Comparative efficacy of stannous fluoride and copper sulfate footbath solutions for the treatment and prevention of digital dermatitis in lactating dairy cows.

The objective of this study was to determine whether a novel footbath solution containing stannous fluoride (SnF2) was superior to 5% copper sulfate solution for the treatment and prevention of digital dermatitis (DD) in dairy cattle. Study 1 was conducted over 4 weeks in Missouri and involved 34 lactating Holstein-Friesian cows with hind feet DD lesions. Cows in group SF walked through a footbath containing a proprietary formulation of SnF2 once weekly, whereas cows in group CS walked through a 5% CuSO4 footbath once daily for 5 d each week. Study 2 was conducted over 8 weeks in California and involved 40 lactating Holstein-Friesian cows with hind feet DD lesions. Cows in group SF walked through a SnF2 footbath for 3 consecutive days then once a week for the following 7 weeks. Cows in group CS walked through a 5% CuSO4 footbath 3 times each week for 8 weeks. Data collection included lesion type, lesion area, locomotion score, and pain score. Digital dermatitis was actively transmitted in study 1, and lesion area and locomotion scores were lower in group SF than group CS. In contrast, DD was not actively transmitted in study 2, and lesion area and locomotion scores were similar in groups SF and CS. Stannous fluoride delayed the development of active DD lesions in study 1 compared with copper sulfate, with a lower relative risk (0.57, P < 0.001) of a hind foot developing an active DD lesion over 28 d. However, SnF2 decreased the rate that active DD lesions transitioned to M3, M4, or M0 lesions compared with 5% copper sulfate in both studies, with the relative risk of a hind foot with an active DD lesion transitioning to M3, M4, or M0 in group SF being slightly lower in study 1 (0.83, P = 0.042) and study 2 (0.90, P = 0.020) than group CS. Our findings demonstrated that walking cows through a stannous fluoride footbath once per week in a herd undergoing active transmission of infection was more effective in preventing active DD lesions, but less effective in treating active DD lesions, than walking cows through a copper sulfate footbath 4 times per week. The novel SnF2 footbath solution shows promise for controlling DD in dairy herds that want an alternative footbath solution to CuSO4 and are interested in limiting the environmental accumulation of copper.

Effect of heating bovine colostrum at 60°C for 90' on colostrum quality and, the health and growth characteristics of Holstein dairy calves.

AIMS: The major objective of this study was to investigate the efficacy of heat-treating colostrum on the subsequent growth characteristics (weight gain, body size, dry matter intake and feed efficiency rate) and health of Holstein calves. METHODS: A total of 1200 neonatal Holstein calves on one commercial dairy farm were enrolled. The calves were divided into heat-treated (60°C for 90 min) and unheated (raw) colostrum groups. Calf serum IgG and total protein concentrations were measured before and after colostrum consumption. Health characteristics and disease prevalence were recorded during the suckling period. RESULTS: Consumption of heat-treated colostrum led to increased serum IgG (P < 0.0001) and total protein (P < 0.0001) concentrations, increased apparent efficacy of IgG absorption (P < 0.0001) and increased general health condition, weight gain (P < 0.0001) and clinical performance. CONCLUSIONS AND CLINICAL RELEVANCE: Heat-treatment of colostrum is an effective method to improve health and increase growth characteristics (weight gain, body size, dry matter intake and feed efficiency rate) of neonatal dairy calves, most likely by decreasing microbial load and facilitating IgG absorption.

Preparation of immunomagnetic beads coupled with a rhodamine hydrazine immunosensor for the detection of Mycobacterium avium subspecies paratuberculosis in bovine feces, milk, and colostrum.

The aim of this study was to develop and evaluate a method for detecting Mycobacterium avium ssp. paratuberculosis (MAP) bacteria in bovine fecal, milk, and colostrum samples using immunomagnetic beads (IMB) and a rhodamine hydrazone immunosensor. Immunomagnetic beads were prepared by using purified antibodies from hyperimmunized sera that were coupled to Fe nanoparticles with diethylene triamine pentaacetic acid (DTPA) or ethyl (dimethyl aminopropyl) carbodiimide (EDC)-N-hydroxy succinimide (NHS) as linkers. Rhodamine hydrazone particles were synthesized and coupled to IgY anti-MAP antibodies using DTPA or EDC-NHS linkers. Separation efficiency of the IMB was tested on bovine fecal, milk, and colostrum samples experimentally contaminated with MAP. The studied methods were evaluated on their ability to detect MAP and separate bacteria in complex mediums. The ELISA results indicated 95% efficacy in antibody coupling to IMB, with the DTPA-IMB method being more efficient than the EDC-NHS-IMB method. By using the DTPA-IMB method, MAP bacteria were successfully recovered from fecal, milk, and colostrum samples. The DTPA-IMB method used in combination with the rhodamine hydrazone immunosensor had a limit of detection equal to 30 and 30,000 MAP cells/mL using chromogenic and fluorescent properties, respectively. Combining the DTPA-IMB separation method with the rhodamine hydrazone immunosensor provides a fast, sensitive, and cost-beneficial method for detecting MAP in bovine feces, milk, and colostrum.

Technical note: Evaluation of a colorimetric point-of-care test for measuring urine ammonium concentration in periparturient dairy cattle.

Urine ammonium concentration ([NH4+]) provides a clinically useful indicator of the magnitude of nutritionally induced systemic acidification in dairy cattle when urine pH < 6.1. The objective of this study was to evaluate the analytical performance of a low-cost point-of-care colorimetric test in measuring urine [NH4+] in dairy cattle consuming an acidogenic ration. A method comparison study was performed using 154 urine samples from 43 periparturient Holstein-Friesian cows. We compared urine [NH4+] measured by an indophenol blue colorimetric test (MColortest, Merck KGaA, Billerica, MA; test method) with levels measured by formaldehyde titration (reference method). Diagnostic performance was evaluated using Pearson correlation coefficient (r), Passing-Bablok regression, Bland-Altman plot, and binary logistic regression. Urine [NH4+] measured by the colorimetric test was strongly correlated (r = 0.98) with urine [NH4+] measured by formaldehyde titration. Method comparison studies indicated that the colorimetric test provided acceptable test performance when urine [NH4+] < 80 mmol/L. Logistic regression analysis indicated that the area under the receiver operating characteristic curve for the colorimetric ammonium test was high at 0.985 when used to identify formaldehyde titration [NH4+] > 10 mmol/L, equivalent to urine pH <6.1. At the optimal cut point ([NH4+] > 11 mmol/L) for the colorimetric test, sensitivity = 0.94, specificity = 0.97, positive likelihood ratio = 27.6, and κ = 0.89, indicating excellent test performance. We conclude that the indophenol blue colorimetric test provided an accurate, low-cost, and practical on-farm test for measuring urine [NH4+] in diluted urine samples from dairy cattle consuming an acidogenic ration.

Clinical utility of plasma progesterone and blood and plasma glucose concentrations in predicting parturition in Holstein cows.

An accurate, practical, and low-cost method for predicting parturition is urgently needed in the dairy industry. The objective of this study was to evaluate changes in plasma progesterone concentration ([prog]) and glucose concentration in whole blood ([gluc]b) and plasma ([gluc]p) as predictors of parturition within 6, 12, and 24 h in primiparous and multiparous Holstein cows. Blood samples were obtained daily at approximately 0900 h from 34 primiparous and 72 multiparous Holstein cows in late gestation and the time of calving recorded to the nearest hour. Plasma [prog] was measured using an ELISA, and [gluc]b and [gluc]p using a low-cost point-of-care glucose meter. The optimal cut-point for predicting parturition was determined using binomial logistic regression with general estimating equations, because the data set consisted of repeated measures for each cow. Diagnostic test performance was evaluated by comparing the area under the receiver operating characteristic curve (AUC) and calculating the sensitivity, specificity, and κ at the optimal cut-point for predicting parturition. Plasma [prog] was the most accurate predictor of parturition within 24 h (AUC = 0.96) and 12 h (AUC = 0.93), whereas [gluc]b was the most accurate predictor of parturition within 6 h (primiparous, AUC = 0.96; multiparous, AUC = 0.86). We conclude that a decrease in plasma [prog] is currently the most accurate test for predicting calving within 24 h. Measurement of [gluc]b is a promising new test for the cow-side prediction of parturition in dairy cows due to its accuracy, practicality, and low cost.

Measurement of urine pH and net acid excretion and their association with urine calcium excretion in periparturient dairy cows.

Urine pH (UpH) and net acid excretion (NAE) are used to monitor the degree of systemic acidification and predict the magnitude of resultant hypercalciuria when feeding an acidogenic ration to control periparturient hypocalcemia in dairy cattle. The objectives of this study were to evaluate the diagnostic performance of urine dipstick and pH paper for measuring UpH, and to characterize the UpH-NAE relationship and the association of urine Ca concentration ([Ca]) with UpH and NAE. Urine samples (n = 1,116) were collected daily from 106 periparturient Holstein-Friesian cows fed an acidogenic ration during late gestation. Net acid excretion was measured by titration, and UpH was measured by a glass-electrode pH meter (reference method), Multistix-SG urine dipsticks (Siemens Medical Solutions Inc., Ann Arbor, MI), and Hydrion pH paper (Micro Essential Laboratory Inc., Brooklyn, NY). Diagnostic performance was evaluated using Spearman correlation coefficient (rs), Bland-Altman plots, and logistic regression. Urine pH measured by urine dipstick (rs = 0.94) and pH paper (rs = 0.96) were strongly associated with UpH. Method-comparison studies indicated that the urine dipstick measured an average of 0.28 pH units higher, and pH paper 0.10 pH units lower, than UpH. Urine [Ca] was more strongly associated with UpH (rs = -0.65) than NAE (rs = 0.52). Goals for controlling periparturient hypocalcemia under the study conditions were UpH <6.22 and <6.11, based on achieving urine [Ca] ≥5 mmol/L and estimated urinary Ca excretion ≥4 g/d, respectively. Urine pH was as accurate at predicting urine [Ca] as NAE when UpH >6.11. We conclude that pH paper is an accurate, practical, and low-cost cow-side test for measuring UpH and provides a clinically useful estimate of urine [Ca].

Evaluation of the analytical performance of a portable ion-selective electrode meter for measuring whole-blood, plasma, milk, abomasal-fluid, and urine sodium concentrations in cattle.

A portable ion-selective electrode (ISE) meter (LAQUAtwin B-722; Horiba Instruments Inc., Irvine, CA) is available for measuring the sodium ion concentration ([Na]) in biological fluids. The objective of this study was to characterize the analytical performance of the ISE meter in measuring [Na] in whole-blood, plasma, milk, abomasal fluid, and urine samples from cattle. Method comparison studies were performed using whole-blood and plasma samples from 106 sick calves and 11 sick cows admitted to a veterinary teaching hospital, 80 milk and 206 urine samples from 16 lactating Holstein-Friesian cows with experimentally induced free water, electrolyte, and acid-base imbalances, and 67 abomasal fluid samples from 7 healthy male Holstein-Friesian calves fed fresh milk with or without an oral electrolyte solution. Deming regression and Bland-Altman plots were used to determine the accuracy of the meter against reference methods. The meter used in direct mode on undiluted samples measured whole-blood [Na] 9.7 mmol/L (7.3%) lower than a direct ISE reference method and plasma [Na] 16.7 mmol/L (12.7%) lower than an indirect ISE reference method. The meter run in direct mode measured milk [Na] 3.1 mmol/L lower and abomasal fluid [Na] 9.0% lower than indirect ISE reference methods. The meter run in indirect mode on diluted samples accurately measured urine [Na] compared with an indirect ISE reference method. We conclude that, after adjustment for the bias determined from Bland-Altman plots, the LAQUAtwin ISE meter provides a clinically useful and low-cost cow-side instrument for measuring [Na] in whole blood, plasma, milk, and abomasal fluid.

Changes in skeletal muscle thickness and echogenicity and plasma creatinine concentration as indicators of protein and intramuscular fat mobilization in periparturient dairy cows.

High-producing dairy cows experience a state of negative energy balance in the periparturient period that is partially addressed by increasing the rate of fat and protein mobilization. Previous studies have focused on the rate of fat mobilization, and consequently the rate of protein mobilization has not been well characterized. The objective of this study was therefore to determine the change in indicators of muscle mass during early lactation using ultrasonographic measurement of muscle thickness and changes in plasma creatinine concentration. The maximum thickness of the gluteus medius and longissimus dorsi muscles of 106 Holstein cows (34 primiparous, 72 multiparous) was determined ultrasonographically on d -3, 0, 3, 7, 14, 21, and 28 relative to the day of parturition. Plasma creatinine concentration was measured periodically during the same period. Mixed models analysis and Passing-Bablok regression were used to analyze the data. Gluteus medius thickness, longissimus dorsi loin thickness (LDLT), and longissimus dorsi thoracic thickness (LDTT) were decreased at 28 d postpartum compared with d 3 antepartum. Plasma creatinine concentration was weakly associated with gluteus medius thickness, LDLT, and LDTT (Spearman's rho = 0.31, 0.39, and 0.32, respectively). Plasma creatinine concentration in primiparous and multiparous cows at 28 d postpartum decreased by 0.24 and 0.30 mg/dL, respectively, compared with values 3 d antepartum. We concluded that ultrasonographic measurement of LDLT and LDTT and change in plasma creatinine concentration may provide practical methods for monitoring the rate of protein mobilization in periparturient dairy cows. Ultrasonographic examination of LDLT and LDTT therefore complements ultrasonographic measurement of backfat thickness and may be useful in the evaluation of energy reserve mobilization in periparturient dairy cows.

Ability of milk pH to predict subclinical mastitis and intramammary infection in quarters from lactating dairy cattle.

Milk pH is increased in lactating dairy cattle with subclinical mastitis (SCM) and intramammary infection (IMI). We hypothesized that milk pH testing provides an accurate, low-cost, and practical on-farm method for diagnosing SCM and IMI. The main objective was to evaluate the clinical utility of measuring milk pH using 3 tests of increasing pH resolution: Multistix 10 SG Reagent Strips for Urinalysis (Multistix strips, Bayer HealthCare Inc., Elkhart, IN), pH Hydrion paper (Microessential Laboratory, Brooklyn, NY), and Piccolo plus pH meter (Hanna Instruments, Woonsocket, RI), for diagnosing SCM and IMI in dairy cattle. Quarter foremilk samples were collected from 115 dairy cows at dry off and 92 fresh cows within 4 to 7 d postcalving. Quarter somatic cell count (SCC) was measured using a DeLaval cell counter (DeLaval, Tumba, Sweden), with SCM defined as SCC >200,000 cells/mL and IMI defined as SCC >100,000 cells/mL and the presence of microorganisms at ≥10 cfu/mL of milk. Milk pH was measured at 37°C using the 3 test methods. The Hydrion pH paper performed poorly in diagnosing SCM and IMI. Receiver operating curve analysis provided optimal pH cutpoints for diagnosing SCM for the pH meter (dry off, ≥6.67; freshening, ≥6.52) and Multistix strips (dry off and freshening, ≥7.0). Test performance of the pH meter and Multistix strips was poor to fair based on area under the receiver operating curve, sensitivity, specificity, positive likelihood ratio, and kappa coefficient. The pH meter and Multistix strips performed poorly in diagnosing IMI at dry off and freshening. We concluded that milk pH does not provide a clinically useful method for diagnosing SCM or IMI in dairy cattle.

Evaluation of 3 esterase tests for the diagnosis of subclinical mastitis at dry-off and freshening in dairy cattle.

Subclinical mastitis (SCM) and intramammary infection (IMI) increase esterase activity in the glandular secretions of dairy cattle. Our objective was to evaluate the clinical performance of 3 commercially available esterase tests for diagnosing SCM and IMI. Foremilk samples were collected from 380 quarters (96 cows) at dry-off and from 329 quarters (83 cows) within 4 to 7 d after calving. Quarter somatic cell count (SCC) was measured using the reference method (DeLaval cell counter; De Laval International AB, Tumba, Sweden) with SCM defined as SCC >200,000 cells/mL. Bacterial culture of foremilk samples was used to diagnose IMI based on the growth of ≥100 cfu/mL. The SCC was estimated using 3 PortaSCC tests (PortaCheck, Moorestown, NJ) from the measured esterase activity and the California Mastitis Test (CMT). Clinical performance was evaluated using logistic regression to determine the area under the receiver operating characteristic curve (AUC) and identify test sensitivity (Se) and specificity (Sp) at the optimal cut-point for diagnosing SCM and IMI. Test agreement was also evaluated using the kappa coefficient (κ) and weighted κ. The PortaSCC color test was the best-performing PortaSCC test for diagnosing SCM at dry-off (AUC = 0.90, Se = 0.91, Sp = 0.81, κ = 0.71) and at freshening (AUC = 0.86, Se = 0.74, Sp = 0.95, κ = 0.72), at an optimal cut-point of ≥250,000 cells/mL but required 45 min to produce a result. For comparison, the CMT required 2 min to produce a result and a CMT score of trace or higher was superior to the PortaSCC color test for diagnosing SCM at dry-off (AUC = 0.95, Se = 0.95, Sp = 0.86, κ = 0.81) and freshening (AUC = 0.88, Se = 0.79, Sp = 0.95, κ = 0.76). The PortaSCC quick test was the best-performing PortaSCC test for diagnosing IMI at dry-off (AUC = 0.81, Se = 0.81, Sp = 0.78 κ = 0.40) and required 5 min to produce a result, whereas the PortaSCC color test was the best performing PortaSCC test for diagnosing IMI at freshening (AUC = 0.80, Se = 0.75, Sp = 0.79 κ = 0.38). For comparison, the CMT was inferior to the PortaSCC quick test for diagnosing IMI at dry-off (AUC = 0.73, Se = 0.76, Sp = 0.60, κ = 0.20) but was equivalent to the PortaSCC color test at freshening (AUC = 0.79, Se = 0.58, Sp = 0.93, κ = 0.50). The PortaSCC color and quick tests and CMT were considered good tests for diagnosing SCM and IMI because clinically useful tests typically have an AUC >0.80 and κ >0.6. Based on the test sensitivity, cost, and analysis time, there does not appear to be a persuasive reason to select the PortaSCC tests over the traditional CMT for diagnosing SCM and IMI.

Evaluation of a portable ion-selective electrode meter for measuring potassium concentrations in whole blood and plasma of calves.

An ion-selective electrode (ISE) handheld meter (LAQUAtwin B-731; Horiba) has recently become available for the measurement of potassium concentrations [K+] in biological fluids. The ISE meter has the potential to facilitate the diagnosis and treatment of potassium balance disorders of critically ill cattle. The objective of this study was to characterise the analytical performance of the ISE meter in a study sample of hospitalised calves with a broad range of plasma [K+]. For the purpose of the study, whole blood and plasma samples from 125 calves (age≤3months) were used for analysis. The accuracy of the meter against the reference method (indirect ISE, Cobas c 311, Roche) was assessed using Passing-Bablok regression and Bland-Altman plots. The [K+] in whole blood as measured by the ISE meter in direct mode ranged from 2.4 to 9.9mmol/L. The meter measured whole blood [K+] as 3.8% higher than plasma [K+]. Passing-Bablok regression for whole blood [K+] measured by the meter against plasma [K+] determined by indirect potentiometry revealed a linear relationship that was almost identical to the line of identity. However, the Bland-Altman plot indicated that the meter measured plasma [K+] 5.1% lower than the reference method. This result was consistent with analytical differences of direct and indirect ISE methods in respect to variation in the plasma protein concentration. In conclusion, the LAQUAtwin B-731 meter provides an accurate, rapid and low-cost tool for the diagnosis of potassium derangements in critically ill calves, particularly when whole blood samples are analysed.

Clinical Utility of Plasma Fructosamine Concentration as a Hypoglycemic Biomarker during Early Lactation in Dairy Cattle.

BACKGROUND: Plasma fructosamine concentration ([FRA]) is a widely used long term hyperglycemic biomarker in humans and dogs, but its clinical usefulness as a hypoglycemic biomarker in dairy cattle is uncertain. OBJECTIVES: To evaluate the relationship between plasma [FRA] and glucose concentration ([gluc]) as well as indices of energy balance during early lactation in dairy cattle, and to characterize the influence of plasma total protein concentration ([TP]) and albumin concentration ([albumin]) on [FRA]. ANIMALS: Convenience sample comprising 103 periparturient Holstein-Friesian cattle. METHODS: Plasma [gluc], [TP], [albumin], and other clinicopathologic indices of energy status were determined periodically from Day 4 postpartum. Body condition score (BCS) was assessed, and backfat thickness (BFT) and longissimus dorsi muscle thickness (LDT) were measured ultrasonographically. Plasma [FRA] was measured at approximately 28 days postpartum. Associations between plasma [FRA] and study variables were evaluated using Spearman's rho and stepwise forward linear regression. Statistical significance was declared at P < 0.05. RESULTS: A positive association was detected between plasma [FRA] and mean plasma [gluc] from Days 4-28 postpartum (rs = +0.36, P < 0.001), and between plasma [FRA] and LDT (rs = +0.28, P = 0.007), BCS (rs = +0.23, P = 0.029), and BFT (rs = +0.21, P = 0.043). Multivariable regression identified a positive association between plasma [FRA] and mean plasma [gluc] and [albumin] from Days 4-28 postpartum. Correcting plasma [FRA] for [albumin] improved the association (rs = +0.46, P < 0.001) between plasma [FRA] and mean plasma [gluc]. CONCLUSIONS AND CLINICAL IMPORTANCE: Plasma [FRA] does not provide a clinically useful method for quantifying the magnitude of hypoglycemia or negative energy balance in dairy cows during early lactation.

Evaluation and Comparison of 2 On-Farm Tests for Estimating Somatic Cell Count in Quarter Milk Samples from Lactating Dairy Cattle.

BACKGROUND: The somatic cell count (SCC) is commonly used to monitor udder health and diagnose subclinical intramammary infection (IMI) in dairy cattle. HYPOTHESIS: The Somaticell test (ST) and California mastitis test (CMT) are clinically useful cow-side tests for diagnosing subclinical IMI. ANIMALS: One hundred and eleven dairy cows at dry-off and 92 cows within 4-7 days postcalving. METHODS: Quarter foremilk samples were obtained and analyzed with a DeLaval cell counter (DCC, reference method), ST, and CMT. The ST was run in a simulated cow-side manner using milk at 37°C instead of 0-8°C as recommended by the manufacturer. Test performance for diagnosing IMI (DCC SCC >200,000 cells/mL) was evaluated by calculating the area under the receiver operating characteristic curve (AUC) and the kappa coefficient (κ) at the optimal cut-point for each test. The effect of milk/reagent temperature also was evaluated. RESULTS: Compared to the reference method, the ST run in a simulated cow-side manner had an AUC = 0.68 and κ = 0.24 at dry-off, and AUC = 0.74 and κ = 0.40 in fresh cows. The CMT performed much better than the ST in diagnosing subclinical IMI with AUC = 0.88 and κ = 0.77 at dry-off, and AUC = 0.87 and κ = 0.76 in fresh cows. The measured ST value decreased with increasing temperature of the milk/reagent mixture. CONCLUSIONS/CLINICAL IMPORTANCE: The ST is optimized for use on milk at 0-8°C and is therefore designed for on-farm use on refrigerated milk samples. The ST is not suited for use as a cow-side screening test for IMI because the milk temperature exceeds the recommended range for the test.

Association of California Mastitis Test Scores with Intramammary Infection Status in Lactating Dairy Cows Admitted to a Veterinary Teaching Hospital.

BACKGROUND: Subclinical mastitis is of concern in veterinary hospitals because contagious mastitis pathogens might be unknowingly transmitted to susceptible cows and then back to their farm of origin. OBJECTIVES: To evaluate the California mastitis test (CMT) as an indicator of intramammary infection (IMI) in lactating dairy cows admitted to a veterinary hospital. ANIMALS: A total of 139 admissions of 128 lactating dairy cows admitted to the University of Illinois Veterinary Teaching Hospital over a 2-year period. METHODS: A retrospective study with a convenience sample was conducted. Medical records of cows with CMT results and milk culture results for the day of admission were reviewed. Breed, age, season, maximum CMT score for the 4 quarters, maximum CMT score difference, and clinical diagnosis were evaluated as predictors of IMI by the chi-square test and stepwise logistic regression. RESULTS: An IMI was identified in 51% of quarters. For cows admitted without evidence of clinical mastitis, the sensitivity of a CMT score ≥trace in predicting an IMI on a quarter or cow basis was 0.45 and 0.68, respectively. The distributions of maximal quarter CMT score and the maximum difference in quarter CMT score for cows without evidence of clinical mastitis did not differ (P = 0.28, P = 0.84, respectively) for cows with and without IMI. Stepwise logistic regression did not identify significant predictors of IMI in cows without clinical mastitis. CONCLUSIONS: Lactating dairy cattle admitted to a veterinary hospital should be managed as if they have an IMI, even in the absence of clinical mastitis.

Effect of postparturient oral calcium administration on serum total calcium concentration in Holstein cows fed diets of different dietary cation-anion difference in late gestation.

Minimizing the severity of post parturient hypocalcemia and the incidence of subclinical hypocalcaemia in multiparous dairy cows are important goals of the transition period. The primary objective of this study was to determine whether feeding an acidogenic ration in late gestation combined with oral CaCl2 administration after parturition improved calcium homeostasis when compared to feeding an acidogenic ration prepartum or oral CaCl2 administration postpartum alone. Forty-two Holstein dairy cows were randomly assigned to one of three groups of 14 cows. Group L were fed a low DCAD ration. Groups L+Ca and M+Ca were fed a low or moderate DCAD ration, respectively, and administered 50g Ca as a CaCl2 solution at calving and 12h later by ororuminal intubation in 500mL of water. Mean serum [calcium] was lower immediately after parturition in group M+Ca (7.1mg/dL) than group L+Ca (8.2mg/dL). Oral CaCl2 administration increased mean serum [calcium] at 6h after treatment in groups M+Ca (8.0mg/dL) and L+Ca (8.7mg/dL), but most of this increase had disappeared at 12h after treatment. Group L+Ca had a higher serum [calcium] at time=6h and 12h than the other two groups, and a higher serum [calcium] than group M+Ca at 1 and 2days after treatment. We conclude that feeding an acidogenic ration in late gestation combined with oral CaCl2 administration provided a higher serum [calcium] at 6 and 12h after parturition than feeding an acidogenic ration prepartum or oral CaCl2 administration postpartum alone.

Effects of profound acidemia on the dynamic glucose and insulin response and plasma potassium and phosphorus concentrations during an intravenous glucose tolerance test in neonatal calves.

Acidemia and electrolyte imbalances such as hyperkalemia are common in neonatal calves with diarrhea. Acidemia negatively affects the cellular response to insulin and may therefore result in deranged glucose, potassium, and phosphorus homeostasis. The primary aim of this study was to compare indices that characterize the dynamic glucose and insulin response between acidemic and nonacidemic neonatal diarrheic calves and a healthy control group during an intravenous glucose tolerance test (IVGTT) that consisted of i.v. administration of 0.3 g of glucose per kg of body weight. Secondary aims were to characterize the associated changes in plasma potassium and phosphorus concentrations. The effect of correction of profound acidemia with a sodium bicarbonate containing infusion on these parameters was also assessed. Thirty calves (age ≤21 d) were purposively assigned to one of the following groups: 10 calves with diarrhea and profound acidemia (venous blood pH <7.20) where an IVGTT was performed before and after treatment with sodium bicarbonate, 10 calves with diarrhea and minimal acid-base disturbance (venous blood pH >7.35), and 10 healthy control calves. Profoundly acidemic diarrheic calves (jugular venous blood pH 6.99 ± 0.10) had a similar initial increase in plasma insulin concentration to that in healthy control calves or nonacidemic calves with diarrhea. However, insulin concentrations remained relatively stable in acidemic calves between 15 and 60 min after the start of the IVGTT, whereas a marked decrease in plasma insulin concentrations occurred in all other groups during the same period of time. We conclude that acidemia does not alter cell glucose availability or the dynamic response of glucose, phosphorus, and potassium to insulin; however, acidemia markedly prolongs plasma insulin concentrations following an IVGTT through an unidentified mechanism. Results of this study emphasize the importance of correcting acidemia and metabolic acidosis in neonatal calves with diarrhea.

Effect of Intravenous Small-Volume Hypertonic Sodium Bicarbonate, Sodium Chloride, and Glucose Solutions in Decreasing Plasma Potassium Concentration in Hyperkalemic Neonatal Calves with Diarrhea.

BACKGROUND: Hyperkalemia is a frequently observed electrolyte imbalance in dehydrated neonatal diarrheic calves that can result in skeletal muscle weakness and life-threatening cardiac conduction abnormalities and arrhythmias. HYPOTHESIS: Intravenous administration of a small-volume hypertonic NaHCO3 solution is clinically more effective in decreasing the plasma potassium concentration (cK) in hyperkalemic diarrheic calves than hypertonic NaCl or glucose solutions. ANIMALS: Twenty-two neonatal diarrheic calves with cK >5.8 mmol/L. METHODS: Prospective randomized clinical trial. Calves randomly received either 8.4% NaHCO3 (6.4 mL/kg BW; n = 7), 7.5% NaCl (5 mL/kg BW; n = 8), or 46.2% glucose (5 mL/kg BW; n = 7) IV over 5 minutes and were subsequently allowed to suckle 2 L of an electrolyte solution. Infusions with NaHCO3 and NaCl provided an identical sodium load of 6.4 mmol/kg BW. RESULTS: Hypertonic NaHCO3 infusions produced an immediate and sustained decrease in plasma cK. Hypertonic glucose infusions resulted in marked hyperglycemia and hyperinsulinemia, but cK remained unchanged for 20 minutes. Between 30 and 120 minutes after initiation of treatment, the most marked decrements in cK from baseline occurred in group NaHCO3 , which were significantly (P < .05) larger during this period of time than in calves in group NaCl, but not group glucose. After 120 minutes, the mean decrease in cK from baseline was -26 ± 10%, -9 ± 8%, and -22 ± 6% in groups NaHCO3 , NaCl, and glucose, respectively. CONCLUSIONS/CLINICAL IMPORTANCE: Small-volume hypertonic NaHCO3 infusions appear to have clinical advantages for the rapid resuscitation of hyperkalemic diarrheic calves, compared to hypertonic NaCl or glucose solutions.

Evaluation of a point-of-care electrochemical meter to detect subclinical ketosis and hypoglycaemia in lactating dairy cows.

OBJECTIVES: To evaluate and validate a hand-held electrochemical meter (Precision Xtra®) as a screening test for subclinical ketosis and hypoglycaemia in lactating dairy cattle. DESIGN: Method comparison study using a convenience sample. PROCEDURE: Blood samples were collected into plain tubes from the coccygeal vessels of 181 Holstein cows at 2-4 weeks of lactation during summer in Iran. Blood ß-hydroxybutyrate concentration (BHB) and glucose concentration were immediately measured by the electrochemical meter after applying 20 µL of blood to the reagent strip. Passing-Bablok regression and Bland-Altman plots were used to determine the accuracy of the meter against laboratory reference methods (BHB dehydrogenase and glucose oxidase). RESULTS: Serum BHB ranged from 0.1 to 7.3 mmol/L and serum glucose ranged from 0.9 to 5.1 mmol/L. Passing-Bablok regression analysis indicated that the electrochemical meter and reference methods were linearly related for BHB and glucose, with a slope estimate that was not significantly different from 1.00. Clinically minor, but statistically significant, differences were present for the intercept value for Passing-Bablok regression analysis for BHB and glucose, and bias estimates in the Bland-Altman plots for BHB and glucose. CONCLUSION: The electrochemical meter provided a clinically useful method to detect subclinical ketosis and hypoglycaemia in lactating dairy cows. Compared with other method validation studies using the meter, we attributed the improved performance of the electrochemical meter to application of a fixed volume of blood (20 µL) to the reagent strip, use of the meter in hot ambient conditions and use of glucose oxidase as the reference method for glucose analysis.

Evaluation of 2 portable ion-selective electrode meters for determining whole blood, plasma, urine, milk, and abomasal fluid potassium concentrations in dairy cattle.

Two low-cost ion-selective electrode (ISE) handheld meters (CARDY C-131, LAQUAtwin B-731; Horiba Ltd., Albany, NY) have recently become available for measuring the potassium concentration ([K(+)]) in biological fluids. The primary objective of this study was to characterize the analytical performance of the ISE meters in measuring [K(+)] in bovine whole blood, plasma, urine, milk, and abomasal fluid. We completed 6 method comparison studies using 369 whole blood and plasma samples from 106 healthy periparturient Holstein-Friesian cows, 138 plasma samples from 27 periparturient Holstein-Friesian cows, 92 milk samples and 204 urine samples from 16 lactating Holstein-Friesian cows, and 94 abomasal fluid samples from 6 male Holstein-Friesian calves. Deming regression and Bland-Altman plots were used to characterize meter performance against reference methods (indirect ISE, Hitachi 911 and 917; inductively coupled plasma-optical emission spectroscopy). The CARDY ISE meter applied directly in plasma measured [K(+)] as being 7.3% lower than the indirect ISE reference method, consistent with the recommended adjustment of +7.5% when indirect ISE methods are used to analyze plasma. The LAQUAtwin ISE meter run in direct mode measured fat-free milk [K(+)] as being 3.6% lower than the indirect ISE reference method, consistent with a herd milk protein percentage of 3.4%. The LAQUAtwin ISE meter accurately measured abomasal fluid [K(+)] compared to the indirect ISE reference method. The LAQUAtwin ISE meter accurately measured urine [K(+)] compared to the indirect ISE reference method, but the median measured value for urine [K(+)] was 83% of the true value measured by inductively coupled plasma-optical emission spectroscopy. We conclude that the CARDY and LAQUAtwin ISE meters are practical, low-cost, rapid, accurate point-of-care instruments suitable for measuring [K(+)] in whole blood, plasma, milk, and abomasal fluid samples from cattle. Ion-selective electrode methodology is not suitable for measuring [K(+)] in bovine urine.

Pharmacokinetics of ketorolac tromethamine in horses after intravenous, intramuscular, and oral single-dose administration.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are an integral component of equine analgesia, yet currently available NSAIDs are both limited in their analgesic efficacy and have adverse effects. The NSAID ketorolac tromethamine (KT) is widely used in humans as a potent morphine-sparing analgesic drug but has not been fully evaluated in horses. The purpose of this study was to determine the pharmacokinetic profile of KT in horses after intravenous (i.v.), intramuscular (i.m.), and oral (p.o.) administration. Nine healthy adult horses received a single 0.5-mg/kg dose of KT via each route of administration. Plasma was collected up to 48 h postadministration and analyzed for KT concentration using HPLC/MS/MS. Noncompartmental analysis of i.v. dosage indicated a mean plasma clearance of 8.4 (mL/min)/kg and an estimated mean volume of distribution at steady-state of 0.77 L/kg. Noncompartmental analysis of i.v., i.m., and p.o. dosages indicated mean residence times of 2.0, 2.6, and 7.1 h, respectively. The drug was rapidly absorbed after i.m. and p.o. administration, and mean bioavailability was 71% and 57% for i.m. and p.o. administration, respectively. Adverse effects were not observed after i.v., i.m., and p.o. administration. More studies are needed to evaluate the analgesic and anti-inflammatory properties of KT in horses.