Katarzyna A. Dembek

Evaluation of Four Diagnostic Tests for Insulin Dysregulation in Adult Light‐Breed Horses

Background Several tests have been evaluated in horses for quantifying insulin dysregulation to support a diagnosis of equine metabolic syndrome. Comparing the performance of these tests in the same horses will provide clarification of their accuracy in the diagnosis of equine insulin dysregulation. Objectives The aim of this study was to evaluate the agreement between basal serum insulin concentrations (BIC), the oral sugar test (OST), the combined glucose‐insulin test (CGIT), and the frequently sampled insulin‐modified intravenous glucose tolerance test (FSIGTT). Animals Twelve healthy, light‐breed horses. Methods Randomized, prospective study. Each of the above tests was performed on 12 horses. Results Minimal model analysis of the FSIGTT was considered the reference standard and classified 7 horses as insulin resistant (IR) and 5 as insulin sensitive (IS). In contrast, BIC and OST assessment using conventional cut‐off values classified all horses as IS. Kappa coefficients, measuring agreement among BIC, OST, CGIT, and FSIGTT were poor to fair. Sensitivity of the CGIT (positive phase duration of the glucose curve >45 minutes) was 85.7% and specificity was 40%, whereas CGIT ([insulin]45 >100 μIU/mL) sensitivity and specificity were 28.5% and 100%, respectively. Area under the glucose curve (AUC g0‐120) was significantly correlated among the OST, CGIT, and FSIGTT, but Bland–Altman method and Lins concordance coefficient showed a lack of agreement. Conclusions Current criteria for diagnosis of insulin resistance using BIC and the OST are highly specific but lack sensitivity. The CGIT displayed better sensitivity and specificity, but modifications may be necessary to improve agreement with minimal model analysis.

Validation of IgG cut-off values and their association with survival in neonatal foals.

REASONS FOR PERFORMING STUDY Serum immunoglobulin (IgG) assessment in neonatal foals is considered standard care in equine hospitals to determine immunity and overall health. However, cut-off values of IgG to predict complete or partial failure of transfer of passive immunity (FTPI) were developed 30 years ago and are largely empirical with little prospective or statistical data to support their use or association with outcome. OBJECTIVES To critically evaluate the traditional cut-off values of IgG in the assessment of FTPI (IgG < 8 g/l), determine the association between various degrees of FTPI and likelihood of nonsurvival and examine whether FTPI can be predicted by serum total protein (TP), albumin and globulin in hospitalised foals. STUDY DESIGN Multicentre, cross-sectional study. METHODS We evaluated clinicopathological variables in 597 foals ≤ 7 days old from 3 equine hospitals including serum IgG, fibrinogen, TP and albumin concentrations. Foals were divided into 3 groups by diagnosis: healthy, sick nonseptic and septic. The aforementioned variables in addition to globulin concentrations were evaluated in a subset of 118 foals. Univariate, multivariate and multinomial logistic regression were used to compute odds ratios for nonsurvival in these foals. RESULTS Our findings support use of the traditional cut-off value of > 8 g/l as adequate transfer of passive immunity (ATPI). Odds of nonsurvival increased in proportion to lower IgG concentrations. Higher TP concentrations were associated with lower likelihood of FTPI; however, higher albumin concentrations were associated with a greater likelihood of FTPI. A regression equation was created to predict IgG in foals using serum proteins. CONCLUSIONS Serum IgG values of <8 g/l in hospitalised foals were proportionally associated with mortality. We recommend immediate assessment of IgG concentrations in hospitalised foals and those with FTPI should receive prompt immunotherapy. The summary is available in Chinese - see Supporting information.

Association of Vitamin D Metabolites with Parathyroid Hormone, Fibroblast Growth Factor-23, Calcium, and Phosphorus in Dogs with Various Stages of Chronic Kidney Disease.

Background Hypovitaminosis D is associated with progression of renal disease, development of renal secondary hyperparathyroidism (RHPT), chronic kidney disease‐mineral bone disorder (CKD‐MBD), and increased mortality in people with CKD. Despite what is known regarding vitamin D dysregulation in humans with CKD, little is known about vitamin D metabolism in dogs with CKD. Objectives The purpose of our study was to further elucidate vitamin D status in dogs with different stages of CKD and to relate it to factors that affect the development of CKD‐MBD, including parathyroid hormone (PTH), fibroblast growth factor‐23 (FGF‐23), calcium, and phosphorus concentrations. Methods Thirty‐seven dogs with naturally occurring CKD were compared to 10 healthy dogs. Serum 25‐hydroxyvitamin D [25(OH)D], 1,25‐dihydroxyvitamin D [1,25(OH)2D], and 24,25‐dihydroxyvitamin D [24,25(OH)2D], and PTH and FGF‐23 concentrations were measured. Their association with serum calcium and phosphorus concentrations and IRIS stage was determined. Results Compared to healthy dogs, all vitamin D metabolite concentrations were significantly lower in dogs with International Renal Interest Society (IRIS) stages 3 and 4 CKD (r [creatinine]: −0.49 to −0.60; P < .05) but not different in dogs with stages 1 and 2 CKD. All vitamin D metabolites were negatively correlated with PTH, FGF‐23, and phosphorus concentrations (r: −0.39 to −0.64; P < .01). Conclusions and Clinical Importance CKD in dogs is associated with decreases in all vitamin D metabolites evaluated suggesting that multiple mechanisms, in addition to decreased renal mass, affect their metabolism. This information could have prognostic and therapeutic implications.

Vitamin D Metabolites and Their Association with Calcium, Phosphorus, and PTH Concentrations, Severity of Illness, and Mortality in Hospitalized Equine Neonates

Background Hypocalcemia is a frequent abnormality that has been associated with disease severity and outcome in hospitalized foals. However, the pathogenesis of equine neonatal hypocalcemia is poorly understood. Hypovitaminosis D in critically ill people has been linked to hypocalcemia and mortality; however, information on vitamin D metabolites and their association with clinical findings and outcome in critically ill foals is lacking. The goal of this study was to determine the prevalence of vitamin D deficiency (hypovitaminosis D) and its association with serum calcium, phosphorus, and parathyroid hormone (PTH) concentrations, disease severity, and mortality in hospitalized newborn foals. Methods and Results One hundred newborn foals ≤72 hours old divided into hospitalized (n = 83; 59 septic, 24 sick non-septic [SNS]) and healthy (n = 17) groups were included. Blood samples were collected on admission to measure serum 25-hydroxyvitamin D3 [25(OH)D3], 1,25-dihydroxyvitamin D3 [1,25(OH) 2D3], and PTH concentrations. Data were analyzed by nonparametric methods and univariate logistic regression. The prevalence of hypovitaminosis D [defined as 25(OH)D3 <9.51 ng/mL] was 63% for hospitalized, 64% for septic, and 63% for SNS foals. Serum 25(OH)D3 and 1,25(OH) 2D3 concentrations were significantly lower in septic and SNS compared to healthy foals (P<0.0001; P = 0.037). Septic foals had significantly lower calcium and higher phosphorus and PTH concentrations than healthy and SNS foals (P<0.05). In hospitalized and septic foals, low 1,25(OH)2D3 concentrations were associated with increased PTH but not with calcium or phosphorus concentrations. Septic foals with 25(OH)D3 <9.51 ng/mL and 1,25(OH) 2D3 <7.09 pmol/L were more likely to die (OR=3.62; 95% CI = 1.1-12.40; OR = 5.41; 95% CI = 1.19-24.52, respectively). Conclusions Low 25(OH)D3 and 1,25(OH)2D3 concentrations are associated with disease severity and mortality in hospitalized foals. Vitamin D deficiency may contribute to a pro-inflammatory state in equine perinatal diseases. Hypocalcemia and hyperphosphatemia together with decreased 1,25(OH)2D3 but increased PTH concentrations in septic foals indicates that PTH resistance may be associated with the development of these abnormalities.

Sudden death of a horse with supraventricular tachycardia following oral administration of flecainide acetate.

OBJECTIVE To describe a case of supraventricular tachycardia and sudden death in a horse following administration of flecainide acetate. CASE SUMMARY An 8-year-old Hanoverian warmblood gelding was treated for chronic, naturally occurring, supraventricular tachycardia with digoxin, procainamide hydrochloride, quinidine sulfate, and flecainide acetate. After oral administration of flecainide, polymorphic ventricular tachycardia (torsades de pointes) and ventricular fibrillation developed, leading to cardiovascular collapse and death. NEW OR UNIQUE INFORMATION PROVIDED Atrial fibrillation is the most commonly diagnosed dysrhythmia associated with poor performance in horses, while atrial tachycardia is rarely documented. Here, we describe a case of sudden death in a horse with atrial tachycardia following the oral administration of flecainide acetate, after the lack of response to other antiarrhythmic drugs. Information provided in this case report is new and will make clinicians aware of the potential complications of flecainide alone or in combination with other drugs, in horses with cardiac dysrhythmias.Objective To describe a case of supraventricular tachycardia and sudden death in a horse following administration of flecainide acetate. Case Summary An 8-year-old Hanoverian warmblood gelding was treated for chronic, naturally occurring, supraventricular tachycardia with digoxin, procainamide hydrochloride, quinidine sulfate, and flecainide acetate. After oral administration of flecainide, polymorphic ventricular tachycardia (torsades de pointes) and ventricular fibrillation developed, leading to cardiovascular collapse and death. New or Unique Information Provided Atrial fibrillation is the most commonly diagnosed dysrhythmia associated with poor performance in horses, while atrial tachycardia is rarely documented. Here, we describe a case of sudden death in a horse with atrial tachycardia following the oral administration of flecainide acetate, after the lack of response to other antiarrhythmic drugs. Information provided in this case report is new and will make clinicians aware of the potential complications of flecainide alone or in combination with other drugs, in horses with cardiac dysrhythmias.

Fibroblast Growth Factor-23 Concentration in Dogs with Chronic Kidney Disease

Background Chronic kidney disease (CKD) is associated with hyperphosphatemia, decreased vitamin D metabolite concentrations, and hyperparathyroidism. This syndrome is known as CKD‐mineral bone disorder (CKD‐MBD). Recently, it has been shown that an increase in fibroblast growth factor‐23 (FGF‐23) concentration is an early biomarker of CKD in people. It is an independent risk factor for both progression of renal disease and survival time in humans and cats with CKD. Information about FGF‐23 in healthy dogs and those with CKD is lacking. Objectives To measure FGF‐23 concentration in dogs with different stages of CKD and determine its association with factors involved in CKD‐MBD, including serum phosphorus and parathyroid hormone (PTH) concentrations. A secondary aim was to validate an ELISA for measurement of plasma FGF‐23 concentration in dogs. Animals Thirty‐two client‐owned dogs with naturally occurring CKD and 10 healthy control dogs. Methods Prospective cross‐sectional study. An FGF‐23 ELISA was used to measure plasma FGF‐23 concentration in dogs and their association with serum creatinine, phosphorus, calcium, and PTH concentrations. Results Plasma FGF‐23 concentrations increased with severity of CKD and were significantly different between IRIS stages 1 and 2 versus stages 3 and 4 (P < .0001). Increases in FGF‐23 concentrations were more frequent than hyperparathyroidism or hyperphosphatemia in this cohort. Serum creatinine and phosphorus concentrations were the strongest independent predictors of FGF‐23 concentration. Conclusions and clinical importance Plasma FGF‐23 concentrations increase in dogs with CKD as disease progresses. Plasma FGF‐23 concentrations appear to be useful for further study of the pathophysiology of CKD‐MBD in dogs.

Development of a Likelihood of Survival Scoring System for Hospitalized Equine Neonates Using Generalized Boosted Regression Modeling

Background Medical management of critically ill equine neonates (foals) can be expensive and labor intensive. Predicting the odds of foal survival using clinical information could facilitate the decision-making process for owners and clinicians. Numerous prognostic indicators and mathematical models to predict outcome in foals have been published; however, a validated scoring method to predict survival in sick foals has not been reported. The goal of this study was to develop and validate a scoring system that can be used by clinicians to predict likelihood of survival of equine neonates based on clinical data obtained on admission. Methods and Results Data from 339 hospitalized foals of less than four days of age admitted to three equine hospitals were included to develop the model. Thirty seven variables including historical information, physical examination and laboratory findings were analyzed by generalized boosted regression modeling (GBM) to determine which ones would be included in the survival score. Of these, six variables were retained in the final model. The weight for each variable was calculated using a generalized linear model and the probability of survival for each total score was determined. The highest (7) and the lowest (0) scores represented 97% and 3% probability of survival, respectively. Accuracy of this survival score was validated in a prospective study on data from 283 hospitalized foals from the same three hospitals. Sensitivity, specificity, positive and negative predictive values for the survival score in the prospective population were 96%, 71%, 91%, and 85%, respectively. Conclusions The survival score developed in our study was validated in a large number of foals with a wide range of diseases and can be easily implemented using data available in most equine hospitals. GBM was a useful tool to develop the survival score. Further evaluations of this scoring system in field conditions are needed.

Somatotropic axis resistance and ghrelin in critically ill foals

REASONS FOR PERFORMING STUDY Resistance to the somatotropic axis and increases in ghrelin concentrations have been documented in critically ill human patients, but limited information exists in healthy or sick foals. OBJECTIVES To investigate components of the somatotropic axis (ghrelin, growth hormone and insulin-like growth factor-1 [IGF-1]) with regard to energy metabolism (glucose and triglycerides), severity of disease and survival in critically ill equine neonates. It was hypothesised that ghrelin and growth hormone would increase and IGF-1 would decrease in proportion to severity of disease, supporting somatotropic axis resistance, which would be associated with severity of disease and mortality in sick foals. STUDY DESIGN Prospective multicentre cross-sectional study. METHODS Blood samples were collected at admission from 44 septic, 62 sick nonseptic (SNS) and 19 healthy foals, all aged <7 days. Foals with positive blood cultures or sepsis scores ≥12 were considered septic, foals with sepsis scores of 5-11 were classified as SNS. Data were analysed by nonparametric methods and multivariate logistic regression. RESULTS Septic foals had higher ghrelin, growth hormone and triglyceride and lower IGF-1 and glucose concentrations than healthy foals (P<0.01). Sick nonseptic foals had higher growth hormone and triglycerides and lower IGF-1 concentrations than healthy foals (P<0.05). Growth hormone:IGF-1 ratio was higher in septic and SNS foals than healthy foals (P<0.05). Hormone concentrations were not different between septic nonsurvivors (n = 14) and survivors (n = 30), but the growth hormone:IGF-1 ratio was lower in nonsurvivors (P = 0.043). CONCLUSIONS Somatotropic axis resistance, characterised by a high growth hormone:IGF-1 ratio, was frequent in sick foals, associated with the energy status (hypoglycaemia, hypertriglyceridaemia) and with mortality in septic foals. POTENTIAL RELEVANCE A functional somatotropic axis appears to be important for foal survival during sepsis. Somatotropic resistance is likely to contribute to severity of disease, a catabolic state and likelihood of recovery.

Preliminary investigation of orally administered benazepril in horses with left-sided valvular regurgitation

BACKGROUND Despite the paucity of data available, orally administered angiotensin-converting enzyme (ACE) inhibitors are empirically used in horses with valvular regurgitation. OBJECTIVE Evaluate the echocardiographic and hormonal changes in response to oral benazepril in horses with left-sided valvular regurgitation. STUDY DESIGN Prospective, randomised double-blind, placebo-controlled trial. METHODS Horses with mitral valve (MR) and/or aortic valve regurgitation (AR) received oral benazepril (n = 6) at a dosage of 1 mg/kg q 12 h or a placebo (n = 5) for 28 days. Echocardiography was performed before drug administration and after 28 days of treatment. Plasma renin activity, serum ACE activity, angiotensin II concentration, aldosterone concentration and biochemical variables were measured before drug administration and after 7 and 28 days of treatment. RESULTS Relative to baseline, horses treated with benazepril had statistically significant reduction in left ventricular internal diameter in systole (mean difference between groups = -0.97 cm; 95% CI = -1.5 to -0.43 cm), aortic sinus diameter (-0.31 cm; -0.54 to -0.07 cm), and percentage of the aortic annulus diameter occupied by the base of the AR jet (-17.05%; -31.17 to -2.93%) compared with horses receiving a placebo. In addition, horses treated with benazepril had a significantly greater increase in cardiac output (11.95 L/min; 1.17-22.73 L/min) and fractional shortening (7.59%; 3.3-11.88%) compared with horses receiving a placebo. Despite profound serum ACE inhibition, renin activity and concentrations of angiotensin II and aldosterone were not significantly different between treatment groups or among time points. MAIN LIMITATIONS Very small sample size and short treatment period. CONCLUSIONS Treatment with oral benazepril resulted in statistically significant echocardiographic changes that might indicate reduced cardiac afterload in horses with left-sided valvular regurgitation. Additional studies with a larger sample size will be necessary to determine if administration of benazepril is beneficial in horses with valvular regurgitation. The Summary is available in Spanish - see Supporting Information.

Effect of Intravenous Administration of Cobalt Chloride to Horses on Clinical and Hemodynamic Variables

Background Cobalt chloride (CoCl2) is administered to racehorses to enhance performance. The purpose of this study was to evaluate the clinical, cardiovascular, and endocrine effects of parenterally administered CoCl2. Objectives To describe the effects of weekly intravenous doses of CoCl2 on Standardbred horses. Animals Five, healthy Standardbred mares. Methods Prospective, randomized, experimental dose‐escalation pilot. Five Standardbred mares were assigned to receive 1 of 5 doses of CoCl2 (4, 2, 1, 0.5, or 0.25 mg/kg) weekly IV for 5 weeks. Physical examination, blood pressure, cardiac output, and electrocardiography (ECG) were evaluated for 4 hours after administration of the first and fifth doses. Blood and urine samples were collected for evaluation of cobalt concentration, CBC and clinical chemistry, and hormone concentrations. Results All mares displayed pawing, nostril flaring, muscle tremors, and straining after CoCl2 infusion. Mares receiving 4, 2, or 1 mg/kg doses developed tachycardia after dosing (HR 60–126 bpm). Ventricular tachycardia was noted for 10 minutes after administration of the 4 mg/kg dose. Increases in systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) occurred after administration of all doses (4, 2, 1, 0.5, and 0.25 mg/kg). Profound hypertension was observed after the 4 mg/kg dose (SAP/DAP, MAP [mmHg] = 291–300/163–213, 218–279). Hemodynamics normalized by 1–2 hours after administration. ACTH and cortisol concentrations increased within 30 minutes of administration of all CoCl2 doses, and cardiac troponin I concentration increased after administration of the 4 and 2 mg/kg doses. Conclusions and Clinical Importance The degree of hypertension and arrhythmia observed after IV CoCl2 administration raises animal welfare and human safety concerns.