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- Author or Editor: Chris J. Jones x
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Abstract
Objective—To evaluate cyclooxygenase (COX) selectivity of several nonsteroidal anti-inflammatory drugs (NSAID) in canine blood in vitro.
Animals—11 healthy adult male hound crosses.
Procedure—9 NSAID were studied at 5 concentrations. Thromboxane B2 (TxB2) was assayed as a measure of COX-1 activity in clotted blood. Prostaglandin E2 (PGE2) was assayed as a measure of COX-2 activity in heparinized, lipopolysaccharide (LPS)-stimulated blood. All assays were competitive ELISA tests. Cyclooxygenase selectivity was expressed as a ratio of the concentration of an NSAID that inhibited 50% of the activity (IC50) of COX-1 to the IC50 of COX-2. A separate ratio of the concentration that inhibited 80% of COX activity (IC80) was also determined. A ratio of < 1.0 indicated selectivity for COX-1, whereas a ratio of > 1.0 indicated COX-2 selectivity.
Results—Ketoprofen, aspirin, and etodolac were COX-1 selective. Piroxicam, meloxicam, and carprofen had COX-2 selectivity. The IC50 and IC80 values were similar for most NSAID.
Conclusion and Clinical Relevance—This methodology provides repeatable data from individual dogs and is comparable to results of previous in vitro and ex vivo models. Findings are also consistent with those of canine studies performed in vivo, suggesting that this is a viable in vitro assessment of the COX selectivity of NSAID in dogs. (Am J Vet Res 2002;63:91–94)
Abstract
Objective—To assess the suitability of lithium dilution as a method for measuring cardiac output in anesthetized horses, compared with thermodilution and transesophageal Doppler echocardiography.
Animals—6 horses (3 Thoroughbreds, 3 crossbreeds).
Procedure—Cardiac output was measured in 6 anesthetized horses as lithium dilution cardiac output (LiDCO), thermodilution cardiac output (TDCO), and transesophageal Doppler echocardiographic cardiac output (DopplerCO). For the LiDCO measurements, lithium chloride was administered IV, and cardiac output was derived from the arterial lithium dilution curve. Sodium nitroprusside, phenylephrine hydrochloride, and dobutamine hydrochloride were used to alter cardiac output. Experiments were divided into 4 periods. During each period, 3 LiDCO measurements, 3 DopplerCO measurements, and 3 sets of 3 TDCO measurements were obtained.
Results—70 comparisons were made between LiDCO, DopplerCO, and triplicate TDCO measurements over a range of 10 to 43 L/min. The mean (± SD) of the differences of LiDCO – TDCO was –0.86 ± 2.80 L/min; LiDCO = –1.90 + 1.05 TDCO (r = 0.94). The mean of the differences of DopplerCO – TDCO was 1.82 ± 2.67 L/min; DopplerCO = 2.36 + 0.98 TDCO (r = 0.94). The mean of the differences of LiDCO – DopplerCO was –2.68 ± 3.01 L/min; LiDCO = –2.53 + 0.99 DopplerCO (r = 0.93).
Conclusions and Clinical Relevance—These results indicate that lithium dilution is a suitable method for measuring cardiac output in horses. As well as being accurate, it avoids the need for pulmonary artery catheterization and is quick and safe to use. Monitoring cardiac output during anesthesia in horses may help reduce the high anesthetic mortality in this species. (Am J Vet Res 2000;61:731–737)
