Effects of intravenous infusion of guaifenesin on electroencephalographic variables in pigs.

OBJECTIVE: To investigate the sedative effects of guaifenesin in pigs by use of electroencephalography. ANIMALS: 10 Norwegian Landrace pigs (5 castrated males and 5 sexually intact females). PROCEDURE: Guaifenesin (150 mg/kg of body weight, IV) was administered during a 5-minute period. Using a 2-channel referential electrode configuration, electroencephalograms were recorded before, during, and after infusion of guaifenesin. Changes in spectral edge frequency 95% (SEF), median frequency (MED), and total power were evaluated. RESULTS: After administration of guaifenesin, SEF decreased significantly, and total power increased significantly; however, MED did not change significantly. Analysis of the data did not reveal differences between pigs on the basis of sex. CONCLUSIONS AND CLINICAL RELEVANCE: We concluded that guaifenesin synchronized the patterns of electroencephalograms. This is a strong indication that the drug has a sedative effect in pigs.

Utilization of dichlorvos and trichlorfon in salmonid farming in Norway during 1981-1988.

The main objectives of this investigation were to quantify the use of dichlorvos and trichlorfon in the treatment of salmon lice infestations, to evaluate the prescribing of these drugs, and to estimate possible changes in the salmon lice problem by use of drug statistics. This study has shown that the use of trichlorfon increased from 4.9 tons in 1981 to 28.3 tons in 1985. This figure declined to 3.2 tons in 1988. The use of dichlorvos increased from 0.3 tons in 1986 to 3.2 tons in 1988. The change in the prescribing from trichlorfon to dichlorvos has dramatically reduced the pollution caused by these substances in the marine environment. Moreover, if necessary safety rules are observed, this change reduces the exposure of the workers on fish farms to these drugs, and also reduces the possibilities of intoxications of the fish during the treatment procedure. The sales figures of dichlorvos and trichlorfon, related to the calculated biomass of farmed salmonids in the sea, indicate a dramatic increase in the salmon lice problem.

Clinical use of dichlorvos (Nuvan) and trichlorfon (Neguvon) in the treatment of salmon louse, Lepeophtheirus salmonis. Compliance with the recommended treatment procedures.

Veterinarians representing one third of the Norwegian fish farms were asked about the clinical use of dichlorvos and trichlorfon by use of a questionnaire. A total of 45 veterinarians had experience in treatment of salmon lice with these organophosphates. Fourty-nine percent of the veterinarians reported that the fish farmers in their region solely used the recommended treatment equipment when delousing the fish, of these 1/4 always oxygenated the treatment solution. Repeated treatment were always prescribed by 24% of the veterinarians, while 44% did this occasionally. Of the 45 veterinarians 7% were often present and 44% were occasionally present at the fish farms in connection with the treatment. The answers showed that compliance with the recommended treatment procedures was unsatisfactory.

Immobilization of mink (Mustela vison) with medetomidine-ketamine and remobilization with atipamezole.

Four groups of mink were immobilized with medetomidine-HCl (MED) 0.1 mg/kg + ketamine (KET) 5 or 7.5 mg/kg at different ambient temperatures. The induction time, degree of immobilization and analgesia, rectal temperature, heart and respiration rates were recorded at intervals throughout the immobilization period. The animals were then given atipamezole-HCl (ATI) 0.5 mg/kg for reversal at different times after injection of MED/KET and the effects of the antagonist were evaluated. Subcutaneous administration of MED/KET induced complete immobilization in all 20 animals, and the highest dose was considered suitable for major surgery. Prolonged immobilization at low ambient temperatures (-10 to +5 degrees C) caused severe hypothermia in all animals. The mean rectal temperature had dropped to 37.8 degrees C and 32.1 degrees C at 15 and 85 min, respectively, after injection of MED/KET, significantly lower than the corresponding values for animals immobilized at room temperature. Intramuscular administration of ATI 20 or 40 min after injection of MED/KET rapidly remobilized the animals without apparent side-effects. Administration of ATI to animals recovering spontaneously 90 min after injection of MED/KET induced thermogenesis (shivering) in animals immobilized at a low ambient temperature, while no such effect was seen in animals immobilized at room temperature. One hour after injection of ATI, the rectal temperatures of all treated animals had returned to normal and there were no signs of abnormal behaviour.

Reversal of xylazine-induced sedation in dairy calves with atipamezole: a field trial.

Dairy calves immobilized with xylazine (XYL) were given atipamezole-HCl (ATI) at different XYL:ATI dose ratios (w/w) for reversal and the antagonistic effect of xylazine was evaluated. Control animals received saline for comparison. Intramuscular administration of xylazine (0.139-0.357 mg/kg) induced sedation with complete immobilization in all animals (n = 195) and there were no spontaneous recoveries before injection of atipamezole or saline. Atipamezole was given 10-81 min and saline 25 min after xylazine administration. Intramuscular administration of atipamezole at XYL:ATI dose ratios of 5:2 (n = 11), 10:3 (n = 21), 4:1 (n = 21) and 5:1 (n = 25) effectively antagonized the xylazine-induced immobilization and sedation. The mean times (standard deviation) from injection of atipamezole until the animals were standing for these dose ratio groups were 6.09 (3.12), 5.15 (2.87), 6.35 (2.54) and 7.86 (3.11) min, respectively. The mean time to standing for control animals (n = 11) was 94.1 (3.0) min. Intravenous administration of atipamezole at XYL:ATI dose ratios of 10:3 (n = 7), 4:1 (n = 33), 5:1 (n = 16), 8:1 (n = 27) and 10:1 (n = 9) rapidly reversed the xylazine-induced immobilization and sedation. The mean times (standard deviation) from injection of atipamezole until the animals were standing for these dose ratio groups were 0.98 (0.22), 1.32 (0.48), 1.09 (0.34), 1.39 (0.52) and 1.60 (0.69) min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical capture of free-ranging cattle: immobilization with xylazine or medetomidine, and reversal with atipamezole.

Twenty-nine free-ranging Norwegian cattle were captured with xylazine (n = 20) or medetomidine (n = 9) using a tranquilizing gun, and the time from darting to recumbency (induction time) was recorded. Twenty-eight animals were given atipamezole IV 15-100 min after darting, and the effects of the antagonist were evaluated. Blood samples (n = 19) for haematology and serum chemistry were collected within 10 min after immobilization was induced. Xylazine (0.55 +/- 0.18 mg/kg; mean +/- SD; n = 18) or medetomidine-HCl (0.039 +/- 0.10 mg/kg; n = 8) induced complete immobilization after a single darting with sternal or lateral recumbency, the induction times being 9.6 +/- 3.8 and 12.0 +/- 6.8 min, respectively. No difference in the clinical effects of the two drugs was observed. Rapid reversal was achieved with 0.057 +/- 0.017 and 0.077 +/- 0.019 mg/kg of atipamezole-HCl in xylazine- and medetomidine-treated animals, respectively. All the animals stood within 2 min after IV administration of the antagonist. Seven animals showed signs of excitement shortly after reversal, but these side-effects were of brief duration. Heavy resedation with relapse into recumbency was seen 3-4 h after reversal in two cows captured with xylazine, while moderate resedation was observed in two medetomidine-treated animals 2 h after reversal. Except for the plasma glucose concentration, which was elevated in both xylazine- and medetomidine-treated animals, the mean values of the haematological and plasma chemical parameters were within the reference ranges established for Norwegian cattle.(ABSTRACT TRUNCATED AT 250 WORDS)

Xylazine-induced sedation in axis deer (Axis axis) and its reversal by atipamezole.

Eight free-ranging axis deer (Axis axis) were captured in drive nets and injected with xylazine (3.4 +/- 0.1 mg/kg; mean +/- SEM) intramuscularly using a hand-held syringe. Xylazine induced complete immobilization and sedation in three animals, heavy sedation in three, and moderate sedation in two. The mean induction time was 10.4 +/- 1.0 min. The mean rectal temperature, heart and respiratory rates of immobilized animals were 39.2 +/- 0.4 degrees C, 75.5 +/- 6.5 beats/min and 62.1 +/- 4.2 breaths/min, respectively. All the animals were given atipamezole intravenously for reversal. The mean time from injection of xylazine to administration of atipamezole was 37.8 +/- 4.6 min. A dose ratio (w/w) for xylazine:atipamezole-HCl of 10:1 was used. The mean time from injection of atipamezole to mobility was 2.41 +/- 0.58 min. Atipamezole given intravenously effectively antagonized xylazine-induced sedation in axis deer. Only one animal showed signs of overalertness after reversal and no cases of resedation were observed.

The antimicrobial susceptibility of Staphylococcus species isolated from canine dermatitis.

In a retrospective study, 1538 strains of beta-haemolysin-producing Staphylococcus species isolated from dermatitis in dogs at three veterinary clinical microbiology laboratories in Norway during 1986-87 and 1993-94 were investigated for their antimicrobial susceptibility. None of the strains was resistant to cloxacillin, cephalexin or the quinolones enrofloxacin and ciprofloxacin. More than 96% of the strains were susceptible to trimethoprim-sulphonamide, bacitracin and fucidic acid. Between 67% and 89% of the strains were susceptible to erythromycin, lincosamides, tetracycline, neomycin and chloramphenicol. Only 37.9% of the strains were susceptible to penicillin. The frequency of penicillin resistance increased significantly between the first and second periods, from 46.0% to 58.6%. The frequency of resistance to lincomycin, clindamycin and erythromycin also increased significantly between the first and second periods, from 3.0%, 2.1% and 3.3% to 25.5%, 19.5% and 24.8%, respectively. A moderate increase in resistance to tetracycline was also noted, from 20.4% in the first to 27.6% in the second period. On the other hand, the frequency of resistance to trimethoprim-sulphonamide decreased significantly from 4.1% in the first to 0.9% in the second period. Many different resistance patterns were observed in each period. However, the proportion of multiresistant strains increased from 2.1% in the first to 10.2% in the second period. There was a decrease in resistance to the combination of trimethoprim-sulphonamide and penicillin from the first to the second period. Resistance to the combination of lincosamides and penicillin increased. For the combinations penicillin-tetracycline-lincosamides, penicillin-lincosamides-erythromycin, and penicillin-tetracycline-lincosamides-erythromycin, there was a striking increase in resistance between the first and the second periods.

A comparison of some of the pharmacokinetic parameters of three commercial sulphadiazine/trimethoprim combined preparations given orally to pigs.

Three sulphadiazine/trimethoprim preparations were administered orally during feeding to pigs. Six male and six female pigs were used. Clinically important pharmacokinetic parameters of the two drugs in the three preparations were determined and compared. The plasma concentrations of sulphadiazine and trimethoprim increased rapidly in the pigs followed by a quite rapid decrease from 4 to 12 h after oral administration. The mean values of the absorption half-lives of sulphadiazine and trimethoprim were 0.9-1.6 h and 0.5-0.8 h, respectively. The corresponding values for the elimination half-lives of sulphadiazine and trimethoprim were 3.1-4.3 h and 3.4-6.0 h, respectively. There were no significant differences between the pharmacokinetic parameters of the two compounds in the three preparations with the exception of Tmax for sulphadiazine and t 1/2 beta for trimethoprim. Comparative bioavailability calculations showed no statistically significant differences between sulphadiazine and trimethoprim in the three preparations. The weight increase of the pigs during the experimental period (mean = 37.3-64.9 kg) did not cause differences in the kinetics of the two drugs which could have consequences for the use of the three combined preparations in clinical practice. No unacceptable or antibacterial residues of sulphadiazine or trimethoprim were found in the kidneys of pigs slaughtered at 5, 7 and 10 days after administration.

Benzathine penicillin G and procaine penicillin G in piglets: comparison of intramuscular and subcutaneous injection.

The disposition of penicillin G in piglets is described after intramuscular or subcutaneous injection of depot preparations. The piglets were injected with 33,000 IU/kg or 100,000 IU/kg benzathine + procaine penicillin G intramuscularly or subcutaneously, or 100,000 IU/kg procaine penicillin G intramuscularly or subcutaneously. Intramuscular injection of benzathine + procaine penicillin resulted in higher maximum concentrations in plasma (Cmax) than did subcutaneous injection. The mean residence time (MRT) of penicillin G was longer when the drugs were injected subcutaneously rather than intramuscularly. The plasma concentration versus time profiles of the subcutaneous injections of benzathine + procaine penicillin revealed secondary peaks, possibly reflecting a certain degree of inflammation at the injection site.