Pharmacokinetics and physiologic/behavioral effects of buprenorphine administered sublingually and intravenously to neonatal foals.

Buprenorphine is absorbed following sublingual administration, which would be a low-stress delivery route in foals. However, the pharmacokinetics/pharmacodynamics are not described in foals. Six healthy foals <21 days of age participated in a blinded, randomized, 3-period, 5-sequence, 3-treatment crossover prospective study. Foals received 0.01-0.02 mg/kg buprenorphine administered SL or IV with an equivalent volume of saline administered by the opposite route. Blood was collected from the cephalic vein for pharmacokinetic analysis. Physiologic parameters (HR, RR, body temperature, GI sounds), locomotion (pedometer), and behavioral data (activity level, nursing time, response to humans) were recorded. Plasma concentration of buprenorphine exceeded a presumed analgesic level (0.6 ng/ml) in five foals in the IV group and one in the SL group but only for a very brief time. Pharmacokinetic analysis following IV administration demonstrated a short elimination half-life (t1/2ß 1.95 ± 0.7 hr), large volume of distribution (6.46 ± 1.54 L/kg), and a high total clearance (55.83 ± 23.75 ml/kg/min), which differs from adult horses. Following SL administration, maximum concentrations reached were 0.61 ± 0.11 ng/ml and bioavailability was 25.1% ± 10.9%. In both groups, there were minor statistical differences in HR, RR, body temperature, locomotion, and time spent nursing. However, these differences were clinically insignificant in this single dose study, and excitement, sedation, or colic did not occur.

Comparison of Enterprise Point-of-Care and Nova Biomedical Critical Care Xpress analyzers for determination of arterial pH, blood gas, and electrolyte values in canine and equine blood.

BACKGROUND: Point-of-care analyzers can provide a rapid turnaround time for critical blood test results. Agreement between the Enterprise Point-of-Care (EPOC) and bench-top laboratory analyzers is important to determine the clinical reliability of the EPOC. OBJECTIVES: The aim of the study was (1) to evaluate the precision (repeatability) of blood gas values measured by the EPOC and (2) to determine the level of agreement between the EPOC and Nova Critical Care Express (Nova CCX) for the assessment of arterial pH, blood gases, and electrolyte variables in canine and equine blood. METHODS: Arterial blood samples from dogs were analyzed on the EPOC and Nova CCX analyzers to determine precision and agreement of pH, PaCO2 , PaO2 , and HCT. The same analytes plus Na+ , K- , and Cl- were analyzed for agreement using equine blood. Statistical analyses included assessment of precision using the coefficient of variation (CV%), and agreement using the Deming regression, Pearson correlation, and Bland-Altman plots. RESULTS: Both analyzers provided precise results of pH, PaCO2 , PaO2, and HCT, meeting CV% quality requirement values. In both species, Deming regression results were acceptable and correlation values were above 0.93 for arterial pH and blood gases, but lower for sodium and chloride. Bland-Altman plots demonstrated varying degrees of bias, but good agreement between the 2 analyzers was seen when arterial blood gases and electrolytes were measured, except for PaCO2 and Cl-. CONCLUSION: The EPOC analyzer provides consistent, reliable results for canine arterial blood gas values and for equine arterial blood gas and electrolyte values. Cl- results could be acceptable with the application of a correction factor, but the PaCO2 results were more variable.

Cardiorespiratory Changes and Pain Response of Lift Laparoscopy Compared to Capnoperitoneum Laparoscopy in Dogs.

OBJECTIVE: To compare intraoperative physiologic variables and post-operative pain associated with lift laparoscopy and conventional capnoperitoneum laparoscopy. STUDY DESIGN: Prospective randomized case controlled study. ANIMALS: Healthy dogs (n = 30). METHODS: Dogs having laparoscopic ovariohysterectomy were randomly assigned to lift laparoscopy (n = 14) or capnoperitoneum (16) laparoscopy. Physiologic variables measured intraoperatively were documented. Postoperatively, pain response was assessed in a blinded fashion using the short Glasgow pain scale and von Frey filament aesthesiometry. RESULTS: Lift laparoscopy was associated with less frequency of hypercapnia, required less anesthetic gas, and was not more time-consuming or painful than capnoperitoneum laparoscopy. CONCLUSIONS: Lift laparoscopy is a feasible alternative to capnoperitoneum laparoscopy, especially in dogs where pressurized capnoperitoneum is not desired.

Effects of intratesticular injection of bupivacaine and epidural administration of morphine in dogs undergoing castration.

OBJECTIVE: To determine the intraoperative and postoperative analgesic efficacy of intratesticular or epidural injection of analgesics for dogs undergoing castration. DESIGN: Randomized controlled trial. ANIMALS: 51 healthy male dogs. PROCEDURES: Dogs were assigned to a control group that received analgesics systemically (hydromorphone [0.1 mg/kg {0.045 mg/lb}, IM] and carprofen [4.4 mg/kg {2.0 mg/lb}, SC]; n = 17), an epidural treatment group that received analgesics systemically and morphine (0.1 mg/kg) epidurally (17), or an intratesticular treatment group that received analgesics systemically and bupivacaine (0.5 mg/kg [0.23 mg/lb]/testis) intratesticularly (17). Dogs were anesthetized and castrated by veterinary students. Responses to surgical stimulation were monitored intraoperatively, and treatments were administered as required. Pain scores were assigned via a modified Glasgow composite pain scale after surgery. Serum cortisol concentrations were determined at various times. Rescue analgesia included fentanyl (intraoperatively) and hydromorphone (postoperatively). RESULTS: Compared with control dogs, dogs in the intratesticular bupivacaine and epidural morphine treatment groups received significantly fewer doses of fentanyl intraoperatively (11, 1, and 5 doses, respectively) and hydromorphone postoperatively (14, 7, and 3 doses, respectively) and had significantly lower postoperative pain scores (mean ± SEM score at first assessment time, 71 ± 0.5, 4.8 ± 0.2, and 4.5 ± 0.4, respectively). At 15 minutes after removal of the testes, serum cortisol concentrations were significantly higher than they were immediately prior to surgery for all groups and values for the intratesticular bupivacaine treatment group were significantly lower versus the other 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Intratesticular or epidural injection of analgesics improved perioperative analgesia for dogs undergoing castration.

Cardiovascular and respiratory effects, and quality of anesthesia produced by alfaxalone administered intramuscularly to cats sedated with dexmedetomidine and hydromorphone.

The cardiovascular and respiratory effects, and the quality of anesthesia of alfaxalone administered intramuscularly (IM) to cats sedated with dexmedetomidine and hydromorphone were evaluated. Twelve healthy adult cats were anesthetized, with six cats receiving dexmedetomidine (0.01 mg/kg IM) followed by alfaxalone (5 mg/kg IM; group DA) and six receiving dexmedetomidine (0.01 mg/kg IM) plus hydromorphone (0.1 mg/kg IM) followed by alfaxalone (5 mg/kg IM; group DHA). Cardiorespiratory (pulse rate, blood pressure, respiratory rate, saturation of oxygen with hemoglobin, end tidal carbon dioxide partial pressure) and bispectral index (BIS) data were collected every 10 mins for 90 mins starting immediately after intubation. The quality of anesthesia was scored by a blinded researcher at induction and at 5 and 60 mins after extubation. Recovery scores ranged from 1 (prolonged struggling) to 4 (no struggling). There were no clinically significant (P >0.05) differences in any data between groups or over time. Physiologic parameters were within normal limits for cats at all times. BIS values were consistent with light anesthesia in both groups. However, recovery was prolonged and marked with excitement, ataxia and hyper-reactivity in all cats. Thus, although cardiovascular and respiratory parameters are stable following IM injection of alfaxalone to cats sedated with dexmedetomidine and hydromorphone, recovery is extremely poor and this route of administration is not recommended for anesthesia in cats.

Effects of 6% hetastarch (600/0.75) or lactated Ringer's solution on hemostatic variables and clinical bleeding in healthy dogs anesthetized for orthopedic surgery.

OBJECTIVE: To evaluate and compare hemostatic variables and clinical bleeding following the administration of 6% hetastarch (600/0.75) or lactated Ringer's solution (LRS) to dogs anesthetized for orthopedic surgery. STUDY DESIGN: Randomized blinded prospective study. ANIMALS: Fourteen, healthy adult mixed-breed hound dogs of either sex, aged 11-13 months, and weighing 20.8±1.2 kg. METHODS: The dogs were randomly assigned to receive a 10 mL kg(-1) intravenous (i.v.) bolus of either 6% hetastarch (600/0.75) or LRS over 20 minutes followed by a maintenance infusion of LRS (10 mL kg(-1)  hour(-1)) during anesthesia. Before (Baseline) and at 1 and 24 hours after bolus administration, packed cell volume (PCV), total protein concentration (TP), prothrombin time (PT), activated partial thromboplastin time (APTT), von Willebrand's factor antigen concentration (vWF:Ag), factor VIII coagulant activity (F VIII:C), platelet count, platelet aggregation, colloid osmotic pressure (COP) and buccal mucosal bleeding time (BMBT) were measured. In addition a surgeon who was blinded to the treatments assessed bleeding from the incision site during the procedure and at 1 and 24 hours after the bolus administration. RESULTS: Following hetastarch or LRS administration, the PCV and TP decreased significantly 1-hour post-infusion. APTT did not change significantly compared to baseline in either treatment group, but the PT was significantly longer at 1-hour post-infusion than at 24 hours in both groups. No significant change was detected for vWF:Ag, FVIII:C, platelet aggregation or clinical bleeding in either group. The BMBT increased while platelet count decreased significantly at 1-hour post-infusion in both groups. The COP decreased significantly in both treatment groups 1-hour post-infusion but was significantly higher 1-hour post-infusion in the hetastarch group compared to the LRS group. CONCLUSIONS AND CLINICAL RELEVANCE: At the doses administered, both hetastarch and LRS can alter hemostatic variables in healthy dogs. However, in these dogs undergoing orthopedic surgery, neither fluid was associated with increased clinical bleeding.