Objective-To determine the pharmacokinetic disposition of IV administered caffeine in healthy Lama spp camelids. Animals-4 adult male alpacas and 4 adult female llamas. Procedures-Caffeine (3 mg/kg) was administered as an IV bolus. Plasma caffeine concentrations were determined by use of high-performance liquid chromatography in 6 animals and by use of liquid chromatography-mass spectrometry in 2 llamas. Results-Median elimination half-life was 11 hours (range, 9.3 to 29.8 hours) in alpacas and 16 hours (range, 5.4 to 17 hours) in llamas. The volume of distribution at steady state was 0.60 L/kg (range, 0.45 to 0.93 L/kg) in alpacas and 0.75 L/kg (range, 0.68 to 1.15 L/kg) in llamas. Total plasma clearance was 44 mL/h/kg (range, 24 to 56 mL/h/kg) in alpacas and 42 mL/h/kg (range, 30 to 109 mL/h/kg) in llamas. Conclusions and Clinical Relevance-High-performance liquid chromatography and liquid chromatography-mass spectrometry were suitable methods for determination of plasma caffeine concentrations in alpacas and llamas. Plasma caffeine concentration-time curves were best described by a 2-compartment model. Elimination half-lives, plasma clearance, volume of distribution at steady state, and mean residence time were not significantly different between alpacas and llamas. Intravenous administration of caffeine at a dose of 3 mg/kg did not induce clinical signs of excitement.

Objective-To determine the effects of meloxicam and butorphanol on minimum alveolar concentration of isoflurane (MAC(ISO)) in rabbits. Animals-10 healthy young adult female rabbits. Procedure-Rabbits were anesthetized with isoflurane on 3 occasions in a blinded, randomized complete block design to determine the MAC(ISO) associated with administration of meloxicam (0, 0.3, or 1.5 mg/kg, PO) and butorphanol (0.4 mg/kg, IV). The MAC(ISO) was determined by use of a paw clamp technique as the end-tidal concentration of isoflurane halfway between the values that allowed or inhibited purposeful movement. Rectal temperature, end-tidal CO2 concentration, heart rate, oxygen saturation, and arterial blood pressure were measured to evaluate cardiopulmonary function. Results-Mean +/- SE MAC(ISO) in saline (0.9% NaCl) solution-treated rabbits was 2.49 +/- 0.07% and was not significantly different from that associated with administration of meloxicam at 0.3 mg/kg (2.56 +/- 0.07%) or 1.5 mg/kg (2.66 +/- 0.07%). Butorphanol significantly reduced the MAC(ISO) to 2.30 +/- 0.07% when administered with saline solution alone, 2.27 +/- 0.07% when administered with 0.3 mg of meloxicam/kg, and 2.33 +/- 0.07% when administered with 1.5 mg of meloxicam/kg. The percentage reduction in MAC(ISO) was significantly greater for rabbits that received butorphanol and meloxicam at either dose, compared with butorphanol and saline solution. Conclusions and Clinical Relevance-Results indicated that meloxicam does not have a direct isoflurane-sparing effect and does not interfere with the anesthetic-sparing effect of butorphanol in rabbits.

Objective-To evaluate the efficacy and safety of intra-articular administration of ethyl alcohol for arthrodesis of tarsometatarsal joints in horses. Animals-8 healthy female horses without lameness or radiographic evidence of tarsal joint osteoarthritis. Procedure-In each horse, 1 tarsometatarsal joint was treated with 4 mL of 70% ethyl alcohol and the opposite joint was treated with 4 mL of 95% ethyl alcohol. Lameness examinations were performed daily for 2 weeks, followed by monthly evaluations for the duration of the 12-month study. Radiographic evaluations of both tarsi were performed 1 month after injection and every 3 months thereafter. Gross and histologic examinations of the tarsi were undertaken at completion of the study. Results-Horses had minimal to no lameness associated with the treatments. Radiography revealed that 8 of 16 joints were fused by 4 months after treatment, with significantly more joints fused in the 70% ethyl alcohol group. Fifteen of 16 joints were considered fused at postmortem examination at 12 months. Gross and histologic examinations revealed foci of dense mature osteonal bone spanning the joint spaces. Bony fusion appeared to be concentrated on the dorsolateral, centrolateral, and plantarolateral aspects of the joints. Significant differences were not detected between treatment groups for lameness or pathologic findings. Conclusions and Clinical Relevance-Administration of ethyl alcohol into the tarsometatarsal joint of healthy horses appeared to facilitate arthrodesis of the joint in a pain-free manner. Results warrant further investigation into the potential use of ethyl alcohol in horses clinically affected with osteoarthritis of the tarsometatarsal and distal intertarsal joints.

Objective-To evaluate the effect of medetomidine on minimum alveolar concentration (MAC), respiratory rate, tidal volume, minute volume (V(M)), and maximum inspiratory occlusion pressure (IOCP(max)) in halothane- and isoflurane-anesthetized dogs. Animals-6 healthy adult dogs (3 males and 3 females). Procedure-The MAC of both inhalants was determined before and 5, 30, and 60 minutes after administration of medetomidine (5 microgram/kg, IV). Dogs were subsequently anesthetized by administration of halothane or isoflurane and administered saline (0.9% NaCl) solution IV or medetomidine (5 microgram/kg, IV). Respiratory variables and IOCP(max) were measured at specific MAC values 15 minutes before and 5, 30, and 60 minutes after IV administration of medetomidine while dogs breathed 0% and 10% fractional inspired carbon dioxide (FICO2). Slopes of the lines for V(M)/FICO2 and IOCP(max)/FICO2 were then calculated. Results-Administration of medetomidine decreased MAC of both inhalants. Slope of V(M)/FICO2 increased in dogs anesthetized with halothane after administration of medetomidine, compared with corresponding values in dogs anesthetized with isoflurane. Administration of medetomidine with a simultaneous decrease in inhalant concentration significantly increased the slope for V(M)/FICO2, compared with values after administration of saline solution in dogs anesthetized with halothane but not isoflurane. Values for IOCP(max) did not differ significantly between groups. Conclusions and Clinical Relevance-Equipotent doses of halothane and isoflurane have differing effects on respiration that are most likely attributable to differences in drug effects on central respiratory centers. Relatively low doses of medetomidine decrease the MAC of halothane and isoflurane in dogs.

Objective-To biomechanically and histologically compare single-layer continuous Cushing and simple continuous appositional cystotomy closure in rats with xylene-induced cystitis. Animals-40 female Sprague-Dawley rats. Procedure-Rats were anesthetized, their urinary bladders catheterized and evacuated, and xylene instilled in each bladder for 5 minutes and then aspirated. Forty-eight hours later, ventral midline celiotomy and cystotomy (8 mm) were performed. Cystotomies were closed with 6-0 poliglecaprone 25 by use of a single-layer continuous Cushing or simple continuous appositional pattern (20 rats/group), and cystotomy times were recorded. Rats were allocated to healing durations (5 rats/group) of 0, 3, 7, and 14 days. Celiotomies were closed in a routine manner. After the allotted healing interval, another celiotomy was performed, the urethra cannulated, and ureters ligated. The cannula was secured to the urethra, and the bladder infused at 0.1 mL/min. Leak pressure volume, leak pressure, peak pressure volume, and peak pressure were recorded via a pressure transducer. Bladders were harvested and histologically assessed. Results-Cystotomy time, biomechanical testing values, and overall inflammation scores did not differ between closure methods for any healing duration. Both methods had significantly greater leak pressures, with the appositional method also having significantly greater peak pressures on day 7, compared to day 0. Biomechanical testing values decreased from day 7 to 14 as a result of juxtaincisional weakening of the bladder and xylene-induced changes in collagen. Conclusions and Clinical Relevance-Simple continuous appositional was equal biomechanically and histologically to continuous Cushing for all comparison variables. Poliglecaprone 25 was acceptable for cystotomy closure.