Summary To induce diarrhoea and hypovolaemia, newly‐weaned conventionally bred piglets (3‐ to 4‐ weeks‐old), were either given secretagogues or were inoculated with enterotoxigenic Escherichia coli (ETEC). Choleratoxin (n = 2), E. coli heat‐labile enterotoxin (n = 2) or castor oil (n = 2) were given intragastrically or piglets were intraperitoneally injected with DL 5‐hydroxytryptophan (n = 3). These substances induced a transient diarrhoea without clinical symptoms of dehydration. Therefore, a combination of castor oil and DL 5‐hydroxytryptophan was given two times a day during 3 consecutive days to 3 piglets. Although diarrhoea lasted for 5 days, still no hypovolaemia occurred. Probably the secretagogues have to be given continuosly to mimic the continuous release of enterotoxins during secretory colibacillary diarrhoea. It was, therefore, tried to reproduce colibacillosis in the just‐weaned piglets. Animals were inoculated with K88ac fimbriae producing ETEC strains (O149: K91: K88ac; LT, STa and STb positive) (n = 7), or pretreated with chloramphenicol followed by the ETEC inoculation (n = 8), or pretreated with the antibiotic, inoculated with an enteropathogenic coronavirus, transmissible gastroenteritis virus (TGEV), and subsequently inoculated with ETEC (n=18). Only the last procedure induced a reproducible diarrhoea (93%) and dehydration resulting in a mortality of 80%. It was concluded that the latter experimental procedure could be used to study diarrhoea and hypovolaemia in newly‐weaned piglets and to evaluate the effect of potentially antisecretory drugs on postweaning diarrhoea in piglets.
Three- to four-week-old, just-weaned piglets were infected with transmissible gastroenteritis (TGE) virus and the next day with K88ac+ enterotoxigenic Escherichia coli (ETEC). Histological examination of caudal jejunum and ileum of piglets killed 2-3 days after virus challenge (1-2 days after ETEC infection) revealed severe villus atrophy especially in the jejunum compared with controls (P less than 0.05). Four-5 days after TGE virus infection villus length increased and after 7 days it was near normal. Villi scraped from jejunal and ileal mucosa of the piglets were incubated in vitro with K88ac+ E. coli and the number of bacteria adhering to 250 micron villus brush border was counted. Attachment of bacteria to villi of piglets killed 2-3 days after TGE virus infection was significantly decreased in comparison with adhesion to villi of non-infected piglets or of piglets killed 7 days after the virus infection. Correlation between in vitro adhesion and villus height was 0.6649 (P less than 0.001). The results suggest that the experimentally-induced villus atrophy was attended with a temporarily diminished susceptibility of villus enterocytes to adhesion of K88ac+ E. coli.
In 45 newly-weaned 3 to 4-week-old piglets, diarrhoea was induced by a combined infection with transmissible gastroenteritis (TGE) virus and enterotoxigenic E. coli (ETEC) strains. In untreated control animals this dual inoculation resulted in profuse diarrhoea, vomiting, hypovolaemic shock and death of 77% of the animals within five days of TGE virus inoculation. Antisecretory drugs were administered intramuscularly for three consecutive days after experimental infection. The neurolepticum chlorpromazine, at 2 mg/kg/24 h, resulted in a significant inhibition of diarrhoea and vomiting, and in an increase in weight gain and survival. Sedation and hypothermia, however, were serious side-effects. The alpha 2 agonist clonidine, at 80 micrograms/kg/12 h, induced a significant antidiarrhoeal effect and a reduction in mortality. The drug, however, provoked decreased activity of alpha 2-adrenergic excitation and incoordination. The beta-adrenergic antagonist propranolol, at 0.33 mg/kg/8 h, and the calcium channel blocker verapamil, at 2 mg/kg/8 h, had no beneficial effect on the experimentally induced diarrhoea.
In newly-weaned 3-4 week old piglets (n = 29) diarrhoea (100%) and vomiting (65%) were induced by inoculation with transmissible gastroenteritis virus and enterotoxigenic E. coli strains (0(149):K91:K88ac; LT, STa and STb enterotoxin positive). This combined infection resulted in pronounced mortality within 7 days. During this period the piglets had decreases in body weight, arterial pressure and leucocyte count and increases in heart rate and in total plasma protein concentration. The plasma pH and lactic acid concentration decreased, whereas the values for pO2, pCO2 and frequency of respiration did not change significantly. No significant changes in the serum concentrations of potassium, chloride or calcium were observed, whereas sodium concentration revealed a transient increase. In shocked and dying piglets an increase in haematocrit was observed, whereas base excess and bicarbonate concentration decreased. Flurbiprofen, a potent non-steroidal anti-inflammatory drug, administered intramuscularly on 3 successive days following the combined infection at a dosage of 1 mg/kg/12 h was without beneficial effect on diarrhoea or mortality.
Summary In just‐weaned piglets (n = 30, 3–4 weeks) diarrhoea (100%) and vomiting (66%) were provoked by inoculation with transmissible gastroenteritis virus and enterotoxigenic E. coli strains (0149: K.91: K88ac; LT, STa and STb enterotoxin positive). This combined infection resulted in a mortality of 71 % within 7 days. During this period animals revealed a decrease in body weight, in arterial pressure, in leukocyte count, in plasma pH and in plasma lactic acid concentrations, and an increase in heart rate and in total plasma protein concentration. In shocked and expiring piglets an increase in haematocrit and a decrease in base excess and actual bicarbonate were observed. Chlorpromazine, administered intramuscularly on 3 successive days following the dual infection in 8 K88ac susceptible pigs, in a dosage of 2 and 1.5 mg/kg ṁ 24 h, somewhat retarded the appearance of severe diarrhoea and suppressed vomiting. These beneficial effects, however, did not result in an increased survival. Zusammenfassung Effekt von Chlorpromazin auf eine experimentell‐induzierte Diarrhoe bei Absatzferkeln Bei frisch abgesetzten Ferkeln (n = 30, Alter: 3–4 Wochen) wurde durch Inokulation mit dem TGE‐Virus und mit enterotoxigenen E. coli‐Stämmen (O149: K91: K88ac; LT‐, STa‐ und STb‐Enterotoxin‐positiv) Diarrhoe (100%) und Erbrechen (66%) ausgelöst. Die kombinierte Infektion führte innerhalb von 7 Tagen zu einer Mortalität von 71 %. Während dieser Zeitspanne ergab sich bei den Tieren eine Abnahme des Körpergewichts, des Blutdrucks, der Leukozytenzahl, des Plasma‐pH und der Milchsäurekonzentration des Plasmas sowie eine Zunahme der Herzfrequenz und der Gesamtproteinkonzentration des Plasmas. Bei den Tieren mit Schock und bei den sterbenden Tieren wurde ein Anstieg des Hämatokrits und ein Abfall des Basenexzesses und des aktuellen Bicarbonats beobachtet. Die intramuskuläre Injektion von Chlorpromazin (Dosis: 2 und 1,5 mg/kg ṁ 24 h) bei 8 K88ac‐empfindlichen Ferkeln an 3 aufeinanderfolgenden Tagen im Anschluß an die Doppelinfektion führte zu einer geringgradigen Besserung der schweren Diarrhoe sowie zum Sisteren des Erbrechens. Diese positiven Effekte hatten allerdings keine Steigerung der überlebensrate zur Folge.
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