In ovo vaccination of broilers against Campylobacter jejuni using a bacterin and subunit vaccine

Campylobacter jejuni and Campylobacter coli originating from poultry meat have been the most important causes of foodborne bacterial gastroenteritis in the European Union since 2005. In-feed application of maternal antibodies from vaccinated hens was shown to confer protection of broilers against Campylobacter infection. Here, it was investigated if these vaccines can be used to protect broilers against Campylobacter infection after in ovo vaccination. Embryos were immunized in ovo at day 18 with a bacterin or a subunit vaccine and at 19 D post hatch, these birds were inoculated with C. jejuni according to a seeder model. Quantification of C. jejuni in the broilers cecal content showed that the in ovo vaccinated birds were not protected against C. jejuni infection. Quantification of blood anti-Campylobacter antibody titers did not show any induction of Campylobacter-specific serological response in the vaccinated birds, which may explain the lack of protection in the vaccinated chicks.

Calcination Enhances the Aflatoxin and Zearalenone Binding Efficiency of a Tunisian Clay

Clays are known to have promising adsorbing characteristics, and are used as feed additives to overcome the negative effects of mycotoxicosis in livestock farming. Modification of clay minerals by heat treatment, also called calcination, can alter their adsorption characteristics. Little information, however, is available on the effect of calcination with respect to mycotoxin binding. The purpose of this study was to characterize a Tunisian clay before and after calcination (at 550 °C), and to investigate the effectiveness of the thermal treatment of this clay on its aflatoxin B1 (AFB1), G1 (AFG1), B2 (AFB2), G2 (AFG2), and zearalenone (ZEN) adsorption capacity. Firstly, the purified clay (CP) and calcined clay (CC) were characterized with X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-IR), cation exchange capacity (CEC), specific surface area (SBET), and point of zero charge (pHPZC) measurements. Secondly, an in vitro model that simulated the pH conditions of the monogastric gastrointestinal tract was used to evaluate the binding efficiency of the tested clays when artificially mixed with aflatoxins and zearalenone. The tested clay consisted mainly of smectite and illite. Purified and calcined clay had similar chemical compositions. After heat treatment, however, some changes in the mineralogical and textural properties were observed. The calcination decreased the cation exchange capacity and the specific surface, whereas the pore size was increased. Both purified and calcined clay had a binding efficacy of over 90% for AFB1 under simulated poultry GI tract conditions. Heat treatment of the clay increased the adsorption of AFB2, AFG1, and AFG2 related to the increase in pore size of the clay by the calcination process. ZEN adsorption also increased by calcination, albeit to a more stable level at pH 3 rather than at pH 7. In conclusion, calcination of clay minerals enhanced the adsorption of aflatoxins and mostly of AFG1 and AFG2 at neutral pH of the gastrointestinal tract, and thus are associated with protection against the toxic effects of aflatoxins.

Mycotoxin Occurrence in Maize Silage-A Neglected Risk for Bovine Gut Health?

Forages are important components of dairy cattle rations but might harbor a plethora of mycotoxins. Ruminants are considered to be less susceptible to the adverse health effects of mycotoxins, mainly because the ruminal microflora degrades certain mycotoxins. Yet, impairment of the ruminal degradation capacity or high ruminal stability of toxins can entail that the intestinal epithelium is exposed to significant mycotoxin amounts. The aims of our study were to assess i) the mycotoxin occurrence in maize silage and ii) the cytotoxicity of relevant mycotoxins on bovine intestinal cells. In total, 158 maize silage samples were collected from European dairy cattle farms. LC-MS/MS-based analysis of 61 mycotoxins revealed the presence of emerging mycotoxins (e.g. emodin, culmorin, enniatin B1, enniatin B, and beauvericin) in more than 70% of samples. Among the regulated mycotoxins, deoxynivalenol and zearalenone were most frequently detected (67.7%). Overall, 87% of maize silages contained more than five mycotoxins. Using an in vitro model with calf small intestinal epithelial cells B, the cytotoxicity of deoxynivalenol, nivalenol, fumonisin B1 and enniatin B was evaluated (0-200 µM). Absolute IC50 values varied in dependence of employed assay and were 1.2-3.6 µM, 0.8-1.0 µM, 8.6-18.3 µM, and 4.0-6.7 µM for deoxynivalenol, nivalenol, fumonisin B1, and enniatin B, respectively. Results highlight the potential relevance of mycotoxins for bovine gut health, a previously neglected target in ruminants.

Gastrostomy tube placement via a laparotomic procedure in growing conventional piglets to perform multi-dose preclinical paediatric drug studies

The use of juvenile conventional pigs as a preclinical animal model to perform pharmacokinetic (PK), pharmacodynamic (PD) and safety studies for the paediatric population is increasing. Repetitive oral administration of drugs to juvenile pigs is however challenging. A representative method which can be used from birth till adulthood is necessary. The current study presents the placement and use of a gastrostomy button in pigs with a weight ranging from 2.4 to 161 kg. The surgical placement was performed via a laparotomic procedure on, each time, 12 pigs (six male, six female) of 1 week, 4 weeks, 8 weeks and 6-7 months old. For every age category, eight pigs were part of a PK study with a non-steroidal anti-inflammatory drug (NSAID) and four pigs served as a control group. No severe complications were observed during surgery. The button remained functional for 10 days in 40 out of 48 pigs. No significant differences in body temperature or white blood cell count were observed during the trial. Three control pigs showed signs of inflammation indicating a NSAID might be warranted. Autopsy revealed minimal signs of major inflammation in the abdominal cavity or the stomach. A limited number of pigs showed mucosal inflammation, ulcers or abscesses in the stomach or around the fistula. These results indicate that the laparotomic placement of a gastrostomy button might be considered safe and easy in growing pigs to perform repetitive oral dosing preclinical studies. However, the method is not advised in pigs weighing more than 100 kg.

Developmental Pharmacokinetics and Safety of Ibuprofen and Its Enantiomers in the Conventional Pig as Potential Pediatric Animal Model

Pediatric drug development, especially in disease areas that only affect children, can be stimulated by using juvenile animal models not only for general safety studies, but also to gain knowledge on the pharmacokinetic and pharmacodynamic properties of the drug. Recently, the conventional growing piglet has been suggested as juvenile animal model. However, more studies with different classes of drugs are warranted to make a thorough evaluation whether the juvenile pig might be a suitable preclinical animal model. Ibuprofen is one of the most widely used non-steroidal anti-inflammatory drugs in human. The present study determined the PK parameters, gastro-intestinal and renal safety of 5 mg/kg BW ibuprofen after single intravenous, single oral and multiple oral administration to each time eight pigs (four males, four females) aging 1, 4, 8 weeks and 6–7 months. Oral administration was performed via a gastrostomy button. A jugular catheter was used for intravenous administration and blood sampling. To assess NSAID induced renal toxicity, renal function was evaluated using iohexol and p-aminohippuric acid as markers for glomerular filtration rate and renal plasma flow, respectively. After the trial, necropsy and histology was performed to evaluate macroscopic and microscopic gastro-intestinal as well as renal lesions. Both enantiomers, R-ibuprofen and S-ibuprofen, were determined in plasma using an in-house developed and validated UHPLC-MS/MS method. Pharmacokinetic parameters were estimated using compartmental analysis. Clearance and volume of distribution of total ibuprofen and both enantiomers increased with age as was observed in human. The rate of stereochemical conversion decreased with age. Multiple oral dosing decreased the absolute oral bioavailability and maximum plasma concentration of R-ibuprofen and food consumption did not influence drug absorption. Based on the limited available pediatric literature, the current study might suggest the conventional pig as suitable animal model to evaluate NSAIDs for pediatric use.

The role of roughage provision on the absorption and disposition of the mycotoxin deoxynivalenol and its acetylated derivatives in calves: from field observations to toxicokinetics

A clinical case in Belgium demonstrated that feeding a feed concentrate containing considerable levels of deoxynivalenol (DON, 1.13 mg/kg feed) induced severe liver failure in 2- to 3-month-old beef calves. Symptoms disappeared by replacing the highly contaminated corn and by stimulating ruminal development via roughage administration. A multi-mycotoxin contamination was demonstrated in feed samples collected at 15 different veal farms in Belgium. DON was most prevalent, contaminating 80% of the roughage samples (mixed straw and maize silage; average concentration in positives: 637 ± 621 µg/kg, max. 1818 µg/kg), and all feed concentrate samples (411 ± 156 µg/kg, max. 693 µg/kg). In order to evaluate the impact of roughage provision and its associated ruminal development on the gastro-intestinal absorption and biodegradation of DON and its acetylated derivatives (3- and 15-ADON) in calves, a toxicokinetic study was performed with two ruminating and two non-ruminating male calves. Animals received in succession a bolus of DON (120 µg/kg bodyweight (BW)), 15-ADON (50 µg/kg BW), and 3-ADON (25 µg/kg) by intravenous (IV) injection or per os (PO) in a cross-over design. The absolute oral bioavailability of DON was much higher in non-ruminating calves (50.7 ± 33.0%) compared to ruminating calves (4.1 ± 4.5%). Immediately following exposure, 3- and 15-ADON were hydrolysed to DON in ruminating calves. DON and its acetylated metabolites were mainly metabolized to DON-3-glucuronide, however, also small amounts of DON-15-glucuronide were detected in urine. DON degradation to deepoxy-DON (DOM-1) was only observed to a relevant extent in ruminating calves. Consequently, toxicity of DON in calves is closely related to roughage provision and the associated stage of ruminal development.

Comparative in vitro cytotoxicity of the emerging Fusarium mycotoxins beauvericin and enniatins to porcine intestinal epithelial cells

The emerging Fusarium mycotoxins beauvericin (BEA) and enniatin (ENN) A, ENN A1, ENN B and ENN B1 gain increasing interest due to their highly prevalent contamination of cereals and cereal products. After oral intake, the gastro-intestinal tract is the first possible site of interaction. In the present in vitro study, the relative cytotoxicity of these mycotoxins towards proliferating and differentiated intestinal porcine epithelial cells of the jejunum (IPEC-J2) was evaluated using flow cytometric viability analysis. IPEC-J2 cells showed the highest sensitivity to BEA and ENN A. In proliferating cells, incubation for 24h with 10 μM BEA caused complete disruption, while the viability percentage declined to 32% after 24h of incubation with 10 μM ENN A. ENN A1 and ENN B1 were less cytotoxic with 87% and 93% viable cells after 24h of incubation with 10 μM ENN A1 and B1, respectively. ENN B was the least cytotoxic since incubation at concentrations up to 100 μM resulted in 83% viable proliferating cells. The same trend was observed for differentiated cells. The limited in vitro cytotoxic effect of ENN B on intestinal cells corroborates previous in vivo findings in broiler chicken in which dietary ENN B had minimal effect on intestinal morphometry.

In vitro model to assess the adsorption of oral veterinary drugs to mycotoxin binders in a feed- and aflatoxin B1-containing buffered matrix

Mycotoxin binders are feed additives which are mixed in the feed to adsorb mycotoxins and thereby reducing their toxic effects on animals. Interactions with orally administered veterinary medicinal products, such as antimicrobials or coccidiostats, have been reported previously. This paper describes an in vitro model to screen the interaction between mycotoxin binders and veterinary drugs with respect to the non-specific binding of drugs. It is designed as a static setup using a single concentration of drug and binder in a feed-containing or a feed-plus-mycotoxin-containing matrix, buffered at different pH values. The model was applied to two frequently used antimicrobials in veterinary medicine, doxycycline (DOX) and tylosin (TYL), one major mycotoxin, aflatoxin B1 (AFB1), and four mycotoxin binders. Proportions of feed, DOX or TYL, AFB1, and binder are equivalent to the in vivo situation for broiler chickens, while pH and volume of the buffer are representative of the gastrointestinal tract of chickens. A substantial binding of DOX (~ 88%) and TYL (~ 66%) to the feed-matrix was observed. For the mycotoxin binders, similar results were obtained for DOX and TYL; more specifically up to an inclusion rate of 20 g binder/kg feed, no significant binding was demonstrated, determined as the free concentration of DOX and TYL. A single exception was noticed for TYL and one specific bentonite-based mycotoxin binder, for which no significant interaction could be demonstrated up to 10 g binder/kg but there was an effect at 20 g/kg. In all cases, there was no competition between the tested drugs DOX or TYL and the mycotoxin AFB1 for binding to the bentonite-based mycotoxin binder.

Mycobacterieel conjunctivaal granuloom bij een Chinese zaagbekeend (Mergus squamatus)

Een vijf jaar oude, vrouwelijke Chinese zaagbekeend werd aangeboden met een chronische en wederkerende conjunctivitis van het linkeroog. Op klinisch onderzoek werden overvloedige traanvloei en een kazig nodulair letsel vastgesteld ter hoogte van de palpebrale conjunctiva. Bij autopsie werd een kazig, necrotisch beleg waargenomen ter hoogte van de linkerconjunctiva en de infraorbitale sinus, en er waren multipele granulomen in diverse interne organen aanwezig. Histologisch onderzoek toonde granulomateuze splenitis, hepatitis, arteritis, fibrinonecrotiserende enteritis, conjunctivitis en tevens amyloïdose van lever en milt aan. Bacteriologisch en moleculair onderzoek van de conjunctiva bij het levende dier toonde respectievelijk de aanwezigheid van een multiresistente Escherichia coli en Chlamydia psittaci aan. Deze bacteriën bleken van ondergeschikt pathogeen belang. Pre mortem werd echter geen cytologisch onderzoek of ziehlneelsen (ZN)-kleuring op de histologische coupe van het conjunctivabiopt uitgevoerd. Bovendien werden pre mortem geen bijkomende onderzoeken, zoals bloedonderzoek en radiografie, uitgevoerd. De definitieve diagnose van een Mycobacterium avium-infectie ter hoogte van de conjunctiva en de inwendige organen werd pas bevestigd na autopsie door middel van een ZNkleuring en polymerasekettingreactie (PCR)- analyse. Lokale en systemische behandelingen met antimicrobiële producten, zoals fluoroquinolonen, tetracyclinen en aminoglycosiden, waren niet succesvol.

Biomarkers for monitoring intestinal health in poultry: present status and future perspectives

Intestinal health is determined by host (immunity, mucosal barrier), nutritional, microbial and environmental factors. Deficiencies in intestinal health are associated with shifts in the composition of the intestinal microbiome (dysbiosis), leakage of the mucosal barrier and/or inflammation. Since the ban on growth promoting antimicrobials in animal feed, these dysbiosis-related problems have become a major issue, especially in intensive animal farming. The economical and animal welfare consequences are considerable. Consequently, there is a need for continuous monitoring of the intestinal health status, particularly in intensively reared animals, where the intestinal function is often pushed to the limit. In the current review, the recent advances in the field of intestinal health biomarkers, both in human and veterinary medicine are discussed, trying to identify present and future markers of intestinal health in poultry. The most promising new biomarkers will be stable molecules ending up in the feces and litter that can be quantified, preferably using rapid and simple pen-side tests. It is unlikely, however, that a single biomarker will be sufficient to follow up all aspects of intestinal health. Combinations of multiple biomarkers and/or metabarcoding, metagenomic, metatranscriptomic, metaproteomic and metabolomic approaches will be the way to go in the future. Candidate biomarkers currently are being investigated by many research groups, but the validation will be a major challenge, due to the complexity of intestinal health in the field.

Antifungal Therapy in Birds: Old Drugs in a New Jacket

The use of antifungals in birds is characterized by interspecies and interindividual variability in the pharmacokinetics, affecting drug safety and efficacy. Oral antifungal drug absorption is a complex process affected by drug formulation characteristics, gastrointestinal anatomy, and physiology. New antifungal drug delivery systems can enhance drug stability, reduce off-target side effects, prolong residence time in the blood, and improve efficacy. Topical administration of antifungals through nebulization shows promising results. However, therapeutic output is highly influenced by drug formulation and type of nebulizer, indicating these factors should be taken into account when selecting this medication route.

Intratumoral chemotherapy in an integumentary squamous cell carcinoma in a cockatiel (Nymphicus hollandicus)

An eight-year-old, female cockatiel (Nymphicus hollandicus) was presented with anorexia, lethargy, a mass at the lower side of the wing and discoloration of the feathers. Physical examination showed an ulcerated nodular integumentary lesion of approximately 4 cm³ ventromedial on the wing at the side of the propatagium and the humerus. Lateral and ventrodorsal radiographs revealed only hepatomegaly. After a stabilization period, surgical excision of the tumor was performed. Based on histopathological evaluation and bacterial culture of the surgically removed tissue, the lesion was typed as an integumentary squamous cell carcinoma with secondary bacterial infection (Corynebacterium sp). Four weeks postoperative, the tumor had recurred. Chemotherapeutic treatment was started with intratumoral carboplatin (1.5 mg/cm³) once a week. Because of further tumor growth after the second administration of carboplatin, resection of the mass was performed before the next infiltration. However, the bird died during anesthesia. Despite increase in tumor size, histopathological and immunohistochemical evaluations showed degeneration of the tumor with intercellular edema and vacuolization of the tumor cells, presumably resulting from carboplatin administration. More research is needed to investigate the efficacy and safety of the intratumoral administration of carboplatin as a treatment option in birds with integumentary squamous cell carcinoma.

Comparative Toxicokinetics and Plasma Protein Binding of Ochratoxin A in Four Avian Species

Ochratoxin A (OTA, 0.25 mg/kg body weight) was absorbed rapidly ( T_max = 0.31-1.88 h) in all avian species (broiler chickens, laying hens, turkeys, and Muscovy ducks) but more slowly in broiler chickens ( T_max = 1.43-4.63 h). The absolute oral bioavailability was complete in these bird species (88.0-109.6%). Ducks have a significantly higher volume of distribution ( V_d) and turkeys a lower V_d compared to chickens and layers (broiler chickens, 0.27 ± 0.12 L/kg; layers, 0.23 ± 0.08 L/kg; turkeys, 0.18 ± 0.04 L/kg; ducks, 0.76 ± 0.44 L/kg). This difference in V_d can be attributed to the species-dependent differences in plasma protein binding of OTA, namely ranging between 82.2 and 88.9% in ducks and between 96.5 and 98.8% in turkeys. No significant gender differences were found in toxicokinetics or plasma protein binding.

Development and Validation of a UPLC-MS/MS and UPLC-HR-MS Method for the Determination of Fumonisin B1 and Its Hydrolysed Metabolites and Fumonisin B2 in Broiler Chicken Plasma

A sensitive and specific method for the quantitative determination of Fumonisin B1 (FB1), its partially hydrolysed metabolites pHFB1a+b and hydrolysed metabolite HFB1, and Fumonisin B2 (FB2) in broiler chicken plasma using ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS) was developed. The sample preparation was rapid, straightforward and consisted of a deproteinization and phospholipid removal step using an Oasis® OstroTM 96-well plate. Chromatography was performed on an Acquity HSS-T3 column, using 0.3% formic acid and 10 mM ammonium formate in water, and acetonitrile as mobile phases. The MS/MS instrument was operated in the positive electrospray ionization mode and the two multiple reaction monitoring transitions were monitored for each component for quantification and identification, respectively. The method was validated in-house: matrix-matched calibration graphs were prepared and good linearity (r ≥ 0.99) was achieved over the concentration ranges tested (1-500 ng/mL for FB1 and FB2; 0.86-860 ng/mL for pHFB1a; 0.72-1430 ng/mL for pHFB1b and 2.5-2500 ng/mL for HFB1). Limits of quantification (LOQ) and detection (LOD) in plasma ranged between 0.72 to 2.5 ng/mL and 0.03 to 0.17 ng/mL, respectively. The results for the within-day and between-day precision and accuracy fell within the specified ranges. Moreover, the method was transferred to an UPLC high-resolution mass spectrometry (HR-MS) instrument in order to determine potential metabolites of HFB1, such as N-acyl-HFB1s and phase II metabolites. The method has been successfully applied to investigate the toxicokinetics and biotransformation of HFB1 in broiler chickens.

Het gebruik van psychofarmaca bij verenplukkende papegaaiachtigen

Verenplukken is een zeer frequent voorkomend probleem bij in gevangenschap gehouden papegaaiachtigen (Psittaciformes). Naast medische oorzaken kunnen ook sociale omgevingsfactoren en neurobiologische oorzaken ten grondslag liggen, waarbij in het laatste geval gesproken wordt over psychogeen verenplukken. De behandeling van dit gedragsprobleem is primair gericht op het aanpassen van de omgeving (bijvoorbeeld door het aanbieden van verrijking) en het teweegbrengen van gedragsveranderingen (gedragstherapie). In de gevallen waarbij deze interventies onvoldoende of geen effect hebben, kunnen psychofarmaca een goede toevoeging aan de behandeling vormen. Echter, om psychofarmaca op een veilige en verantwoorde manier te gebruiken, is een grondige kennis nodig van het werkingsmechanisme, de farmacokinetiek en toxiciteit van deze geneesmiddelen. Specifieke informatie over de werking van psychofarmaca bij vogels ontbreekt in de meeste gevallen, met als gevolg dat het (off-label) gebruik daarvan vooral gebaseerd is op empirische bevindingen en dosisextrapolatie uit onderzoek bij zoogdieren. Dit brengt risico’s met zich mee omdat de metabolisatie en gevoeligheid voor de geneesmiddelen kunnen verschillen tussen vogels en zoogdieren, wat kan leiden tot therapiefalen en/of ernstige bijwerkingen. Het in achtnemen van deze beperkingen en de zorgvuldige monitoring van de patiënt zijn dan ook onontbeerlijk voor een verantwoord gebruik van psychofarmaca bij gezelschapsvogels.

Microbial shifts associated with necrotic enteritis

An outbreak of necrotic enteritis (NE) is a complex process requiring one or a number of predisposing factors rather than just the presence of pathogenic Clostridium perfringens. Examples are dietary influences, such as high levels of non-starch polysaccharides and fishmeal, and factors that evoke epithelial cell damage, such as Fusarium mycotoxins in feed and Eimeria infections. Recent studies have shown that different predisposing factors induce similar shifts in the intestinal microbiota composition. Butyrate-producing-strains of the Ruminococcaceae family are decreased in abundance by both fishmeal and Eimeria. Similarly, a decreased abundance of butyrate-producing-strains belonging to the Lachnospiraceae family has been induced by fishmeal. Also shifts are observed in the lactic acid-producing bacteria, such as decreased abundance of Lactobacillus johnsonii or Weissella confusa, when broilers were fed a fishmeal-based diet or a Fusarium mycotoxin contaminated diet. Finally, the abundance of Candidatus Savagella was decreased in broilers following Eimeria challenge or feeding a fumonisins contaminated diet. The nature of the microbiota shifts indicate that immune modulatory actions of the intestinal microbiota may play a critical role in the effect on the necrosis inducing activity of C. perfringens. Indeed, colonization with butyrate-producing bacteria plays a key role in counteracting inflammation in the gut and preserving intestinal integrity, while Candidatus Savagella is involved in stimulating Th17 and immunoglobulin A responses. Lactic acid bacteria stimulate colonization of lactate-utilizing and butyrate-producing Lachnospiraceae. Future research needs to clarify the role of the microbiota changes in the pathogenesis of NE.

Emerging Fusarium and Alternaria Mycotoxins: Occurrence, Toxicity and Toxicokinetics

Emerging Fusarium and Alternaria mycotoxins gain more and more interest due to their frequent contamination of food and feed, although in vivo toxicity and toxicokinetic data are limited. Whereas the Fusarium mycotoxins beauvericin, moniliformin and enniatins particularly contaminate grain and grain-based products, Alternaria mycotoxins are also detected in fruits, vegetables and wines. Although contamination levels are usually low (µg/kg range), higher contamination levels of enniatins and tenuazonic acid may occasionally occur. In vitro studies suggest genotoxic effects of enniatins A, A1 and B1, beauvericin, moniliformin, alternariol, alternariol monomethyl ether, altertoxins and stemphyltoxin-III. Furthermore, in vitro studies suggest immunomodulating effects of most emerging toxins and a reproductive health hazard of alternariol, beauvericin and enniatin B. More in vivo toxicity data on the individual and combined effects of these contaminants on reproductive and immune system in both humans and animals is needed to update the risk evaluation by the European Food Safety Authority. Taking into account new occurrence data for tenuazonic acid, the complete oral bioavailability, the low total body clearance in pigs and broiler chickens and the limited toxicity data, a health risk cannot be completely excluded. Besides, some less known Alternaria toxins, especially the genotoxic altertoxins and stemphyltoxin III, should be incorporated in risk evaluation as well.

Pathofysiologie van lipopolysaccharide geïnduceerde inflammatoire respons bij vogels

Inflammatie is een beschermende respons op infectie en/of weefselschade die gepaard gaat met de migratie van immuuncellen en mediatoren van de circulatie naar het betreffende weefsel. Deze respons dient om de initiële noxe (onder andere lipopolysaccharide of LPS) te verwijderen en genezing en herstel van het beschadigde weefsel te bekomen. LPS is een onderdeel van de buitenste celmembraan van gramnegatieve bacteriën dat pro-inflammatoire eigenschappen heeft en na toediening bij vogels een ontstekingsreactie teweegbrengt. Deze ontstekingsreactie gaat gepaard met onder andere veranderingen in lichaamstemperatuur, de productie van pro-inflammatoire cytokinen en vorming van acutefase-eiwitten, leukocytose en ziektegedrag. In welke mate elk van deze symptomen aanwezig is bij vogels hangt af van de vogelsoort. Bovendien zijn er verschillen met zoogdieren. De karakteristieken en pathofysiologische gevolgen van een ontstekingsreactie worden vaak bestudeerd in LPS-inflammatiemodellen. Deze inflammatiemodellen kunnen vervolgens toegepast worden in farmacodynamiekstudies om het klinisch effect van anti-inflammatoire geneesmiddelen, zoals niet-steroïdale ontstekingsremmers (NSAIDs) te beoordelen. In dit artikel wordt een overzicht gegeven van de LPS-geïnduceerde inflammatoire respons bij vogels.

The Impact of Deoxynivalenol on Pigeon Health: Occurrence in Feed, Toxicokinetics and Interaction with Salmonellosis

Seed-based pigeon diets could be expected to result in exposure of pigeons to mycotoxins such as deoxynivalenol (DON). Ingestion of low to moderate contamination levels of DON may impair intestinal health, immune function and/or pathogen fitness, resulting in altered host-pathogen interactions and thus different outcome of infections. Here we demonstrate that DON was one of the most frequently detected mycotoxins in seed-based racing pigeons feed, contaminating 5 out of 10 samples (range 177–1,466 μg/kg). Subsequently, a toxicokinetic analysis revealed a low absolute oral bioavailability (F) of DON in pigeons (30.4%), which is comparable to other avian species. Furthermore, semi-quantitative analysis using high-resolution mass spectrometry revealed that DON-3α-sulphate is the major metabolite of DON in pigeons after intravenous as well as oral administration. Following ingestion of DON contaminated feed, the intestinal epithelial cells are exposed to significant DON concentrations which eventually may affect intestinal translocation and colonization of bacteria. Feeding pigeons a DON contaminated diet resulted in an increased percentage of pigeons shedding Salmonella compared to birds fed control diet, 87 ± 17% versus 74 ± 13%, respectively. However, no impact of DON was observed on the Salmonella induced disease signs, organ lesions, faecal and organ Salmonella counts. The presented risk assessment indicates that pigeons are frequently exposed to mycotoxins such as DON, which can affect the outcome of a Salmonella infection. The increasing number of pigeons shedding Salmonella suggests that DON can promote the spread of the bacterium within pigeon populations.

Marek's disease virus associated ocular lymphoma in Roulroul partridges (Rollulus rouloul)

Two 1-year old Roulroul partridges (Rollulus rouloul), one male and one female, were presented because of eye problems and anorexia. Twenty of the 30 Roulroul partridges in the owner's collection had already died. The affected birds stopped eating, became thinner, and eventually died. Antibiotic treatment, which started because of the suspicion of a septicaemic process, was unsuccessful. At clinical examination of the two partridges it was found that in both birds, one eye ball was filled with a whitish yellow amorphous material and the other eye ball of the female showed a distinct corneal opacity. Both presented birds were euthanized. Necropsy revealed no significant abnormalities in addition to the eye lesions. Histology and immunohistochemistry of the female's eye revealed an infiltrate of T-lymphocytes corresponding to ocular lymphoma. Herpesvirus genus-specific PCR, followed by Sanger sequencing confirmed the presumptive diagnosis of Marek's disease in both birds. To our knowledge, this is the first confirmed case of infection with Gallid Herpesvirus 2 (Marek's disease virus) in partridges and the first case in this specific species.

Comparative Oral Bioavailability, Toxicokinetics, and Biotransformation of Enniatin B1 and Enniatin B in Broiler Chickens

A toxicokinetic study of the Fusarium mycotoxins enniatin B1 (ENN B1) and enniatin B (ENN B) was performed in broiler chickens. Each animal received ENN B1 or B orally via an intracrop bolus and intravenously at a dose of 0.2 mg/kg body weight. Both enniatins were poorly absorbed after oral administration, with absolute oral bioavailabilities of 0.05 and 0.11 for ENNs B1 and B, respectively. Both enniatins were readily distributed to the tissues, with mean volumes of distribution of 25.09 and 33.91 L/kg for ENNs B1 and B, respectively. The mean total body clearance was rather high, namely, 6.63 and 7.10 L/h/kg for ENNs B1 and B, respectively. Finally, an UHPLC-HRMS targeted approach was used to investigate the phase I and II biotransformations of both mycotoxins. Oxygenation was the major phase I biotransformation pathway for both ENNs B1 and B. Neither glucuronide nor sulfate phase II metabolites were detected.

Feed contamination with Fusarium mycotoxins induces a corticosterone stress response in broiler chickens

The aim of the present study was to evaluate the effect of the Fusarium mycotoxins deoxynivalenol (DON) and fumonisins (FBs) on the stress response in broiler chickens, using corticosterone (CORT) in plasma as a biomarker. Chickens were fed either a control diet, a DON contaminated diet, a FBs contaminated diet, or a DON and FBs contaminated diet for 15 d at concentrations close to the European Union maximum guidance levels for DON and FBs in poultry. Mean plasma CORT levels were significantly higher in broiler chickens fed a DON contaminated and a DON and FBs contaminated diet compared to birds fed a control diet. A similar trend was observed for animals fed a FBs contaminated diet. Consequently, feeding broilers a diet contaminated with DON and/or FBs induced a CORT stress response, which may indicate a negative effect on animal welfare.

Farmacokinetiek van geneesmiddelen bij vogels en de toepassingen en beperkingen van dosisextrapolatie

De farmacokinetische processen van geneesmiddelen, i.e. absorptie, distributie, metabolisatie en excretie, kunnen sterk verschillen tussen vogels en zoogdieren. Zo worden aminoglycosiden bij vogels trager geklaard en hebben een lager distributievolume dan bij zoogdieren. Deze farmacokinetische verschillen zijn hoofdzakelijk het gevolg van anatomische, biochemische en fysiologische verschillen tussen vogels en zoogdieren. Deze diersoortverschillen en verschillen in geobserveerde en voorspelde farmacokinetische parameters van geneesmiddelen bij vogels geëxtrapoleerd vanuit zoogdieren, zoals de klaring voor enrofloxacine, salicylzuur, meloxicam en flunixine, wijzen erop dat farmacokinetische gegevens van een geneesmiddel bij zoogdieren nauwelijks geëxtrapoleerd kunnen worden naar vogels. Ook tussen vogelsoorten onderling kunnen er verschillen aanwezig zijn. Indien mogelijk dient de dosisselectie van een geneesmiddel voor vogels bijgevolg te gebeuren op basis van de farmacokinetische gegevens van de desbetreffende vogelsoort. Indien dergelijke gegevens niet beschikbaar zijn, kan er gebruik gemaakt worden van allometrische schaling, waarbij de dosisselectie gebeurt op basis van de farmacokinetische gegevens van een andere vogelsoort gecorreleerd aan het lichaamsgewicht van deze vogelsoorten. Schaling op basis van zoogdiergegevens wordt slechts aangeraden indien de farmacokinetische gegevens van andere vogelsoorten niet beschikbaar zijn en het betreffende geneesmiddel een lage toxiciteit heeft.

Niet-steroïdale, anti-inflammatoire geneesmiddelen bij vogels: farmacokinetiek, farmacodynamiek en toxiciteit

Niet-steroïdale, anti-inflammatoire geneesmiddelen (NSAID’s) verhinderen de omzetting van arachidonzuur naar prostanoïden door inhibitie van cyclo-oxygenase iso-enzymen. Bij mens en dier worden NSAID’s voornamelijk gebruikt als pijnstillend en ontstekingsremmend geneesmiddel bij aandoeningen van de gewrichten, het skelet en de spieren, bij abdominale pijn en in mindere mate bij postoperatieve pijn. De farmacokinetiek, farmacodynamiek en toxiciteit van NSAID’s zijn sterk verschillend per geneesmiddel, per diersoort en per vogelsoort, bijvoorbeeld zangvogels, papegaaien, roofvogels, watervogels, hoendervogels en duiven. Speciesspecifieke verschillen in de farmacokinetische processen (absorptie, distributie, biotransformatie en excretie) bemoeilijken de extrapolatie van gegevens tussen de verschillende vogelsoorten. Uit farmacodynamische studies blijken effectieve doseringen bij de behandeling van onder meer artritis eveneens speciesafhankelijk te zijn, wat opnieuw het belang weergeeft van farmacodynamische studies van de doeldiersoort. De meeste neveneffecten van NSAID’s bij vogels zijn geassocieerd met nefrotoxiciteit, spiernecrose en gastro-intestinale toxiciteit. Het is dan ook belangrijk om met deze farmacologische en toxicologische eigenschappen rekening te houden bij het gebruik van NSAID’s bij vogels.