Sedative and cardiopulmonary effects of medetomidine hydrochloride and xylazine hydrochloride and their reversal with atipamezole hydrochloride in calves

OBJECTIVE: To assess the sedative and cardiopulmonary effects of medetomidine and xylazine and their reversal with atipamezole in calves. ANIMALS: 25 calves. PROCEDURES: A 2-phase (7-day interval) study was performed. Sedative characteristics (phase I) and cardiopulmonary effects (phase II) of medetomidine hydrochloride and xylazine hydrochloride administration followed by atipamezole hydrochloride administration were evaluated. In both phases, calves were randomly allocated to receive 1 of 4 treatments IV: medetomidine (0.03 mg/kg) followed by atipamezole (0.1 mg/kg; n = 6), xylazine (0.3 mg/kg) followed by atipamezole (0.04 mg/kg; 7), medetomidine (0.03 mg/kg) followed by saline (0.9% NaCl; 6) solution (10 mL), and xylazine (0.3 mg/kg) followed by saline solution (10 mL; 6). Atipamezole or saline solution was administered 20 minutes after the first injection. Cardiopulmonary variables were recorded at intervals for 35 minutes after medetomidine or xylazine administration. RESULTS: At the doses evaluated, xylazine and medetomidine induced a similar degree of sedation in calves; however, the duration of medetomidine-associated sedation was longer. Compared with pretreatment values, heart rate, cardiac index, and PaO(2) decreased, whereas central venous pressure, PaCO(2), and pulmonary artery pressures increased with medetomidine or xylazine. Systemic arterial blood pressures and vascular resistance increased with medetomidine and decreased with xylazine. Atipamezole reversed the sedative and most of the cardiopulmonary effects of both drugs. CONCLUSIONS AND CLINICAL RELEVANCE: At these doses, xylazine and medetomidine induced similar degrees of sedation and cardiopulmonary depression in calves, although medetomidine administration resulted in increases in systemic arterial blood pressures. Atipamezole effectively reversed medetomidine- and xylazine-associated sedative and cardiopulmonary effects in calves.     

Comparative evaluation of sedative and clinical effects of dexmedetomidine and xylazine in dromedary calves (Camelus dromedarius)

ObjectiveTo compare the sedative and clinical effects of intravenous (IV) administration of dexmedetomidine and xylazine in dromedary calves.Study designExperimental, crossover, randomized, blinded study.AnimalsA total of seven healthy male dromedary calves aged 14 ± 2 weeks and weighing 95 ± 5.5 kg.MethodsCalves were assigned three IV treatments: treatment XYL, xylazine (0.2 mg kg⁻¹); treatment DEX, dexmedetomidine (5 μg kg⁻¹); and control treatment, normal saline (0.01 mL kg⁻¹). Sedation scores, heart rate (HR), respiratory rate (f_R), rectal temperature (RT) and ruminal motility were recorded before (baseline) and after drug administration. Sedation signs were scored using a 4-point scale. One-way anova and Mann–Whitney U tests were used for data analysis.ResultsCalves in treatments XYL and DEX were sedated at 5–60 minutes. Sedation had waned in XYL calves, but not DEX calves, at 60 minutes (p = 0.037). Sedation was not present in calves of any treatment at 90 minutes. HR decreased from baseline in XYL and DEX at 5–90 minutes after drug administration and was lower in DEX than XYL at 5 minutes (p = 0.017). HR was lower in DEX (p = 0.001) and XYL (p = 0.013) than in control treatment at 90 minutes. f_R decreased from baseline in XYL and DEX at 5–60 minutes after drug administration and was lower in DEX than XYL at 5 minutes (p = 0.013). RT was unchanged in any treatment over 120 minutes. Ruminal motility was decreased in XYL at 5, 90 and 120 minutes and absent at 10–60 minutes. Motility was decreased in DEX at 5, 10 and 120 minutes and was absent at 15–90 minutes.Conclusion and clinical relevanceThe duration of sedation from dexmedetomidine (5 μg kg^–1) and xylazine (0.2 mg kg^–1) was similar in dromedary calves.     

Pharmacokinetics of enrofloxacin and danofloxacin in premature calves

The aim of this study was to determine the pharmacokinetics/pharmacodynamics of enrofloxacin (ENR) and danofloxacin (DNX) following intravenous (IV) and intramuscular (IM) administrations in premature calves. The study was performed on twenty‐four calves that were determined to be premature by anamnesis and general clinical examination. Premature calves were randomly divided into four groups (six premature calves/group) according to a parallel pharmacokinetic (PK) design as follows: ENR‐IV (10 mg/kg, IV), ENR‐IM (10 mg/kg, IM), DNX‐IV (8 mg/kg, IV), and DNX‐IM (8 mg/kg, IM). Plasma samples were collected for the determination of tested drugs by high‐pressure liquid chromatography with UV detector and analyzed by noncompartmental methods. Mean PK parameters of ENR and DNX following IV administration were as follows: elimination half‐life (t_1/2λz) 11.16 and 17.47 hr, area under the plasma concentration–time curve (AUC_0‐48) 139.75 and 38.90 hr*µg/ml, and volume of distribution at steady‐state 1.06 and 4.45 L/kg, respectively. Total body clearance of ENR and DNX was 0.07 and 0.18 L hr^?1 kg^?1, respectively. The PK parameters of ENR and DNX following IM injection were t_1/2λz 21.10 and 28.41 hr, AUC_0‐48 164.34 and 48.32 hr*µg/ml, respectively. The bioavailability (F) of ENR and DNX was determined to be 118% and 124%, respectively. The mean AUC_0‐48CPR/AUC_0‐48ENR ratio was 0.20 and 0.16 after IV and IM administration, respectively, in premature calves. The results showed that ENR (10 mg/kg) and DNX (8 mg/kg) following IV and IM administration produced sufficient plasma concentration for AUC_0‐24/minimum inhibitory concentration (MIC) and maximum concentration (C_max)/MIC ratios for susceptible bacteria, with the MIC₉₀ of 0.5 and 0.03 μg/ml, respectively. These findings may be helpful in planning the dosage regimen for ENR and DNX, but there is a need for further study in naturally infected premature calves.     

Pharmacokinetics and bioavailability of cefquinome and ceftriaxone in premature calves

The aim of this study was to evaluate the pharmacokinetics and bioavailability of cefquinome (CFQ) and ceftriaxone (CTX) following intravenous (IV) and intramuscular (IM) administrations in premature calves. Using a parallel design, 24 premature calves were randomly divided into the two antibiotic groups. Each of the six animals in the first group received CFQ (2 mg/kg) through IV or IM administration. The second group received CTX (20 mg/kg) via the same administration route. Plasma concentrations of the drugs were analyzed by high‐performance liquid chromatography and noncompartmental methods. Mean pharmacokinetic parameters of CFQ and CTX following IV administration were as follows: elimination half‐life (t_1/2λz) 1.85 and 3.31 hr, area under the plasma concentration–time curve (AUC_0–∞) 15.74 and 174 hr * μg/ml, volume of distribution at steady‐state 0.37 and 0.45 L/kg, and total body clearance 0.13 and 0.12 L hr^?1 kg^?1, respectively. Mean pharmacokinetic parameters of CFQ and CTX after IM injection were as follows: peak concentration 4.56 and 25.04 μg/ml, time to reach peak concentration 1 and 1.5 hr, t_1/2λz 4.74 and 3.62 hr, and AUC_0–∞ 22.75 and 147 hr * μg/ml, respectively. The bioavailability of CFQ and CTX after IM injection was 141% and 79%, respectively. IM administration of CFQ (2 mg/kg) and CTX (20 mg/kg) can be recommended at 12‐hr interval for treating infections caused by susceptible bacteria, with minimum inhibitory concentration values of ≤0.5 and ≤4 μg/ml, respectively, in premature calves. However, further research is indicated to assess the pharmacokinetic parameters following multiple doses of the drug in premature calves.     

A COMPARISON OF THE SEDATIVE EFFECTS OF MEDETOMIDINE AND XYLAZINE IN THE HORSE.

The sedative effects in horses of the new α₂-agonist medetomidine were compared with those of xylazine. Four ponies and one horse were treated on separate occasions with two doses of medetomidine (5 mμ/kg bodyweight and 10 μg/kg bodyweight) and with one dose of xylazine (1 μg/kg bodyweight) given by intravenous injection. Medetomidine at 10 μg/kg was similar to 1 mg/kg xylazine in sedative effect but produced greater and more prolonged ataxia. Ataxia was so severe following 10 μg/kg of medetomidine that one animal fell over during the study. Medetomidine (5 μg/kg) produced less sedation but a similar degree of ataxia to 1 mg/kg xylazine.     

The impact of MK‐467 on plasma drug concentrations,sedation and cardiopulmonary changes in sheep treated with intramuscular medetomidine and atipamezole for reversal

The effect of MK‐467, a peripheral α₂‐adrenoceptor antagonist, on plasma drug concentrations, sedation and cardiopulmonary changes induced by intramuscular (IM) medetomidine was investigated in eight sheep. Additionally, the interactions with atipamezole (ATI) used for reversal were also evaluated. Each animal was treated four times in a randomized prospective crossover design with 2‐week washout periods. Medetomidine (MED) 30 μg/kg alone or combined in the same syringe with MK‐467 300 μg/kg (MMK) was injected intramuscular, followed by ATI 150 μg/kg (MED + ATI and MMK + ATI) or saline intramuscular 30 min later. Plasma was analysed for drug concentrations, and sedation was subjectively assessed with a visual analogue scale. Systemic haemodynamics and blood gases were measured before treatments and at intervals thereafter. With MK‐467, medetomidine plasma concentrations were threefold higher prior to ATI, which was associated with more profound sedation and shorter onset. No significant differences were observed in early cardiopulmonary changes between treatments. Atipamezole reversed the medetomidine‐related cardiopulmonary changes after both treatments. Sedation scores decreased more rapidly when MK‐467 was included. In this study, MK‐467 appeared to have a pronounced effect on the plasma concentration and central effects of medetomidine, with minor cardiopulmonary improvement.     

Pharmacokinetics,tissue residues,and ex vivo pharmacodynamics of tylosin against Mycoplasma anatis in ducks

The pharmacokinetics of tylosin were investigated in 3 groups of ducks (n = 6). They received a single dose of tylosin (50 mg/kg) by intravenous (IV), intramuscular (IM), and oral administrations, respectively. Plasma samples were collected at various time points to 24 hr post-administration to evaluate tylosin concentration over time. Additionally, tylosin residues in tissues and its withdrawal time were assessed using 30 ducks which received tylosin orally (50 mg/kg) once daily for 5 consecutive days. After IV administration, the volume of distribution, elimination half-life, area under the plasma concentration–time curve, and the total body clearance were 7.07 ± 1.98 L/kg, 2.04 hr, 19.47 µg hr/ml, and 2.82 L hr⁻¹ kg⁻¹, respectively. After IM and oral administrations, the maximum plasma concentrations were 3.70 and 2.75 µg/ml achieved at 1 and 2 hr, and the bioavailability was 93.95% and 75.77%, respectively. The calculated withdrawal periods of tylosin were 13, 8, and 5 days for kidney, liver, and muscle, respectively. For the pharmacodynamic profile, the minimum inhibitory concentration for tylosin against M. anatis strain 1,340 was 1 µg/ml. The calculated optimal oral dose of tylosin against M. anatis in ducks based on the ex vivo pharmacokinetic/pharmacodynamic modeling was 61 mg kg⁻¹ day⁻¹.     

Effect of bupivacaine on epidural analgesia produced by xylazine or medetomidine in buffaloes (Bubalus bubalis)

ObjectiveTo evaluate and compare the effect of epidural bupivacaine on analgesia produced by epidural xylazine or medetomidine in buffaloes.Study designProspective, blinded study.AnimalsTen male buffalo calves (6-8 months of age; body weight 70-90 kg) were used on two occasions to conduct a total of 20 investigations.MethodsCaudal extradural analgesia was produced in four buffalo calves each by the injection of either xylazine (0.05 mg kg^?1), medetomidine (15 μg kg^?1) or 0.5% bupivacaine (0.125 mg kg^?1), or combinations of xylazine and bupivacaine (0.05 and 0.125 mg kg^?1), or medetomidine and bupivacaine (15 μg kg^?1 and 0.125 mg kg^?1) at the first intercoccygeal extradural space. Analgesia was tested using deep pinprick stimuli.ResultsExtradural administration of xylazine or medetomidine resulted in complete analgesia of the tail, perineum, inguinal region and the upper parts of the hind limbs, which was faster in onset and longer in duration in the medetomidine group than in the xylazine group. Addition of bupivacaine increased the intensity of the analgesia produced by xylazine, but not that produced by medetomidine. All the drugs caused mild to moderate ataxia, but signs of sedation were apparent only in animals which received xylazine or medetomidine. The extradural injections of all the drugs caused significant decrease in heart rate (p = 0.024), respiratory rate (p = 0.026) and rectal temperature (p = 0.036) from the respective baseline values, but the differences between the groups were not significant.ConclusionsMedetomidine produced a longer duration of analgesia than that produced by xylazine. Bupivacaine prolonged the analgesia produced by xylazine, but the analgesia produced by the combination of medetomidine and bupivacaine was not superior to that produced by medetomidine alone.Clinical relevanceBupivacaine may be used to prolong the extradural analgesia produced by xylazine, but not that produced by medetomidine in buffaloes.     

Sedative and cardiopulmonary effects of buprenorphine and xylazine in horses

This study investigated the sedative, cardiopulmonary, and gastrointestinal effects produced by buprenorphine and xylazine given in combination to horses. Six healthy adult horses underwent 4 randomized treatments, with an interval of 1 wk between treatments. A control group was given a saline solution intravenously (IV) and the experimental groups received buprenorphine [10 μg/kg bodyweight (BW)] in combination with 1 of 3 different doses of xylazine: 0.25 mg/kg BW (BX25), 0.50 mg/kg BW (BX50), or 0.75 mg/kg BW (BX75), all of them by IV. Cardiopulmonary parameters were evaluated for 120 min after the drugs were administered and intestinal motility was observed for 12 h after treatment. Sedation was found to be dose-dependent in all groups receiving buprenorphine and xylazine and it was observed that the heart rate decreased in the first 5 min and increased at the end of the sedation period. Arterial blood gas tension analyses showed minimal alterations during the experiment. Gastrointestinal hypomotility was observed for up to 8 h. The combination of buprenorphine and 0.50 mg/kg BW of xylazine (BX50) provided a 30-minute period of sedation without intense ataxia and maintained cardiopulmonary parameters within acceptable limits for the species.     

Cardiovascular effects of medetomidine, detomidine and xylazine in horses

The cardiovascular effects of medetomidine, detomidine, and xylazine in horses were studied. Fifteen horses, whose right carotid arteries had previously been surgically raised to a subcutaneous position during general anesthesia were used. Five horses each were given the following 8 treatments: an intravenous injection of 4 doses of medetomidine (3, 5, 7.5, and 10 microg/kg), 3 doses of detomidine (10, 20, and 40 microg/kg), and one dose of xylazine (1 mg/kg). Heart rate decreased, but not statistically significant. Atrio-ventricular block was observed following all treatments and prolonged with detomidine. Cardiac index (CI) and stroke volume (SV) were decreased with all treatments. The CI decreased to about 50% of baseline values for 5 min after 7.5 and 10 microg/kg medetomidine and 1 mg/kg xylazine, for 20 min after 20 microg/kg detomidine, and for 50 min after 40 microg/kg detomidine. All treatments produced an initial hypertension within 2 min of drug administration followed by a significant decrease in arterial blood pressure (ABP) in horses administered 3 to 7.5 microg/kg medetomidine and 1 mg/kg xylazine. Hypertension was significantly prolonged in 20 and 40 microg/kg detomidine. The hypotensive phase was not observed in 10 microg/kg medetomidine or detomidine. The changes in ABP were associated with an increase in peripheral vascular resistance. Respiratory rate was decreased for 40 to 120 min in 5, 7.5, and 10 microg/kg medetomidine and detomidine. The partial pressure of arterial oxygen decreased significantly in 10 microg/kg medetomidine and detomidine, while the partial pressure of arterial carbon dioxide did not change significantly. Medetomidine induced dose-dependent cardiovascular depression similar to detomidine. The cardiovascular effects of medetomidine and xylazine were not as prolonged as that of detomidine. KEY WORDS: cardiovascular effect, detomidine, equine, medetomidine, xylazine.     

Comparison of the clinical utility of medetomidine/ketamine and xylazine/ketamine combinations for the ovariectomy of cats

A controlled trial was conducted to assess suitability of combinations of medetomidine and ketamine for the ovariectomy of cats, to investigate the possible side effects, and to compare medetomidine/ketamine with a combination of xylazine and ketamine. Three hundred and thirty-seven cats were submitted to surgery; 100 were anaesthetised with 80 micrograms/kg medetomidine and 5 mg/kg ketamine, 137 with 80 micrograms/kg medetomidine and 7.5 mg/kg ketamine, and 100 were anaesthetised with 1 mg/kg xylazine and 10 mg/kg ketamine. The combinations were injected intramuscularly in the same syringe. The anaesthesia provided by the medetomidine/ketamine combinations was characterised by good muscle relaxation, good analgesia and minimal side effects. The only difference between the two doses of ketamine was the length of the period of anaesthesia. The advantages of the medetomidine/ketamine combination in comparison with xylazine/ketamine were the need for a lower dose of ketamine, a longer duration of action and better analgesia. Similar side effects were observed with both medetomidine/ketamine and xylazine/ketamine combinations.     

Behavioral and Cardiopulmonary Effects of a Constant Rate Infusion of Remifentanil–Xylazine for Sedation in Horses

Xylazine and remifentanil in constant rate infusion (CRI) could be used for sedation in horses without adverse effects. The objective was to evaluate behavioral and cardiopulmonary effects of an intravenous (IV) infusion of xylazine and remifentanil for sedation in horses. Xylazine (0.8 mg/kg IV) followed after 3 minutes by a CRI of xylazine and remifentanil (0.65 mg/kg/h and 6 μg/kg/h, respectively) was administered in 10 healthy horses for 60 minutes. Sedation, ataxia, and cardiopulmonary, hematological, and blood gases variables were evaluated. Heart rate decreased significantly during the first 25 minutes after CRI of xylazine and remifentanil, whereas the respiratory rate showed a significant decrease at 20 minutes and remained significantly low until the endpoint. There were no statistically significant fluctuations in blood arterial pressure, blood pH, partial pressure of arterial carbon dioxide, lactate, creatinine, calcium, chlorine, and sodium, compared with baseline values. Blood partial pressure of arterial oxygen and bicarbonate values were significantly higher compared with baseline values, whereas potassium decreased. Sedation and ataxia developed immediately after the administration of xylazine in all horses. All horses recovered successfully within 10 minutes after interruption of the CRI of xylazine and remifentanil, with no ataxia. No adverse effects were observed. The use of a combination of xylazine and remifentanil as sedation protocol has no adverse effects at the described dosage.     

Clinicophysiological Effects of Spinally Administered Ketamine and Its Combination with Xylazine and Medetomidine in Healthy Goats

The study was conducted in 9 healthy adult goats of either sex, weighing 15–20 kg, to evaluate and compare the clinicophysiological effects of spinally administered ketamine alone and in combination with xylazine and medetomidine. Nine trials each of the three treatments were conducted randomly by injecting ketamine (2.5 mg/kg) (n = 9), ketamine and xylazine (2.5 mg/kg and 0.05 mg/kg) (n = 9) and ketamine and medetomidine (2.5 mg/kg and 10 μg/kg) (n = 9). The drugs were administered at the lumbosacral subarachnoid space under strict aseptic conditions. The treatments were evaluated on the basis of clinicophysiological, haematological, biochemical and haemodynamic observations. Ketamine produced mild to moderate analgesia of the hindquarters. Its combination with either xylazine or medetomidine produced complete analgesia of the hindquarters for 45–60 min. Ataxia was moderate in the ketamine group, whereas animals attained sternal recumbency in the combination groups. A moderate degree of sedation was recorded in the combination groups. Heart rate and respiratory rate depression in the combination groups and heart rate and respiratory rate stimulation in ketamine group were recorded. Haematological parameters decreased in all the groups. Increase in serum glucose, creatinine and urea nitrogen was recorded in all the groups. Serum electrolytes did not show any significant change. The results showed that the combination of ketamine with xylazine or medetomidine at these dose rates produced a comparable degrees of analgesia of hindquarters with transient and minimal cardiopulmonary side effects.     

Clinical comparison of xylazine and medetomidine for premedication of horses

OBJECTIVE: To compare the analgesic and cardiopulmonary effects of medetomidine and xylazine when used for premedication of horses undergoing general anesthesia. DESIGN: Randomized clinical trial. ANIMALS: 40 horses. PROCEDURE: Twenty horses were premedicated with medetomidine (10 microg/kg [4.5 microg/lb], i.m.) and the other 20 were premedicated with xylazine (2 mg/kg [0.9 mg/kg], i.m.). Horses were then anesthetized with a combination of guaifenesin and ketamine; anesthesia was maintained with halothane. Additional doses of medetomidine or xylazine were given if horses were not sufficiently sedated at the time of anesthetic induction. After induction of anesthesia, sodium pentothal was administered as necessary to prevent limb movements. Hypotension was treated with dobutamine; hypoventilation and hypoxemia were treated with intermittent positive-pressure ventilation. The quality of anesthetic induction, maintenance, and recovery and the quality of the transition to inhalation anesthesia were scored. RESULTS: Scores for the quality of the transition to inhalation anesthesia were significantly higher for horses premedicated with medetomidine than for horses premedicated with xylazine. However, other scores, recovery times, and numbers of attempts needed to achieve sternal recumbency and to stand were not significantly different between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that medetomidine is suitable for premedication of horses undergoing general anesthesia. Analgesic and cardiopulmonary effects of medetomidine were similar to those of xylazine, except that the transition to inhalation anesthesia was smoother when horses were premedicated with medetomidine, rather than xylazine.     

Medetomidine/ketamine sedation in calves and its reversal with atipamezole

Atipamezole was used to reverse the sedation induced in calves by medetomidine/ketamine. Thirteen claves subjected to umbilical surgery received medetomidine 20 μg/kg bodyweight (bwt) and ketamine 0.5 mg/kg bwt intravenously (iv) from a mixture of the drugs in one syringe. Atipamezole was given at doses of 20 to 60 μg/kg iv and intramuscularly (im) to the calves at the end of the operation. Following the administration of medetomidine and ketamine, PaCO₂ increased whereas pH, PaO₂ and heart rate decreased. Reversing the effects of medetomidine with atipamezole did not cause undesirable effects; recovery was rapid and smooth, most of the animals reached a standing position within 1 to 3 mins after the atipamezole injection.     

Effects of xylazine, medetomidine, detomidine, and diazepam on sedation, heart and respiratory rates, and cloacal temperature in rock partridges (Alectoris graeca).

In this study, heart and respiratory rates, cloacal temperature, and quality of sedation were evaluated before (0 min) and after (10, 20, and 30 min) i.m. administration of xylazine (10 mg/kg; n = 7), medetomidine (75 li; n = 6), detcmidine (0.3 mg/kg; n = 6), or diazepam (6 mg/kg; n = 7) in rock partridges (Alectoris graeca). All partridges recovered from sedation without any disturbance. Xylazine and diazepam administration did not induce significant changes in heart rate, which did decrease significantly after medetomidine and detomidine administration (P < 0.001). Mean respiratory rate was decreased dramatically at 20 and 30 min after xylazine (P < 0.001) and medetomidine (P < 0.005) administration, and at all stages of sedation after detomidine injection (P < 0.001), whereas there was not any significant change after diazepam injection. In all groups, cloacal temperature measured at 10, 20, and 30 min tended to decrease compared with baseline values. Sedative effects of the drugs started within 2.1+/-0.2 min for detomidine, 2.6 +/- 0.4 min for diazepam, 3.1 -+/-.4 min for xylazine, and 4.8+/-0.8 min for medetomidine application. There was an extreme variability in time to recovery for each drug: 205 +/-22.2 min for xylazine, 95 -12.2 min for medetomidine, 260+/-17.6 min for detomidine, and 149 + 8.3 min for diazepam. In conclusion, xylazine, medetomidine, detomidine, and diazepam produced sedation, which could permit some clinical procedures such as handling and radiographic examination of partridges to occur. Of the four drugs, xylazine produced stronger and more efficient sedation compared to the others, which could permit only minor procedures to be performed. However, depending on the drug used, monitoring of heart and respiratory rates and cloacal temperature might be required.     

Glucose and insulin response after intravenous and subcutaneous somatostatin administration in healthy horses

Equine metabolic syndrome (EMS) is prevalent in the equine population, and somatostatin analogs might be useful for diagnosis and/or treatment of EMS in horses. The purpose of this study was to evaluate the glucose and insulin responses to subcutaneous and intravenous administration of somatostatin. Six healthy research horses were included in this prospective study. An initial pilot study was performed to assess several different doses (10–22 µg/kg [4.5–10 µg/lb]) in two horses, then a final dosage of 22 µg/kg (10 µg/lb) was administered to six horses IV and SQ in a two‐period randomized cross‐over study performed over a 3‐month study period. Blood samples were collected for measurement of plasma insulin and glucose concentrations during a 24‐hr study period. Both IV and SQ somatostatin resulted in decreased insulin and increased glucose concentrations. SQ somatostatin resulted in a longer clinical effect, with return to baseline insulin occurring at 1.5 hr postadministration, versus 45 min for IV. Both IV and SQ administration of somatostatin to normal horses resulted in decreased insulin and increased glucose concentrations, likely due to suppression of insulin secretion by somatostatin. A more prolonged effect was seen following SQ administration as compared to IV administration, and no adverse effects were noted at varying doses. This study provides additional information regarding the effect of somatostatin administration on insulin and glucose concentrations in clinically healthy horses.     

Medetomidine, a new sedative-analgesic for use in the dog and its reversal with atipamezole

The sedative and physiological effects of intramuscular medetomidine (20 and 40 μg/kg) in dogs were compared with those of xylazine (2 mg/kg). The efficacy of atipamezole (200 μg/kg), as an antagonist given 15 or 45 minutes after medetomidine (40 μg/kg) was studied. Following medetomidine, onset of sedation was rapid, and depth and duration of sedation were dose dependent. The higher dose produced jaw relaxation, depression of the pedal reflex, downward rotation of the eye and dogs could be positioned for radiography of the hips. Side effects were similar after either medetomidine or xylazine, and included bradycardia, a fall in respiratory rate and muscle tremor. Vomiting during induction was less frequent after medetomidine than after xylazine. Intramuscular administration of atipamezole rapidly reversed the sedative effects of medetomidine. Signs of arousal were seen within three minutes; all dogs could stand within 10 minutes and appeared clinically normal. Heart and respiratory rates rose, but did not return to presedation values. Relapse to sedation was not noted.     

ACE inhibition in goats under fixed‐time artificial insemination protocol increases the pregnancy rate and twin births

To assess the effect of the angiotensin‐converting enzyme (ACE) inhibition on the efficiency of the fixed‐time artificial insemination (TAI), 69 goats were divided randomly into two groups: enalapril (n = 35) and control (n = 34). In the experiment, all animals underwent the protocol of fixed‐time artificial insemination for 12 days. Enalapril group received enalapril maleate dissolved in saline (Enalapril, Lab Teuto Ltda) subcutaneously at the following doses: 0.2 mg/kg/day in D0‐D2; 0.3 mg/kg/day in D3‐D6 and 0.4 mg/kg/day in D7‐D11. The control group received the corresponding volume of 0.9% saline solution. We performed a single insemination 36 hr after sponge removal using frozen semen from two adult male goats with recognized fertility. The ultrasound pregnancy diagnosis was 30 days after the artificial insemination (AI). There was significant increase in pregnancy rates and twinning as well as a decrease in foetal loss in animals receiving enalapril (p < .01). The use of ACE inhibitors during the TAI protocol was shown to be a promising alternative to increase the efficiency of such reproductive biotechnology.     

Comparison of intraoperative cardiorespiratory and behavioral responses to medetomidine combined with tramadol or butorphanol during standing laparoscopic ovariectomy in horses

The purpose of this study was to assess the cardiorespiratory and behavioral responses to the combination of medetomidine and tramadol (M-T) or butorphanol (M-B) in standing laparoscopic ovariectomy in horses. One ovary was removed under M-T and the contralateral ovary was removed under M-B with at least 4 weeks between operations at random. Horses were sedated using intravenous medetomidine (5 µg/kg) followed by tramadol (1 mg/kg) or butorphanol (10 µg/kg) after 5 min. Sedation was maintained through the repeated injection of medetomidine (1 µg/kg) and tramadol (0.4 mg/kg) or medetomidine (1 µg/kg) and butorphanol (4 µg/kg) every 15 min. Cardiorespiratory function and behavioral responses, including, sedation, ataxia, and analgesia, were assessed during the surgery. There were no significant differences in cardiorespiratory values and sedation and analgesia scores between M-T and M-B. Ataxia scores were significantly lower in M-T than in M-B. This result suggests that M-T could maintain smooth and stable standing surgery with minimal cardiorespiratory changes in horses.