summary 82 glands, 99.2 % of the mandibular glands, 88.9% of the zygomatic glands and 51,4 % of the ventral buccal glands could be identified. In both groups the other small salivary glands could not be visualized neither in CT nor in MRI. Anatomical landmarks such as the external ear canal, the M. masseter, the M. pterygoideus medialis and the Bulbus oculi facilitate the identification. The mean density of the parotid gland, the mandibular gland and the zygomatic gland was 65 HU, 62 HU and 57 HU, respectively. The parotid gland was mainly modestly hyperintense to muscle and hypointense to fat. The mandibular, zygomatic and ven-tral buccal glands were hyperintense to muscle and hypointense to fat. Signal intensi-ties were similar for T1W, T2W and T2W SPIR images. Sizes were comparable for both groups and modalities and measured about 17x6 mm (lateral to medial and dor-sal to ventral) for the parotid gland, 8 x 17 mm for the mandibular gland, 10x7 mm for the zygomatic gland and 3x10 mm for the ventral buccal gland. Conclusions: Landmarks were recorded and data regarding the density/signal in-tensity and the size of the parotid gland, the mandibular gland, the zygomatic gland and the ventral buccal gland could be gathered. The discrepancy between depicting the small glands and the above mentioned glands can be explained mainly by the lack of contrast to the surrounding tissue in CT and the low spatial resolution in low-field MRI. Advanced MRI techniques are expected to produce more detailed images and therefore those techniques could be used to also describe the small salivary glands.

Einleitung: Der frühzeitigen Detektion pulmonaler Rundherde kommt eine Schlüsselrolle bei neoplastischen Erkrankungen von Hund und Katze zu, indem sie maßgeblich Prognose und Behandlungsoptionen beeinflusst. Ziel unserer ersten Studie war, die aktuelle diagnostische Wertigkeit und mögliche Limitationen der klassischen Röntgenuntersuchung bei der Detektion pulmonaler Rundherde darzustellen. Unsere zweite Untersuchung beschäftigt sich mit dem Ziel der computerassistierten Detektion (CAD) und deren Einsatz in der Tiermedizin. Material und Methoden: Der Untersuchungszeitraum umfasste die Jahre 2005–2011. In die erste Studie wurden Hunde und Katzen mit pulmonalen Rundherden aufgenommen, an denen zunächst eine klassische Röntgenuntersuchung und anschließend innerhalb von 14 Tagen eine computertomographische Untersuchung (CT) durchgeführt wurde. Neben der Darstellung möglicher Limitationen der klassischen Röntgenuntersuchung wurde auch deren Sensitivität hinsichtlich des Vorliegens pulmonaler Rundherde im Vergleich zur CT als Goldstandard untersucht. Gemäß den Einschlusskriterien wurden 50 Hunde und 20 Katzen in die erste Studie aufgenommen. Die zweite Untersuchung beschäftigt sich mit der Sensitivität eines computerassistierten Detektionssystems sowie dessen möglichen Mehrgewinns für den Radiologen bei der Detektion pulmonaler Rundherde in der Tiermedizin. Darüber hinaus wurden die möglichen Limitationen eines solchen Systems untersucht. In die Untersuchung wurden nicht nur Tiere mit Rundherden eingeschlossen, sondern auch solche mit Massen (Herde größer 3 cm). Ausgeschlossen waren Patienten mit mehr als 50 Rundherden pro Lungenhälfte sowie Rundherde/Massen, die vollständig in Atelektasen eingebettet waren. Gemäß den Einschlusskriterien wurden bei 51 Hunden und 16 Katzen insgesamt 586 Rundherde als Referenzwert für die CAD zugrunde gelegt. Ergebnisse: Als ein Ergebnis aus der vorliegenden ersten Studie zeigt sich für die Projektionsradiographie eine Detektionsrate von insgesamt 61 % (64 % für Hunde und 55 % für Katzen) verglichen mit der CT als Goldstandard. Gründe für eine fehlende Detektion liegen vor allem darin, dass die Röntgenuntersuchung im Ergebnis ein Summationsbild liefert. Daneben spielt auch die Rundherdgröße eine (untergeordnete) Rolle. Das in der zweiten Studie eingesetzte Detektionssystem zur computerassistierten Detektion pulmonaler Rundherde wies für die Tiermedizin eine Sensitivität von 69,4 % auf. Gleichzeitig wurde eine hohe Anzahl falsch positiver sowie falsch negativer Befunde durch die CAD verzeichnet. Dennoch ließ sich durch den Einsatz der CAD die Sensitivität von Untersucher 1 von 89,2 % auf 94,7 % steigern, die von Untersucher 2 von 87,4 % auf 90,8 %. Schlussfolgerungen: Aufgrund der engen Einschlusskriterien dieser Studie kann für die Detektion pulmonaler Rundherde in der Projektionsradiographie als Mindestwert die hier ermittelte durchschnittliche Sensitivität von 61 % zugrunde gelegt werden. Die klassische Röntgenuntersuchung eignet sich weiterhin als erstes bildgebendes Verfahren für die pulmonale Rundherddetektion, für ein genaues Staging sollte allerdings die CT angewandt werden. Für eine fehlende Rundherddetektion war nicht primär die geringe Größe der Rundherde ursächlich, sondern vielmehr Begleiterkrankungen, die mit einer Transparenzminderung der Lunge einhergingen. Daher sollte insbesondere dann die CT zum Einsatz kommen, wenn zusätzliche Veränderungen wie beispielsweise ein Pleuraerguss vorliegen. Für die Detektion pulmonaler Rundherde in der CT-Untersuchung gilt, dass die Sensitivität des Radiologen grundsätzlich durch ein automatisches Detektionssystem gesteigert werden kann. Somit eignet es sich insbesondere dann, wenn kein zweiter radiologischer Befunder vorhanden ist. Allerdings weist die CAD eine sehr hohe Anzahl falsch positiver sowie einige falsch negative Befunde auf, so dass sich für ihren routinemäßigen Einsatz in der Tiermedizin derzeit noch Limitationen ergeben. / Introduction: The early detection of pulmonary nodules plays a key role in neoplastic conditions of dogs and cats substantially influencing prognosis and therapy options. The aim of our first study was to outline the actual diagnostic value as well as the potential limitations of projection radiography for detection of pulmonary nodules. Our second study addresses the newer aspect of computer assisted detection (CAD) and its possible application in veterinary medicine. Materials and methods: The investigation period was between 2005 and 2011. In our first study we included those dogs and cats with pulmonary nodules that underwent a radiographic examination as well as a computed tomographic examination (CT) within a period of 14 days. Aside from the description of possible limitations of projection radiography, we also evaluated its sensitivity for detection of pulmonary nodules compared to CT as gold standard. According to the inclusion criteria 50 dogs and 20 cats were admitted to this study. The second study dealt with the sensitivity of a computer assisted detection system and its potential benefit for radiologists for the detection of pulmonary nodules in veterinary medicine. Furthermore, we outlined possible limitations of the detection system. This study not only comprised dogs and cats with pulmonary nodules, but also those with pulmonary masses (i.e. nodules > 3 cm). We excluded patients with more than 50 nodules either in the right or the left lung as well as nodules/masses embedded in a massive atelectasis. According to our inclusion criteria, we determined 586 nodules in total, distributed on 51 dogs and 16 cats used as reference value for the CAD. Results: As one result of our first study, we found a detection rate of 61 % (64 % for dogs and 55 % for cats) for projection radiography in comparison to CT as gold standard. Reasons for a missing detection of pulmonary nodules are predominantly limitations that come along with superimpositions using projection radiography; apart from that, nodule size is of some subsidiary meaning. The detection system for the computer assisted detection of pulmonary nodules used in the second study showed a sensitivity of 69.4 % in veterinary medicine. Additionally a high number of false positive findings as well as false negative findings was detected by CAD. However, due to the use of CAD the sensitivity of examiner 1 increased from 89.2 % to 94.7 %, the sensitivity of examiner 2 increased from 87.4 % to 90.8 %. Conclusions: Based on the strict inclusion criterion in this study the average sensitivity of 61 % can be used as a minimum for the detection of pulmonary nodules using radiographs. Projection radiography is suitable as first line diagnostic tool for the detection of pulmonary nodules. For accurate tumor staging CT should be used. Since predominant reasons for a missing detection of pulmonary nodules consisted of limitations that come along with superimpositions (like pleural effusion) CT is especially recommended in those cases. In general, the sensitivity of radiologists can be improved by an automatic detection system concerning the detection of pulmonary nodules using CT. Especially in those cases, when no second reader is available, CAD is suitable. However, the CAD system we used herein yielded a high number of false positive findings as well as false negative findings; therefore, its use in veterinary medicine on a routine basis still has some limitations.

This thesis will attempt to scrutinize Günter Grass's message to his people and show his concern for the spiritual health of his country. Each of his three novels bears directly upon political, religious, and moral issues vital to Germany and to the world. The examination is based upon the assumption that Grass as an author is more concerned that Germans see themselves as they are and as they have been than he is concerned with the image of Germany which his novels present to the world. It is, paradoxically, this very special and sincere concern which gives his work universal appeal.

Sensory neocortex contains a significant number of inhibitory neurons that use gamma-aminobutyric acid (GABA) as their neurotransmitter. Functional roles for these neurons have been identified in physiological studies. For example, in primary somatosensory cortex (SI), blockade of GABAa receptors with bicuculline leads to expansion of receptive fields (RFs). The magnitude of RF enlargement varies between SIpopulations of GABAergic neurons were identified by labeling specific calcium binding proteins.

Purpose: The purpose of this study was to correlate the presence of Streptococcus mutans and Streptococcus sobrinus with the incidence of dental caries in children as detected by the polymerase chain reaction (PCR).Methods: Subjects between the ages 2 to 16 years of age were used in this study. After the subjects received a dental examination, dental plaque samples were collected by rubbing a toothpick on the buccal surface of the most posterior tooth in each quadrant of the mouth. Children were grouped into low, moderate, and high caries risk categories by two different Caries Risk Assessment Tools (CAT 1 and CAT 2). PCR was used to amplify the dextranase (Dex) gene of S. mutans and S. sobrinus. Dextranase is an enzyme that hydrolyses glucans in a plaque matrix and is believed to be involved in the pathogenesis of dental caries. Identification of the amplified Dex gene sequences was made by gel electrophoresis which in turn was used to determine the presence of S. mutans and S. sobrinus.Results: S. mutans was detected in 57% of patients (65/115), S. sobrinus was detected in 10% of patients (12/115) and both organisms were present in 9% of patients (10/115). According to CAT 1, the incidence of S. mutans was 64.6%, 9.2%, and 26.2% in low, moderate, and high caries risk, respectively. The incidence of S. sobrinus was 66.6%, 16.7%, and 16.7% in low, moderate, and high caries risk, respectively. Conclusion: Presence of S. mutans and/or S. sobrinus as evaluated in this study had no direct correlation with caries risk level in children.

Orientador: Maria Cecília Rui Luvizotto / Resumo: O objetivo desta pesquisa foi avaliar o comportamento dos biomarcadores renais dimetilarginina simétrica (SDMA), creatinina sérica (CRs) e a relação proteína:creatinina urinária (UPC) em gatos aparentemente saudáveis (n: 20) e gatos portadores de doença renal crônica (n:10). No grupo de gatos com doença renal crônica (DRC) os valores médios de SDMA, CRs e UPC foram 20,4 ± 3,1 µg/dL, 2,4 ± 0,7 mg/dl e 0,6 ± 0,23, respectivamente. Para o grupo aparentemente saudável a SDMA, CRs e UPC obtidos foram 9,8 ± 1,8 µg/dL, 0,9 ± 0,4 mg/dl e 0,28 ± 0,08. Para o grupo positivo para DRC, o coeficiente de correlação entre a SDMA e CRs foi r = 0,52, indicando ser correlação moderada entre estes marcadores renais. Pelo exposto conclui-se que os gatos sintomáticos para DRC necessitam serem subestadiados pelos critérios da IRIS (2017) (UPC, CRs, PAS e SDMA) e execução de medidas de renoproteção como tentativa de controle da progressão da DRC presente. Para os gatos aparentemente saudáveis o comportamento da SDMA deu-se dentro da normalidade para a espécie, com um valor de UPC limítrofe, sugerindo monitoramento e acompanhamento trimestral ou semestral, conforme avaliação clínica. / Abstract: The objective of this study was to evaluate the behavior of the renal biomarkers dimethylarginine symmetric (SDMA), serum creatinine (CRs) and protein: urinary creatinine ratio (UPC) in apparently healthy cats (n: 20) and cats with chronic kidney disease (10). In the group of cats with chronic kidney disease (CKD) the mean values of SDMA, CRs and UPC were 20,4 ± 3,1μg / dL, 2,4 ± 0,7 mg / dl and 0,6 ± 0,23, respectively. In the apparently healthy group the SDMA, CRs and UPC obtained were 9,8 ± 1,8 μg / dL, 0,9 ± 0,4 mg/dl and 0,28 ± 0,08. In the group of cats with chronic kidney disease the correlation of SDMA and CRs was r = 0.52, indicating a moderate correlation between these renal biomarkers. Based on those findings concluded that cats with CKD require a detailed diagnosis by IRIS (2017) (UPC, CRs, PAS and SDMA) to perform kidney protection and attempt to control the progression of CKD. For apparently healthy cats, the behavior of SDMA was the normal range for the species, with a borderline UPC value, suggesting monitoring and quarterly or semi-annual follow-up, according to clinical evaluation. / Doutor

Obesidade na clínica de felinos é um problema frequente e tornou-se motivo de grande preocupação para a medicina veterinária. A obesidade é definida como acúmulo excessivo de tecido corporal adiposo. O objetivo do presente estudo observacional prospectivo foi determinar os principais fatores de riscos relacionados ao excesso de peso em gatos com ênfase na interação tutor-gato. Para tanto, foram selecionados gatos, divididos em dois grupos, a saber: grupo dos gatos obesos (n=18) nesse grupo foram incluídos gatos com escore de condição corporal entre 8 e 9; grupo dos gatos não obesos (n=18) com escore de condição corporal 5. Foram excluídos do estudo os gatos que apresentaram outras comorbidades, além da obesidade. A pesquisa dos prováveis fatores de risco relacionados a obesidade foi realizada mediante a utilização de um questionário respondido por todos os tutores dos 36 gatos. Nenhuma das variáveis qualitativas estudadas nos aspectos demográficos dos gatos obesos e não obesos demonstrou significância, ou seja, não houve associação entre obesidade e o sexo, o status sexual, as raças e o tamanho do pelame. Assim como, nenhuma das variáveis qualitativas analisadas nos aspectos demográficos dos tutores de gatos obesos e não obesos demonstrou significância; Não houve relação entre obesidade e o sexo do tutor, ao estado civil, a profissão (inclusive os clínicos veterinários), a escolaridade e a renda média familiar dos tutores. Com relação aos aspectos antrozoológicos, contatou-se que ambos os grupos têm uma relação estreita de afeto com seus tutores, contudo a porcentagem do grau de afeto tende a ser maior no grupo obeso, apesar de não ter sido evidenciada diferença estatística. Sobre os aspectos ambientais, oito variáveis foram presumivelmente consideradas importantes na manutenção e no controle do peso dos gatos. Constatou-se que felinos do grupo não obeso costumam brincar sozinhos e com outros animais, enquanto que gatos obesos são menos interativos. Ainda, o enriquecimento ambiental, assim como o manejo alimentar com dieta úmida influenciaram na condição física desses gatos. Constatou-se que o número de felinos não obesos que recebe ração úmida é bem maior que o daqueles pacientes com excesso de peso. Finalmente, o escore de condição corporal atribuído pelos tutores de felinos com excesso de peso tende a ser subestimado quando comparado ao do profissional especializado. Os principais riscos ocasionados pelo excesso de peso identificados neste estudo foram o tipo de alimentação oferecido, principalmente dietas secas, e a inatividade física. Apesar de os aspectos antrozoológicos não demonstrarem valor estatístico, o grau de afeto tende a ser levemente superior quando se analisa valores percentuais. / Feline obesity is a frequent problem and has become a major concern in veterinary medicine. Obesity is defined as excessive accumulation of body fat. The purpose of this prospective observational clinical study was to determine the main risk factors related to obesity in cats with emphasis on owner-cat interaction. Thus, the studied cats were divided into two groups: obese cats (n=18) with a body condition score between 8 and 9; and non-obese cats (n=18) with a body condition score of 5. All cats were healthy at the time of the study was conducted and cats with any other disease, besides obesity were excluded. The study of the risk factors related to obesity was performed using a questionnaire answered by all owners of the 36 cats. None of the qualitative variables in demographic aspects of obese and non-obese cats showed significance, and there was no association between obesity and gender, sexual status, race and coat size. Also, none of the qualitative variables in demographic aspects of the owners of obese cats and non-obese cats showed significance. Besides that, there was no relationship between obesity and the gender of the cat owner, marital status, profession (including veterinarians), schooling and the average family income of the owner. Regarding the antrozoological aspects, we concluded that both groups of cats a close affectionate relationship with their owners, but the percentage of the degree of affection tends to be higher in the obese group, despite there being no statistical difference. Considering the environmental aspects, eight variables were presumably important in maintaining and controlling the weight of cats. It was found that non obese cats usually play alone and with other cats, while obese cats were less interactive. Moreover, environmental enrichment as long as the moisture of the diet influenced the physical condition of these cats. Non obese cats usually had more moist food than obese cats. Finally, the body condition score given by the owners of obese cats tends to be underestimated when compared to the experts score. The main risks to the overweight findings in this study were type of food offered, especially dry diets and the physical inactivity. Also, despite the anthrozoological aspects evaluated have not shown any significance as risk factors for obesity in cats, the degree of affection between owner-cat tend to be slightly higher in obese cats group.