Effect of induction dose, lactation stage and body condition on tiletamine-zolazepam anaesthesia in adult female grey seals (Halichoerus grypus) under field conditions.

Tiletamine-zolazepam (TZ) was used at a mean (sd) dose of 1.18 (0.15) mg/kg administered intramuscularly to anaesthetise adult female grey seals (Halichoerus grypus) under field conditions at three different stages during their lactation period. A significant correlation was observed between the induction dose and time to induction (r=-0.582, P=0.011). Stage of lactation had a significant effect on condition index (CI), calculated as axial girth divided by length (P<0.001), and time to induction (P=0.009). No effect of CI on induction or recovery time was demonstrated. Respiratory rate decreased during induction and increased significantly (P<0.001) during surgical biopsy of blubber. Recovery occurred after 32.5 (11.9) minutes. Minor complications (tremor, vocalisation and mild dyspnoea) were observed in a small number of cases, none of which required treatment.

Estimating the rate of poisoning by insecticide-treated seeds in a bird population.

Poisonings of granivorous birds by cereal seed treatments have been reported in the UK, but the true frequency of poisonings is unknown. We aimed to measure the rate of mortality due to poisoning by seed treatments in woodpigeons (Columba palumbus) in an area of East Anglian farmland where the risk from these compounds appeared high. Woodpigeons were fitted with temperature-sensing radio-tags and monitored daily during the winters of 1994/95 and 1995/96. Birds' deaths were detected and attempts made to retrieve carcasses for post-mortem examination including, where possible, analysis for pesticide residues. Ninety-one woodpigeons were monitored. Eleven birds died, but the causes of their deaths were uncertain: one contained a low residue of insecticide and in the other ten cases, no carcass was recovered, so no analysis was possible. Therefore, the number poisoned by pesticides could lie anywhere between zero and eleven. During 1994/95, estimated mortality ranged from 0% to 52%, depending on how many (if any) of the 11 casualties were poisoned. During 1995/96 there were no casualties. Using conservative diagnostic rules for classifying birds as poisoned by OP seed treatments, no link was found between the availability of treated fields in the study area and the rate of poisonings, and there were no significant differences between the two study years. For reasons discussed in the paper, true mortality resulting from exposure to insecticide seed treatments was considered likely to lie in the range 0-5%.

Analysing collaborative trials for qualitative microbiological methods: accordance and concordance.

In qualitative (detection) food microbiology, the usual measures of repeatability and reproducibility are inapplicable. For such studies, we introduce two new measures: accordance for within laboratory agreement and concordance for between laboratory agreement, and discuss their properties. These measures are based on the probability of finding the same test results for identical test materials within and between laboratories, respectively. The concordance odds ratio is introduced to present their relationship. A method to test whether accordance differs from concordance is discussed.

The occurrence of ixodid ticks on wild mink Mustela vision in England and Wales.

Four species of ticks found to infest 1391 American mink (Mustela vison) in Britain in five years were, in declining order of frequency, Ixodes hexagonus, Ixodes canisuga, Ixodes ricinus and Ixodes acuminatus. Ixodes hexagonus and I. canisuga occurred on 40% and 2.5% of mink respectively. Infestation rates (the proportion of infested mink) of adult females, nymphs and larvae were similar and tended to be lower in summer. The distribution of infestation size (the number of ticks per host) for adult females describes a negative binomial. The mean infestation size of nymphs varied with the sex of the host was 5.2 for males and 4.2 for females. Mink are competent hosts for I.hexagonus.

The development of a blood clotting response test for discriminating between difenacoum-resistant and susceptible Norway rats (Rattus norvegicus, Berk.).

1. A new test for identifying levels of difenacoum resistance in the Norway rat is described, based upon the differential physiological response to difenacoum administration. 2. This test is based on changes in blood clotting activity over 4 days, following administration of the rodenticide difenacoum in conjunction with menadione (vitamin K3). 3. The anticoagulant effect is reduced only in rats that are resistant or tolerant to difenacoum. 4. This test procedure is quicker than traditional feeding tests, and identifies the degree of resistance in both laboratory and wild rats that have difenacoum resistance genes.