VTechWorks Repository :: Browsing by Author "Panciera, David L."

Browsing by Author "Panciera, David L."

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Adrenocortical Challenge Response and Genomic Analyses in Scottish Terriers With Increased Alkaline Phosphate Activity
Zimmerman, Kurt L.; Panciera, David L.; Hoeschele, Ina; Monroe, William E.; Todd, S. Michelle; Werre, Stephen R.; LeRoith, Tanya; Fecteau, Kellie; Lake, Bathilda B. (Frontiers, 2018-10-09)
Scottish terriers (ST) frequently have increased serum alkaline phosphatase (ALP) of the steroid isoform. Many of these also have high serum concentrations of adrenal sex steroids. The study’s objective was to determine the cause of increased sex steroids in ST with increased ALP. Adrenal gland suppression and stimulation were compared by low dose dexamethasone (LDDS), human chorionic gonadotropin (HCG) and adrenocorticotropic hormone (ACTH) response tests. Resting plasma pituitary hormones were measured. Steroidogenesis-related mRNA expression was evaluated in six ST with increased ALP, eight dogs of other breeds with pituitary-dependent hyperadrenocorticism (HAC), and seven normal dogs. The genome-wide association of single nucleotide polymorphisms (SNP) with ALP activity was evaluated in 168 ST. ALP (reference interval 8–70 U/L) was high in all ST (1,054 U/L) and HAC (985 U/L) dogs. All HAC dogs and 2/8 ST had increased cortisol post-ACTH administration. All ST and 2/7 Normal dogs had increased sex steroids post-ACTH. ST and Normal dogs had similar post-challenge adrenal steroid profiles following LDDS and HCG. Surprisingly, mRNA of hydroxysteroid 17-beta dehydrogenase 2 (HSD17B2) was lower in ST and Normal dogs than HAC. HSD17B2 facilities metabolism of sex steroids. A SNP region was identified on chromosome 5 in proximity to HSD17B2 that correlated with increased serum ALP. ST in this study with increased ALP had a normal pituitary-adrenal axis in relationship to glucocorticoids and luteinizing hormone.We speculate the identified SNP and HSD17B2 gene may have a role in the pathogenesis of elevated sex steroids and ALP in ST.
Bile duct obstruction associated with pancreatitis in 46 dogs
Wilkinson, Ashley R.; DeMonaco, Stefanie M.; Panciera, David L.; Otoni, Cristiane C.; Leib, Michael S.; Larson, Martha M. (Wiley, 2020)
Background: Pancreatitis is a common cause of extrahepatic bile duct obstruction (EHBDO) in dogs. Information describing the clinical course of dogs with pancreatitis associated bile duct obstruction (PABDO) is limited. Objectives: To describe the clinical course of PABDO in dogs and determine if presumed markers of disease severity are predictors of survival. Animals: Forty-six client-owned dogs with PABDO. Methods: A retrospective review of medical records from dogs diagnosed with PABDO was performed. Data, including clinical signs and biochemical changes, were collected 6 times throughout the course of disease. Outcome was defined as either survival (discharge from the hospital) or death. Results: Thirty-three (79%) out of 42 dogs with PABDO survived. Thirty-one (94%) of the 33 dogs that survived received medical management alone. Time from onset of clinical signs to initial documented increase in serum bilirubin concentration, peak bilirubin elevation, and initial decline in serum bilirubin concentration were 7 (median), 8, and 15 days, respectively. The median number of days from onset of clinical signs to outcome date was 13. Clinical signs of fever, vomiting, and anorexia were decreased in frequency from the onset of clinical signs to the time of peak bilirubin. Median bile duct dilatation at the time of ultrasonographic diagnosis of PABDO and peak bilirubin were not different between survivors (7.6 mm, 11.7 mg/dL) and nonsurvivors (6 mm, 10.6 mg/dL, P = .12, P = .8). Conclusions: Dogs with PABDO often have a prolonged course of illness and improve clinically despite biochemical evidence of progression of EHBDO.
Canine Platelet Concentrates: An In Vitro Study to Effectively Provide a Source of Functional Platelets
Sink, Carolyn A. (Virginia Tech, 2002-03-25)
This study monitored the storage lesion of 15 units of canine platelet concentrates harvested by differential centrifugation. Canine platelet concentrates were stored at 20-24°C in a platelet rotator for a total of 9 days; the storage lesion of three second generation platelet storage containers was compared. The battery of in vitro tests used to monitor the storage lesion were selected from previous studies performed with human platelet concentrates separated by differential centrifugation. Based on these tests, canine platelet concentrates exhibited a storage lesion similar to human platelet concentrates. Metabolic analytes demonstrated decreasing pH, carbon dioxide, bicarbonate and glucose concentrations concurrent with increasing oxygen and lactate dehydrogenase activity over the 9-day period. Platelet structural changes were monitored by mean platelet volume, which began to increase on Day-5. Platelet function appeared to be compromised, as indicated by aggregation studies using collagen and adenosine diphosphate as agonists. Product sterility was maintained. There was no consensus of data supporting superior performance of one platelet storage container. This study indicates that canine platelet concentrates may be harvested by differential centrifugation of whole blood. In vitro studies utilizing three second-generation platelet storage bags support a previous study and concurs that canine platelet concentrates stored at 20-24°C using continuous agitation are viable for at least 5 days.
Cardiac Biomarkers in Hyperthyroid Cats
Sangster, Jodi Kirsten (Virginia Tech, 2013-04-03)
Background: Hyperthyroidism has substantial effects on the circulatory system. The cardiac biomarkers NT-proBNP and troponin I (cTNI) have proven useful in identifying cats with myocardial disease but have not been as extensively investigated in hyperthyroidism. Hypothesis: Plasma NT-proBNP and cTNI concentrations are higher in cats with primary cardiac disease than in cats with hyperthyroidism and higher in cats with hyperthyroidism than in healthy control cats. Animals: Twenty-three hyperthyroid cats, 19 cats with HCM without congestive heart failure, and 19 euthyroid, normotensive healthy cats eight years of age or older. Fourteen of the hyperthyroid cats were re-evaluated three months after administration of 131I. Methods: A complete history, physical examination, complete blood count, serum biochemistries, urinalysis, blood pressure measurement, serum T4 concentration, plasma concentrations of NT-proBNP and cTNI, and echocardiogram was prospectively obtained from each cat. Results: Hyperthyroid and HCM cats had plasma NT-proBNP and cTNI concentrations that were significantly greater than healthy older cats, but there was no significant difference between hyperthyroid and HCM cats with respect to concentration of either biomarker. In hyperthyroid cats that were re-evaluated three months after 131I treatment, plasma NT-proBNP and cTNI concentrations as well as ventricular wall thickness decreased. Conclusions and Clinical Relevance: Although there may be a role for NT-proBNP in monitoring the cardiac response to treatment of hyperthyroidism, neither NT-proBNP nor cTNI can be used to distinguish hyperthyroid cats from cats with HCM. Therefore, the thyroid status of older cats should be ascertained prior to interpreting results of cardiac biomarker testing.
A Comparison of Liver Biopsy Techniques in Dogs
Kemp, Stephanie D. (Virginia Tech, 2013-05-15)
Background: The liver biopsy technique in dogs that consistently provides samples adequate for accurate histopathologic interpretation and the variability of histopathology among lobes is unknown. Hypothesis: Liver biopsy specimens obtained via punch, cup biopsy, and 14 gauge needle biopsy would result in similar histopathologic diagnoses to those found on deeply sectioned samples of liver obtained at necropsy and that discordant results would not differ between lobes. Animals: Seventy dogs undergoing necropsy. Methods: Liver specimens were obtained from the left lateral liver lobe with an 8 mm punch, a cup, and a 14 gauge needle. Two larger tissue samples were then collected near the center of the left lateral lobe and used as a histologic standard for comparison. Samples were also obtained from all remaining lobes. Histopathologic features and numbers of portal triads in each sample were compared. Results: The mean number of portal triads were 2.9 in needle biopsies, 3.4 in cup biopsies, 12 in punch biopsies, and 30.7 in the necropsy samples. Sixty-six percent of needle biopsies, 60% of laparoscopic cup samples, and 69% of punch samples were in agreement with the necropsy samples, differences that were not significantly different. The corresponding kappa coefficient were 0.59 for needle biopsies, 0.52 for cup biopsies, and 0.62 for punch biopsies. Discordant results did not differ between the liver lobes. Conclusions and Clinical Relevance: A single biopsy using any of the tested techniques is insufficient for reliable diagnosis of liver disease in the dog. Multiple biopsies from 2 lobes is recommended.
A Comparison of Liver Sampling Techniques in Dogs
Kemp, Stephanie D.; Zimmerman, Kurt L.; Panciera, David L.; Monroe, William E.; Leib, Michael S.; Lanz, Otto I. (American College of Veterinary Internal Medicine, 2015-01)
Background: The liver sampling technique in dogs that consistently provides samples adequate for accurate histopathologic interpretation is not known. Hypothesis/ Objectives: To compare histopathologic results of liver samples obtained by punch, cup, and 14 gauge needle to large wedge samples collected at necropsy. Animals: Seventy dogs undergoing necropsy. Methods: Prospective study. Liver specimens were obtained from the left lateral liver lobe with an 8 mm punch, a 5 mm cup, and a 14 gauge needle. After sample acquisition, two larger tissue samples were collected near the center of the left lateral lobe to be used as a histologic standard for comparison. Histopathologic features and numbers of portal triads in each sample were recorded. Results: The mean number of portal triads obtained by each sampling method were 2.9 in needle samples, 3.4 in cup samples, 12 in punch samples, and 30.7 in the necropsy samples. The diagnoses in 66% of needle samples, 60% of cup samples, and 69% of punch samples were in agreement with the necropsy samples, and these proportions were not significantly different from each other. The corresponding kappa coefficients were 0.59 for needle biopsies, 0.52 for cup biopsies, and 0.62 for punch biopsies. Conclusion and Clinical Importance: The histopathologic interpretation of a liver sample in the dog is unlikely to vary if the liver biopsy specimen contains at least 3- 12 portal triads. However, in comparison large necropsy samples, the accuracy of all tested methods was relatively low.
Echocardiographic Assessment of the Canine Right Heart: Reference Intervals and Repeatability
Gentile, Jessica M. (Virginia Tech, 2012-01-27)
Objectives: Phase 1) Establish echocardiographic reference intervals for measurements of the normal canine right heart. Phase 2) Describe the repeatability of normal right heart echocardiographic measurements. Phase 3) Describe the repeatability of right heart echocardiographic measurements which predict pulmonary artery pressure. Materials and Methods: Phase 1) 45 healthy adult dogs. Dogs underwent one echocardiographic examination by the same operator. Phase 2) 6 randomly selected dogs from the pool of Phase 1 dogs. Dogs underwent repeated echocardiograms by two operators. Phase 3) 4 client-owned dogs. Dogs underwent repeated echocardiographic examination by two operators. Results: Phase 1) The linear relationship between dimension and transformed body weight was highly variable. For linear dimensions, most of the scaling exponents were close to the theoretical value of 1/3. For area measurements, most of the scaling exponents were close to 2/3. Phase 2) Of the 168 within-day, between-day and between-operator coefficients of variation (CV) generated, 154 (91.7%) were below 15% and 135 (80.4%) were less than 10%. Phase 3) Of the 100 within-day, between-day and between-operator CVs generated, 72 (72%) were below 20% and 46 (46%) were below 10%. Conclusions: The right heart can be measured with relatively low repeatability. Measurement of the tricuspid regurgitation velocity should be the first priority when attempting to predict pulmonary artery pressure. If tricuspid regurgitation is not present, the use of transpulmonic acceleration time (AT) and the ratio of transpulmonic acceleration-to-ejection time (AT:ET) to indirectly assess pulmonary artery pressure is recommended.
The Effect of Hypothyroidism on Glucose Tolerance in Dogs
Inteeworn, Natalie (Virginia Tech, 2008-04-17)
Background: Canine hypothyroidism is thought to cause abnormalities in glucose homeostasis, but the effect on glucose tolerance and insulin sensitivity has not been determined to date. Hypothesis/Objectives: The purpose of the study was to investigate whether hypothyroidism has an effect on glucose tolerance and insulin sensitivity in dogs. We hypothesized that hypothyroidism causes insulin resistance. Animals: Sixteen euthyroid bitches were randomly selected and allocated into two groups. In 8 dogs, hypothyroidism was induced by administration of 1 mCi/kg I-131. Experiments were performed on non-anesthetized, fasted dogs in anestrous approximately 12 months after hypothyroidism was induced. Methods: The insulin-modified frequently sampled intravenous glucose tolerance test (FSIGT) and minimal model analysis were used to determine basal insulin and glucose concentrations, acute insulin response to glucose (AIRg), insulin sensitivity (SI), glucose effectiveness (SG) and the disposition index (DI). Results: In the hypothyroid group, basal glucose concentrations were mildly decreased (P = 0.0079), whereas basal insulin was increased (P = 0.019). Insulin sensitivity was reduced in the hypothyroid group (P<0.001), whereas AIRg was higher (P=0.01). Other parameters were not different between groups. Conclusions/Clinical Importance: Hypothyroidism negatively affects glucose homeostasis by inducing insulin resistance. In hypothyroid dogs, the disposition index (insulin sensitivity x insulin secretion) remained unchanged due to a compensatory increase in insulin secretion, thereby maintaining glucose tolerance. In cases with impaired insulin secretion, such as canine diabetes mellitus, concurrent hypothyroidism can have important clinical implications in the successful management of the disease.
Effect of Levothyroxine Administration on Hemostatic Analytes in Doberman Pinschers with von Willebrand's Disease
Heseltine-Heal, Johanna Colleen (Virginia Tech, 2004-04-23)
This study tested the hypothesis that levothyroxine supplementation increases plasma von Willebrand factor (vWf) concentration and enhances vWf function. The effects of levothyroxine administration were evaluated in 8 euthyroid Doberman Pinschers with plasma vWf concentration <30%. Levothyroxine (0.04mg/kg PO q12hours) and placebo were administered for 30 days in a 2-period, 2-treatment, double-blinded, crossover design with a 30-day washout period between treatments. Buccal mucosal bleeding time (BMBT), vWf antigen concentration (vWf:Ag), vWf collagen binding activity (vWf:CBA), Factor VIII coagulant activity (FVIII:C), serum total thyroxine (T4), free thyroxine (fT4), 3,5,3â -triiodothyronine (T3), and thyroid stimulating hormone were measured on days 0, 2, and 30 of each treatment period. The dogs had markedly low plasma vWf:Ag concentrations (mean 8.9%; reference range 70-180%) and vWf:CBA (mean 11.1%; reference range >70%). All dogs had FVIII:C activity within reference range. The response to placebo versus active levothyroxine treatment revealed no significant differences between groups at any time for BMBT, vWf:Ag, vWf:CBA, and FVIII:C. Serum total thyroxine, fT4, and T3 were significantly higher in the levothyroxine-treated group compared to the placebo group at days 2 and 30. Thyroid stimulating hormone was significantly lower in the levothyroxine-treated group compared to the placebo group at days 2 and 30. Levothyroxine (0.04mg/kg) caused laboratory evidence of hyperthyroidism but did not affect plasma FVIII:C and vWf:Ag concentration or the vWf-dependent functional parameters of collagen binding and BMBT. The results of this study do not reveal a direct action of levothyroxine supplementation on plasma vWf concentration or activity in euthyroid Doberman Pinschers.
The Effects of Anesthesia and Surgery on Thyroid Function Tests in Dogs
Wood, Melinda Anne (Virginia Tech, 2007-07-02)
Background: Many non-thyroidal factors affect thyroid function tests. Anesthesia and surgery have been documented to affect thyroid function tests in humans but have not been extensively studied in dogs. Hypothesis: Anesthesia alone and anesthesia combined with surgery will affect thyroid function tests in dogs. Animals: 15 euthyroid mongrel dogs. Methods: Dogs were assigned to one of three groups: control, general anesthesia, and general anesthesia plus abdominal exploratory surgery. Blood samples were collected from each dog immediately prior to pre-medication, 20 minutes after pre-medication, 55 minutes after anesthesia induction, once daily for an additional 6 days, and 14 days post-procedures. Sampling was performed at identical times in the control group. Thyroxine (T4), free T4 (fT4) by equilibrium dialysis, triiodothyronine (T3), reverse T3 (rT3) and thyroid-stimulating hormone (TSH) concentrations were measured in all samples. Results: Results of all thyroid function tests were not significantly different between control and anesthesia groups. Serum T3 for the surgery group decreased significantly from baseline compared to the control and anesthesia groups at multiple times. Serum T4 and rT3 for the surgery group increased significantly from baseline compared to the control and anesthesia groups at multiple times. Serum fT4 for the surgery group increased significantly from baseline compared to the control and anesthesia groups at 48 hours only. Conclusions and Clinical Importance: Surgery has a significant effect on thyroid function tests, while the anesthetic protocol used in this study does not. Because serum T4 and fT4 concentrations increased rather than decreased, evaluating these hormones following surgery is unlikely to lead to a misdiagnosis of hypothyroidism in euthyroid dogs.
Effects of hyperlipidemia on gallbladder motility in dogs
Villm, Jessica Ann (Virginia Tech, 2021-07-16)
Background: The pathogenesis of gallbladder mucocele is unknown in the dog. It has been proposed that hyperlipidemia could impair gallbladder motility and contribute to gallbladder mucocele formation. Objectives: The objective of this study was to compare gallbladder motility in dogs with hyperlipidemia to healthy, control dogs using ultrasonography. We hypothesized that hyperlipidemic dogs have decreased gallbladder motility, defined by increased fasting gallbladder volume (GBV) and decreased gallbladder ejection fractions at 60 (EF60) and 120 minutes (EF120) compared to controls. Animals: 26 hyperlipidemic dogs, 28 healthy control dogs Methods: Twenty-six hyperlipidemic and 28 healthy, age-matched control dogs were prospectively enrolled. Hyperlipidemia was defined as hypercholesterolemia (>332 mg/dL) and/or hypertriglyceridemia (>143 mg/dL). Dogs with both primary and secondary causes of hyperlipidemia were included. All dogs were fasted for at least 12 hours prior to collection of plasma biochemistry and pre-prandial ultrasound. Ultrasound was performed on dogs in the fasted state as well as at 60 and 120 minutes after being fed 10g/kg of a high fat diet (Hill's a/d diet; Hill's Pet Nutrition, Topeka, Kansas, USA). GBVs and EFs were calculated using the following formulas: GBV = (0.52 x L x W x H)/kg and EF = ((GBV0- GBV60,120)/GBV0) x 100, respectively. GBV0, GBV60, GBV120, EF60 and EF120 were compared between dogs with hyperlipidemia and controls using the Wilcoxon rank sum test. Statistical significance was set to p<0.05. Results: Hypercholesterolemia and hypertriglyceridemia were present in 15/26 (58%) and 21/26 (81%) hyperlipidemic dogs, respectively and 10/26 (38%) had elevations in both parameters. The median age in both groups was 10 years. Median (range) cholesterol concentration was 346 mg/dL (181-1372 mg/dL) and 238 mg/dL (153-324) in hyperlipidemic and control dogs, respectively. Median triglyceride concentration was 330 mg/dL (52-2213) and 65.5 mg/dL (32-142) in hyperlipidemic and control dogs, respectively. Eleven (42%) hyperlipidemic dogs were considered severely hyperlipidemic based on the triglyceride and/or cholesterol concentrations above 500 mg/dL. There were significant differences in GBV0 and GBV60 between hyperlipidemic and control dogs. Dogs with severe hyperlipidemia had significantly larger GBVs at all time points. Dogs with hypercholesterolemia also had significantly greater GBVs at all times compared to dogs without hypercholesterolemia. Median EF60 and EF120 were not significantly different between hyperlipidemic and control dogs nor severely hyperlipidemic and mildly hyperlipidemic dogs. Conclusions: Hyperlipidemic dogs have significantly greater fasting and postprandial GBVs but similar ejection fractions when compared to control dogs. Gallbladder emptying is unaltered in hyperlipidemic dogs, but gallbladder volume is higher in hyperlipidemic dogs after feeding. This distention could contribute to bile retention of bile and potentially gallbladder disease.
The effects of illness on urinary catecholamines and their metabolites in dogs
Cameron, Kristin Nicole (Virginia Tech, 2010-04-23)
Background: Urinary catecholamines and metanephrines have been proposed as a diagnostic tool for identifying canine pheochromocytomas, but the effects of critical illness on urine concentrations of catecholamines and metanephrines is currently unknown. Objectives: To examine the effects of illness on urine concentrations of catecholamines and metanephrines in dogs. Animals: Twenty-five critically ill dogs and twenty-five healthy age- and gender-matched control dogs. Methods: Prospective observational study. Urine was collected from healthy and critically ill dogs and urine concentrations of epinephrine, norepinephrine, metanephrine, and normetanephrine were measured by high-performance liquid chromatography (HPLC) with electrochemical detection. Urinary catecholamine and metanephrine:creatinine ratios were calculated and compared between groups. Results: Urinary epinephrine, norepinephrine, metanephrine, and normetanephrine:creatinine ratios were higher in critically ill dogs when compared to a healthy control population (P = 0.0009, P < 0.0001, P < 0.0001, and P < 0.0001 respectively). Conclusions and Clinical Relevance: Illness has a significant impact on urinary catecholamines and their metabolites in dogs. Further investigation of catecholamine and metanephrine concentrations in dogs with pheochromocytomas is warranted to fully evaluate this test as a diagnostic tool, however the findings of this study suggest that the results may be difficult to interpret in dogs with concurrent illness.
Effects of Levothyroxine Adminstration and Withdrawal on the Hypothalamic-Pituitary-Thyroid Axis in Euthyroid Dogs
Ziglioli, Vincent (Virginia Tech, 2016-05-17)
Background: Because of the vague clinical signs and limitations of thyroid function tests, misdiagnosis of hypothyroidism in dogs is common and leads to inappropriate treatment with levothyroxine. Chronic supplementation can suppress the hypothalamic-pituitary-thyroid axis (HPTA) and make it difficult to assess thyroid function following withdrawal of levothyroxine. Objectives: To determine if the HPTA is suppressed following levothyroxine administration in euthyroid dogs and the time required for resolution of any suppression. Animals: Twenty-eight healthy euthyroid dogs Methods: A prospective randomized study administering levothyroxine to euthyroid dogs with levothyroxine, for either 8 weeks (group 1) or 16 weeks (group 2). Serum concentrations of total thyroxine (T4), free thyroxine (fT4) by equilibrium dialysis, thyrotropin (TSH), and 3,5,3'-triiodothyronine (T3) were measured every 4 weeks during supplementation and for 16 weeks after levothyroxine was discontinued. Results: Mean serum T4 and fT4 were significantly higher and TSH was lower in all dogs during levothyroxine administration compared to baseline. Mean serum concentrations of T4 and fT4 in both groups and TSH in group 1, beginning 1 week after levothyroxine was discontinued, were significantly different compared to values during levothyroxine administration but not compared to baseline values. Conclusions and Clinical Importance: Suppression of the HPTA occurred during levothyroxine supplementation and mean serum T4, fT4 and TSH concentrations were not significantly different compared to baseline 1 week after discontinuation in both groups. Assessing thyroid function tests 1 week after cessation of levothyroxine will likely provide an accurate assessment of thyroid function in euthyroid dogs.
The Effects of Prednisone and Prednisone Plus Ultralow-dose Aspirin on Coagulation Parameters in Healthy Dogs
O'Kell, Allison Louise (Virginia Tech, 2012-01-27)
Objectives: To determine the effects of prednisone and prednisone plus ultralow-dose aspirin on coagulation in healthy dogs, and to determine intra-individual variation in thromboelastography (TEG). Animals: 14 healthy experimental dogs and 10 healthy client-owned dogs Procedures: Prospective, randomized, blinded study. TEG was performed twice three days apart on each experimental dog prior to treatment and intra-individual variation was calculated. Dogs were given prednisone (2 mg/kg/day) plus aspirin (0.5 mg/kg/day) or prednisone (2 mg/kg/day) plus placebo for 14 days, after which TEG and other baseline tests were repeated. Changes from baseline between and within each group were compared using t-tests or Wilcoxon 2 sample tests. Client owned dogs had TEG performed twice three days apart to determine intra-individual variation. Results: Intra-individual variation in TEG parameters were <10% for MA (maximum amplitude) and angle. For experimental dogs, MA and fibrinogen significantly increased from baseline whereas Ly30 (percent lysis 30 minutes after MA) and antithrombin activity significantly decreased within each group. For the prednisone plus placebo group, Ly60 (percent lysis 60 minutes after MA) significantly decreased from baseline. For all parameters, there was no difference between groups for change from baseline. Conclusions and Clinical Relevance: Prednisone caused hypercoagulability in healthy dogs evidenced by increased MA and fibrinogen and decreased antithrombin activity. Concurrent use of ultra-low dose aspirin had no effect on measured TEG parameters. Intra-individual variation in some TEG parameters is high and may preclude routine clinical utility.
Efficacy and safety of iopanoic acid for treatment of experimentally-induced hyperthyroidism in cats
Gallagher, Alexander Edward (Virginia Tech, 2008-03-07)
Objective: To determine the efficacy and safety of iopanoic acid for the treatment of experimentally-induced hyperthyroidism in cats. Animals: 15 healthy adult domestic short hair cats Procedures: Hyperthyroidism was induced by daily subcutaneous administration of levothyroxine for 42 days. On day 28, cats were randomized to a control group receiving a placebo PO every 12 hours, a low dose group receiving 50 mg iopanoic acid PO every 12 hours, and a high dose group receiving 100 mg iopanoic acid PO every 12 hours. Cats were treated for 14 days. Weight and heart rates were obtained on days -8, 0, 28, 35, and 42. Blood was collected for CBC and biochemical analysis and for T4, T3, and rT3 measurement on days -8, 28, 35, and 42. Results: Two cats were removed prior to day 28 due to prolonged anorexia and another on day 36 because of heart failure. The low dose and high dose groups had significantly lower T3 concentrations on days 35 and 42 compared to the control group and to their own T3 concentrations on day 28. The T3 concentrations in cats administered iopanoic acid were not different from those obtained prior to induction of hyperthyroidism. Body weight and food consumption were not altered by iopanoic acid treatment, while heart rate was decreased in the low dose group on day 35 when compared to day 28. Conclusions and clinical relevance: Iopanoic acid was effective in decreasing T3 concentrations, but its effect on clinical signs of hyperthyroidism was less apparent. Studies evaluating the long-term efficacy in cats with naturally-occurring hyperthyroidism are warranted.
Evaluation of gallbladder motility assessed by ultrasonography in dogs with hyperlipidemia
Villm, Jessica A.; DeMonaco, Stefanie M.; Panciera, David L.; Larson, Martha M.; Bolton, Timothy A. (Wiley, 2023-05)
Background: The pathogenesis of gallbladder (GB) mucoceles in dogs is unknown. It has been proposed that hyperlipidemia could impair GB motility and contribute to GB mucocele formation. Hypothesis/Objectives: The objective of this study was to compare GB motility in dogs with hyperlipidemia to control dogs using ultrasonography. We hypothesized that hyperlipidemic dogs will have decreased GB motility compared with controls. Animals: Twenty-six hyperlipidemic and 28 healthy, age-matched control dogs were prospectively enrolled. Methods: Cholesterol and triglyceride concentrations were measured in all dogs. Hyperlipidemia was defined as hypercholesterolemia (>332 mg/dL) and/or hypertriglyceridemia (>143 mg/dL) using a biochemical analyzer. Ultrasound was performed before feeding, and 60 and 120 minutes after ingestion of a high fat diet. Gallbladder volumes (GBV) and ejection fractions (EF) were calculated. Results: Hyperlipidemic dogs had significantly larger GBVs (ml/kg) before feeding and 60 minutes after feeding of 1.2 (0.4-7.5; P = .008) and 0.6 (0.1-7.2; P = .04) compared with controls 0.6 (0.2-2.6) and 0.4 (0.1-1.9), respectively. Severely hyperlipidemic dogs had significantly larger GBV at baseline, 60 minutes, and 120 minutes of 1.7 (0.6-7.5; P = .03), 1.3 (0.4-7.2; P = .02), and 1.3 (0.2-8.2; P = .04), respectively compared with mildly hyperlipidemic dogs. EFs at 60 and 120 minutes between controls, hyperlipidemic, and severely hyperlipidemic were all 0.3 at 60 minutes and 0.5, 0.3, and 0.3 at 120 minutes, respectively which were not statistically different. Conclusions and Clinical Importance: Hyperlipidemia leads to GB distention in dogs which could lead to retention of bile and gallbladder disease.
Evaluation of hemostasis in hyperthyroid cats
Keebaugh, Audrey Elizabeth (Virginia Tech, 2020-07-17)
Background: Hyperthyroid cats are predisposed to thrombus formation. The mechanism for thrombogenesis is currently unknown, but could be associated with altered hemostasis as seen in hyperthyroid humans. Objective: The purpose of this study was to evaluate markers of hemostasis in hyperthyroid cats compared to healthy cats, and in hyperthyroid cats before and after treatments with radioactive iodine (RIT). Methods: Twenty-five cats with hyperthyroidism and 13 healthy euthyroid cats > 8 years of age were studied. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, antithrombin (AT), D-dimers, thrombin-antithrombin complexes (TAT), von Willebrand Factor antigen (vWF:Ag), and activity of factors VIII and IX were measured. An echocardiogram was performed in all cats and healthy cats with abnormal echocardiograms were excluded. Measurements of hemostasis were evaluated again in 7 cats > 6 months after RIT and deemed to have restored euthyroid status. Results: There is a significant likelihood of being in hypercoagulable state based on hyperthyroid state (P = 0.019) and serum T4 level is significantly associated with predicating hypercoagulability (P = 0.043). Hyperthyroidism is associated with significantly higher median fibrinogen concentration (P < 0.0001), higher median AT activity (P < 0.0001), and higher median vWF:Ag level (P = 0.01) with all values decreasing significantly post-RIT. Fibrinogen and AT had a strong positive correlation with serum T4 value (r = 0.79; 95% CI 0.63 - 0.89 and r = 0.70; 95% CI 0.50 - 0.84, respectively). Presence of an abnormal echocardiogram in hyperthyroid cats was associated with a significantly higher median fibrinogen concentration (P = 0.03). Echocardiographic status did not have a significant impact on the remaining hemostatic markers in hyperthyroid cats. Conclusions: These results provide evidence of altered hemostasis and hypercoagulability in hyperthyroid cats that do not appear to be solely attributed to cardiac abnormalities. These differences of altered hemostasis resolved after radioiodine therapy, but further studies are warranted to determine if hypercoagulable state resolves.
Evaluation of pressor sentivity to norepinephrine infusion in dogs with iatrogenic hyperadrenocorticism
Martinez, Nivia Ivellise (Virginia Tech, 2002-04-15)
Objective: To evaluate pressor sensitivity to catecholamines in dogs after induction of iatrogenic hyperadrenocorticism (I-HAC) by serial arterial blood pressure measurements during infusions of increasing dose rates of norepinephrine. Animals: Eight dogs with I-HAC induced by administration of oral hydrocortisone at a mean dose of 3.3 mg/kg PO TID for 42-49 days and 8 control dogs which received empty gelatin capsules PO TID for 42-49 days. Procedure: Systolic, diastolic, mean blood pressure and heart rate measurements were recorded after sequential administration of increasing dose rates of norepinephrine (0.1, 0.125, 0.2, 0.3, 0.4, 0.6 and 0.8 mg/kg/min) for 10 minutes. The changes in systolic, diastolic, mean blood pressure and heart rate were compared between control dogs and dogs with I-HAC. Results: Dogs in the I-HAC group had a more pronounced pressor response to norepinephrine infusions than control dogs. The infusions were not completed in 7 of the 8 dogs in the I-HAC group versus 3 dogs in the control group due to severe elevations in systolic blood pressure. The mean change in systolic blood pressure was consistently higher in dogs in the I-HAC group. The difference was statistically significant at the 0.2 mg/kg/min norepinephrine dose rate. The mean change in heart rate was consistently lower in the I-HAC group, a difference that was significant at the 0.2 mg/kg/min norepinephrine dose rate. Conclusions and clinical relevance: Increased pressor sensitivity or decreased baroreceptor response to norepinephrine was seen in dogs with I-HAC suggesting that this mechanism is involved in the development of hypertension in canine hyperadrenocorticism.
Evaluation of the effects of clomipramine on the canine hypothalamic-pituitary-thyroid axis
Gulikers, Keven Peter (Virginia Tech, 2002-04-08)
Tricyclic antidepressants have been shown to alter thyroid function in man and laboratory animals, but have not been evaluated in the dog. The effect of administration of clomipramine on canine thyroid function was studied in a prospective protocol in which 14 mature, healthy dogs were administered clomipramine (3 mg/kg PO q12h) for 112 days. Thyroid-stimulating hormone (TSH), total thyroxine (T4), total 3,5,3' triiodothyronine (T3), free thyroxine (fT4), and 3,3',5' triiodothyronine (reverse T3; rT3) concentrations were measured on selected days. Thyrotropin-releasing hormone (TRH) response tests were performed concurrently. Repeated measures analysis of variance was applied to test for effects of day of treatment; when significance (p < 0.05) was noted, it was further investigated using orthogonal polynomial trends. Significant decreases were found in serum T4 (26 ± 1.2 to 17 ± 0.5 nmol/L, p < 0.001), fT4, (29 ± 2.4 to 19 ± 1.3 pmol/L, p < 0.0002), and rT3 (1.2 ± 0.1 to 0.83 ± 0.08 nmol/L, p < 0.0001) concentrations. The effect of time on serum T3 concentration was also significant (p < 0.0001), but no consistent trend could be identified. No significant effect of time was noted in either pre- or post-TRH TSH concentrations. The results of this study indicate that significant and substantial decreases in T4 (35%), fT4 (38%), and rT3 can occur during clomipramine administration. Long-term administration of clomipramine may result in a misdiagnosis of hypothyroidism if a dog is tested while taking this medication and, since decreased serum fT4 occurs, hypothyroidism may result.
Evaluation of Thyroid to Background Ratios in Hyperthyroid Cats
Bettencourt, Ann Elizabeth (Virginia Tech, 2014-07-17)
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.

Browsing by Author "Panciera, David L."

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