Copper toxicosis in veal calves

Copper toxicosis was diagnosed in 7 veal calves, 10-16 weeks old, from 5 separate farms. All calves died without specific clinical signs, although 4 of the calves were icteric. The calves' dietary rations had been supplemented with various copper-containing hematinics. Peritoneal hemorrhage was reported at post-mortem in 2 calves. Microscopic evidence of hepatopathy consisted of hepatocellular degeneration and necrosis, hemorrhage, and fibrosis. Concentrations of copper in livers from intoxicated calves ranged from 277 to 684 ppm and in kidneys from 1.1 to 82.0 ppm. The extent and severity of lesions in livers appeared to correlate with concentrations of copper. Nephrosis was minimal, without evidence of hemoglobinuria.     

Pharmacokinetics of florfenicol in veal calves

The pharmacokinetic disposition of florfenicol was described in veal calves after administration of a single 22-mg/kg dose intravenously, orally after a 12-h fast and orally 5 min post feeding. Both serum concentrations and urinary excretion were studied. After intravenous administration the median elimination half-life was 171.9 min while the half-life of the distribution phase was 5.9 min. The median body clearance (Cl) and apparent volume of distribution (Vz) were 2.85 ml/kg/min and 0.78 l/kg, respectively. Following oral administration the median bio-availability (f) was 0.88 for calves dosed after a 12-h fast and 0.65 for calves dosed 5 min post feeding. Calves given the oral doses had a complex absorption pattern with delayed absorption. Slightly more than 50% of the administered dose both orally and intravenously was recovered as unchanged florfenicol in the urine by 30 h.     

Transportation of veal calves in Switzerland

The analysis and optimization of transportation routes of calves to slaughterhouses by means of a GIS (geographical information system) route planning and time limitation software for the fleet management in transportation industry was performed. As basic data the farms (last locations of the calves) and the slaughterhouses were available in each case with addresses and coordinates. 150 data records from 258 veal calves could be evaluated. None of the calves was transported longer than 6 hours. Therefore, in all cases the Swiss law for animal protection was obeyed concerning maximum length of transportation time. In the road model, 82% of calves were transported too far.     

A Bayesian approach for the evaluation of six diagnostic assays and the estimation of Cryptosporidium prevalence in dairy calves

The prevalence of Cryptosporidium in calves and the test properties of six diagnostic assays (microscopy (ME), an immunofluorescence assay (IFA), two ELISA and two PCR assays) were estimated using Bayesian analysis. In a first Bayesian approach, the test results of the four conventional techniques were used: ME, IFA and two ELISA. This four-test approach estimated that the calf prevalence was 17% (95% Probability Interval (PI): 0.1-0.28) and that the specificity estimates of the IFA and ELISA were high compared to ME. A six-test Bayesian model was developed using the test results of the 4 conventional assays and 2 PCR assays, resulting in a higher calf prevalence estimate (58% with a 95% PI: 0.5-0.66) and in a different test evaluation: the sensitivity estimates of the conventional techniques decreased in the six-test approach, due to the inclusion of two PCR assays with a higher sensitivity compared to the conventional techniques. The specificity estimates of these conventional assays were comparable in the four-test and six-test approach. These results both illustrate the potential and the pitfalls of a Bayesian analysis in estimating prevalence and test characteristics, since posterior estimates are variables depending both on the data at hand and prior information included in the analysis. The need for sensitive diagnostic assays in epidemiological studies is demonstrated, especially for the identification of subclinically infected animals since the PCR assays identify these animals with reduced oocyst excretion, which the conventional techniques fail to identify.     

Bayesian mixture models for within-herd prevalence estimates of bovine paratuberculosis based on a continuous ELISA response

Diagnostic inference by use of assays such as ELISA is usually done by dichotomizing the optical density (OD)-values based on a predetermined cut-off. For paratuberculosis, a slowly developing infection in cattle and other ruminants, it is known that laboratory factors as well as animal specific covariates influence the OD-value, but while laboratory factors are adjusted for, the animal specific covariates are seldom utilized when establishing cut-offs. Furthermore, when dichotomizing an OD-value, information is lost. Considering the poor diagnostic performance of ELISAs for diagnosis of paratuberculosis, a framework for utilizing the continuous OD-values as well as known coavariates could be useful in addition to the traditional approaches, e.g. for estimating within-herd prevalences.

The objective of this study was to develop a Bayesian mixture model with two components describing the continuous OD response of infected and non-infected cows, while adjusting for known covariates. Based on this model, four different within-herd prevalence indicators were considered: the mean prevalence in the herd; the age adjusted prevalence of the herd for better between-herd comparisons; the rank of the age adjusted prevalence to better compare across time; and a threshold-based prevalence to describe differences between herds. For comparison, the within-herd prevalence and associated rank using a traditional dichotomization approach based on a single cut-off for an OD corrected for laboratory variation was estimated in a Bayesian model with priors for sensitivity and specificity.

The models were applied to the OD-values of a milk ELISA using samples from all lactating cows in 100 Danish dairy herds in three sampling rounds 13 months apart. The results of the comparison showed that including covariates in the mixture model reduced the uncertainty of the prevalence estimates compared to the cut-off based estimates. This allowed a more informative ranking of the herds where low ranking and high ranking herds were easier to identify.     

Oral absorption and bioavailability of flumequine in veal calves

Summary

The oral absorption and bioavailability of flumequine was studied in 1‐, 5‐ and 18‐week‐old calves following intravenous and oral administration of different formulations of flumequine (Flumix^®, Flumix C^® and pure flumequine). Increasing age had a negative influence on the C_max after the administration of Flumix^®, based on a larger V_D in the older calves. The C_max decreased from 5.02 ± 1.46 μg/ml in the first week to 3.28 ± 0.42 μg/ml in the 18th week. Adding colistin sulfate to the flumequine formulation and administring pure flumequine mixed with milk replacer had a negative effect on the C_max of flumequine after oral administration of 5 and 10 mg/kg body weight. The bioavailability of the orally administered flumequine formulations was 100% in all cases except after the administration of Flumix C^®, for which it was 75.9 ± 18.2%. The urinary recovery of flumequine after intravenous injection of a 10% solution varied from 35.2 ± 2.3% for Group B. to 41.2 ± 6.3% for Group C.

The dosage of 5 mg/kg body weight Flumix^® twice daily in 1‐week‐old veal calves is sufficient to reach therapeutic plasma concentrations, based on a MIC value of 0.8 μg/ml of the target bacteria.

In older calves it is advisable to increase the dosage 7.5 or 10 mg/kg body weight every 12 hours. In combination with colistin sulfate it is also advisable to increase the dosage slightly because of the negative effect of the colistin sulfate on the C_max of flumequine.     

Pharmacokinetics of oxytetracycline and therapeutic implications in veal calves

Pharmacokinetic parameters of oxytetracycline were analysed in healthy preruminant veal calves after intravenous, intramuscular and oral administration. The serum half-lives in the β-elimination phase of both 10% and 20% solutions after i.v. injection of 10 mg/kg were similar (7.07 ± 1.36 h and 7.16 ± 1.17 h, mean ± SD), whereas the total body clearance and the apparent volume of distribution were higher for the 20% solution. Serum concentrations above 0.5 μg/ml were maintained with both formulations during 12–24 h but were only above 4 μg/ml to 5 h. Intramuscular administration of the 20% solution gave a complete absorption with two rate constants of absorption, a faster (t_1/2a1= 0.27 h) and a slower one (t_1/2a2= 10.90 h) responsible for the delayed elimination half-life after this route of application (t_1/2β= 9.83 ± 1.35 h). Mean serum concentrations reached a maximum level of 3.01 ± 0.72 μg/ml at 4.01 ± 2.84 h and decreased to 0.5 μg/ml between 12 and 24 h. 50 mg/kg given orally with a milk replacer were found to have a mean bioavailability of 46.35%. A mean serum peak level of 4.99 ± 1.37 μg/ml was achieved at 9.16 ± 1.99 h and the mean concentration was still above 0.5 μg/ml after 48 h. The elimination half-life (t_1/2β= 10.66 ± 3.15 h) reflected the slow absorption step (t_1/2a2= 10.15 h) following that responsible for the initial faster absorption (t_1/2a2= 1.99 h). Comparison of the area under the serum curves gave mean values of 117% for tetracycline and of 53% for chlortetracycline relative to oxytetracycline (arbitrarily fixed at 100%) after identical oral dosage of the three tetracyclines. We also propose and discuss a dosage schedule based on minimal inhibitory concentrations of different susceptible pathogens     

Oral absorption and bioavailability of flumequine in veal calves

The oral absorption and bioavailability of flumequine was studied in 1-, 5- and 18-week-old calves following intravenous and oral administration of different formulations of flumequine (Flumix, Flumix C and pure flumequine). Increasing age had a negative influence on the Cmax after the administration of Flumix, based on a larger VD in the older calves. The Cmax decreased from 5.02 +/- 1.46 micrograms/ml in the first week to 3.28 +/- 0.42 micrograms/ml in the 18th week. Adding colistin sulfate to the flumequine formulation and administring pure flumequine mixed with milk replacer had a negative effect on the Cmax of flumequine after oral administration of 5 and 10 mg/kg body weight. The bioavailability of the orally administered flumequine formulations was 100% in all cases except after the administration of Flumix C, for which it was 75.9 +/- 18.2%. The urinary recovery of flumequine after intravenous injection of a 10% solution varied from 35.2 +/- 2.3% for Group B, to 41.2 +/- 6.3% for Group C. The dosage of 5 mg/kg body weight Flumix twice daily in 1-week-old veal calves is sufficient to reach therapeutic plasma concentrations, based on a MIC value of 0.8 micrograms/ml of the target bacteria. In older calves it is advisable to increase the dosage 7.5 or 10 mg/kg body weight every 12 hours. In combination with colistin sulfate it is also advisable to increase the dosage slightly because of the negative effect of the colistin sulfate on the Cmax of flumequine.     

A survey of abomasal ulceration in veal calves

Abomasal ulceration was found in 264 of 304 commercially reared veal calves at slaughter. The incidence and severity of lesions were greatest in loose housed calves with access to straw and fed milk substitute ad libitum. The majority of lesions were located in the distal pylorus. There was no evidence that the abomasal erosions and ulcers found in the majority of veal calves affected their growth rate or were deleterious to their welfare. It is suggested that pyloric ulceration may be related to the diet of veal calves.     

Relative bioavailability of microgranulated sulfadimidine in veal calves

The kinetics of free and microgranulated sulfadimidine were compared in milk-fed calves dosed orally (180 mg/kg) in a crossover study. Microgranulation results in delayed absorption of sulfadimidine and poor bioavailability, with the area under the plasma concentration-time curve ( AUC (O-oo)) reduced from 7400 to 3781 μg·h/mL, and maximum plasma concentration ( C _max) reduced from 188.1 ± 39.0 to 84.41 ± 22.6 μg/mL. It is concluded that sulfadimidine microgranulated with long chain fatty acids is not suitable for use in milk-fed calves; the gastrointestinal transit time is too rapid to allow full release of the drug, markedly limiting its bioavailability. In adult animals, or in the young of other animal species in which digesta transit time is slower than in calves, the bioavailability of microgranulated sulfadimidine may be much greater.     

Salmonellosis in veal calves. Some therapeutic aspects

Summary

The present investigation was undertaken to improve regimens dosage of amoxycillin, chloramphenicol or trimethoprim‐sulphadiazine in Salmonella dublin infected veal calves. The pharmacokinetics of these drugs were studied after i.v., oral, and i. m. administration (bioavailability, local irritation at the injection site, volume of distribution, and elimination half life). The most important conclusion was that amoxycillin, chloramphenicol, and trimethoprim were suitable for oral administration to veal calves, although the bioavailability of chloramphenicol and trimethoprim was significantly less when concurrently administered with a milk replacer. In vitro, the antibacterial activities of these drugs were compared. Addition of trimethoprim to sulphadiazine lowered its MIC for S. dublin, but sulphadiazine reduced the killing rate compared to that of trimethoprim alone. In the efficacy studies the activities of several serum enzymes and the plasma concentrations of Fe, Zn, and Cu were measured, but it appeared, that these biochemical parameters were no better than the clinical parameters body temperature and body weight. Using optimal dosage regimens based on MIC values and blood levels, treatment with either of the three drugs was of equal efficacy.     

Salmonellosis in veal calves. Some therapeutic aspects

The present investigation was undertaken to improve regimens dosage of amoxycillin, chloramphenicol or trimethoprim-sulphadiazine in Salmonella dublin infected veal calves. The pharmacokinetics of these drugs were studied after i.v., oral, and i.m. administration (bioavailability, local irritation at the injection site, volume of distribution, and elimination half life). The most important conclusion was that amoxycillin, chloramphenicol, and trimethoprim were suitable for oral administration to veal calves, although the bioavailability of chloramphenicol and trimethoprim was significantly less when concurrently administered with a milk replacer. In vitro, the antibacterial activities of these drugs were compared. Addition of trimethoprim to sulphadiazine lowered its MIC for S. dublin, but sulphadiazine reduced the killing rate compared to that of trimethoprim alone. In the efficacy studies the activities of several serum enzymes and the plasma concentrations of Fe, Zn, and Cu were measured, but it appeared, that these biochemical parameters were no better than the clinical parameters body temperature and body weight. Using optimal dosage regimens based on MIC values and blood levels, treatment with either of the three drugs was of equal efficacy.     

Enteric infections in veal calves: A longitudinal study on four veal calf units

Summary

Forty‐five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.     

The pharmacokinetics and residues of clenbuterol in veal calves.

Seven female Brown Swiss calves were used to study the pharmacokinetics of clenbuterol after an effective anabolic dosage of 5 micrograms/kg of BW was given twice daily for 3 wk. Analyses of clenbuterol concentrations in different tissues was done by enzyme immunoassay (EIA). Tissue samples were taken from three calves on the last day of administration and from two more after 3.5 or 14 d of clenbuterol withdrawal. The rate of clenbuterol elimination was dependent on time and tissue. Clenbuterol concentrations in the lung dropped from a mean of 76 ng/g to a level of less than .08 ng/g after 14 d, whereas in the liver the clenbuterol concentrations decreased from 46 ng/g to .6 ng/g within 14 d of withdrawal. Highest levels were always found in the eye: 118 ng/g, 57.5 ng/g, and 15.1 ng/g after 0, 3.5, and 14 d of withdrawal, respectively. These data reveal that different compartments contribute to the elimination of clenbuterol; therefore, concentrations in urine do not follow first order kinetics. An initial rapid decline in the concentration of clenbuterol in urine with a half-life of 10 h is followed by a slower elimination with a half-life of about 2.5 d. Treatments using the anabolic dose of 5 micrograms/kg of BW require longer withdrawal times than the therapeutic dose (.8 micrograms/kg BW).     

Enteric infections in veal calves: a longitudinal study on four veal calf units

Forty-five calves on four veal calf units were monitored during the first four weeks after their arrival. Faecal samples were collected on alternate days and screened for the presence of rotaviruses, bovine coronavirus, Cryptosporidium oocysts, K99 positive strains of E. coli and Salmonella spp. Rotaviruses and Cryptosporidium were the most commonly detected agents (78% and 60% respectively of the calves). Bovine coronavirus was detected in the faeces of 18% of the calves, whilst K99 positive E. coli was only found in 2 samples from one calf. Salmonella spp. were not isolated from any of the 646 faecal samples examined. Shedding of rotaviruses occurred in a bimodal pattern beginning in the first week of the survey. Cryptosporidium oocysts were detected most frequently in the interval between the two peaks of rotavirus shedding. The presence of rotaviruses or Cryptosporidium oocysts in faeces was not strongly associated with scour, nor were combined infections with these agents or the cases of bovine coronavirus infection. The condition of the calves throughout the survey was generally satisfactory.     

Bayesian estimation of the true prevalence,sensitivity and specificity of the Rose Bengal and indirect ELISA tests in the diagnosis of bovine brucellosis

Serology is the most convenient method for detecting brucellosis but the efficient use of such tests in disease control requires evaluation of diagnostic performance and discriminative ability. The objective of this study was to assess the performance of the Rose Bengal test (RBT) and an indirect ELISA (iELISA) in diagnosing brucellosis in 995 serum samples collected from cattle in the Ivory Coast between 2005 and 2009. A Bayesian approach was used to evaluate the two tests by estimating their sensitivities and specificities.The correlation-adjusted sensitivity of the iELISA was estimated to be 96.1% (credibility interval [CrI], 92.7–99.8), whereas that of the RBT was 54.9% (CrI, 23.5–95.1). High correlation-adjusted specificities were found for both tests (95.0%; [CrI, 91.1–99.6] for the iELISA and 97.7%; [CrI, 95.3–99.4] for the RBT, respectively). The true prevalence of brucellosis was estimated from the serum samples to be 4.6% (95%; [CrI, 0.6–9.5]). The level of agreement between the two tests was evaluated using indices of agreement (n = 995). Good agreement was found for negative results (96.6%; confidence interval [CI], 95.7–97.4), a finding supported by an estimated significant correlation of 0.37 (95%; CI, 0.01–0.73) within the sera testing negative. Agreement was lower for sera testing positive (52.2% CI: 41.9–62.5). The findings highlight the importance of using these two tests in combination as part of any brucellosis control programme.     

Pathology and residues in veal calves treated experimentally with clenbuterol

Six veal calves were medicated with clenbuterol at 20 μg kg bodyweight⁻¹ day⁻¹ for 42 days before they were slaughtered, to evaluate the lesions and residues in target organs. Compared with six unmedicated calves the most noticeable changes were tracheal dilatation, decreased uterine weight, slight mucous hypersecretion in the uterus and vagina and depletion of liver glycogen. The highest concentrations of clenbuterol (62 to 128 ng/g⁻¹) were recorded in the choroid/retina, and the aqueous humour had the lowest concentration (0·5 to 2·4 ng ml⁻¹). The residue concentrations were higher than the maximum residue level set for clenbuterol (0·5 ng g⁻¹)     

Herd prevalence of Salmonella spp. in Danish pig herds after implementation of the Danish Salmonella Control Program with reference to a pre-implementation study

The problems addressed are: (1) comparison of prevalences of Salmonella spp. in different herd types in the Danish pig population after implementation of the Danish Salmonella Control Program (DSCP), and (2) to make a reference to a study from 1993/1994 (pre-implementation) with a discussion of possible biases when diagnostic methods differ slightly. The objectives were to present the prevalences of Salmonella spp., Salmonella Typhimurium, and multiresistant S. Typhimurium DT104 in Danish pig herds in 1998. Further, to discuss how herd prevalences may be compared to a previous study.A bacteriological study in 1998 comprised: (a) a random sample of slaughter pig producing herds (N=1962); (b) a random sample of farrow-to-grower (sow) herds (N=305); and (c) all breeding and multiplying (genetic) herds (N=366). A previous bacteriological study on Salmonella presence in 1993/1994 served as a model for the present study. The results of the study were that multiresistant S. Typhimurium DT104 was detected in one herd producing slaughter pigs. The herd apparent prevalences (HAPs) of Salmonella spp. were 11.7, 16.7 and 11.4% in genetic, sow, and slaughter pig herds, respectively. The conclusion of the study was that prevalence of multiresistant S. Typhimurium DT104 was low in the examined slaughter pig herds. The herd true prevalence (HTP) of Salmonella spp. in pigs had declined from before the start of the DSCP in 1993/1994 to 4 years later (1998).