Equine proliferatieve enteropathie veroorzaakt door Lawsonia intracellularis: geen zeldzame aandoening meer!

Equine proliferatieve enteropathie, veroorzaakt door Lawsonia intracellularis, werd pas op het einde van de vorige eeuw voor het eerst beschreven en werd initieel beschouwd als een sporadisch voorkomende aandoening, maar ze komt tegenwoordig steeds vaker voor. Als kenmerkende klinische symptomen worden vermageren, lethargie, ventraal oedeem, koorts en eventueel diarree en koliek vermeld bij veulens van twee tot acht maanden oud. Bij bloedonderzoek valt vooral een uitgesproken hypoalbuminemie op. De diagnose kan gesteld worden aan de hand van serologie en een PCR-analyse van de mest. Sinds een paar jaar wordt het duidelijk dat een zeer groot deel van onze veulens en paarden seropositief is voor Lawsonia, hetgeen wijst op een sterke verspreiding van het agens in de omgeving. Daarom moet equine proliferatieve enteropathie (EPE) momenteel als een belangrijke differentiaal diagnostische mogelijkheid aanzien worden bij veulens met gewichtsverlies of andere digestieve klachten.

Endoscopy and antiplatelet agents. European Society of Gastrointestinal Endoscopy (ESGE) Guideline

With the increasing use of antiplatelet agents (APA), their management during the periendoscopic period has become a more common and more difficult problem. The increase in use is due to the availability of new drugs and the widespread use of drug-eluting coronary stents. Acute coronary syndromes can occur when APA therapy is withheld for noncardiovascular interventions. Guidelines about APA management during the periendoscopic period are traditionally based on assessments of the procedure-related risk of bleeding and the risk of thrombosis if APA are stopped. New data allow better assessment of these risks, of the necessary duration of APA discontinuation before endoscopy, of the use of alternative procedures (mostly for endoscopic retrograde cholangiopancreatography [ERCP]), and of endoscopic methods that can be used to prevent bleeding (following colonic polypectomy). This guideline makes graded, evidence-based, recommendations for the management of APA for all currently performed endoscopic procedures. A short summary and two tables are included for quick reference.

Isolation of a clonal population of Clostridium perfringens type A from a Belgian Blue calf with abomasal ulceration

A case of abomasal ulceration in a 3-month-old Belgian Blue calf is described. Microscopical examination revealed the ulcers to be demarcated by a band of neutrophilic inflammation that separated underlying healthy tissue from the superficial fibrinous necrotic material in which bacteria were present. Clostridium perfringens type A was isolated from multiple ulcers and from the intestinal contents of the animal and pulsed field gel electrophoresis confirmed that the isolates comprised a genetically clonal population.

The use of slaughterhouse-obtained small intestinal tissue as control material in histological studies should be applied with prudence

This study aimed to evaluate the reliability of slaughterhouse-obtained small intestinal tissue as control material in equine colic research where molecular stress responses in small intestinal tissue are investigated. For this purpose, small intestinal samples from colic horses were collected during surgery or immediately after euthanasia at the oral border of strangulation resection sites and routinely processed for histopathology (i.c. rinsed with 4°C Krebs' solution, fixated overnight with 4% neutral buffered formaldehyde (FH) at room temperature). Control samples consisted of pieces of mid-jejunum, collected at the slaughterhouse and routinely processed for histopathology under 4 different conditions. The 4 conditions differed with regard to incubation and fixation temperature and whether or not oxygenated Krebs' solution was used. Histological scoring revealed that slaughterhouse samples had a higher mean lesion score (P<0.001) than colic samples. In addition, more slaughterhouse samples had a higher mean inflammation score than colic samples (P=0.001). The inflammatory cells in the small intestine consisted mostly of eosinophils and as such were very suggestive for parasitic infestation. Hypoxia-inducible factor-1α (HIF1α) nuclear immunoreactivity was more pronounced in slaughterhouse tissue, probably as a result of the delay between slaughter and sampling (P=0.034). The histopathological score (P=0.291), the inflammation score (P=0.248) and the HIF1α nuclear immunoreactivity (P=0.538) did not differ between the different collection protocols. It is concluded that slaughterhouse-obtained small intestinal tissue shows distinct alterations and that its use as control tissue when evaluating molecular stress responses should be applied with prudence.

Multiple oral dosing of valacyclovir in horses and ponies

The aim of the current study was to investigate whether multiple oral dosing of valacyclovir could result in plasma concentrations exceeding the EC(50)-value of acyclovir against equine herpesvirus 1 (EHV1) during the majority of the treatment period. Additionally, we wanted to determine the concentration of acyclovir in nasal mucus and cerebrospinal fluid (CSF). Valacyclovir was administered to four horses and two ponies, three times daily, at a dosage of 40 mg/kg, for four consecutive days. Blood was collected prior to each administration and 1 h after dosing. Nasal mucus samples and CSF were collected once during treatment; 1 h after the last administration. This dosage regimen resulted in plasma concentrations that were higher than the EC(50)-value of 1.7 microg/mL, i.e. EC(50) of an isolate highly susceptible to acyclovir, for 80% of the treatment period; and higher than the EC(50)-value of 3.0 microg/mL, i.e. EC(50) of an isolate less susceptible to acyclovir, for 60% of the treatment period. Concentration in nasal mucus samples and CSF was 0.36-1.17 microg/mL and 0.11-0.23 microg/mL, respectively. This study illustrates that multiple dosing of valacyclovir may result in a therapeutic benefit as plasma concentrations could be maintained above the EC(50)-value of acyclovir against EHV1 for more than 50% of the treatment period. Acyclovir could be detected in both nasal mucus samples and CSF. However, these concentrations were lower than the EC(50).

Haemorrhagic diathesis in neonatal calves: an emerging syndrome in Europe

In 2008 and 2009 a large number of cases of haemorrhagic diathesis (HD) in neonatal calves were reported in different European countries. In Flanders, 84 cases of neonatal HD in 30 herds were reported in this period. The disease typically affects calves younger than 1 month old from different breed and gender. Prominent clinical signs are cutaneous bleeding, petechiae on all mucosae, melena and often high fever. Early in the disease, the mental state of the animals is uncompromised. The typical haematological finding is pancytopenia, with severe to complete thrombocytopenia being the cause of the increased susceptibility to bleeding. In seven of the affected herds blood samples of calves of the same age group as the clinical case were collected and on six of those farms at least one subclinical case could be identified. Necropsy findings were generalized petechiae, ecchymoses or haemorrhages and variable lymphadenopathy. Histopathology of haemorrhagic lesions revealed multifocal extravasation of red blood cells (haemorrhage) with preservation of tissue architecture and absence of other abnormalities. Total bone marrow aplasia and depletion of all lymphoid tissue was the most prominent finding on histology. Activated macrophages and haemophagocytosis were seen on bone marrow cytology from two live calves. Polymerase chain reaction for bovine viral diarrhoea virus, bluetongue and epizootic haemorrhagic disease virus was negative. Several attempts to isolate a viral agent were unsuccessful.

Temporary transvenous atrial pacing in horses: threshold determination

The purpose of this study was to perform temporary atrial pacing and to determine the atrial strength-duration (S-D) curve which displays the minimal pulse intensity necessary to achieve atrial capture. In 7 horses, atrial pacing was applied using a temporary pacing catheter and a pacemaker as electrical pulse generator. Using the stimulus reduction method, 3 approaches for atrial threshold determination were used. With the fixed pulse width method, at several pulse widths, the corresponding minimal amplitudes to achieve capture were determined, describing an S-D curve. With the fixed amplitude method, the corresponding threshold pulse widths were determined at several fixed amplitudes. The third method proved to be the best and was a combination of both aforementioned methods to determine 2 points of the S-D curve. From these 2 points the whole S-D curve was calculated using a mathematical equation. Temporary pacing can be used to terminate atrial flutter, to induce atrial arrhythmias or to obtain more information about the electrophysiological properties of the heart, such as the atrial refractory period, atrial vulnerability and atrioventricular conduction.

Four cases of omental herniation in cattle

Four cases in cattle of omental herniation through an acquired omental rent are described. Clinical signs were indistinguishable from other causes of mechanical ileus and exploratory laparotomy was necessary to establish a diagnosis. In all cases a variably sized portion of jejunal loops was obstructed in an omental rent in the deep layer of the greater omentum. In two cases simple reduction was possible, and in one case incision of the hernial ring was necessary before reduction could be performed. Resection was necessary only in a calf, in which the incarceration was complicated by severe abomasal distension and local peritonitis. In all four cases the omental rent was closed by a serosa-serosa suture. Three cases made an uneventful recovery and returned to normal production, but one of these animals died three months postoperatively from an unknown cause. The calf was euthanased two days postoperatively because of persistent ileus.

Contractile effects of 5-hydroxytryptamine (5-HT) in the equine jejunum circular muscle: functional and immunohistochemical identification of a 5-HT1A-like receptor

REASONS FOR PERFORMING STUDY

Prokinetic drugs used to treat gastrointestinal ileus in man have equivocal results in horses. In man, prokinetic drugs have 5-hydroxytryptamine4(5-HT4) receptors as their target, but little is known about the 5-HT-receptor subtypes in the equine small intestine.

OBJECTIVE

Functional and immunohistochemical identification of the serotonin receptor subtype(s) responsible for the 5-HT induced contractile response in the equine circular jejunum.

METHODS

Isometric organ-bath recordings were carried out to assess spontaneous and drug-evoked contractile activity of equine circular jejunum. Histological investigations by immunofluorescence analyses were performed to check for presence and localisation of this functionally identified 5-HT receptor subtype.

RESULTS

Tonic contractions were induced by 5-HT in horse jejunal circular muscle. Tetrodotoxin, atropine and NG-nitro L-arginine did not modify this response. A set of 5-HT receptor subtype selective antagonists excluded interaction with 5-HT1B, 1D, 2A, 3, 4 and 7 receptors. The selective 5-HT1A receptor antagonists WAY 100635 and NAN 190 caused a clear rightward shift of the concentration-response curve to 5-HT. The contractile effect of 5-CT, that can interact with 5-HT1A, 1B, 1D, 5 and 7 receptors was also antagonised by WAY 100635, identifying the targeted 5-HT receptor as a 5-HT1A-like receptor. Immunohistology performed with rabbit polyclonal anti-5-HT1A receptor antibodies confirmed the presence of muscular 5-HT1A receptors in the muscularis mucosae, and both longitudinal and circular smooth muscle layers of the equine jejunum.

CONCLUSIONS

Contractile responses in equine jejunal circular smooth muscle induced by 5-HT involves 5-HT1A-like receptors.

Bluetongue virus serotype 8-associated congenital hydranencephaly in calves

Hydranencephaly, the almost complete absence of the cerebral parenchyma, induced by infection with modified live bluetongue virus (BTV) crossing the placenta has previously been reported in sheep and rarely in cattle in the USA and in South Africa. The current study describes 29 cases of hydranencephaly in bovine foetuses and 'dummy' calves up to 3 months of age in Belgium associated with natural BTV serotype 8 infection very early in gestation. Histological examination of the remaining cerebral parenchyma showed moderate to severe atrophy of the neural tissue. The lesions observed support the hypothesis of BTV-induced destruction of precursor cells. However, in several calves a slight infiltration of the walls of venules and arterioles with T lymphocytes (vasculitis) was observed as well, which seems to be responsible for at least some of the lesions. Bluetongue viral RNA was detected in 15 animals using a BTV-specific real-time RT-PCR with a much higher success rate in brain tissues compared with blood and spleen samples. Virus isolation in embryonated eggs was unsuccessful. In conclusion, hydranencephaly in calves can be associated with natural wild-type BTV-8 intra-uterine infection.

Effects of an adapted intravenous amiodarone treatment protocol in horses with atrial fibrillation

REASON FOR PERFORMING STUDY

Good results have been obtained with a human amiodarone (AD) i.v. protocol in horses with chronic atrial fibrillation (AF) and a pharmacokinetic study is required for a specific i.v. amiodarone treatment protocol for horses.

OBJECTIVES

To study the efficacy of this pharmacokinetic based i.v. AD protocol in horses with chronic AF.

METHODS

Six horses with chronic AF were treated with an adapted AD infusion protocol. The protocol consisted of 2 phases with a loading dose followed by a maintenance infusion. In the first phase, horses received an infusion of 6.52 mg AD/kg bwt/h for 1 h followed by 1.1 mg/kg bwt/h for 47 h. In the second phase, horses received a second loading dose of 3.74 mg AD/kg bwt/h for 1 h followed by 1.31 mg/kg bwt/h for 47 h. Clinical signs were monitored, a surface ECG and an intra-atrial electrogram were recorded. AD treatment was discontinued when conversion or any side effects were observed.

RESULTS

Three of the 6 horses cardioverted successfully without side effects. The other 3 horses did not convert and showed adverse effects, including diarrhoea. In the latter, there were no important circulatory problems, but the diarrhoea continued for 10-14 days. The third horse had to be subjected to euthanasia because a concomitant Salmonella infection worsened the clinical signs.

CONCLUSION

The applied treatment protocol based upon pharmacokinetic data achieved clinically relevant concentrations of AD and desethylamiodarone.

POTENTIAL RELEVANCE

Intravenous AD has the potential to be an alternative pharmacological treatment for AF in horses, although AD may lead to adverse drug effects, particularly with cumulative dosing.