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Feline oral squamous cell carcinomas (FOSCCs) are locally aggressive tumours and a common cause of mortality and morbidity. Current treatment options are rarely successful and animals are frequently euthanised upon diagnosis due to their grave prognosis. Epidermal Growth Factor Receptor (EGFR) is a tyrosine kinase receptor which is frequently dysregulated in SCC of the head and neck (HNSCC) in man. Recent advances in human medicine have identified EGFR as a therapeutic target in HNSCC. In this study the role of EGFR in FOSCC was investigated. Sixty seven biopsy samples were immunohistochemically labelled for EGFR and Ki67, a proliferation marker. The tyrosine kinase region of feline EGFR was cloned and sequenced, and six small interfering RNAs (siRNAs) targeting the tyrosine kinase region were developed. The most effective siRNA as well as an EGFR specific tyrosine kinase inhibitor, gefitinib, was then used on a feline SCC cell line (SCCF1), and the effect of EGFR targeting alone, or in combination with irradiation, on the cell line was determined. The majority of the biopsy samples were labelled positively for EGFR and Ki67, and high proliferation corresponded with poor prognosis. The siRNA caused reduction in EGFR mRNA by Real-Time Polymerase Chain Reaction and protein levels as assessed by western blot analysis. Reduced cell proliferation and migration were also observed by proliferation assays and scratch assays respectively. Combining EGFR knockdown with irradiation caused an additive effect on the ability of the cell line to form colonies. These results support the role of EGFR as a potential therapeutic target in FOSCCs.

The microbiome of the gastrointestinal tract is a vast ecosystem that is important to host health. Imbalances in this ecosystem are involved in disease, therefore studying this relationship is important for understanding disease pathophysiology. Research in this area has rapidly expanded due to accessibility, lower costs of sequencing techniques, as well as an increased awareness of its scientific impact. Gut microbiome studies are often performed on fecal samples. In most species, acquiring fecal samples is a relatively simple way study the microbiome. However, fecal collection in cats is more complicated due to their unique husbandry and elimination behaviors. Fecal identification is challenging in group-housing and multi-cat households. Nonetheless, these samples are required for research and clinical purposes. One solution to this problem is the administration of fecal identification markers. Oral administration of crayon shavings and glitter have been used as fecal markers clinically, but their impact on the fecal microbiome is unknown. The objective of this research was to determine the impact of fecal identification markers, specifically crayon shavings and glitter, on the feline microbiome. A randomized crossover experiment was performed with six healthy sterilized purpose-bred cats who were group-housed in a dedicated research facility. Cats received either glitter or crayon shavings mixed in a feline canned adult maintenance diet for 14 days. A 14-day washout was performed between crossovers. Feces was collected daily from each cat for 16S rRNA gene sequencing (V4 region). Amplicon analysis was performed in R-studio using DADA2 and Phyloseq packages. Pairwise PERMANOVA analysis compared samples across experimental phases and marker order. Fecal identification markers were readily identified in the feces of all cats. Statistically significant changes to the microbiome were identified with marker order (p < 0.05) and across experimental phases (p < 0.05) for 5/6 cats. Microbiome changes were cat-dependent (p < 0.001), suggesting idiosyncratic microbiome responses to oral administration of glitter and crayon shavings. Both glitter and crayon shavings allow for identification of individual feline fecal samples; however, these markers may impact the microbiome and therefore are not recommended in studies with microbiome endpoints. The difference in response to these markers among cats highlights the individuality of the feline microbiome.

The inability to control one’s environment is well recognized as a major stressor for all animals. As millions of cats enter United States shelters each year, they experience this exact stressor with lack of control of their surroundings. With a growing interesting in domestic cat welfare, there has been a push for understanding and improving the general housing environment, yet there remains a divided opinion on compartment size and setup. There are two main housing configurations used in shelters: a smaller single compartment where all resting, feeding, and litterbox components are located within a single small space, or a double compartment, which is larger and contains the feeding/resting areas on a separate side from the litterbox area, with a pass-through hole to connect. Shelters considering whether to house their cats in single compartment versus double compartment housing face a trade-off between the desire to maximize the number of spots available and the need to provide adequate space to cats. However, technology can be used to gather data so shelters can make data-driven decisions about housing. Technological advances have made it is possible to collect data on activity and location using autonomous methods, which reduces the intense personnel effort previously required and enables the collection of wider and larger data sets, including 24-hr monitoring. While promising, these technologies need to first be validated within their intended use. We tested two common types of these automated technologies: accelerometers to quantify activity, and radio frequency identification (RFID) to detect locations, for monitoring the domestic cat (Felis silvestris catus) in a shelter-like setting. Two cats were placed in a double compartment housing at separate times: one to evaluate activity levels via a Fitbit Zip and one to evaluate location with an RFID system. Both technologies were compared to manually scored video recordings of each animal. The results demonstrated that these technologies could be a reliable means for monitoring domestic cats for activity and location in this type of setup. We then used these autonomous data collection methods in shelters within Cincinnati, Ohio to compare the activity patterns of 33 cats, stress levels for 29 cats, and location patterns for 12 cats in either single or double compartment layouts. We had one individual with two stays at the same shelter (separated by an adoption period). This cat was used opportunistically as a case study to compare double and single compartments differences in the same individual. In general, we found that across both housing configurations cats showed decreasing cortisol and increasing activity as time passed, but there was a higher percentage of significantly decreasing cortisol patterns within the double compartment housing. Cats in double compartments demonstrated a 45/55 split between spending more time in non-litterbox and litterbox side, respectively; however, cats in double compartment housing spent significantly less time over the litterbox compared to cats in single compartments. These findings support that double compartment setups may be beneficial to the welfare and behavior of shelter cats, but continued research is warranted.

In the Unites States, approximately 1.5 million people currently have a spinal cord injury and suffer permanent sensory and motor loss due to the disruption of the spinal cord. Due to the significant morbidity, it is vital to understand the functional impact of disrupting neural descending pathways that modulate spinal neurons involved in intermuscular coordination critical for gait behaviors. Tasks that are more difficult require additional input from these neural pathways; therefore, fourteen feline subjects were familiarized with level overground locomotion and stair descent gait tasks. After collection of baseline kinematic data, the subjects received either a dorsal or ventral quadrant injury at spinal T9/T10 junction. Two types of injuries allowed for the study of disruption of different combinations of descending neural pathways. A ventral quadrant injury disrupts the vestibulospinal, pontine reticulospinal, and medullary reticulospinal tracts, and a dorsal quadrant injury disrupts the rubrospinal corticospinal, and medullary reticulospinal tracts. Post-operative gait performances were captured six weeks post-injury. Due to the critical nature of weight support for effective gait, analyses focused on the stance phase. Changes in gait features during stance were observed following both localized injuries: dorsal quadrant injuries had symmetrical gait features and ventral quadrant injuries had asymmetrical gait features. In particular, weight acceptance was altered as evidenced by exaggerated flexion at one or more of the hindlimb joints in early stance during level overground locomotion. Dorsal quadrant injuries had This work improves our understanding of the effect of spinal cord injury and descending neural pathways located in different spinal areas on the stance phase of gait, and contributes to the knowledge necessary to promote recovery in those with a spinal cord injury.

Background: The use of stapling equipment for intestinal surgery in cats is rarely reported, and appropriate staple sizes for cat intestine are unknown. Objective: To determine staple cartridge sizes for thoracoabdominal (TA) and endoscopic gastrointestinal anastomosis (EndoGIA) that will simultaneously prevent leakage of small intestinal contents while also allowing for sufficient vascular permeability past the staple lines for intestinal healing. Methods: Two sizes of EndoGIA cartridges (2.0/2.5/3.0mm and 3.0/3.5/4.0mm) and two sizes of TA cartridges (2.5mm and 3.5mm), applied in a transverse manner across fresh cadaveric cat jejunum, were evaluated via intestinal burst pressure testing for maximum intraluminal pressure prior to leaking, and via infusion of an intravascular dye at normal arterial pressures to determine percentage of vascular patency past the staple lines. Vascular patency was compared not only from pre-and post-staple segments of the same intestinal sample, but also EndoGIA vascular patency was evaluated against TA vascular patency. Results: Two cats met study criteria. All samples had intraluminal burst pressures over twice the chosen minimum (of 30mmHg). Vascular patency post- staple line ranged from 0-90.8%, with the most consistently high numbers noted with the TA 3.5mm cartridges. No EndoGIA cartridge had a post- staple line vascular patency higher than 31.1%, and no intravascular dye was noted in any post- staple line sample in the EndoGIA 2.0/2.5/3.0mm group. Conclusions: While statistical analysis of the dataset was unable to be performed due to low numbers of samples for comparison, both intestinal intraluminal burst pressure trends and intravascular dye patterns suggested both the TA 3.5mm cartridge and (to a lesser extent) the 3.0/3.5/4.0mm EndoGIA cartridge could provide the ideal combination of intraluminal seal without restriction of vascular access for healing. The intravascular dye infusion technique, developed during this research, shows promise as a future instrument to determine vascular patterns around intestinal implants in cadaveric cat specimens.

There are an estimated 172 million owned and feral cats in the United States, and wildlife enthusiasts and cat owners are often at odds over how best to manage free-roaming cats. Management is needed because of the documented impacts of free-ranging cats on wildlife. Targeting these management efforts, however, is hampered by an imperfect understanding of cat distribution in the landscape. My study used game cameras and capture-recapture sampling to estimate abundance of free-roaming cats across a habitat gradient in Bulloch County, Georgia, USA. In all, I detected cats at 51% (25/49) sites with a mean of 2.1 cats per site. Cat abundance was significantly related to percentage of forest, distance to buildings, and density of buildings. Ultimately, density of buildings was the single best predictor of free-ranging cat abundance. With free-roaming cats having a significant, positive relationship with density of human buildings as determined by this study, it can be concluded that the free-roaming cat population of Bulloch County can be predicted to be found mostly in urbanized zones. As urbanization increases, current management strategies must be revised based on this data to target areas with high structural density to mitigate free-roaming cat impacts and hasten the removal of the species from the environment.

The prevalence of overweight and obesity in the feline population is estimated to be 25.7% and 33.8%, respectively. Feline obesity is associated with comorbidities such as insulin resistance and hepatic lipidosis. Several risk factors are associated with obesity including middle age, neuter status, decreased activity, and diet. Obesity management is multifaceted and includes client education, diet modification, and consistent monitoring. Successful obesity management may be dependent on owner perception of their cat's quality of life during a prescribed weight loss plan. Poor quality of life perception may result in failure to complete the weight loss process. Food toys may be used to enhance environmental enrichment, allow cats to express their natural predatory behavior and overall improve owner-perceived quality of life. Therefore, we set out to investigate the role of food toys in owner-perceived quality of life of obese cats during a prescribed weight loss plan. Fifty-five cats with a BCS > 7 were enrolled in a double-blinded weight loss study and randomized into one of two groups: food toy (n=26) or food bowl (n=29). Each cat was provided a prescribed weight loss diet and instructions. Body weight and body condition score were evaluated monthly. Additionally, owners completed a monthly questionnaire to assess their cat's quality of life. Of the 44 cats in the final analysis, 66% (n=29) successfully completed the study and lost > 2 BCS points and/or achieved an ideal BCS of 5/9. Low-calorie vegetables were offered to the majority of cats (n= 32) due to owner reports of disruptive food seeking behavior. Of the cats offered vegetables, 87.5% (n=28) cats required a commercial palatant to consume the vegetables. All enrolled cats had a higher (p

Dorsal root ganglia (DRG), the hubs of neurons conducting sensory information into the spinal cord, are promising targets for clinical and investigative neural interface technologies. DRG stimulation is currently a tertiary therapy for chronic pain patients, which has an estimated prevalence of 11-40% of adults in the United States. In pre-clinical studies, combined neural recording and stimulation at DRG has been used as part of closed-loop systems to drive activity of the limbs and the urinary system. This suggests a role for clinical DRG interfaces to assist, among other patient groups, the nearly 300,000 spinal cord injured patients in the United States. To maximize the utility of DRG interfaces, however, there remains a strong need to improve our understanding of DRG structure. Neural interface technologies for both stimulation and recording rely heavily on the spatial organization of their neural targets. To record high-fidelity neural signals, a microelectrode must be placed within about 200 µm of a neural cell body. Likewise, effective neural stimulation is believed to act on a subset of DRG axons based on their size and target. The spatial organization of DRG, however, has not been previously quantified. In this thesis, I demonstrate a novel algorithm to transform histological cross-sections of DRG to a normalized circular region for quantifying trends across many samples. Using this algorithm on 26 lumbosacral DRG from felines, a common preclinical DRG model, I found that the highest density of neural cell bodies was in the outer 24% radially, primarily at the dorsal aspect. I extended this analysis to a semi-automated cross-DRG analysis in 33 lower lumbar DRG from 10 human donors. I found that the organization of human DRG was similar to felines, with the highest density of cell bodies found in the outer 20-25% of the DRG, depending on spinal level. I also found a trend toward lower small-axon density at the dorsal aspect of L5 DRG, a key region for stimulation applications. To take advantage of this quantitative knowledge of DRG organization, future neural interfaces with DRG will require more advanced technologies. Standard silicon-based electrode arrays, while useful for short-term DRG recordings, ultimately fail in chronic use after several weeks as a result of mechanical mismatch with neural tissue. In this thesis, I demonstrate sensory recording from the surface and interior of sacral DRG during acute surgery using a variety of flexible polyimide microelectrode arrays 4-μm thick and minimum site separation 25 to 40 μm. Using these arrays, I recorded from bladder and somatic afferents with high fidelity. The high density of sites allowed for neural source localization from surface recordings to depths 25 to 107 µm. This finding supports the anatomical analysis suggesting a high density of cell bodies in the dorsal surface region where the surface array was applied. The high site density also allowed for the use of advanced signal processing to decrease analysis time and track neural sources during movement of the array which may occur during future behavioral experiments. This thesis represents significant advances in our understanding of DRG and how to interface with them, particularly related to the way anatomy can inform development of future technologies. Going forward, it will be important to expand the anatomical maps based on organ function and to test the novel flexible arrays in chronic implant experiments.

In recent years, kidney transplants have become a viable treatment option for chronic kidney disease in felines. Chronic kidney disease is the leading disease in geriatric cats with 20% of these geriatric cats being affected. Feline kidney transplantation has been met with many different issues regarding ethics, diagnosis, methods, and complications. There are some individuals that believe kidney transplants should not be done in felines because consent from the feline cannot be obtained. The diagnosis of chronic kidney disease has been on the rise in recent years which may be due to new classification standards. There have been many different methods used to carry out the vascular anastomosis and ureteroneocystostomy. There have been many improvements of these methods to help reduce complications and mortality.

Swallowing motility disorders (dysphagia) are a major complication following radiation treatment for head and neck cancer, affecting ~50% of those treated. One reason for this is that radiation causes muscle damage, provoking sensorimotor pathologies. Previous work has suggested that injury may cause discoordination between breathing and swallowing behaviors. We sought to determine if muscle injury provokes changes in this behavior. We hypothesized that acute suprahyoid muscle damage would alter cross-behavior excitability, causing destabilization of the respiratory-swallow pattern. Swallowing was evoked in anesthetized spontaneously breathing cats via injection of a 3cc bolus of water into the oropharyngeal cavity. A suprahyoid injury was induced unilaterally by applying a ~2mm cryoprobe to the belly of the mylohyoid muscle. Electromyography (EMG) activity (duration, amplitude) was measured concurrently in thyrohyoid, mylohyoid, thyropharyngeal, and diaphragm muscles. Swallow-breathing coordination (SBC) was measured by determining inspiration/expiration phase during the onset and offset of a swallowing event, based off the mylohyoid initiation and thyropharyngeal termination bursts, respectively. Results showed an injury-related effect in the mylohyoid muscle, as indicated by a significant decrease in the mean amplitude post-injury compared to pre-injury. During swallowing, the expiratory phase was found to predominate the respiratory cycle in both pre- and post-injury. No significant changes to the swallow-breathing coordination were found following injury. Results demonstrate that mylohyoid muscle injury does not appear to interfere with short-term changes in the respiratory-swallow pattern. Although deficits in muscle function were found immediately following injury, an extended time or more severe injury may be needed to adversely inhibit these behaviors. Thus, disrupting the stable coupling between respirations and swallowing, which has been found clinically, may not be apparent immediately after injury and require long-term changes in function.

Access to positron emission tomography (PET), and more recently PET combined with computed tomography (PET/CT), is increasing in veterinary medicine. This molecular imaging technology allows clinicians to map biological functions within patients based on the distribution and selective uptake of specialized positron-emitting radiopharmaceuticals. Although most clinical studies utilize 2-deoxy-2-[18F]fluoro-Dglucose (18FDG), a versatile but relatively nonspecific tracer that interrogates the energy metabolism of tissues, there is a growing need to establish reference values for alternative or adjunct tracers in veterinary species. Among these is 3’-deoxy-3’- [18F]fluorothymidine (18FLT), a thymidine analog that selectively accumulates in proliferating tissues. In the present work, 18FLT distribution in clinically healthy adult dogs and young adult cats was imaged using a state-of-the-art PET/CT scanner to define normal uptake levels within numerous tissues, including major parenchymal organs, bone marrow, and other sites of increased radiopharmaceutical uptake. The marrow signal was subsequently segmented into separate skeletal regions, and used to quantitatively define the adult marrow distribution pattern in the dog. Marrow activity is concentrated in the vertebral column (particularly within the thoracic and lumbar regions), sternum, ribs, and proximal aspects of the appendicular skeleton in the adult dog. Feline marrow distribution is similar; however, considerable uptake within more distal appendicular structures suggests that age-related marrow conversion is ongoing in 3-year-old cats. Outside the marrow compartment, physiologic uptake was observed within the urinary and biliary systems, intestinal tract, and variably within lymphoid structures. Prominent uptake within the hepatic parenchyma was also observed in cats, but not dogs, at the times imaged in this study. The details of normal canine and feline 18FLT biodistribution included in this dissertation may be used to inform lesion interpretation in dogs and cats with suspected disease. Likewise, quantitative details of adult marrow distribution in dogs may be used by clinicians to guide the selection of marrow sampling sites or inform tissue-sparing efforts during radiotherapeutic planning in canine patients.

Background: Radioiodine is the treatment of choice for feline hyperthyroidism. The ideal method of dose determination of 131I remains controversial. Objective: To compare a method of radioiodine dose determination that utilized thyroid scintigraphy with a standard fixed dose for treatment of feline hyperthyroidism. Methods: Fifty-seven and 23 cats were in the novel and fixed dose groups, respectively. Cats with a percent dose uptake as determined using 99mTcO4- uptake on thyroid scintigraphy 10% were designated to receive 3 mCi, 3.5 mCi, or 4.5 mCi of 131I, respectively, administered subcutaneously. Radioiodine dose was adjusted by thyroid size, determined by evaluating the thyroid:salivary size ratio (T:S) and categorized as 10. If the thyroid size fell into a higher dosing category than percent uptake, the dose was increased accordingly. Cats in the fixed dose group received 4.5 mCi of 131I. Six months after treatment, cats were determined to be euthyroid, hypothyroid, or hyperthyroid based on serum T4 concentrations relative to an established reference interval. Univariate analysis using Chi-square was used to determine associations between treatment and outcome. Results: There was no difference in outcome between the novel and fixed dose treatments. Euthyroidism, hypothyroidism, and hyperthyroidism developed in 61, 30, and 9% of cats in the fixed dose group, respectively compared to 58, 26, and 16% in the novel dose group. Conclusions: A modified fixed dose method of radioiodine based upon thyroid size and percent dose uptake was ineffective in improving outcomes over a standard fixed dose method.

Feline oral squamous cell carcinoma (FOSCC) is the most common oral cancer in cats. This cancer is very aggressive and has the ability to invade into the adjacent bone resulting in poor quality of life and a grave prognosis in affected cats. FOSCC has been shown to be comparable to human OSCC in many aspects. However, the pathogenesis of FOSCC remains unclear. Similar to human OSCC, FOSCCs respond poorly to the available standard therapy. Therefore, novel molecular targets as well as effective therapies are required for this cancer. The usefulness of p16, p53, and pRb immunohistochemistry (IHC) for human OSCC classification has been reported. Low p16 frequently associates with non-viral-associated OSCCs, while high p16 with low p53 and pRb usually occurs in HPV-associated OSCC. In addition, a favorable prognosis was found in patients with HPV-associated OSCC and a grave prognosis was observed in patients with non-viral-associated OSCC. In this study, the IHC pattern of p16, p53, and pRb in FOSCC was investigated. We found that low p16 IHC is common in FOSCCs and high p16 IHC is present in a subset of patients with this cancer. However feline papillomavirus was not detected in these samples. These results indicate that FOSCCs have more than one type of classification and a variation in pathogenesis may occur in FOSCC.Increased osteoprotegerin (OPG) has been found to reduce tumor size and bone invasion in many human bone-invasive cancers. Low levels of feline OPG (fOPG) mRNA expression were previously observed in a bone-invasive FOSCC cell line (SCCF2). The role of fOPG in bone-invasive FOSCC in vitro and in vivo was investigated using a novel bone-invasive FOSCC cell line with high fOPG mRNA expression (SCCF2-OPGv.1).We found that overexpression of fOPG reduced tumor growth and inhibited bone invasion in bone-invasive FOSCC in vivo. Thus, fOPG could be effective adjuvant therapy for FOSCC-associated bone lysis. Telomerase, a protein complex with cell immortalization activity, has been speculated as a novel therapeutic target for human cancers. Telomerase transcriptase catalytic subunit (TERT) and the non-coding RNA template are the main components of this protein. Pre-mRNA alternative splicing occurs in human TERT gene and more than 20 human TERT alternative splice variants were identified. In this study, high levels of telomerase activity were observed in FOSCC cells (SCCF1, SCCF2, and SCCF3) and in 2 of 3 FOSCC tumors. Full-length and 10 novel feline TERT (fTERT) alternative splice variants were identified. Full-length and the deletion of exon 10 (Del-e10) splice variant of fTERT were the two common variants in FOSCCs with high telomerase activity found in this study. These findings suggest that alternative splicing is important for the regulation of telomerase activity and provide critical information to further the understanding of telomerase in feline cancers.

The coronavirus spike protein is a critical determinant of cell tropism and pathogenicity. It is expressed on the viral surface and is responsible for binding the host cell receptor and initiating fusion of the viral and host cell membranes. The work presented herein is an investigation into the genetic and biochemical properties of spike that influence the in vivo pathogenesis of feline and canine coronaviruses. A targeted sequencing approach was undertaken to identify mutations in a key viral activation site that correlate with the development of systemic disease after feline coronavirus infection. A similar strategy was used to characterize the spike proteins of canine coronaviruses associated with fatal enteritis in dogs and a thorough histopathologic characterization was performed in an attempt to independently confirm reports pantropic canine coronavirus variants.

Exenatide extended-release (ER) is a microencapsulated formulation of the GLP-1-receptor agonist exenatide. It has a protracted pharmacokinetic profile that allows a once-weekly injection with comparable efficacy to insulin and an improved safety profile in type-2 diabetic people. Here we studied the pharmacology of Exenatide-ER in 6 healthy cats. A single subcutaneous injection of Exenatide-ER (0.13 mg/kg) was administered on day 0. Exenatide concentrations were measured for 12 weeks. A hyperglycemic clamp (target = 225 mg/dL) was performed on days minus 7 (Clamp-I) and 21 (Clamp-II) with measurements of insulin and glucagon concentrations. Glucose tolerance was defined as the amount of glucose required to maintain hyperglycemia during the clamp. Continuous glucose monitoring (CGM) was performed on weeks 0, 2 and 6 post-injection. Plasma concentrations of exenatide peaked at 1 hour and 4 weeks post-injection. Comparing Clamp-1 to Clamp-2, fasting BG decreased (mean [±SD] = -11 ± 8 mg/dL, P = 0.02), glucose tolerance improved (median [range] +33% [4-138%], P = 0.04), insulin concentrations increased (+36.5% [-9.9-274.1%], P = 0.02) and glucagon concentrations decreased (-4.7% [0-12.1%], P = 0.005). Compared to pre-injection values on CGM, glucose concentrations decreased and the frequency of readings < 50 mg/dL increased at 2 and 6 weeks post-injection of Exenatide-ER. This did not correspond to clinical hypoglycemia. No other side effects were observed throughout the study. Exenatide-ER was safe and effective in improving glucose tolerance 3 weeks after a single injection. Further evaluation is needed to determine its safety, efficacy and duration of action in diabetic cats.

Hyperthyroidism is the most common feline endocrinopathy. 131I is the treatment of choice, and over 50,000 cats have been treated using an empirical fixed dose. Better treatment responses could be achieved by tailoring the dose based on the severity of disease. Scintigraphy is the best method to quantify the severity of the disease. Previously established scintigraphic quantitative methods, thyroid to salivary ratio (T:S ratio) and % dose uptake, are the most widely recognized measurements. Recently, the thyroid to background ratio (T:B ratio) has been proposed as an alternate method to assess function and predict 131I treatment response. The purpose of this study was to determine the best location of a background ROI, which should be reflective of blood pool activity. We also hypothesized that the T:B ratio using the determined background ROI would provide improved correlation to T4 when compared to T:S ratio and % dose uptake in hyperthyroid cats. Fifty-six hyperthyroid cats were enrolled. T4 was used as the standard measure of thyroid function and was obtained prior to thyroid scintigraphy and 131I therapy. Blood samples were collected at the time of scintigraphy and radioactivity within the sample was measured. The plasma radioactivity was compared to the background ROI count densities in 8 anatomic regions using linear regression analysis for 55 cats. One cat was excluded from the study because of an injection error during scintigraphy. T:B and T:S ratios, and % dose uptake on scintigraphy were then compared to serum T4 by linear regression analysis for 39 cats. Sixteen cats were excluded because of recent methimazole or Y/D diet use, or incomplete data. The heart ROI correlated best to plasma pertechnetate activity (r = 0.70). % dose uptake correlated best to serum T4 (r = 0.74), followed by T:S ratio (r = 0.66), followed by the T:B ratio using the heart ROI (r = 0.59). Placing an ROI over the heart is the best method of quantifying plasma radioactivity. T:B ratio using the heart ROI as the background is a good predictor T4 but percent dose uptake and T:S ratio proved to be better predictors of T4 than any of the T:B ratios. Therefore, our hypothesis was not supported. The T:B ratio may not provide the best scintigraphic measurement of thyroid function. Hence it is unlikely to accurately predict treatment response to 131I therapy.

Abstract: Two studies examined the effects of 3 commercial cat diets varying in glycemic index (GI) based on ingredient composition and starch content (34.1, 29.5, and 23.6% NFE for high, medium, and low GI, respectively) on metabolizable energy (ME), indirect calorimetry and blood measurements. In Study 1, the modified Atwater equation underestimated diet ME by 12%. In Study 2, the RQ decreased with GI (P

A relevant subset of cats with hypertrophic cardiomyopathy (HCM) develop dynamic obstruction of the left ventricular outflow tract and mitral regurgitation secondary to hypertrophy of the left ventricle and systolic anterior motion (SAM) of the mitral valve. This leads to an increase in left ventricular systolic pressure, and thus wall stress, that may ultimately lead to progression of the disease. While prospective studies documenting the morbidity and mortality associated with dynamic obstruction have not been performed in feline HCM, it is possible that the results would be similar to human studies, in which SAM has been proven repeatedly to be a negative prognostic indicator in HCM, as well as an independent predictor of disease progression and sudden death. Beta-blockers are the primary medication used to reduce heart rate and relieve dynamic left ventricular outflow tract obstruction in cats with HCM, however, side effects or contraindications sometimes limit their use. Ivabradine is a highly selective If current inhibitor that exerts negative chronotropic effects without significant effects on inotropy, lusitropy, or dromotropy as documented in multiple species. Ivabradine has been studied in cats, and has been shown to have unique heart rate lowering properties. The drug is clinically well tolerated without any discernable side effects, has only minimal effects on central hemodynamics, has pharmacokinetic and pharmacodynamic properties that allow for twice daily dosing, and enhances left atrial function. The purpose of this study was to determine whether ivabradine, at a single dose of 0.3 mg/kg PO, could reduce or eliminate dynamic obstruction of the left ventricular outflow tract in cats with HCM.In this prospective, randomized, double-blind, active-control single dose study, 21 cats with preclinical HCM and dynamic left ventricular outflow tract obstruction received one dose of atenolol at approximately 2 mg/kg PO or one dose of ivabradine at 0.3 mg/kg PO. Baseline and 3-hour post-treatment heart rate, echocardiographic variables, and blood pressure were recorded. Statistical comparisons were made using analysis of covariance (ANCOVA).Peak velocity in the left ventricular outflow tract was significantly decreased compared to baseline for both drugs, however the mean change in velocity was more reduced for atenolol (2.54 m/s; 95% confidence interval 1.83 m/s to 3.25 m/s) compared to ivabradine (0.51 m/s; 95% confidence interval 0.01 m/s to 1.01 m/s; P

The microcirculation consists of vessels less than ten microns in diameter. Each microcirculatory unit has a feeder arteriole, capillaries and draining venules. Traditionally, when monitoring perfusion in patients, macrocirculatory parameters such as heart rate, blood pressure, cardiac output, lactate levels and central venous oxygen saturation have been utilized. Unfortunately, research in humans and dogs has demonstrated that these macrovascular parameters show poor correlation with changes at the microvascular level and thereby may poorly reflect tissue perfusion. Newer technologies, such as sidestream dark field microscopy (SDF) allow for direct imaging of the microcirculation and the ability to evaluate changes related to various stimuli, such as anesthesia, surgery, shock, and sepsis. This technology has been validated in humans, rodents and dogs, but has not yet been explored in cats. We sought to establish baseline clinical values for microcirculatory parameters in healthy, anesthetized cats using SDF and to determine if surgical manipulation alters these values during ovariohysterectomy.Eighteen healthy cats presenting for elective ovariohysterectomy were anesthetized using a standardized protocol. Three 20-second microcirculatory videos were obtained from the sublingual mucosa at three intervention points: after induction but before placement of the first towel clamp, after ligation of the first ovarian pedicle and after placement of the final skin suture and towel clamp removal. At each time point, macrovascular parameters (heart rate, respiratory rate, blood pressure), pulse oximetry, end tidal carbon dioxide, and end tidal inhalant anesthetic concentrations were recorded. In addition, SDF videos of the microcirculation were obtained from the sublingual mucosa using previously established consensus criteria. Videos were assessed for quality; only those deemed acceptable were included. Qualifying videos were analyzed by a single observer blinded to intervention point. Total vessel density (TVD), proportion of perfused vessels (PPV), perfused vessel density (PVD) and microvascular flow index (MFI) were determined using vascular analysis software. Microvascular parameters were analyzed for significant changes between intervention points and correlation with macrovascular parameters. Twelve cats were included in final video analysis; six were removed for poor video quality. There was no significant variation in TVD, PPV and PVD with surgical manipulation, however MFI showed a significant increase from baseline. The MFI had independent positive correlation with mean arterial pressure, heart rate, respiratory rate and systolic blood pressure and had negative correlation with temperature [p < 0.05]. However, when multivariate analysis was conducted, these correlations failed to retain significance. Pearson correlation showed no relationship between length of anesthesia and changes in microcirculatory parameters.These results show that surgical tissue manipulation did not significantly alter microvascular vessel density or the proportion of perfused vessels, although tissue manipulation did increase MFI. The length of time under anesthesia did not affect the microcirculatory parameters in the study cats. As documented in other species, changes in macrovascular parameters do not correlate well to changes in microcirculatory perfusion parameters.This study demonstrated that SDF can be successfully utilized in cats, allowing real-time imaging of the sublingual microvasculature. This technology has potential as a tool in experimental and clinical monitoring of microcirculatory changes. However, there are several potential limitations to its use, such as the difficulty in obtaining high quality images, the need for general anesthesia and the time consuming nature of the offline video analysis. Future experimental and clinical investigation is warranted, including assessment of microvasculatory changes in disease states like shock, sepsis, congestive heart failure and diabetes mellitus.

The human hippocampus has several unique attributes and is one of the more structurally discrete structures of the limbic system. Humans exposed to chronic stress or pain, most notably patients with posttraumatic stress disorder and chronic pelvic pain syndromes, have detectably smaller hippocampal structures. Interstitial cystitis (IC) in humans is a recognized syndrome of chronic pelvic pain. Feline interstitial cystitis (FIC) is a spontaneous animal model for IC. Therefore, documenting volume changes in the hippocampus in cats may lead to further understanding of chronic pain in all species. The aim of this study is to evaluate the feasibility of measuring the volume of the feline hippocampus using magnetic resonance imaging (MRI). Brain MRI of 3 cats (2 nonsymptomatic cats from an FIC colony and 1 normal cat from an unrelated study) was performed using 3 Tesla (T) and 7T MR systems. T2w images were made with extremity coils designed specifically for each magnet, and a smaller surface coil in the 7T magnet. Transverse, sagittal, and dorsal plane images were acquired in each imaging session. Cats were imaged in vivo, post perfusion fixation, and at various durations (4-181 days) of immersion fixation of the brain in 10% formalin using both magnets. DICOM images were imported into ImageJ and each hippocampus was manually outlined on all images. The areas were then multiplied by the image thickness (including spacing) and the area from each slice was summed to obtain a volume. The average measured in vivo hippocampal volume was 277.2 + 18.9 mm3 on the transverse images of the 3T system which equated to 1% of the total brain volume (each hippocampus). The average volumes obtained in the 3T system in the other planes were 228.0 + 47.2 mm3 on the sagittal images and 207.0 + 47.5 mm3 on the dorsal images. Average volumes obtained in vivo in the 7T system were 286.8 + 47.1 mm3 on the transverse images, 221.5 + 41.0 mm3 on the sagittal images, and 273.5 + 9.5 mm3 on the dorsal images. Detection of changes in volume of the hippocampus using MRI is possible in populations of cats, but not likely to be useful in individuals.

Bone invasion negatively effects prognosis for patients with oral squamous cell carcinoma (OSCC). Despite the clinical significance, mechanisms responsible for OSCC invasion into bone are not fully understood. There is limited availability of experimental models which recapitulate the bone invasive behavior of OSCC in which to study disease pathogenesis and treatment. The purpose of this body of work was to develop and characterize models of bone invasive OSCC, to investigate the factors responsible for osteoclastic bone resorption, and to evaluate treatment strategies designed to inhibit bone resorption and tumor growth. The first objective was to characterize a naturally occurring model of bone invasive OSCC in domestic cats, and to determine if expression of parathyroid hormone-related protein (PTHrP) is associated with osteolytic behavior. Bone invasive feline OSCC was characterized by osteoclastic bone resorption and PTHrP expression and nuclear localization was increased in osteolytic tumors; supporting a relationship between PTHrP expression and bone-invasive behavior. The second objective was to investigate the mechanisms responsible for OSCC-associated bone resorption in relevant in vitro and in vivo models of bone invasive OSCC. In bone invasive OSCC cells, PTHrP expression was associated with ability to stimulate in vitro and in vivo bone resorption, in addition to stimulation of receptor activator of nuclear factor κB ligand (RANKL) expression and inhibition of osteoprotegerin (OPG) in murine preosteoblasts. In vitro bone culture released factors which stimulated tumor cell proliferation and PTHrP expression in feline and human OSCC cells, suggesting the existence of a vicious cycle between OSCC growth and osteoclastic bone resorption. The final two objectives were to evaluate the effectiveness of targeting osteoclastic bone resorption in a novel, bioluminescent orthotopic model of maxillary invasive OSCC. Zoledronic acid (ZOL, an aminobisphosphonate osteoclast inhibitor) reduced tumor growth and bone resorption associated with xenograft growth. OSCC cells expressed cyclooxygenase-2 (COX-2), and COX-2 expression was stimulated by factors in bone conditioned medium. A preferential cyxlooxygenase-2 inhibitor (meloxicam) was more effective than ZOL at reducing xenograft growth but did not have a significant effect on bone resorption. The combination of meloxicam and ZOL was well tolerated but did not stimulate additional tumor suppression or inhibition of bone loss compared to meloxicam or ZOL monotherapy. These studies support the role of OSCC-expression of PTHrP and COX-2 in the pathogenesis of bone invasive OSCC, and support the presence of a vicious cycle between OSCC growth and bone resorption. Additionally, valuable experimental models of maxillary invasive OSCC were developed for the advancement of OSCC mechanistic and preclinical research.

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats and is associated with high morbidity and mortality. Evidence suggests that tachycardic events may trigger syncope, decompensation, or sudden death in otherwise well compensated human patients with HCM. Bradycardic agents used in feline HCM include beta-receptor antagonists or calcium channel blockers; hoverer, their clinical use may be limited by potential adverse effects. A drug that selectively and specifically lowers heart rate (HR), without intrinsic effects on cardiac function, may therefore be superior in the long-term treatment of feline HCM. Ivabradine is a highly selective funny current (If) inhibitor that acts directly on the sinoatrial node to induce a use- and dose-dependent reduction of HR. Ivabradine has been shown to have favorable effects on cardiac function in experimental animals but its use has not yet been studied in cats. The first study describes the pharmacokinetics of ivabradine and its major metabolite S-18982 after single and repeated oral administration of ivabradine (Procorolan®, Les Laboratoires Servier, France) in healthy cats. Two-compartmental and one-compartmental models with first-order input and elimination provided the best fit to the data for both ivabradine and S-18982.The two models were combined to produce a single 4-compartment model characterizing pharmacokinetics of ivabradine and S-18982. The second study describes the use of immunoblot analysis to evaluate myocardial expression of hyperpolarization-activated, cyclic nucleotide-gated (HCN) proteins in cats. In cats with HCM, HCN4 was significantly upregulated in left ventricular (LV) myocardial tissue whereas in right ventricular tissue only a trend was found. We also observed that maturation of ventricular cardiomyocytes toward the adult phenotype regarding HCN4 expression is completed prior to the age of 2-3 months. The results of the third catheter-based study demonstrate that intravenous administration of ivabradine consistently reduces HR and the rate-pressure product in anesthetized cats with HCM. LV systolic and diastolic function as well as left atrial (LA) performance were either unchanged or only minimally affected by ivabradine. Elevation of HR induced by catecholamines was significantly blunted by ivabradine in healthy cats as well as in cats with HCM. In the last two experiments, the non-inferiority of four weeks of oral ivabradine compared to atenolol and the effects of both drugs on reproducibility of echocardiographically-derived indices are described. Ivabradine demonstrated more favorable effects on several echocardiographic variables, including indices of LV systolic wall stress, LV relaxation, and LA function. Overall, the majority of echocardiographic variables obtained had excellent to good reproducibility justifying their use in the clinical setting. However, although unexpected, both drugs failed to increase reproducibility of the majority of echocardiographically-derived indices. Ivabradine was specifically useful in the separation of diastolic filling waves, making assessment of LV diastolic function clinically feasible. Based on these studies, oral ivabradine appears to be clinically well tolerated, safe and useful for effective HR control in cats. This may make ivabradine attractive in the treatment of feline HCM, although its long-term effects in cats with HCM and in particular in cats with dynamic LV outflow obstruction require further investigation.

Objective: To assess effects of bisection nephrotomy on renal function, size, and morphology in cats over a period of 12 weeks. Study Design: Controlled, randomized, blinded experiment. Sample Population: Ten adult female cats. Methods: Glomerular filtration rate (GFR), as determined by quantitative renal scintigraphy using 99mTc-DTPA, urinalysis, urine culture, and sonographic measurement of renal size were performed pre-operatively. A left or right nephrotomy (five randomly assigned cats in each group) was performed. Total and individual kidney GFRs were determined in each cat 2, 28 and 84 days post-operatively. Both kidneys were measured sonographically 28 and 86 days postoperatively and an ultrasound-guided biopsy of each kidney was obtained 86 days postoperatively. Results: No significant differences in mean GFR and kidney size of the operated versus un-operated kidneys were observed at any time period. Individual GFR and renal size of all except one of the cats remained within normal limits. Two additional cats had evidence of transient ureteral obstruction in the immediate post-operative period. No significant histologic abnormalities were observed in any biopsy. Conclusions: Bisection nephrotomy in normal cats did not adversely affect renal function or morphology over the three month post-operative period. Clinical Relevance: Bisection nephrotomy can be safely performed in normal feline kidneys without causing a significant deleterious effect on renal function. Studies in animals with pre-existing renal insufficiency are needed to insure no adverse effects would occur in clinical cases where this surgical procedure is warranted.

High lipid : low dextrose (HL:LD) parenteral admixture (PA) is high in polyunsaturated fatty acids (PUFA) that are sensitive to peroxidation. This study evaluated the antioxidative effect of vitamin E in both HL:LD PA and in obese cats given HL:LD PA. Natural d-α-tocopherol (Vital E-300) was added to HL:LD PA at seven concentrations (8, 12, 16, 24, 32, 48, or 64 IU/g of lipid). PA were exposed to fluorescent light for 24 hours at room temperature. Hydroperoxides were measured at baseline and 24 hours hang time. Significantly lower hydroperoxide concentrations were found with > 24 IU/g of lipid at baseline (P < 0.01). A higher d-α-tocopherol concentration was required (> 48 IU/g lipid) to lower hydroperoxides at 24 hours (P < 0.0001). HL:LD PA with 40 IU/g lipid/day d-α-tocopherol was delivered intravenously to obese cats (PA Toc⁺) over 48 hours. Control cats (PA Toc⁻) received HL:LD PA without a d-α-tocopherol supplementation. Oxidative status of cats was evaluated at baseline and 24, 48, and 96 hours. Cats in both groups exhibited an increase in MDA concentration (time effect; P < 0.0001). WBC-tGSH and WBC-GPx did not change in either group of cats. RBC-tGSH and RBC-GPx changed over time (time effects; P = 0.0005; P = 0.0016, respectively) with the PA Toc⁺ cats exhibiting a higher RBC-tGSH concentration (treatment x time interaction; P = 0.012). Serum α- and γ-tocopherol concentrations increased in PA Toc⁺ cats (treatment effect; P < 0.0001). These findings suggest that d-α-tocopherol significantly alters oxidative status in vivo.

Objective: We sought to determine N-terminal proatrial natriuretic peptide concentrations [Nt-proANP] in plasma from cats with hypertrophic cardiomyopathy (HCM). Secondarily, we wished to evaluate the relationship between [Nt-proANP] and echocardiographic variables. Methods: Venous blood samples were obtained from seventeen cats with HCM and from nineteen healthy cats. Plasma [Nt-proANP] was determined using an ELISA assay. The relationship between plasma [Nt-proANP] and M-mode, 2-dimensional and Doppler echocardiographic variables was evaluated. Cats that were hyperthyroid or had evidence of renal disease were excluded from the study. Results: The mean plasma [Nt-proANP] was higher in cats with HCM (3.81 +/- 1.23 pmol/l) than in control cats (3.08 +/- 1.41 pmol/l); however, this difference was not statistically significant (p=0.17). There was a significant correlation between plasma [Nt-proANP] and left ventricular posterior wall thickness (r = 0.42; p=0.01). Additionally, plasma [Nt-proANP] was correlated with left atrial size (r = 0.35; p=0.03). A linear regression model was developed to further explore these relationships. LAs2D and LVPWd had an interactive effect on plasma [Nt-proANP] (R2 = 0.2737; p= 0.02). There was no correlation between any other echocardiographic variable and plasma [Nt-proANP]. There was no correlation between plasma [Nt-proANP] and heart rate (HR), body-weight, or age. Conclusions: Cats with HCM do not have significantly higher plasma [Nt-proANP] than normal cats. There was a significant linear relationship between [Nt-proANP] and LAs2D, LVPWd and the model that described their interaction.