Technical note: A PET/MR coil with an integrated, orbiting 511 keV transmission source for PET/MR imaging validated in an animal study.

BACKGROUND: MR-based methods for attenuation correction (AC) in PET/MRI either neglect attenuation of bone, or use MR-signal derived information about bone, which leads to a bias in quantification of tracer uptake in PET. In a previous study, we presented a PET/MRI specific MR coil with an integrated transmission source (TX) system allowing for direct measurement of attenuation. In phantom measurements, this system successfully reproduced the linear attenuation coefficient of water. PURPOSE: The purpose of this study is to validate the TX system in a clinical setting using animals and to show its applicability compared to standard clinical methods. METHODS: As test subject, a 15-kg piglet was injected with 53 MBq of 18F-NaF. The µ-map obtained with the TX system and the reconstructed activity distribution were compared to four established AC methods: a Dixon sequence, an ultra-short echo time (UTE) sequence, a CT scan, and a 511 keV transmission scan using a Siemens ECAT EXACT HR+ as the reference. The PET/MRI measurements were performed on a Siemens Biograph mMR to obtain the µ-map using the TX system as well as the Dixon and UTE sequence directly followed by the CT and ECAT measurements. RESULTS: The reconstructed activity distribution using the TX system for AC showed similar results compared to the reference (<5% difference in hot regions) and outperformed the MR-based methods as implemented in the PET/MRI system (<10% difference in hot regions). However, the additional hardware of the TX system adds complexity to the acquisition process. CONCLUSION: Our porcine study demonstrates the feasibility of post-injection transmission scans using the developed TX system in a clinical setting. This makes it a useful tool for PET/MRI in cases where transmission information is needed for AC. Potential applications are studies using larger animals where state-of-the-art atlas-based or artificial intelligence AC methods are not available.

Autoclaving as a Routine Method for the Decontamination of Animal Carcasses in a Biosafety Level 3 Facility.

Introduction: Carcasses from animal experiments with RG-3 pathogens should be decontaminated onsite in Austria. Objective: The aim of this study was to find out if the use of pass-through autoclaves for the decontamination of animal carcasses (up to 40 kg of weight) could serve as a routine method for smaller laboratories, as the installation of special carcass decontamination plants may be cost prohibitive. Methods: Biological indicators (BIs) were implanted into the carcasses of animals of different sizes and species with a novel method using stainless steel pipes. The bodies were placed in autoclavable plastic bags and equipped with thermal probes by insertion through the rectum. Subsequently a factory default autoclave cycle for liquids was performed, which holds a core temperature of 121°C for 20 min. Results: The weight of the carcasses ranged from 1 to 42 kg, the duration of the individual cycles reached from 2.2 to 17.23 h. Decontamination was successful every single time as shown by the BIs. The application through the natural orifices with the help of the application tools seems to offer a reliable alternative for implanting the BIs into the carcasses without creating new openings. Insulation properties did not pose substantial challenges to the process. Limitations on the packaging procedure were identified in carcasses larger than 30 kg. Conclusion: Based on the results of this study, using pass-through autoclaves represents an option as a routine method for the decontamination of animal carcasses up to at least 40 kg.

Preclinical Incorporation Dosimetry of [18F]FACH-A Novel 18F-Labeled MCT1/MCT4 Lactate Transporter Inhibitor for Imaging Cancer Metabolism with PET.

Overexpression of monocarboxylate transporters (MCTs) has been shown for a variety of human cancers (e.g., colon, brain, breast, and kidney) and inhibition resulted in intracellular lactate accumulation, acidosis, and cell death. Thus, MCTs are promising targets to investigate tumor cancer metabolism with positron emission tomography (PET). Here, the organ doses (ODs) and the effective dose (ED) of the first 18F-labeled MCT1/MCT4 inhibitor were estimated in juvenile pigs. Whole-body dosimetry was performed in three piglets (age: ~6 weeks, weight: ~13-15 kg). The animals were anesthetized and subjected to sequential hybrid Positron Emission Tomography and Computed Tomography (PET/CT) up to 5 h after an intravenous (iv) injection of 156 ± 54 MBq [18F]FACH. All relevant organs were defined by volumes of interest. Exponential curves were fitted to the time-activity data. Time and mass scales were adapted to the human order of magnitude and the ODs calculated using the ICRP 89 adult male phantom with OLINDA 2.1. The ED was calculated using tissue weighting factors as published in Publication 103 of the International Commission of Radiation Protection (ICRP103). The highest organ dose was received by the urinary bladder (62.6 ± 28.9 µSv/MBq), followed by the gall bladder (50.4 ± 37.5 µSv/MBq) and the pancreas (30.5 ± 27.3 µSv/MBq). The highest contribution to the ED was by the urinary bladder (2.5 ± 1.1 µSv/MBq), followed by the red marrow (1.7 ± 0.3 µSv/MBq) and the stomach (1.3 ± 0.4 µSv/MBq). According to this preclinical analysis, the ED to humans is 12.4 µSv/MBq when applying the ICRP103 tissue weighting factors. Taking into account that preclinical dosimetry underestimates the dose to humans by up to 40%, the conversion factor applied for estimation of the ED to humans would rise to 20.6 µSv/MBq. In this case, the ED to humans upon an iv application of ~300 MBq [18F]FACH would be about 6.2 mSv. This risk assessment encourages the translation of [18F]FACH into clinical study phases and the further investigation of its potential as a clinical tool for cancer imaging with PET.

Occupational swine exposure and Hepatitis E virus, Leptospira, Ascaris suum seropositivity and MRSA colonization in Austrian veterinarians, 2017-2018-A cross-sectional study.

We investigated the prevalence of Hepatitis E Virus (HEV), Leptospira and Ascaris suum (A. suum) seropositivity, and of nasal methicillin-resistant Staphylococcus aureus (MRSA) colonization among Austrian practising veterinarians, and assessed the association with occupational swine livestock exposure. The 261 participants completed a questionnaire on demographics, intensity of occupational swine livestock contact and glove use during handling animals and their secretions. Participants' blood samples were tested for HEV, Leptospira and A. suum seropositivity and nasal swabs cultured for MRSA. We compared swine veterinarians (defined as >3 swine livestock visits/week) to non-swine veterinarians (≤3 swine livestock visits/week) with regard to the outcomes through calculating prevalence ratio (PR) and 95% confidence interval (CI). Furthermore, the relationship between occupational swine livestock contact and the study outcomes was examined by age (3 occupational swine livestock visits per week is associated with HEV and A. suum seropositivity and nasal MRSA colonization and that glove use may play a putative preventive role in acquiring HEV and A. suum. Further analytical epidemiological studies have to prove the causality of these associations.

Specific detection and differentiation of tick-borne encephalitis and West Nile virus induced IgG antibodies in humans and horses.

Tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) are important arthropod-borne zoonotic flaviviruses. Due to the emergence of WNV in TBEV-endemic regions co-circulation of both viruses is increasing. Flaviviruses are structurally highly similar, which leads to cross-reacting antibodies upon infection. Currently available serological assays for TBEV and WNV infections are therefore compromised by false-positive results, especially in IgG measurements. In order to discriminate both infections novel diagnostic methods are needed. We describe an ELISA to measure IgG antibodies specific for TBEV and WNV, applicable to human and horse sera. Mutant envelope proteins were generated, that lack conserved parts of the fusion loop domain, a predominant target for cross-reacting antibodies. These were incubated with equine and human sera with known TBEV, WNV or other flavivirus infections. For WNV IgG, specificities and sensitivities were 100% and 87.9%, respectively, for horse sera, and 94.4% and 92.5%, respectively, for human sera. TBEV IgG was detected with specificities and sensitivities of 95% and 96.7%, respectively, in horses, and 98.9% and 100%, respectively, in humans. Specificities increased to 100% by comparing individual samples on both antigens. The antigens could form the basis for serological TBEV- and WNV-assays with improved specificities.

Efficacy of live attenuated porcine reproductive and respiratory syndrome virus 2 strains to protect pigs from challenge with a heterologous Vietnamese PRRSV 2 field strain.

BACKGROUND: Effective vaccines against porcine reproductive and respiratory syndrome virus (PRRSV), especially against highly pathogenic (HP) PRRSV are still missing. The objective of this study was to evaluate the protective efficacy of an experimental live attenuated PRRSV 2 vaccine, composed of two strains, against heterologous challenge with a Vietnamese HP PRRSV 2 field strain. For this reason, 20 PRRSV negative piglets were divided into two groups. The pigs of group 1 were vaccinated with the experimental vaccine, group 2 remained unvaccinated. All study piglets received an intranasal challenge of the HP PRRSV 2 on day 0 of the study (42 days after vaccination). Blood samples were taken on days 7 and 21 after vaccination and on several days after challenge. On day 28 after challenge, all piglets were euthanized and pathologically examined. RESULTS: On days 7 and 21 after vaccination, a PRRSV 2 viraemia was seen in all piglets of group 1 which remained detectable in seven piglets up to 42 days after vaccination. On day 3 after challenge, all piglets from both groups were positive in PRRSV 2 RT-qPCR. From day 7 onwards, viral load and number of PRRSV 2 positive pigs were lower in group 1 than in group 2. All pigs of group 1 seroconverted after PRRSV 2 vaccination. PRRSV antibodies were detected in serum of all study pigs from both groups from day 14 after challenge onwards. In group 2, moderate respiratory symptoms with occasional coughing were seen following the challenge with HP PRRSV 2. Pigs of group 1 remained clinically unaffected. Interstitial pneumonia was found in four piglets of group 1 and in all ten piglets of group 2. Histopathological findings were more severe in group 2. CONCLUSIONS: It was thus concluded that the used PRRSV 2 live experimental vaccine provided protection from clinical disease and marked reduction of histopathological findings and viral load in pigs challenged with a Vietnamese HP PRRSV 2 field strain.

Ability of ELISAs to detect antibodies against porcine respiratory and reproductive syndrome virus in serum of pigs after inactivated vaccination and subsequent challenge.

BACKGROUND: In this study, six enzyme-linked immunosorbent assays (ELISA), intended for routine porcine reproductive and respiratory syndrome virus (PRRSV) herd monitoring, are tested for their ability to detect PRRSV specific antibodies in the serum of pigs after vaccination with an inactivated PRRSV type 1 vaccine and subsequent infection with a highly pathogenic (HP) PRRSV field strain. For this reason, ten piglets (group V) from a PRRSV negative herd were vaccinated twice at the age of 2 and 4 weeks with an inactivated PRRSV vaccine. Ten additional piglets (group N) from the same herd remained unvaccinated. Three weeks after second vaccination, each of the piglets received an intradermal application of an HP PRRSV field strain. Serum samples were taken before first vaccination as well as before and 3, 7, 10 and 14 days after HP PRRSV application. All serum samples were tested for PRRSV RNA by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) as well as for PRRSV antibodies with all six study ELISAs. RESULTS: At the beginning of the study (before vaccination), all of the piglets were PRRSV antibody negative with all study ELISAs. They also tested negative for PRRSV RNA measured by RT-qPCR. From day 3 after HP PRRSV application until the end of the study, a viremia was detected by RT-qPCR in all of the piglets. On day 0 (day of HP PRRSV application), nine out of ten piglets of the pre-vaccinated group tested PRRSV antibody positive with one of the tested ELISAs, although with lower S/P values than after infection. On day 10 after HP PRRSV application, all study ELISAs except one had significantly higher S/P or OD values, respectively more positive samples, in group V than in group N. CONCLUSIONS: Only one of the tested ELISAs was able to detect reliably PRRSV antibodies in pigs vaccinated with an inactivated PRRSV vaccine. With most of the tested ELISAs, higher S/P values respectively more positive samples after PRRSV infection were seen in the pre-vaccinated group than in the non-vaccinated.

[Occurrance of antibodies against Leptospira in horses in Middle Germany]. / Vorkommen von Antikörpern gegen Leptospiren bei Pferden im mitteldeutschen Raum.

Aim of the study was to detect antibodies and potential risk factors for an infec- tion with Leptospira in horses in Middle Germany. Serum samples of 314 horses were examined retrospectively by microscopic agglutination test for the presence of antibodies against eight Leptospira serovars. In total, 17.2% (n = 54) of the horses were positive for one or more of the serovars analyzed. The most prevalent serovar was lcterohaemorrhagiae (11.1%), followed by serovar Bratislava (9.6 %) and Grippotyphosa (1.9%). Mares showed a significantly higher occurrence of antibodies (p < 0.05) than geldings or stallions. Horses used for breeding have a significantly lower risk than horses used in sport or horses used for leisure activity. There was also a significantly higher prevalence (p < 0.05) in summer than in the other seasons. No significant influence of breed, husbandry conditions and age on the antibody occurrence was observed (p > 0.05). The clinical chemical parameters did not differ significantly between horses with positive or negative Leptospira antibody result (p > 0.05). It became apparent that horses can be infected with Leptospira without developing of clinical symptoms.

[Comparison of sampling strategies to detect porcine reproductive and respiratory syndrome virus in a simulated pig producing plant]. / Vergleich von Stichprobenverfahren zum Nachweis des Porzinen Reproduktiven und Respiratorischen Syndrom-Virus in einem simulierten Schweinezuchtbetrieb.

The effectivity of different sampling schemes for the early detection of the introduction of porcine reproductive and respiratory syndrome virus into a pig herd was evaluated using Monte Carlo simulation. Within a theoretical breeding herd of 300 animals, disease transmission was simulated using a stochastic SEIR model incorporating actual animal movement data. The following parameters were evaluated for different sample sizes, sampling frequencies and diagnostic procedures (ELISA, PCR): the time from virus introduction until detection, the daily detection probability and the number of holdings to which infected animals are shipped before the disease is detected. The results show that the sample size has an influence on early detection. The biggest effects are, however, achieved by shortening the sampling intervals. The median detection time is approximately ten days shorter for PCR than for ELISA. If, however, the sampling intervals are chosen too wide there is a chance of overlooking the disease using PCR alone.

First detection, clinical presentation and phylogenetic characterization of Porcine epidemic diarrhea virus in Austria.

BACKGROUND: Porcine epidemic diarrhea (PED) is a syndrome that is characterized by rapidly spreading watery diarrhea affecting pigs of all ages, but with major effects on suckling piglets. The disease, as well as the causative Alphacoronavirus, the Porcine epidemic diarrhea virus (PEDV), was first described in Europe in the 1970s and since then has spread over many Asian and American countries, where it recently led to devastating effects on swine health and pork industry. While the disease was seldom reported in Europe within the last few decades, a few recent reports re-emergence of PED in German pig farms. The hitherto isolated German strain seems to be closely related to a low pathogenic PEDV variant from the USA. This case report describes the first detection of PEDV in Austria. CASE PRESENTATION: Reduced feed uptake and occasional diarrhea were observed in December 2014 in a group of fattening pigs, kept on an Austrian swine farm. The concerned pigs had been recently purchased from Germany. Within a few weeks, diarrhea became apparent also in pigs of Austrian origin, which were kept in a different stable on the same farm. Gastrointestinal symptoms among fattening pigs were generally mild, quickly resolving and did not lead to death. PEDV RNA was identified by RT-qPCR in pooled feces and serum and PEDV antibodies were detectable in serum in both groups of pigs. Phylogenetic analysis of the nearly complete PEDV spike gene shows that the Austrian PEDV strain is highly similar to other strains involved in recent outbreaks in Western and Central Europe. CONCLUSION: This is the first report demonstrating the presence of PEDV in Austria. The virus was probably introduced by purchasing piglets from a German source, which underlines the significance of trans-boundary animal trade for the distribution of highly contagious diseases, such as PED.

Evaluation of the specificity of a commercial ELISA for detection of antibodies against porcine respiratory and reproductive syndrome virus in individual oral fluid of pigs collected in two different ways.

BACKGROUND: The monitoring of infectious diseases like the porcine reproductive and respiratory syndrome (PRRS) using pen-wise oral fluid samples becomes more and more established. The collection of individual oral fluid, which would be useful in the monitoring of PRRSV negative boar studs, is rather difficult. The aim of the study was to test two methods for individual oral fluid collection from pigs and to evaluate the specificity of a commercial ELISA for detection of PRRSV antibodies in these sample matrices. For this reason, 334 serum samples from PRRSV negative pigs (group 1) and 71 serum samples from PRRSV positive pigs (group 2) were tested for PRRSV antibodies with a commercial ELISA. Individual oral fluid was collected with a cotton gauze swab from 311 pigs from group 1 and 39 pigs from group 2. Furthermore, 312 oral fluid samples from group 1 and 67 oral fluid samples from group 2 were taken with a self-drying foam swab (GenoTube). The recollected oral fluid was then analysed twice with a commercial ELISA for detection of PRRSV antibodies in oral fluid. RESULTS: All serum samples from group 1 tested negative for PRRSV antibodies. The collection of oral fluid was sufficient in all samples. Sampling with GenoTubes was less time consuming than sampling with cotton gauze swabs. False positive results were obtained in 7 (measure 1) respectively 9 (measure 2) oral fluid samples recollected from cotton gauze swabs and in 9 and 8 samples from GenoTubes. The specificity of the oral fluid ELISA was 97.4% for cotton gauze swabs and 97.3% for GenoTubes. 70 out of 71 serum samples and all oral fluid samples from group 2 tested positive for PRRSV antibodies. The sensitivity of the oral fluid ELISA was 100%. According to the kappa coefficient, the results showed an almost perfect agreement between serum and oral fluid collected in both ways (kappa > 0.8). CONCLUSIONS: Both methods used for individual oral fluid collection proved to be practical and efficient and can be used for PRRSV antibody detection. It has to be considered, however, that false positive results may occur more often than in serum samples.

Performance of ELISAs for detection of antibodies against porcine respiratory and reproductive syndrome virus in serum of pigs after PRRSV type 2 live vaccination and challenge.

BACKGROUND: The aim of the study was to evaluate the performance of different newly developed and/or commercially available ELISAs for detection of PRRSV specific antibodies. Consequently, ten PRRSV negative piglets (group V) were vaccinated with a PRRSV type 2 vaccine. Blood samples were taken before as well as seven, 21 and 42 days after vaccination. At day 42 after vaccination (day 0 of the study) all of the piglets from group V and 10 non-prevaccinated PRRSV negative piglets (group N) were challenged with an HP PRRSV type 2 field strain. Blood samples were taken before and at days 3, 7, 10, 14, 21 and 28 after challenge. The success of vaccination and challenge was measured with RT qPCR. All serum samples were tested with six ELISAs for detection of PRRSV antibodies. Three of them are nucleocapsid-based, two use a glycoprotein extract and one uses inactivated whole virus as antigen. The specificity of the ELISAs was evaluated using 301 serum samples of piglets from PRRSV negative herds. RESULTS: The piglets from group V tested positive by RT qPCR at day 7 after vaccination and all piglets tested positive at day 3 after challenge. PRRSV specific antibodies were seen with all nucleocapsid-based ELISAs from day 21 after vaccination onwards in group V and from day 10 after challenge in group N. The glycoprotein-based ELISAs detected antibodies from day 42 after vaccination (group V) and day 21 after challenge (group N). The agreement according to kappa-coefficient was almost perfect. The glycoprotein-based ELISAs were able to distinguish PRRSV type 2, although with some cross reactions. Regarding specificity, the ELISAs performed differently (specificity between 97.4 % and 100 %), whereas most of the ELISAs with higher sensitivity had a slightly lower specificity. CONCLUSIONS: All tested ELISA were able to detect PRRSV antibodies in the serum of pigs vaccinated with a PRRSV type 2 vaccine and after challenge with an HP PRRSV type 2 field strain. The onset on antibody detection differed, depending on the type of antigen used in the ELISAs. Most of the ELISAs with a higher sensitivity had a lower specificity.

Comparison of different commercial ELISAs for detection of antibodies against porcine respiratory and reproductive syndrome virus in serum.

BACKGROUND: In recent years, several new ELISAs for the detection of antibodies against the porcine reproductive and respiratory disease virus (PRRSV) in pig serum have been developed. To interpret the results, specificity and sensitivity data as well as agreement to a reference ELISA must be available. In this study, three commercial ELISAs (INgezim PRRS 2.0 - ELISA II, Priocheck® PRRSV Ab porcine - ELISA III and CIVTEST suis PRRS E/S PLUS - ELISA IV, detecting PRRSV type 1 antibodies) were compared to a standard ELISA (IDEXX PRRS X3 Ab Test - ELISA I). The serum of three pigs vaccinated with an attenuated PRRSV live vaccine (genotype 2) was tested prior to and several times after the vaccination. Furthermore, serum samples of 245 pigs of PRRSV positive herds, 309 pigs of monitored PRRSV negative herds, 256 fatteners of assumed PRRSV negative herds with unknown herd history and 92 wild boars were tested with all four ELISAs. RESULTS: ELISAs II and III were able to detect seroconversion of vaccinated pigs with a similar reliability. According to kappa coefficient, the results showed an almost perfect agreement between ELISA I as reference and ELISA II and III (kappa > 0.8), and substantial agreement between ELISA I and ELISA IV (kappa = 0.71). Sensitivity of ELISA II, III and IV was 96.0%, 100% and 91.5%, respectively. The specificity of the ELISAs determined in samples of monitored PRRSV negative herds was 99.0%, 95.1% and 96.4%, respectively. In assumed negative farms that were not continually monitored, more positive samples were found with ELISA II to IV. The reference ELISA I had a specificity of 100% in this study. CONCLUSIONS: All tested ELISAs were able to detect a PRRSV positive herd. The specificity and sensitivity of the tested commercial ELISAs, however, differed. ELISA II had the highest specificity and ELISA III had the highest sensitivity in comparison to the reference ELISA. ELISA IV had a lower sensitivity and specificity than the other ELISAs.

Effect of time of second GnRH vaccination on feed intake, carcass quality and fatty acid composition of male fatteners compared to entire boars and barrows.

Objective of the study was to evaluate the influence of time point of second vaccination with the GnRH analogon Improvac on growth performance, carcass quality and fatty acid composition of male fatteners compared to surgically castrated pigs and entire boars. The pigs (Piétrain-crossbreds) were divided into two vaccination groups with first GnRH vaccination at eleven weeks of age and second vaccination at 21 (group IA, n = 84) or 18 weeks (IB, n = 83) of age, one group with surgically castrated males (C, n = 90) and one with entire males (EM, n = 91). Body weight, feed conversion rate, carcass quality and fatty acid composition in back fat were estimated. Feed conversion rate until second vaccination was better (P < 0.05) in the vaccination groups (1:2.39) and in group EM (1:2.34) than in group C (1:2.55). Carcass weight did not differ between the groups. Vaccination groups had significantly (P < 0.01) leaner meat (IA: 58.9%, IB: 58.3%) and less back fat (IA: 14.6 mm, IB: 15.5 mm) than group C (56.5%, 17.1 mm). Fatty acid composition was shifted to polyunsaturated fatty acids (PUFA) in back fat in vaccination groups and EM compared to C. The time lag between second vaccination and slaughter had no influence on growth performance, feed intake and carcass quality. C18:3 and C20:2 were significantly (P < 0.01) higher in group IB than in IA, but PUFA did not differ between vaccination groups. GnRH vaccinated fatteners were economically superior to surgically castrated in this study.

Comparative evaluation of serum, FTA filter-dried blood and oral fluid as sample material for PRRSV diagnostics by RT-qPCR in a small-scale experimental study.

Recently, research into alternative sample materials, such as oral fluid or filter-dried blood has been intensified, in order to facilitate cost-effective and animal-friendly sampling of individuals or groups of pigs for diagnostic purposes. The objective of this study was to compare the sensitivity of porcine reproductive and respiratory syndrome virus (PRRSV)-RNA detection by reverse transcription quantitative real-time PCR (RT-qPCR) in serum, FTA filter-dried blood and oral fluid sampled from individual pigs. Ten PRRSV negative pigs were injected with an EU-type PRRSV live vaccine. Blood and oral fluid samples were taken from each pig before, and 4, 7, 14 and 21 days after vaccination. All samples were then analyzed by PRRSV RT-qPCR. In serum, eight often pigs tested RT-qPCR positive at different time points post infection. Absolute quantification showed low serum PRRSV-RNA loads in most samples. In comparison to serum, sensitivity of PRRSV-RNA detection was strongly reduced in matched FTA filter-dried blood and in oral fluid from the same pigs. These results indicate that with low PRRSV-RNA loads the diagnostic sensitivity of PRRSV-RNA detection by RT-qPCR achieved with serum is currently unmatched by either FTA filter-dried blood or oral fluid.

[Relevance, measurement and assessment of the antioxidative status in farm animals]. / Die Bedeutung, Erhebung und Bewertung des antioxidativen Status bei landwirtschaftlichen Nutztieren.

Reactive oxygen species (ROS) are generated in living organisms under physiological and pathological conditions. They have to be neutralized by the antioxidative system which consists of enzymatic and non enzymatic antioxidants. Both, the activity of antioxidative enzymes and the capacity of non enzymatic antioxidants are known as the antioxidative status of the organism. If the balance between prooxidative processes and antioxidative system is disturbed oxidative stress occurs. Oxidative stress is considered to be a major risk factor for the reduction of defence mechanisms and development of diseases. The aim of the present work is to describe various aspects of the antioxidative status in several production animal species. Conclusions for management and therapy are drawn when possible. Furthermore the paper provides an overview of methods for assessment of antioxidative metabolism. Farm animals undergo several periods of severe challenge of the antioxidative system during the production cycle. Especially young animals in the first weeks of their life and animals during the periparturient period are at high risk. High yielding live stock generally have to carry a higher oxidative burden in comparison to animals which are on a medium production level or in extensive systems. Other risk factors are unsuitable or spoiled components in the diet and heat stress. Exogenous antioxidant supply can be optimized by feeding fresh roughage or silage of good quality or if necessary by using additives. Changes of the antioxidative system have been described in association with displaced abomasum (DA), abomasal volvulus (AV) and reproductive problems in swine. Pre- and postoperative supplementation of antioxidants has been used with good results as supportive treatment in therapy of cattle with DA.

Effect of preoperative erythromycin or dexamethasone/vitamin C on postoperative abomasal emptying rate in dairy cows undergoing surgical correction of abomasal volvulus.

OBJECTIVE: To determine the effects of preoperative erythromycin or combined dexamethasone/vitamin C treatment on postoperative abomasal emptying rate in cows undergoing surgical correction of abomasal volvulus (AV). STUDY DESIGN: Prospective, controlled, clinical study using a convenience sample. ANIMALS: Lactating Holstein-Friesian cows (n=45) with AV were alternately assigned to 3 groups (n=15): group C: untreated (control); group E: erythromycin (10 mg/kg intramuscularly [IM]); group D: dexamethasone (0.02 mg/kg intravenously [IV]) and vitamin C (10 mg/kg IV). METHODS: Drugs were administered 1 hour before surgical correction of AV. D-xylose solution (50%, 0.5 g/kg body weight) was injected into the abomasal lumen during surgery. Jugular venous blood samples for determination of serum d-xylose concentration were periodically obtained. Time to maximal serum D-xylose concentration (T(max-model)) was pharmacokinetically determined. RESULTS: Abomasal emptying rate was significantly (P<0.05) faster in group E (T(max-model)=182+/-69 min; mean+/-SD) than in group C cows (T(max-model)=237+/-64 min). Abomasal emptying rate was similar in group D (T(max-model)=196+/-47 min) and group C. Both treatments improved postoperative milk yield within 1 day after surgery. CONCLUSION: Preoperative injection of erythromycin (10 mg/kg IM) is an effective method for ameliorating postoperative abomasal hypomotility in cows with AV. CLINICAL RELEVANCE: Parenteral erythromycin can be recommended for preoperative treatment of cows with AV.