ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05644.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe long term efficacy of an irradiation attenuated larval (L3) vaccine againstStrongylus vulgariswas tested in ponies which were reared on pasture. Prior to foaling, mares were divided into two groups. One group of mares and foals received regular (eight weekly) treatment with ivermectin and the second group remained untreated. Half the foals in each pasture group were vaccinated at eight to ten weeks of age. Foals were weaned at three to four months of age and maintained on separate pastures. At eight to ten months of age, ponies were placed in box stalls and half of each treatment group were challenged withS. vulgaris(5 × 1000 L3). Clinical signs and lesions typical of acute verminous arteritis were found at necropsy in the ivermectin treated non‐vaccinated challenged yearlings. Ivermectin treated vaccinated challenged yearlings did not show these clinical signs, had markedly reduced to absent arterial lesions and showed an 89 per cent reduction in arterial larval burdens post mortem. Significant differences in clinical signs, arterial lesions or arterial larval burdens were not seen between vaccinated and non‐vaccinated foals reared without benefit of ivermectin treat

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05645.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe myoelectrical activity of the ileum, caecum and large colon was monitored from Ag‐AgCl bipolar recording electrodes in four conscious ‘parasite‐naive’ weanling foals. All foals were inoculated with 1000 infective 3rd‐stageStrongylus vulgarislarvae and alterations to the myoelectrical activity observed. The frequencies of caecal and colonic spike bursts increased significantly in all post infection periods coinciding with assumed larval penetration into the intestinal mucosa and migration through the vasculature. Peaks in caecal and colonic activity occurred at Days 1 to 5 post infection. In the caecum, peaks occurred again at Days 15 and 31 post infection, preceding similar rises in colonic spike burst frequency at Days 19 and 35. Longer term changes indicated a return towards pre‐infection levels of activity suggesting smooth muscle adaptation to decreased blood flow. The analysis of caecal and colonic spike burst propagation indicated that the increases in burst frequency were not attributable to an increase in the propagation of spike bursts in any particular direction, but rather to proportional increases in all directions of activity. There was a slight decrease in the simple ileal spike burst frequency immediately post‐infection. None of the experimental animals exhibited signs of abdominal pain during the trial, and there was no evidence of bowel infarction at post mortem examination despite the presence of severe parasite‐induced arterial lesions. The results suggest that increased caecal and colonic motility is an important host response in susceptible foals exposed toS.

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05646.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryPlasma thromboxane B2(TXB2) the stable inactive metabolite of thromboxane A2(TXA2), was measured daily by specific radioimmunoassay in three groups of animals before and after experimental infection withStrongylus vulgaris. Infection of four ‘parasite naive’ foals produced a typical acute syndrome with intermittent but statistically insignificant rises in TXB2levels. Interpretation of results was complicated by the presence of a non‐septic peritonitis associated with implantation of the foals with electrodes for recording myoelectrical activity. In two foals of similar age, with some natural exposure toS. vulgaris, there was little or no clinical response to infection and increases in TXB2were absent. Baseline levels were also much lower, indicating that the peritonitis may have affected the results obtained in the first group of foals. Severe mesenteric arteritis was confirmed at necropsy in all six foals. A third group of yearling horses, all with natural exposure to the parasite, were generally resistant to infection. One animal developed arteritis with clinical signs of diarrhoea and mild colic, and also showed intermittent increases in TXB2. The mean plasma TXB2level after infection was significantly higher than in the control period, although absolute levels were lower than those recorded in the ‘parasite naive’ foals. Other animals in this group had low TXB2levels and minimal arteritis was found at necropsy. These results indicate that although infection appears to have an effect on plasma TXB2, the changes are inconsistent and not reliable indicators of the presence of verminous arteritis. The results also confirm the difficulty in establishing infection and the variability of the response in animals with previous

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05647.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryTen healthy, mature ponies were orally infected withEhrlichia risticiiusing Ehrlichia‐infected P388D1 mouse monocyte tissue culture cells. Seven developed signs of equine ehrlichial colitis including fever, depression, anorexia, reduced borborygmi, increased abdominal hyperresonance, and diarrhoea. Three remained clinically normal apart from early fever in one. Indirect fluorescent antibody titres were detected in the clinically affected ponies by Days 12 to 17 post infection and increased rapidly to high levels (1:640 to 1:5120) which were maintained until the end of the observation period (Day 28 post infection). Mean antibody titres significantly increased from Days 12 to 14 and from Days 14 to 17 post infection. The rapid increase in antibody titre which occurs close to first appearance of clinical signs may explain the insignificant rise in antibody titres in many naturally occurring case

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05648.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummarySix healthy six to eight‐month‐old horses were surgically prepared with Ag bipolar electrodes sutured to the gastric antrum and duodenum. Leads from the electrodes were exteriorised through a stab incision in the flank. During experimental sessions the horses were lightly restrained in stocks and electrode leads were connected to a physiograph to record antroduodenal myoelectrical activity. Intravenous (iv) injection of 0.05 mg/kg bodyweight (bwt) of the opioid agonist/antagonist, butorphanol was followed within 2 to 3 mins by a normal appearing period of repetitive spike activity, or phase III, of the migrating motor complex (MMC) on the duodenum. This was followed by a period of no spike activity, or phase I, of the MMC and then resumption of intermittent spike activity, or phase II, of normal duration. Pre‐treatment with 15 μg/kg bwt of the non‐selective opioid antagonist, naloxone, or with 1 mg/kg bwt of the (α2‐adrenergic antagonist, tolazoline, did not block the myoelectrical response to butorphanol. It was concluded that a dose of butorphanol that has effective analgesic effects in a colicky horse resets the antroduodenal MMC without causing undesirable effects on antroduodenal motility. This particular effect of butorphanol might not be mediated by either a2‐adrenergic or opioid receptors, although the latter question needs further

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05649.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryEndotoxin (LPS) was quantitated in experimental subjects and in horses with naturally occurring gastrointestinal strangulation obstruction and/or septicaemic diseases to establish the fate of LPS and the clinical usefulness of the Limulus amoebocyte lysate (LAL) assay. The assay was validated for sensitivity (10 pg/ml), recovery (90 to 106 per cent), intra‐assay precision (CV = 5.5 per cent) inter‐assay precision (CV = 11 per cent), and stability of diluted, heat treated, frozen samples (at least 90 days). Plasma concentrations of LPS after sublethal (3 μg/kg) jugular or portal vein bolus injections of LPS rose to 4000 pg/ml and 1500 pg/ml respectively followed by a rapid phase of clearance. Peak plasma concentrations of LPS, associated with slow portal infusion, were lower than peak values associated with bolus injections, remained elevated during the infusion (2 h), but rapidly decreased after infusion was stopped. Thirty seven horses with 38 episodes of naturally occurring gastrointestinal or septicaemic disease were assayed for LPS. Eight episodes involving gastrointestinal disease and eight involving septicaemic disease were positive for LPS. It is concluded that the LAL assay is sensitive and reliable for detecting LPS in equine plasma and it may have clinical value for establishing the severity of endotoxaemia or for distinguishing between septic and non‐septic conditions. Problems of rapid clearance of LPS from plasma, low concentrations, the possibility of sample contamination, and the time and method of sample procurement remain to be add

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05650.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummarySerum immunoglobulin (Ig) titres to core lipopolysaccharide (LPS) were determined in 102 horses admitted to a university referral hospital during a 12‐month period for evaluation of colic. Serum samples were collected again 10–14 days later from 84 of the horses. Titres to core LPS were quantitated by an indirect enzyme‐linked immunosorbent assay (ELISA), utilising the J‐5 mutant ofEscherichia coli0111:B4 as the solid‐phase antigen. All horses had natural antibodies to core LPS at the time of admission and the titre was not affected significantly by age, sex or type of gastrointestinal disorder. The geometric mean titres to core LPS increased significantly within 14 days of admission in those horses with large colon displacement (25), ileal impaction (13), small intestinal strangulating obstruction (11) and small colon obstruction (4). Twenty four (28.6 per cent) of the horses had at least a 4‐fold rise in titre (seroconversion) to core LPS within 14 days of admission. The incidence of seroconversion to core LPS was significantly greater (P<0.05) in horses with disorders requiring surgical intervention (35.8 per cent) than in those with disorders (proximal enteritis, colitis, large colon impaction and unknown) which only required medical treatment (16.1 per cent). Seroconversion rate was not statistically different between groups of horses with diseases of the small intestine which required surgical or medical treatments. The results of this study indicate that gastrointestinal disorders that cause colic in horses result in IgG production to core LPS, and the latter is more prevalent in disorders requir

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05651.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe effects of slow intravenous (iv) infusion of a very low dosage of endotoxin (a cumulative dosage of 0.03 μg/kg bodyweight [bwt] infused over 60 mins) were evaluated in six conscious healthy horses. Duodenal, right ventral colon, and caecal contractions were detected with strain gauge force transducers. Lateral caecal arterial blood flow was measured using transit time ultrasonic blood flow probes. Duodenal contractile activity was not significantly altered by infusion of endotoxin. In contrast, the contractile activity of the right ventral colon 90 and 270 mins after infusion of endotoxin was less than after infusion of saline solution (control). The contractile activity of the caecal body 30, 60, 90, 120 and 240 mins after infusion of endotoxin was significantly less than control. The contractile activity of the caecal apex 60, 90, 120, 240 and 270 mins after termination of endotoxin infusion was significantly less than control. Lateral caecal arterial blood flow was significantly less than control at the end of endotoxin infusion and at 30, 45, 60, 90, 105 and 120 mins afterwards. Average carotid arterial pressure was significantly greater than control at 210, 225, 240, 255 and 270 mins after endotoxin infusion. Infusion of endotoxin increased heart rate, respiratory rate and body temperature significantly. The decrease in caecal contractile activity occurred before the increase in body temperature. All horses became depressed and developed injected mucous membranes. Signs of abdominal pain (including stretching, pawing, kicking at abdomen) were seen in four of the six horses

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05652.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryPost operative ileus is a serious complication of abdominal surgery in horses and there is evidence that endotoxin plays a significant role in its pathogenesis. Pre‐treatment with intravenous (iv) flunixin (1.1 mg/kg bodyweight [bwt]) or phenylbutazone (4.4 mg/kg bwt) significantly antagonised the acute disruption of gastric, small intestinal and large intestinal motility induced by 0.1 μg/kg bwt iv endotoxin in ponies implanted with gastrointestinal strain gauges. Phenylbutazone was more effective than flunixin and this was significant (P<0.01) for the stomach and left dorsal colon. Both drugs reduced the acute systemic side‐effects of the endotoxin and flunixin was slightly more effective than phenylbutazone in antagonising the cardiovascular effects. These results suggest that the acute effects of endotoxin on bowel motility are mediated at least in part by a cyclooxygenase dependant pathway. Flunixin and phenylbutazone showed a relative selectivity for the cardiovascular and gastrointestinal effects of endotoxin, respectively. Phenylbutazone may be of use clinically in acute colic cases, antagonising the disruptive effects of endotoxin on bowel motility, without entirely blocking the cardiovascular effects which can indicate that the patient has a condition requiring sur

ISSN:0425-1644    

DOI:10.1111/j.2042-3306.1989.tb05653.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY