Influence of zinc bacitracin and Bacillus licheniformis on microbial intestinal functions in weaned piglets

The influence of zinc bacitracin (ZB) and of Bacillus licheniformis on host microbial-related functions in young piglets was investigated by applying the concept of microflora-associated characteristics. Six biochemical parameters were determined before and after weaning in faecal samples from piglets in four litters having access to a diet containing ZB, to a diet containing B. licheniformis, to a diet with both additives, or to a diet with no additives, from 3 weeks of age. Statistically significant differences were found in three of the intestinal functions investigated: formation of short-chain fatty acids (at 7 and 10 weeks of age). degradation of mucin (at 7 and 10 weeks of age) and conversion of bilirubin to urobilins (at 7 weeks of age). We also found age-dependent influences on the formation of short-chain fatty acids, on conversion of cholesterol to coprostanol and on conversion of bilirubin to urobilins. We conclude that a functional approach is appropriate for measuring exogenous influence(s) on the microbial intestinal metabolisms in weaned piglets.

Influence of bacitracin on microbial functions in the gastrointestinal tract of horses

This study investigated the influence of zinc bacitracin on the intestinal flora of horses. The functionally active intestinal flora was examined in 6 horses during treatment with zinc bacitracin. Utilising gas chromatography, spectrophotometry, gel electrophoresis and paper chromatography, samples were analysed on biochemical markers reflecting the action of parts of the intestinal flora. The following 5 flora-related functions were studied in faecal samples and intestinal samples from different sections of the hindgut: conversion of cholesterol to coprostanol and of bilirubin to urobilinogens, degradation of mucin and of beta-aspartylglycine and inactivation of tryptic activity. Conversion to coprostanol, conversion to urobilinogens and degradation of mucin were affected by treatment of zinc bacitracin and conversion to coprostanol was most sensitive. All functions were normalised in a short time, in contrast to man and rats. Differences in environmental exposures are probably the reason for a more rapid normalisation of the intestinal flora functions in horses.

The absorption and distribution of 14C-bacitracin in rainbow trout (Salmo gairdneri) after a single oral dose, as observed by whole body autoradiography

This study was performed to investigate the absorption, distribution and elimination of orally given radiolabelled bacitracin methylene disalicylate (BMD) in rainbow trout kept in salt water. The level of radioactivity in skeletal muscle tissue remained low, but stable throughout the experiment, while radioactivity in bile and liver tissue increased for about 48 hr, before decreasing. There was a trapping of BMD and/or its metabolites in excretory kidney tissue, where the amount of radioactivity continued to increase when radioactive material was being removed from other tissues. The maximum concentration found in excretory kidney tissue was about 7 times as high as the maximum concentration found in the liver. Even though there is no appreciable absorption of BMD from the gastrointestinal tract in homoiotherms, we found the absorption in rainbow trout to be significant.

Cholinesterase activities in uterus of normal and fenchlorphos treated blue foxes (Alopex lagopus) during various reproductive states

The uterine acetylcholinesterase and total cholinesterase (acetylcholinesterase plus butyrylcholinesterase) activities in normal and fenchlorphos treated blue fox vixens were determined during various reproductive states.

AChE and Total-ChE of non-medicated vixens in oestrus were about one half of those in anoestrus. In pregnant uteri (luteal phase) the activities were 25 % and 30% compared to anoestrus.

In vixens given 100 mg/kg fenchlorphos for 3 weeks during anoestrus, the remaining activity of AChE in uterus were in average 37%. Pregnant and non-pregnant vixens in the luteal phase medicated prior to mating and during time of implantation, displayed AChE activities which were only moderabely reduced (remaining activities 83% and 72% compared to medicated animals in anoestrus: remaining activity 37%).

Plasma ChE-activity increased during pregnancy in the controls while enzyme activity was strongly reduced in animals given 100 mg/kg fenchlorphos daily through the whole pregnancy.

It was concluded that the previous reported embryotoxic effect of fenchlorphos in the blue fox did not seem to be directed towards the moderate inhibition of the uterine cholinesterases.

Neurotoxic effects of prenatal trichlorfon administration in pigs

Pregnant sows were administered trichlorfon (Neguvon®) during gestation. Examination of the offspring revealed clinical symptoms which included ataxia and tremor. The weights of the cerebrum and the celebellum were significantly reduced (67% and 41% of the control values). There was a clear correlation between the decrease in total brain weight and decrease in cerebellar weight (r = 0.94). Histological examination showed a well preserved lamination of the cerebral and cerebellar cortex. Periodical loss of Purkinje cells was the most notable finding in the cerebellum. The molecular layer in such regions was markedly thinned. Neurochemical investigations of the cerebellum showed a significant decrease in specific activity of the transmitter synthesizing enzymes choline acetyltransferase, glutamate decarboxylase and aromatic amino acid decarboxylase (61.6%, 30.3% and 47.1% of the control values, respectively). No effect in high affinity D-aspartate uptake was observed.

Neurotoxicological examination of the piglet brain after prenatal and postnatal exposure to trichlorfon

Piglets were given 10 repeated doses of the orga-nophosphorus compound trichlorfon during the postnatal period in order to examine the effect on the brain development (Experiment 1). Following prenatal exposure to trichlorfon, the ability of a presumptive hypoplastic cerebellum and cerebrum at birth, to regenerate postnatally was investigated (Experiment 2).

Administration of repeated doses of trichlorfon postnatally was accompanied by only small changes in brain weights, morphology and transmitter enzyme activity (choline acetyltransferase, glutamate decarboxylase, aromatic amino acid decarboxylase) in 35 days old piglets. Animals exposed prenatally, and sacrificed at the age of 35 days, showed a significant increase in brain weights and enzyme activities. The animals did, however, not reach control values in cerebral weight, cerebellar weight or total enzyme activities. Morphological changes still showed regional loss of Purkinje cells in the cerebellum. The study clearly indicated that the pig brain was less vulnerable to trichlorfon in the postnatal period of development than when exposed to the compound prenatally.

Distribution and placental transfer of trichlorfon in guinea pigs

Radiolabelled trichlorfon, dimethyl-(2,2,2-trichloro-1-hydroxyethyl)phosphonate, was administered by stomach tube to pregnant guinea pigs on days 37 and 52 of gestation and examined by the whole body autoradiography method. The results showed that the radiolabelled compound was rapidly distributed to the main organs of the dam with the highest concentrations in the liver, the kidney and the lung. No substantial concentration of radioactivity occurred in the fetuses until 30 min after administration. The uptake in the fetuses was more pronounced at the later gestational stage when the concentration in the fetal liver equalled that of the placenta.

Prenatal effects of trichlorfon on the guinea pig brain

The organophosphorus compound trichlorfon, dimethyl (2,2,2-trichloro-1-hydroxyethyl) phosphonate, was administered by stomach tube (100 mg/kg) to pregnant guinea pigs at two different stages of gestation (days 36, 37, 38 and 51, 52, 53). The pups developed locomotory disturbances, and post mortem examination revealed significantly decreased weights of the total brain and the cerebellum, as compared to controls. There was also a significant weight reduction particularly of the medulla oblongata, but also of the hippocampus, the thalamus, and the colliculi. Histological examination of the cerebellum revealed reduction of the external granular layer and the molecular layer, and regional absence of Purkinje cells. The activities of the neurotransmitter enzymes choline acetyltransferase (ChAT), and glutamate decarboxylase (GAD) in cerebellum were reduced as compared to the control values.

[Clinical effects of ivermectin in the treatment of Sarcoptes scabiei var canis in farm foxes]

The efficacy of ivermectin against natural infection of the mange mite Sarcoptes scabiei var canis in foxes was evaluated. The investigations consisted of two field studies and one controlled study. In experiment 1, ivermectin was given as a single subcutaneous dose at 200 micrograms/kg in six foxes. In experiment 2, was one group, consisting of five animals, administered 200 micrograms ivermectin/kg s.c. twice with an interval of 35 days. Group two, consisting of four animals, was given one subcutaneous injection of 400 micrograms ivermectin/kg. In experiment 3, ten foxes were given 1 ml 0.2% Eqvalen s.c. (i.e. 340-440 micrograms ivermectin/kg). A control group of ten animals was not medicated. Before and after treatment a clinical evaluation and skin scraping for microscopic examination was carried out in all three experiments. The results indicated that ivermectin was a good alternative in the therapy of the Sarcoptes mange in foxes by moderate mite infection. A progressive clinical improvement of the mange lesions was evident in the treated foxes. Mites were not detected in skinscraping, except in one animal in experiment 3. It was concluded that ivermectin should be administered, in an initial dose of 400 micrograms/kg and a repeated dose of 200 micrograms/kg 2-3 weeks after the first treatment.

Ovarian and testicular function in the blue fox (Alopex lagopus) after oral administration of fenchlorphos during the breeding season

The possible effect of fenchlorphos, 0-0-dimethy1-0-(2.4.5-trichlorophenyl) phosphorothioate, upon the reproductive endocrinology in blue foxes (Alopex lagopus) was investigated. Five females were administered fenchlorphos orally at a dose of 100 mg/kg daily from 10 days before oestrus and up to the 21st day of gestation. This dose represents the therapeutic dose for the treatment of sarcoptic mange. Blood samples were collected for the analyses of progesterone, oestradiol-17β and luteinizing hormone (LH) in plasma. The vixens were ovario-hysterectomized on day 23, except 1 animal in the control group which was operated on day 17. Additionally, sperm quality and mating performance in 3 male blue foxes, which were administered 100 mg/kg fenchlorphos daily during the first 3 weeks of the mating season, were examined.

Pregnancy was recorded in 2 medicated and 4 control animals. No pathological changes were observed in the uterus and the ovaries. The plasma concentrations of the hormones were similar to those obtained from the control group. No evidence of any disturbances concerning spermatogenesis in the males was observed. However, their libido appeared to be reduced. None of the males achieved a mating during and after the period of medication.

Teratogenicity and embryotoxicity of orally administered fenchlorphos in blue foxes

Pregnant blue foxes (Alopex lagopus) were administered fenchlorphos (0-0-dimethyl-0-(2,4,5-trichlorophenyl) phos-phorothioate) orally at a dose of 100 mg/kg/day in different periods of gestation. The dose chosen represents the therapeutic dose for the treatment of parasitic lesions. At term the mean number of whelps were recorded, and they were killed and examined for external, visceral and skeletal malformations. Of 19 medicated vixens the mean number of live whelps at term was 1.2 per vixen versus 9.5 in the control group. There was an evident predominance of males in the medicated groups. Several malformations of the head were registered, among them incomplete ossification of the skull bones, cleft palate, hydrocephalus internus and externus. Minor malformations like extra ribs or missing ribs occurred in the medicated groups. Congenital alopecia, hypoplastic kidneys, and hydronephrosis were observed in all the whelps in 1 medicated group. No significant difference in total brain weight, cerebellum weight or the cerebellum-to-total-brain weight was observed.

Histological examination of the cerebellum showed a narrowing or absence of the granular and the molecular layers of the cortical zone.