Brain damage in sheep from penetrating captive bolt stunning

Objective To determine the severity and distribution of structural changes in the brains of adult sheep stunned by penetrating captive bolt.
Procedure The unconstrained heads of ten, anaesthetised, unhorned, 2-year-old Merino sheep were impacted at the summit of the head with a penetrating captive bolt pistol. Six sheep were ventilated and four received no respiratory support. Two hours after impact, brains from the six ventilated sheep were perfusion-fixed with 4% paraformaldehyde. Sixteen whole, serial coronal sections from each brain were stained with haematoxylin and eosin and immunohistochemi-cally for amyloid precursor protein, a sensitive marker of axonal and neuronal reaction in the brain after trauma. Pathological changes in these brains were then quantified by morphometric analysis.
Results Structural change in all impacted brains was a mixture of focal injury around the wound track and more widely distributed damage in the cerebral hemispheres, cerebellum and brainstem, but varied considerably in severity between individual sheep. All nonventilated sheep died rapidly following respiratory arrest.
Conclusions After penetrating captive bolt stunning, damage to the central reticular formation, axonal connections, and the cortical mantle is the likely reason for failure of respiratory control and traumatic loss of consciousness.     

Brain damage in sheep from penetrating captive bolt stunning

OBJECTIVE: To determine the severity and distribution of structural changes in the brains of adult sheep stunned by penetrating captive bolt. PROCEDURE: The unconstrained heads of ten, anaesthetised, unhorned, 2-year-old Merino sheep were impacted at the summit of the head with a penetrating captive bolt pistol. Six sheep were ventilated and four received no respiratory support. Two hours after impact, brains from the six ventilated sheep were perfusion-fixed with 4% paraformaldehyde. Sixteen whole, serial coronal sections from each brain were stained with haematoxylin and eosin and immunohistochemically for amyloid precursor protein, a sensitive marker of axonal and neuronal reaction in the brain after trauma. Pathological changes in these brains were then quantified by morphometric analysis. RESULTS: Structural change in all impacted brains was a mixture of focal injury around the wound track and more widely distributed damage in the cerebral hemispheres, cerebellum and brainstem, but varied considerably in severity between individual sheep. All nonventilated sheep died rapidly following respiratory arrest. CONCLUSIONS: After penetrating captive bolt stunning, damage to the central reticular formation, axonal connections, and the cortical mantle is the likely reason for failure of respiratory control and traumatic loss of consciousness.     

1株羊源致病性屎肠球菌的分离与鉴定

鄂尔多斯市某羊场发生羊不明原因死亡的疫情,为了寻找病因并制定治疗方案和防治措施,本研究通过临床检查和实验室病理及分子生物学诊断方法确诊并提供治疗方案。试验以病死羊为试验材料,首先对其进行临床检查,包括尸体剖检和病理组织学采样。随后,采用常规无菌操作方法取回其脑组织至实验室,进行触片、染色镜检和分离细菌。病死羊剖检发现,肺脏淤血实变、心外膜点状出血、肾脏质地变软如泥、脑严重水肿等。选取脑组织制备病理切片,在镜下可观察到大脑皮质中性粒细胞浸润及中性粒细胞性血管管套现象;深层脑组织进行触片染色后,在镜下可见单个或成对排列的革兰氏阳性球菌,并分离出1株可疑细菌,命名为NEF1;采用Mega 6.0生物软件依据该分离株的16S rRNA基因而绘制的遗传进化树分析结果显示,分离株NEF1与屎肠球菌的国内分离株（MT197247.1）和伊朗分离株（KM495939.1）聚类在同一分支上,而与GenBank中其他屎肠球菌参考菌株遗传距离较远;药物敏感性试验结果表明,分离株NEF1只对环丙沙星呈现中度敏感,而对青霉素等其他选定的抗生素类药物均呈现明显的耐药性。本试验从病死羊脑组织中成功分离并鉴定了1株屎肠球菌NEF1,同时通过药物敏感性试验方法筛选出来的敏感药物有效控制了该病在发病羊场的进一步蔓延,为该地区羊细菌性疾病的有效防治提供了行之有效的试验数据。     

The pathology of peracute experimental Clostridium perfringens type D enterotoxemia in sheep.

The pathological findings in sheep with peracute experimental Clostridium perfringens type D enterotoxemia are described. Of 16 animals inoculated intraduodenally with a whole culture of this microorganism and a starch solution in the abomasum, 12 developed clinical signs including increased respiratory efforts, recumbency, paddling, bleating, convulsions, blindness, and opisthotonus. Diarrhea was not observed in any of the animals. The time lapse between the beginning of intraduodenal infusion and onset of clinical signs varied between 30 minutes and 26 hours, and the clinical course varied between 1 and 9 hours. Gross postmortem changes were observed in these 12 animals and included pulmonary edema; excess pericardial, peritoneal, or pleural fluid with or without strands of fibrin; liquid small intestinal contents; leptomeningeal edema; cerebellar coning; and subcapsular petechiae on kidneys. Histological changes consisted of severe edema of pleura and interlobular septa and around blood vessels and airways and acidophilic, homogeneous, proteinaceous perivascular edema in the brain. Five of 12 animals (42%) with clinical signs consistent with enterotoxemia lacked specific histological lesions in the brain. None of the intoxicated or control animals developed nephrosis. Glucose was detected in the urine of 3 of 6 animals that were tested for this analyte. These results stress the importance of the use of histological examination of the brain, coupled with epsilon toxin detection, for a definitive diagnosis of C. perfringens type D enterotoxemia in sheep.     

Experimental chronic copper toxicity in sheep. Changes that follow the cessation of dosing at the onset of haemolysis.

Eight sheep were given daily oral doses of copper sulphate until haemolysis occurred. Three of the sheep developed further periods of haemolysis after dosing ceased. Serum enzyme and urea levels were measured throughout the experiment and compared to those obtained from three undosed control sheep. Serum enzyme levels rose prior to haemolytic crises and urea levels rose subsequent to haemolysis in animals that died or were killed in extremis. Severe morphological changes were seen in liver, kidney and brain. Tissue levels of copper and iron were markedly elevated. It is concluded that tissue damage continues even after the cessation of ingestion of copper and that the damage can be severe enough to lead to repeated haemolytic crises.     

Effect of Clostridium perfringens epsilon toxin on the blood brain barrier of mice.

It was shown that Clostridium perfringens epsilon toxin has the effect of allowing the passage of 125I polyvinyl-pyrrolidone and 125I human serum albumin into mouse brain. These substances did not enter the brains of normal control mice. The passage of albumin into the brains of mice poisoned with epsilon toxin was extremely rapid. When large doses of toxin (+/-4 000 MLD) were given death ensued within 2-3 min at which stage 1,5% of the injected albumin had already entered the brain. In cases where smaller doses were given and the time interval between injection and death was longer the figure was increased to 2-2 1/2% of the injected plasma albumin.     

A protein toxin from Pasteurella multocida type D causes acute and chronic hepatic toxicity in rats

Pasteurella toxin given subcutaneously to rats caused severe liver damage and growth suppression in doses as low as 15.6 ng. Toxin was lethal at and above 31.25 ng. Survival times were dose-dependent, and lesions differed with time of survival after toxin. Rats dead of acute toxicity had focal hepatic necrosis. Liver lesions were associated with diffuse endothelial damage, intravascular trapping of leukocytes, and degeneration of hepatocytes (characterized by glycogen depletion, development of vacuoles, and eosinophilic cytoplasmic inclusions). Endothelial cells, Kupffer cells, and macrophages had evidence of activation, e.g., increased cellular size with increases in Golgi vesicles, granules, and lysosomes. Rats with chronic toxicity (survival greater than 150 hr) had cirrhosis, intestinal villous atrophy, and markedly reduced body weight and fat. These data show that the rat is highly sensitive to toxins of Pasteurella multocida, and that even low doses of toxin cause liver injury and growth suppression.     

Naturally acquired antibodies against Clostridium perfringens epsilon toxin in goats

Clostridium perfringens type D-producing epsilon toxin is a common cause of death in sheep and goats worldwide. Although anti-epsilon toxin serum antibodies have been detected in healthy non-vaccinated sheep, the information regarding naturally acquired antibodies in ruminants is scanty. The objective of the present report was to characterize the development of naturally acquired antibodies against C. perfringens epsilon toxin in goats. The levels of anti-epsilon toxin antibodies in blood serum of goat kids from two different herds were examined continuously for 14 months. Goats were not vaccinated against any clostridial disease and received heterologous colostrums from cows that were not vaccinated against any clostridial disease. During the survey one of these flocks suffered an unexpectedly severe C. perfringens type D enterotoxemia outbreak. The results showed that natural acquired antibodies against C. perfringens epsilon toxin can appear as early as 6 weeks in young goats and increase with the age without evidence of clinical disease. The enterotoxemia outbreak was coincident with a significant increase in the level of anti-epsilon toxin antibodies.     

The toxicity of phomopsin for sheep

Pure phomopsin was administered to young Merino x Border Leicester wethers by single subcutaneous (SC) and by single and multiple intraruminal (IR) injection. The toxicity after IR injection was influenced by the size of individual doses and the time over which the total dose was given. At high levels of ingestion the toxicity of phomopsin may be limited by absorption rates; with low daily doses the capacity to repair liver damage may be sufficient to prevent cumulative effects. By SC injection a single dose of 10 micrograms/kg approximated the LD50. By IR injection the overall clinical, biochemical and histological responses closest to these of this SC dose resulted from a single dose of 1,000 micrograms/kg. The same total dose administered at daily rates of 50 or 200 micrograms/kg was more toxic and killed all sheep. A single dose of 500 micrograms/kg caused significant liver damage, but no deaths. Single doses of 125 and 250 micrograms/kg and repeated daily doses of 12.5 micrograms/kg over 16 weeks caused no detectable tissue damage. Inappetence was the most sensitive indicator of phomopsin toxicity. About 10% of the sheep differed substantially from the rest of the flock in their susceptibility to phomopsin poisoning.     

A survey of more than 11 years of neurologic diseases of ruminants with special reference to transmissible spongiform encephalopathies (TSEs) in Greece

The first cases of scrapie were detected in Greece in a flock of sheep in October 1986. All the animals of the affected flock and all sheep in two flocks that were in contact were killed and buried. A systematic investigation of all available cases with signs indicating a neurological disease started in sheep and goats in late 1986, as well as in cattle in 1989. The investigation was based on clinical examination, necropsy or macroscopical examination of the brain and viscera, and histological examination of the brain in all animals except those with coenurosis. Histological examinations of specimens from the spinal cord and other tissues, and if considered necessary bacteriological, toxicological and serological examinations were also carried out. In October 1997, scrapie was diagnosed in sheep of a second flock (a mixed flock of sheep and goats), grazing in a pasture close to the place where scrapie was initially detected. All animals of the second flock were also killed and buried. Diagnosis in the first flock was based on clinical signs and histological lesions, and in the second immunoblotting was also used. Distinctive lesions of scrapie were found in the brain and/or the spinal cord of eight sheep with clinical signs from the two flocks. The lesions were revealed in the brain stem and/or in the cervical spinal cord, and tended to be symmetrical. In one sheep, severe lesions in the cortex of cerebral hemispheres and of the cerebellum were also found. In the brain of two sheep from the second flock the pathological isoform of PrP protein was detected. Despite the eradication scheme applied, scrapie in sheep reappeared after 11 years in a place close to where it occurred initially. This may indicate that the effectiveness of the eradication scheme implemented was not adequate and additional approaches may be needed.     

Clinical signs, treatment, and postmortem lesions in dairy goats with enterotoxemia: 13 cases (1979-1982).

Enterotoxemia attributable to Clostridium perfringens type D in goats is difficult to diagnose because of a lack of specific clinical signs or postmortem lesions, on which to base the diagnosis. This report describes the clinical signs, postmortem lesions, and clinical responses to treatment and vaccination in 4 goat herds, in which a diagnosis of enterotoxemia was confirmed. Four clinical cases had the diagnosis confirmed on the basis of signs of diarrhea or sudden death and the isolation of C perfringens and epsilon toxin from the feces at the time of admission. The 10 necropsy cases were diagnosed on the basis of the isolation of C perfringens (not typed) or epsilon toxin from the intestinal contents of goats that died with clinical signs compatible with enterotoxemia and without lesions associated with a second serious disease. Enterocolitis was the most consistent lesion reported at necropsy in the 10 goats with enterotoxemia. Ovine enterotoxemia vaccines were of limited value in preventing enterotoxemia. These observations imply that naturally induced enterotoxemia in goats involves a different pathophysiologic mechanism than that associated with enterotoxemia in sheep.     

Sulfur-induced polioencephalomalacia in sheep: some biochemical changes.

The effect of high dietary sulfur (S) supplementation on blood thiamine (B1) concentration, biochemical indices of liver, muscle and kidney damage and selected plasma electrolytes was studied in six sheep. Three of these sheep received an additional 230 mg thiamine/kg diet (Group 2). After approximately 2.5-3 weeks on this diet, all three sheep in the non-B1-supplemented group (Group 1) showed loss of appetite and developed mild neurological signs: depression, intermittent signs of excitation and head pressing. Increases in blood B1 concentration and plasma creatine kinase (CK) and aspartate aminotransferase (AST) were observed during this time in all affected animals. Clinical signs lasted only for two to five days. Sheep in group 2 were clinically normal throughout the experiment, but all of these animals also had elevated blood B1 concentrations and plasma CK activity at the 3 wk sampling. Plasma magnesium concentrations of group 1 sheep were elevated at the 2.5-3 wk and 6 wk samplings but they declined significantly (p less than 0.05) to low normal levels thereafter. Magnesium concentrations of group 2 sheep were low at the beginning but progressively increased during the course of the experiment. At necropsy, brain lesions suggestive of polioencephalomalacia (PEM) were observed in all sheep but were most marked in group 1. It is speculated that PEM may be caused by a direct toxic effect of S, S metabolites or B1 antimetabolites in the brain rather than by an in vivo B1 deficiency per se.     

Copper toxicity in sheep: the effects of repeated intravenous injections of copper sulphate

Four Clun Forest, Suffolk cross sheep were given daily intravenous injections of copper sulphate. Three similar sheep acted as controls. The copper dosed sheep developed haemolysis and showed liver, kidney and brain damage similar to that seen in chronic copper poisoning. All animals survived for 30 days and two would have lived longer. Reticulocytes were produced after four days and continued to be produced, sometimes in high number throughout the course of the experiment.     

Tryptamine alkaloid toxicosis in feedlot sheep

Tryptamine alkaloid toxicosis (Phalaris staggers) was diagnosed in feedlot sheep. Clinical signs of toxicosis, which were exacerbated by excitement, included gait abnormalities, muscular tremors, nystagmus, and convulsions. An estimated 8% of the most severely affected lambs had clinical signs of toxicosis. Gross lesions detected in the brain of affected lambs consisted of focal gray-green discoloration in the brain stem and thalamus; these areas had microscopic evidence of intraneuronal pigment accumulation. Brain specimens obtained at slaughter indicated that 60% of the lambs had lesions consistent with tryptamine alkaloid toxicosis. Tryptamine alkaloids were found in low concentrations in the feed. Lambs exposed to these feeds had higher death losses than those that were not exposed to the feeds. Cobalt concentration in the feed was higher than that previously reported to be associated with Phalaris staggers.     

Lysis of bovine platelets by Pasteurella haemolytica leukotoxin

Pasteurella haemolytica A1 culture supernatants caused rapid cytolysis (less than 5 minutes) of isolated bovine platelets as measured by leakage of the cytoplasmic enzyme lactate dehydrogenase (LD). The platelet lytic factor had several features similar to P haemolytica leukotoxin. Like P haemolytica leukotoxin, the platelet lytic factor was produced by P haemolytica during logarithmic growth phase, was heat-labile, and was active against target cells (platelets) from ruminant species (cattle and sheep), but not from non-ruminant species (horses, pigs, and human beings). Additionally, the platelet lytic factor was neutralized with antileukotoxin rabbit serum. The amount of LD leaked by a fixed concentration of bovine platelets was proportional to the amount of toxin added at low toxic doses and became maximal at 88 +/- 11% of the total platelet LD activity for high doses of toxin. When a fixed dose of toxin was used and the platelet concentration was varied, LD leakage was initially proportional to the platelet concentration, but plateaued at higher platelet concentrations. The platelet lytic factor required Ca2+ and was inhibited by addition of the Ca2+ chelator ethylene glycol-bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid. Toxin-mediated platelet damage may be important in thrombi formation and fibrin exudation typically associated with P haemolytica pleuropneumonia of cattle.     

产气荚膜梭菌ε毒素及其疫苗研究进展

产气荚膜梭菌病是由产气荚膜梭菌引起的一种重要的人兽共患传染病,可导致山羊、绵羊等动物的肠毒血症或坏死性肠炎,并且可引起动物脑、心、肺和肾组织的水肿.B型和D 型产气荚膜梭菌所产生的ε毒素是引起动物上述病理变化和死亡的重要因素之一.虽然甲醛灭活的毒素疫苗能对动物产生保护性抗体,但是,灭活苗潜在的安全性原因使其在应用上受到限制.因此,基于ε毒素基因的重组疫苗和弱毒疫苗就成为人们研究的目标.     

In vitro effect of T-2 mycotoxin on the immune response of mice

The in vitro biologic effects of T-2 mycotoxin on the immune response of mice was undertaken. Twenty nanograms of toxin abrogated the immune response to the T-dependent antigen sheep RBC, whereas a partial response was observed when 2 ng was used. Analysis of cell culture viabilities indicated that cell death occurred with toxin doses that coincided with the diminished immune responses. A similar decreased response was observed against the T-independent antigen, TNP-lipopolysaccharide, indicating toxic effects on both B and T lymphocyte populations. Delay of toxin administration as much as 116 hours of the 120-hour incubation period still resulted in a substantially diminished immune response, indicating the toxin acts on both the afferent and efferent immune systems. Equal effects were observed for mice of the b, d, and k haplotype, indicating no apparent strain variability in sensitivity to T-2 mycotoxin effects. These results indicated that T-2 mycotoxin can modulate the immune response, and that this modulation is attributable to direct toxic effects on the cells of the immune system.     

羊源肺炎克雷伯菌的分离鉴定及毒力基因检测

为了调查内蒙古通辽市某羊场发病羊死亡的原因,对疑似致病菌进行分离、鉴定及部分生物学特性研究.对病死羊进行剖检,无菌条件下采集心脏、肝脏、脾脏、肺脏等组织脏器进行细菌分离培养;对分离菌进行小鼠致病性试验、细菌生化检测、16S rDNA基因扩增及同源性比对分析和药物纸片扩散法敏感性试验.结果显示,分离菌株符合肺炎克雷伯菌生...     

Association between incubation time and genotype in sheep experimentally inoculated with scrapie-positive brain homogenate

OBJECTIVE: To compare incubation time and clinical signs of scrapie in codon 136/171 alanine-valine/glutamine-glutamine (AVQQ) experimentally inoculated sheep with that in sheep with the more common 136/171 AAQQ genotype. ANIMALS: 60 Suffolk sheep. PROCEDURE: Twenty-seven 171 QQ ewes purchased from 2 private flocks were bred with a 171 QQ Suffolk ram before being inoculated with a 20% solution of scrapie-positive brain homogenate (5 mL, PO) from sheep containing genotypes 136/154/171 AA/arginine-arginine (RR)/QQ, AVRRQQ, and VVRRQQ that had died of scrapie. Ewes had 33 lambs, which were inoculated in the same manner on the day of birth. RESULTS: All 16 genotype 136/154/171 AVRRQQ sheep that died of scrapie were 9 to 11 months of age; clinical signs lasted 1 day to 3 weeks with no wasting and only mild pruritus. The first AARRQQ sheep died with typical clinical signs of scrapie 27 months after inoculation, and 14 were still alive 37 to 42 months after inoculation. The 136/171 AVQQ sheep had minimal accumulation of modified cellular protein (PrP(SC)) as determined by immunohistochemical (IHC) staining within affected cells; thus the severity of clinical signs and time of death were not associated with brain lesions or the amount of PrP(SC) in brain TISSUE OF 136/154/171 AVRRQQ sheep as determined by IHC staining. CONCLUSIONS AND CLINICAL RELEVANCE: The rapid incubation time may have been influenced by the codon 136 genotype, a new unreported valine (V)-dependent strain of scrapie similar to strain SSBP/1, or the inoculum may have contained a traditional strain and a V-dependent or SSBP/1-like strain of scrapie.     

Comparison of Surgical Methods of Transient Middle Cerebral Artery Occlusion between Rats and Mice

Rodent models of focal cerebral ischemia that do not require craniotomy have been developed by intraluminal suture middle cerebral artery occlusion (MCAo). Mouse MCAo models have been widely used and extended to genetic studies of cell death or recovery mechanisms. Therefore, we compared surgery-related parameters and techniques between such rats and mice. In rodent MCAo models, has to be considered body temperature during the operative period, as well as the need for the use of a standardized tip in terms of the outer diameter of probes. Induction of focal cerebral ischemia was measured by neurological dysfunction parameters. Our methods could induce stable moderate-severity ischemic brain injury models and histological alteration at 24 hr after MCAo surgery. Moreover approximately 80% (rats) and 85% (mice) survival ratios were shown indicating with model engineering success. Finally, we described and compared major parameters between rats and mice, including probe size, thread insert length, operation and occlusion periods, and differences in the procedures.