Residue study of mebendazole and its metabolites hydroxy-mebendazole and amino-mebendazole in eel (Anguilla anguilla) after bath treatment.

Mebendazole (MBZ) is extensively used in eel culture for treatment of Pseudodactylogyrus spp. infections. This use may lead to residues of MBZ in eel tissues. Consequently, the residue profile of MBZ in eel after treatment with the drug is of special concern. Therefore, a residue study was performed in European eels (Anguilla anguilla), bath-treated with MBZ at a dose of 1 mg/liter for 24 hr and kept at a water temperature of 25 degrees C. Liver, kidney, fat, skin, and muscle tissues samples were collected at intervals during and after treatment and analyzed for MBZ and its metabolites, hydroxy-MBZ (MBZ-OH) and amino-MBZ (MBZ-NH2), by HPLC. Results showed that MBZ is extensively metabolized to MBZ-OH and MBZ-NH2. Liver and kidney were found to contain the highest levels of MBZ metabolites, and fat contained the highest levels of the parent compound. Skin contained higher residue levels for all three compounds, compared with muscle tissue. MBZ and its hydroxy metabolite were eliminated within 5 days from the edible parts (muscle and skin) of the eels, whereas MBZ-NH2 could be detected by the 14th day after the end of the treatment period. Consequently, although MBZ and MBZ-OH constitute the residues of toxicological concern, MBZ-NH2 should be taken as the compound of interest for estimating the withdrawal time for consumption of eel treated with MBZ.

Influence of flumequine and oxytetracycline on the resistance of the European eel against the parasitic swimbladder nematode Anguillicola crassus.

The effect of the antibacterial drugs flumequine (FQ) and oxytetracycline (OTC) on the defence system of the European eel (Anguilla anguilla L., 1758) was investigated using an experimentally induced infection with the parasitic swimbladder nematode Anguillicola crassus. Eight weeks after oral administration of infective larvae, the mean recovery of the parasites in FQ-treated eels was lower than in non-medicated control animals, and significantly lower than in OTC-treated eels. Mean numbers of peripheral blood granulocytes and B-lymphocytes, as well as the total number of circulating lymphoid cells, showed a significant increase as a result of the infection, while drug treatment merely affected the quantity of the lymphoid cells. The difference in protection against the parasite after FQ or OTC administration points to a modulation of the fish resistance as a result of the drug treatment. The results favour a modulation of the cellular rather than the humoral response, as no specific antibodies were found.

Hydroxyzine premedication--does it provide better anxiolysis than a placebo?

OBJECTIVES: To determine how effective hydroxyzine is compared with a placebo in providing pre-operative anxiolysis in our hospital population, and to assess the anxiolytic effect of our pre-operative visit. DESIGN: Double-blind, randomised, prospective, controlled trial. Anxiety levels assessed with visual analogue scales (VAS), by patient and investigator. Haemodynamic parameters measured: heart rate, blood pressure, respiratory rate. SETTING: Hillbrow Hospital, Johannesburg. PARTICIPANTS: Sixty female patients aged 20-60 years, American Society of Anesthesiologists status I-III, scheduled for elective gynaecological surgery under general anaesthesia. The overall participation rate was 100%. All cases were randomly selected. INTERVENTION: Hydroxyzine (Aterax) 1-2 mg/kg, or a placebo administered orally as anaesthetic premedication. OUTCOME MEASURES: Anxiolytic effect of agents and of pre-operative visit. Time interval between premedication and induction of anaesthesia. Blood pressure, heart rate, respiratory rate, other signs of autonomic hyperactivity (restlessness, tremors, sweating). RESULTS: A statistically significant reduction in anxiety followed the administration of hydroxyzine (P < 0.05) and the placebo (P < 0.03); however, no statistically or clinically significant difference could be demonstrated between the two agents. No significant anxiolysis occurred following the premedication visit. The average premedication-induction interval was 72 minutes. There were no significant differences in haemodynamic parameters between the two groups. CONCLUSIONS: Hydroxyzine, in the dose administered and after an appropriate premedication-induction interval, provided no better anxiolysis than a placebo in the pre-operative period. No significant anxiolytic effect was demonstrated by our routine premedication visit.

Weight gain of calves during natural lungworm challenge infection is non-linearly related to previous infection history.

Calves, previously subjected to different rates of artificial lungworm infection for 10 weeks, were challenged with a natural lungworm infection on pasture after a 6-week housing period. The results showed a parabolic relationship between the effect of the natural challenge on weight gain and the previous rate of artificial infection. The highest average daily weight gains were observed in the calves previously subjected to intermediate rates of artificial infection. The results suggest the existence of an optimal rate of initial infection at which there is sufficient development of immunity to resist the pathogenic effects of reinfection without a concomitant penalty on weight gain.

[A study of the cause of massive mortality among marine-cultured rainbow trout (Oncorrhynchus mykiss, Walbaum) in a fish farm in the southwestern Netherlands]. / Een onderzoek naar de oorzaak van massale sterfte van marien gekweekte regenboogforellen (Oncorhynchus mykiss, Walbaum) op een aquacultuurbedrijf in zuidwest Nederland.

The present study investigated the mass mortality of marine cultured young rainbow trout (Oncorhynchus mykiss, Walbaum) in the Netherlands. The course of the disease, the clinical symptoms, and bacteriological and virological investigations lead to the diagnosis: 'primary infectious pancreatic necrosis virus (IPNV) infection followed by secondary vibriosis'. Treatment with flumequine seemed to be effective. The trout were possible infected with IPNV at the trout hatchery and nursery from which they originated.

Influence of flumequine on in vivo mitogen responses of European eel (Anguilla anguilla L., 1758) lymphoid cells.

The influence of flumequine on mitogen induced lymphoid cell proliferation in European eels (Anguilla anguilla L., 1758) was studied. For this purpose an in vivo test, using peroral drug administration followed by successive intraperitoneal injections with concanavalin A (ConA) or bacterial lipopolysaccharides (LPS) and 5-bromo-2'-deoxyuridine, was applied. Direct counting of proliferated cells in blood smears revealed that flumequine possesses mitogenic properties. A synergistic and an antagonistic effect of the drug was observed after LPS and ConA stimulation, respectively. Flow cytometric analysis of peripheral blood lymphoid cells showed a significant reduction of the mean proportion surface immunoglobulin positive cells in the flumequine-treated animals. It is concluded that flumequine enhances proliferation of lymphoid cells (probably surface immunoglobulin negative cells) in eel under the present experimental conditions.

Production, characterisation and applicability of monoclonal antibodies to European eel (Anguilla anguilla L., 1758) immunoglobulin.

Monoclonal antibodies (mAbs) to European eel (Anguilla anguilla L., 1758) immunoglobulin (Ig) were produced, characterised and tested for applicability in a number of immuno(cyto)chemical assays. The selected mAbs, WEI 1 and WEI 2, were specifically reactive with Ig heavy and light chain, respectively. WEI 1 appeared to react with all or nearly all Ig molecules, B cells and plasma cells. WEI 2 was reactive with a subpopulation of those cells, indicating that European eel possesses at least two antigenically different light chain types. Both mAbs could be used for detection of antigen-specific antibodies in plasma by means of an enzyme-linked immunosorbent assay (ELISA).

[Animal and veterinarian out of equilibrium?!]. / Dier(en)arts uit balans?!

Veterinarians can influence how animals are kept, and the way animals are kept can influence animal health and well-being. Veterinarians may come into conflict with themselves as this is also partly their responsibility. This conflict might have consequences for the aptitude of the individual to be a veterinarian.

Influence of gastro-intestinal nematodes on the productivity of dairy cattle in the wet highlands of Sri Lanka.

To study the response and economics of nematode control in cattle, trials with anthelmintics were carried out in the wet season at New Zealand farm in the highlands of Sri Lanka. Three age groups were used: stall fed yearlings, grazing heifers and lactating cows. Groups were treated with ivermectin or febantel and monitored along with control groups for faecal egg counts, growth and milk production. Treatment reduced the trichostrongylid faecal egg counts in yearlings, heifers and cows for six to 10 weeks, for more than 10 weeks and for 140 days respectively. The growth rate of treated yearlings did not increase significantly while treated heifers did grow significantly faster. Treated cows produced an average of 115 kg more milk over 133 days (P less than 0.05). The economic gains in reducing the age at first service and in terms of milk yield far outweighed the cost of anthelmintics used.

The effects of Dictyocaulus viviparus infection on energy metabolism of calves.

To determine the effects of lungworm infection on energy metabolism and rate of weight gain, five 3-mo-old male Friesian calves were infected orally twice each week with 640, third-stage larvae of Dictyocaulus viviparus (D.v.) over an 8-wk period. Infected calves were matched with uninfected controls on the basis of similar rates of feed consumption and weight gain during the acclimation period before infection. Infected calves were fed 2 kg of concentrates daily (88% DM), about 8.5 Mcal/d. Controls each received approximately 250 g less, about 7.5 Mcal/d. Similar amounts of hay (5.6 to 5.8 Mcal/d) were provided to all calves. Clinical, serum chemical, hematological and parasitological criteria, weight gain and utilization of energy were monitored on a weekly basis. Serum chemical and hematological analyses and clinical examinations of infected animals revealed signs typical of lungworm infection. Fecal and sputum sample examinations for infected calves were positive for D.v. larvae and ova, respectively. Control animals gained approximately 80 g.animal-1.d-1 more than infected calves. Lungworm infection had no significant effect on digestibility of energy or protein. Metabolizability of energy ingested was somewhat higher in the infected calves due to a higher dietary concentrate to roughage ratio. Utilization of metabolizable energy and protein tended to be less efficient for infected animals. Results showed that D.v.-infected calves need more feed for gain than do uninfected animals. This extra requirement is due to an increased maintenance requirement and probably to a reduced protein retention from digested protein.

Clinical signs following experimental lungworm infection and natural bovine respiratory syncytial virus infection in calves.

Similar clinical signs have been reported in calves infected either by Dictyocaulus viviparus or bovine respiratory syncytial virus. Three experiments were carried out to establish the clinical picture and the course of the disease in animals with these infections. The clinical signs of calves infected with lungworm included coughing, nasal discharge, tachypnoea, abdominal breathing and pyrexia, and auscultation of their lungs revealed increased bronchial sounds. Similar signs were also observed after infection with bovine respiratory syncytial virus, but the signs were more acute and resolved more rapidly than in animals infected with lungworm larvae. Calves infected with lungworm had more serious clinical signs after infection with bovine respiratory syncytial virus than calves, which were not infected with lungworm.

Relationship between cytologic changes in bronchoalveolar lavage fluid and weight gain in calves with gastrointestinal nematodes and lungworms.

Two of three groups of 10 calves each were infected with either 100,000 infective larvae (L3) of Ostertagia spp. and 100,000 L3 of Cooperia spp. or with 4000 L3 of Dictyocaulus viviparus, respectively, at the age of 14 weeks. The third group was not infected. After treatment with an anthelminthic five calves from each group were challenged with either 100,000 L3 of Ostertagia spp. and 100,000 L3 of Cooperia spp. or 4000 L3 of Dictyocaulus at the age of 20 weeks. The calves were 25 weeks old when slaughtered. Total and differential cell counts were determined in bronchoalveolar lavage fluid and showed that neutrophils were the most frequent and eosinophils the least frequent cell present. There was a significant negative relationship between eosinophil levels and weight gain of the calves.

Sero-epidemiological survey of Dictyocaulus viviparus infections in first-season grazing calves in The Netherlands.

A sero-epidemiological survey of Dictyocaulus viviparus infections in calves was carried out using an enzyme-linked immunosorbent assay. Infection level with D viviparus was correlated with farm, herd and management characteristics. At least 75 per cent of the herds were infected with D viviparus. Calves on zero-grazing farms were infected at a lower level than calves grazing pasture. No regional differences in infection rate were observed. On 15 per cent of the farms calves had clinical husk while 51 per cent of farms had experienced husk in the past. A higher level of infection was seen when calves were housed later in the autumn. The number of calves grazing together and the stocking rate had a significant positive influence on the level of infection. No significant difference in the occurrence of clinical husk was observed between calves vaccinated against lung-worm disease and calves not vaccinated against the disease.

Effect of infection with lungworms (Dictyocaulus viviparus) on energy and nitrogen metabolism in growing calves.

1. Ten Friesian male calves of about 100 kg and 3 months old were reared similarly and were worm-free. From 13 weeks of age five calves received a dose of 640 infective larvae (L3) of lungworms (Dictyocaulus viviparus) twice weekly for 8 weeks to simulate continuous infection. Animals not infected were fed to the same level as the infected animals (about 1.2-1.3 kg concentrates and 1.4-1.5 kg good-quality hay/d). 2. Heat production was measured twice weekly during 48 h (days 2 and 3, and days 5 and 6) in each group of experimental animals. 3. Infection caused considerable damage to the lungs, increased respiration frequency and clearly produced antibody titres against D. viviparus. 4. Animals infected with lungworms had on average a lower rate of weight gain, reduced by 70 g/d per animal. Digestibility was not affected. Nitrogen retention was much lower in infected animals (12.0 v. 14.6 g/d per animal in controls). 5. Metabolizability of energy was slightly reduced in infected animals. Heat production as found in infected animals may be associated with an increased maintenance energy requirement of 30 kJ/kg live weight 0.75 per d or reduced partial efficiency of feed conversion above maintenance in animals infected with lungworms (58.5 v. 64.1% in the control animals). 6. It was concluded that the depression in rate of gain was related to reduced intake of feed and to decreased N retention.

Use of ELISA to assess lungworm infection in calves.

The enzyme-linked immunosorbent assay (ELISA) technique was applied to the detection of lungworm infections in calves. In experimentally infected animals different responses to larval and adult worm antigens were observed. The response to adult worm antigens was delayed in vaccinated animals when infection occurred by the gradual uptake of infective larvae from contaminated pasture. A serological survey in The Netherlands demonstrated a high incidence of lungworm infection in both vaccinated and unvaccinated herds. There was a good correlation between anti-adult worm and anti-larval ELISA-titres. ELISA appeared to be a useful technique for assessing the level of lungworm infection in a herd.

Physiological effects of experimental verminous bronchitis in Friesian calves.

Pulmonary function values were measured in five Friesian calves of five months of age during the patent phase of an experimental moderate lungworm infection and were compared with the pulmonary function values recorded in four control animals. All the nine calves were free of any previous challenge with Dictyocaulus viviparus and were submitted to the same standardized conditions of body conformation, housing, feeding and procedures for pulmonary function testing. A significant increase of respiratory rate, minute ventilation, total pulmonary resistance and power of breathing and a significant decrease of tidal volume, dynamic lung compliance and PaO2 were observed in the infested animals. The absolute intrapleural pressure values were also significantly more negative. The conclusions of the statistical analysis were almost identical when predicted instead of measured pulmonary function values were used in the control group. The clinical, functional and pathological findings in the infested animals were all consistent with the picture of a lower airway obstructive disease.

Parasitological, serological and clinical effects of continuous graded levels of Dictyocaulus viviparus inoculations in calves.

To investigate the parasitological, serological, clinical and growth effects of continuous graded levels of Dictyocaulus viviparus inoculations in calves an experiment was carried out with 10 groups of 5 calves each. Calves were inoculated twice a week during a period of ten weeks. The range of the doses was 10-2560 infective larvae (L3) per inoculation. The results were analysed by linear and curvilinear regression of various traits on infection level. It is concluded that: A continuous exposure of calves to L3 of D. viviparus was followed by a continuous larval excretion at all levels; Results of the ELISA technique gave a very good reflection of the level of infection; Clinical signs and weight loss were evident before the parasitological and serological results were positive; The serological parameter and the parasitological parameters were mainly linearly related to the level of infection. The clinical parameters were mainly cubically related to the level of infection.

The incidence of Dictyocaulus viviparus infections in cattle in the Netherlands. II. Survey of sera collected in the field.

Examination of nearly 2000 sera indicated that approximately 90 per cent of cattle had acquired Dictyocaulus viviparus infections during the previous grazing season. No differences were found between provinces. Large differences were seen between herds. Antibody titres of milk cows on zerograzing farms were significantly lower than on comparable farms where animals were pastured. The need for further epidemiological work is stressed. In such work serology can be helpful.