Research in veterinary science
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Near infrared spectroscopy (NIRS) was used to detect changes in brain oxygenation in five tranquilised calves that were placed on a hypoxic gas mixture (10 per cent O2/90 per cent N2) and hyperoxic gas mixture (30 per cent O2/70 per cent N2) for five minutes at each concentration. A NIRO 500 (Hamamatsu, Japan) was used for the NIRS, with the incident light source and separate detector (optodes) placed on shaved skin on the most dorsal surface of the frontal bone. Sequential arterial blood gas sample analyses provided confirmation of the appropriate change in systemic oxygenation status. ⋯ The accompanying arterial blood gas changes included significant increases in PaO2 (30.9 mmHg, P<0.05), arterial O2 saturation (11.7 per cent, P<0.05), and significantly decreased pH (-0.026, P<0.05). This study showed that NIRS can be used to continuously and non-invasively detect cerebral oxygenation changes in the live calf in response to both increased and decreased systemic arterial oxygen. Additionally, despite induction of profound hypoxaemia, cytochrome aa3 in the brain did not appear to become reduced.
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Comparative Study
A comparison of the neuromuscular and cardiovascular effects of vecuronium, atracurium and mivacurium in sheep.
Neuromuscular and cardiovascular effects of vecuronium, atracurium and mivacurium were compared in 45 sheep. The onset and duration of neuromuscular block produced with loading doses of vecuronium (25 microg kg(-1)), atracurium (500 microg kg(-1)) and mivacurium (200 microg kg(-1)) and maintained with incremental doses (7, 170 and 70 microg kg(-1), respectively) were monitored using train-of-four stimulation of the n. facialis-m. levator nasolabialis unit. The electrocardiogram, heart rate and arterial blood pressure were recorded during onset of neuromuscular blockade. ⋯ Cardiac dysrrhythmias were not observed in any group. Atracurium and mivacurium produced intermediate- and short-duration neuromuscular blockade, respectively. Vecuronium produced a prolonged effect after a slow onset.
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Comparative Study
A comparison of edrophonium and neostigmine for the reversal of mivacurium-induced neuromuscular blockade in sheep.
The rate of reversal of neuromuscular block was compared in 36 sheep receiving either edrophonium (500 microg kg(-1)) and atropine (80 microg kg(-1)), neostigmine (50 microg kg(-1)) and atropine (80 microg kg(-1)) or saline (10 ml), using the train of four count (TO4C) recorded at n. facialis-m. levator nasolabialis. Neuromuscular block was produced with mivacurium (200 microg kg(-1)) followed later by a single incremental dose of 70 microg kg(-1). Antagonists or saline were given when spontaneous recovery from the incremental dose (TO4C = 1) had begun. ⋯ The TO4C was 4 in all animals five minutes after edrophonium, and seven minutes after neostigmine; differences were not statistically significant. The TO4C was significantly higher with edrophonium two and three minutes after antagonism compared with saline. The data show that spontaneous recovery from mivacurium is rapid in sheep, although reversal is accelerated by anticholinesterase drugs.
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Haemostatic alterations in dogs experimentally infected with Leishmania infantum were studied before and after therapy with meglumine antimonate. Haemostatic function tests including platelet count, collagen-induced platelet aggregation, prothrombin time, activated partial thromboplastin time, thrombin time, plasma fibrinogen determination, and serum fibrinogen/fibrin degradation products concentration were performed. ⋯ Haemostatic parameters returned to normal values after therapy. The results indicate that Leishmania infection may impair haemostasis suggesting induction of disseminated intravascular coagulation (DIC), and that treating dogs in an early stage of infection may potentially avoid the possibility of developing an uncompensated DIC.
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The aim of this study was to determine cardiac contractility using indices derived from cardiac catheterisation in conscious healthy dogs during dobutamine infusion. Eight dogs were studied. An ECG was recorded together with left ventricular pressure and volume which were measured using a conductance catheter with an integrated microtip pressure sensor. ⋯ All these six indices were significantly correlated with each other. Conversely, the ratio PEP/LVET and the LVET corrected for heart rate dependency showed a maximal percentage change of only -10+/-1 per cent and -16+/-7 per cent, respectively, during the dobutamine infusion and were not significantly correlated with the other contractility indices. This study demonstrated the feasibility of the conductance method to determine cardiac contractility in conscious healthy dogs submitted to a pharmacological stress testing and provides control values for eight indices of left ventricular contractility during dobutamine infusion at increasing dosages.