Comparison of the effects of oral or subcutaneous carprofen or ketoprofen in rats undergoing laparotomy

Rats undergoing laparotomy received either carprofen (5 mg/kg) or ketoprofen (5 mg/kg) administered orally in flavoured gelatin, or by subcutaneous injection. A control group that received no analgesic showed a significant (3 per cent) fall in bodyweight (P = 0.009) after laparotomy. This decrease was greater than that seen in the groups receiving carprofen (P = 0.006) or ketoprofen (P = 0.012) administered subcutaneously, which continued to gain weight following surgery. All animals showed a significant fall in food consumption but this decrease was greater in the jelly alone group (47 per cent) than in the group receiving carprofen (17 per cent) (P = 0.015) administered subcutaneously. A significant fall in water consumption occurred in the control group (40 per cent) and in animals that received oral carprofen (13 per cent) or Ketoprofen (22 per cent). No significant decrease was seen in groups receiving either carprofen or ketoprofen administered subcutaneously (P > 0.1). This study shows that a relatively simple surgical procedure results in a major reduction in food and water consumption in rats. This reduction can be minimised by the administration of ketoprofen or carprofen (5 mg/kg subcutaneously), but higher dose rates are required if these drugs are to be administered by the oral route.     

Evaluation of auditory evoked potentials to predict depth of anaesthesia during fentanyl/fluanisone−midazolam anaesthesia in rats

Objectives To assess a method for monitoring depth of anaesthesia using components of middle latency auditory evoked potential (AEP) waveforms during anaesthesia with fentanyl/fluanisone and midazolam. Study design Prospective observational study. Animals Five female Wistar rats weighing between 210 and 250 g. Methods Implanted electrodes were used to record AEPs in animals receiving five doses of anaesthetic. Recordings were made at 5 minutes post‐injection (deep anaesthesia; no pedal withdrawal response, PWR) and then at 25 minutes (light anaesthesia; strong PWR). Responses showed five characteristic peaks occurring at 11, 14, 23, 42 and 68 ms that were measured for latency of occurrence and peak amplitude. Results Auditory evoked potential peaks P14, N23 and P42 were increased significantly in latency with successive anaesthetic injections [avg. F(1,4) = 12.53, p < 0.001; avg. F(1,4) = 10.6, p < 0.001; avg. F(1,4) = 3.9, p = 0.02, respectively]. Peak N23 showed a significant reduction in latency during the 20 minute recovery period following both the first and second anaesthetic injections (t(3) = 7.52, p = 0.005; t(4) = 5.17, p = 0.007, respectively). Peak P42 occurred significantly earlier 20 minutes following the second anaesthetic injection (t(4) = 4.75, p = 0.009). The mean overall depth of anaesthesia assessed using PWR scores was significantly correlated with the mean latency of peak N23, such that as the strength of PWR increased, N23 occurred significantly earlier (r = ?0.99, p = 0.01). The amplitude difference between peaks N23 and P42 increased after the second and third drug administrations [avg. F(1,4) = 10.65, p = 0.031 and avg. F(1,4) = 11.24, p = 0.028, respectively]. Conclusion The characteristics of these peaks, and in particular latency of peak N23, may provide a useful tool for assessing depth of anaesthesia produced by this, and possibly other anaesthetic agents.     

Assessment of ketamine/medetomidine anaesthesia in the New Zealand White rabbit

Objective To compare the characteristics of anaesthesia induced with four dose combinations of ketamine/medetomidine. Design Prospective randomized study. Animals Five female New Zealand White (NZW) rabbits of approximately 2.3 kg. Methods Rabbits were given one of four drug combinations (25/0.25; 15/0.5; 15/0.25 and 10/0.5 mg kg^?1 IM) on four successive occasions with a four day interval. Response to injection and then arterial blood gas and cardiovascular parameters were recorded at predetermined time points. Toe and ear pinch reflexes gave measures of total duration of surgical anaesthesia and total sleep time. Analyses used repeated measures analysis of variance. Results Induction was smooth with little reaction to injection and intubation achieved easily. Two combinations (15/0.25, 10/0.5) produced moderate hypoxaemia (mean pO₂ < 8.0 kPa) and two (25/0.25, 15/0.5) very marked hypoxaemia (mean pO₂ < 5.3 kPa). This was reversed within 15 minutes of oxygen administration and all rabbits recovered uneventfully. Heart rates fell in all cases, with only minimal effects on arterial blood pressure and no cardiac arrhythmias. Mean duration of surgical anaesthesia was significantly longer for dose groups 25/0.25 (57 ± 12 minutes) and 15/0.5 (59 ± 17 minutes, p = 0.01) compared to dose group 15/0.25 (27 ± 8 minutes). Only three animals in the 10/0.5 mg kg^?1 group achieved surgical anaesthesia. Mean duration of loss of the ear pinch reflex was similar between doses, being, respectively, 64 ± 13, 81 ± 7, 60 ± 22 and 62 ± 24 minutes. Sleep time was significantly longer for the 15/0.5 dose (112 ± 10 minutes) compared to 15/0.25 (86 ± 22 minutes, p = 0.04). Sleep times for the 25/0.25 and 10/0.5 mg kg^?1 doses were, respectively, 103 ± 23 and 108 ± 12 minutes. Conclusions Ketamine/medetomidine reliably produces smooth induction and recovery in the NZW rabbit, but due to the degree of hypoxaemia produced, should only be used with simultaneous provision of oxygen. Clinical relevance Currently recommended dose rates of ketamine/medetomidine for minor procedures such as ovariohysterectomy in rabbits (25 mg/0.5 mg kg^?1) are unnecessarily high; a dose of 15/0.25 mg kg^?1 should be adequate for 15–30 minutes of surgical anaesthesia.     

Mercury content of some foodstuffs of vegetable origin

An analytical method and results are given for the determination of total mercury residues in: Brussels sprouts; cabbages, heading broccoli and kale; potatoes; apples; carrots; imported tomatoes; tinned tomatoes, tomato juices and purees; rice; sugar. Residues in the 146 samples were in the range <0.001 to 0.010 parts/million, the mean being 0.0027 parts/million.     

Pesticide residues in foodstuffs in Great Britain XIV.—Mercury residues in potatoes

The total mercury contents of the skin and flesh fractions of potatoes from 87 commercial crops grown in England were in the range 0.0–0.08 ppm with the majority in the range 0.01–0.04 ppm.     

Effects of surgery and analgesic administration on spontaneous behaviour in singly housed rats

The study examined the use of behaviour in assessing post-laparotomy pain in rats given subcutaneous injections of saline (0.2 ml 100 g(-1)) or the analgesics buprenorphine (0.05 mg kg(-1)) or ketoprofen (5 mg kg(-1)). Procedural control influences (handling/movement, anaesthesia, injections) were studied in a second group. Of 150 behaviours examined, discriminant analysis classified the main treatment effects, and class mean frequencies were compared between treatments within each group. With the exception of buprenorphine treatment, control procedures reduced the frequency of active, attentive and grooming behaviour, and increased sleeping during 24 hours following each treatment. Moving animals to the theatre was the main factor responsible for these changes. Surgery also reduced active and attentive behaviour. Animals given pre-operative saline were more frequently inactive than those given ketoprofen. These effects most likely resulted from post-surgery pain, but this was not significantly diminished with the ketoprofen dose used. In all cases, buprenorphine outweighed these effects, causing a sustained increase in active, inactive and attentive behaviour, such that determination of any analgesic effects was impossible. The study underlined a role for pain assessments based on rat behaviour. Drug-related effects emphasised a need for more comprehensive assessments encompassing procedural influences, before behaviour changes that are potentially pain related may be determined accurately.     

Residues of some chlorinated hydrocarbon pesticides in milk and milk products after their addition to the feed of cows

Lactating cows fed 0.05 part/million aldrin, 0.2 part/million γ-BHC and 2.0 parts/million pp'-DDT in their concentrate ration gave detectable residues of dieldrin, γ-BHC, pp'-DDE, pp'-TDE and pp'-DDT in the milk and also aldrin in the butter and cheese. The levels found after 28 days of feeding were not significantly greater than those after 14 days. Subsequent increase of the pesticide content of the feed increased the residue content of the milk, butter and cheese. Only a small percentage of pesticide residue was found in the buttermilk, separated milk and the whey.     

Pesticide residues in foodstuffs in England and Wales. Part I: Inorganic bromide ion in lettuce grown in soil fumigated with bromomethane

Surveys of lettuce, produced commercially in England and Wales, were carried out during the years 1977–82 to determine residues of inorganic bromide ion, following soil sterilisation with bromomethane. Lettuce grown on unfumigated soil contained less than 10 mg bromide ion kg⁻¹, while most lettuce grown on bromomethane-fumigated soil were found to contain higher levels of bromide ion, with a proportion in excess of 1000 mg kg⁻¹. The accumulation of bromide ion appeared to be related to the interval between soil fumigation and planting, and also to the frequency of bromomethane application to the soil. A limited amount of data is presented on the levels of bromide ion in imported lettuce.     

Effects of different propofol infusion rates on EEG activity and AEP responses in rats

Parameters calculated from the auditory-evoked potential (AEP) recorded over the auditory cortex and from the electroencephalogram (EEG) recorded over the near vertex were compared in rats at three different infusion rates of propofol (62.5, 35 and 25 mg/kg/h). Depth of anaesthesia was assessed clinically using the strength of the pedal withdrawal reflex. Well-defined AEP responses were consistently obtained. As the propofol concentration was reduced, peak latencies decreased and peak to peak amplitudes increased. Amplitude and latency values were closely associated with the strength of the pedal withdrawal responses. Parameters calculated from the EEG showed no significant change as the propofol concentration was reduced. Periods of burst suppression became more frequent as the propofol infusion rate was increased. The study showed some of the difficulties that may be encountered when using EEG as a tool to assess depth of anaesthesia during propofol infusion. The AEP showed dose dependent changes in rats at different infusion rates of propofol. However, large variability between animals limits the use of this technique for monitoring depth of anaesthesia.