Mantle values of thermal conductivity and the geotherm from phonon lifetimes

A model for thermal conductivity kappa, based on phonon lifetimes obtained from infrared reflectivity, replicates experimental data at ambient conditions. The pressure and absolute temperature dependences of transport properties are accurately obtained from the Gruneisen parameter gammaTh, bulk modulus KT, and thermal expansivity alpha: The lattice contribution kappalat equals kappa298(298/T)a exp[-(4gammaTh + 1/3) integral298Talpha(theta)dtheta] with a = 0.33 for silicates (or 0.9 for MgO), and partial differential[ln(kappalat)]/ partial differentialP = (1/3 + 4gammaTh)/KT. The smaller, pressure-independent radiative contribution kapparad equals 0.0175 - 0.0001037T + (2.245T2/10(7)) - (3.407T3/10(11)), in units of watts per meter-kelvin, if Fe2+ is present. The resulting lithospheric geotherm is steep. Consequently, the mantle geotherm is hot if the low-velocity zone is anhydrous, but cold if hydrated.     

Opioid dysphoria in three dogs

Objective: To describe the clinical manifestations and response to management of opioid dysphoria in 3 dogs. Case summary: Three dogs being managed for post‐operative pain were evaluated. All 3 dogs had been managed with various opioids including morphine, hydromorphone, and fentanyl following the surgical procedure. The 3 dogs exhibited vocalization that did not respond to interaction and did not change with administration of analgesic and anxiolytic agents. The dogs were treated with naloxone and, within 5 minutes of its administration, ceased vocalizing, and became aware and interactive with their environment. Further pain management consisted of non‐steroidal anti‐inflammatory medications, alpha‐2 (α₂) receptor agonists or the partial μ‐receptor opioid agonist, buprenorphine. New and unique information provided: Vocalization and lack of response to interaction with humans are clinical signs which can be seen in dogs with opioid dysphoria, and generally are not responsive to analgesics or sedation. Reversal with naloxone results in rapid resolution of vocalization and opioid‐induced dysphoria.     

Systematic review of clinical trials of treatments for osteoarthritis in dogs

OBJECTIVE: To identify and critically evaluate the quality of evidence of the most commonly used pharmacologic, nutraceutical, and purported slow-acting drugs of osteoarthritis for the management of osteoarthritis in dogs by use of the FDA's evidence-based medicine scoring system. DESIGN: Systematic review. SAMPLE POPULATION: 16 clinical trials. PROCEDURES: A broad bibliographic search was performed prior to May 2006. Inclusion criteria focused on prospective trials evaluating commonly used medical treatment interventions for the management of osteoarthritis in dogs and published in peer-reviewed journals. The analysis consisted of the following: study design rating, quality factor rating, quantity rating, consistency rating, relevance to disease risk reduction rating, and cumulative strength of evidence ranking. RESULTS: 4 trials evaluating meloxicam were rated as type I. Three trials evaluating carprofen were rated as type I, and 2 trials were rated as type III. One trial evaluating each of the following agents was rated as type 1: etodolac; P54FP; polysulfated glycosaminoglycan; and a combination of chondroitin sulfate, glucosamine hydrochloride, and manganese ascorbate. Two trials evaluating pentosan polysulphate and 2 trails evaluating green-lipped mussels were rated as type I. One trial evaluating hyaluronan was rated as type III. CONCLUSIONS AND CLINICAL RELEVANCE: A high level of comfort exists for meloxicam that the claimed relationship is scientifically valid and that its use is clinically efficacious for the treatment of osteoarthritis in dogs. A moderate level of comfort exists for carprofen; etodolac; pentosan polysulphate; green-lipped mussels; P54FP; polysulfated glycosaminoglycans; and a combination of chondroitin sulfate, glucosamine hydrochloride, and manganese ascorbate. An extremely low level of comfort exists for hyaluronan.     

Effects of diazepam or lidocaine premedication on propofol induction and cardiovascular parameters in dogs

The effects of diazepam or lidocaine on the propofol induction dose and certain cardiovascular parameters were documented in this randomized, blinded study. Dogs received 0.9% saline (0.1 mL/kg intravenously [i.v.]), lidocaine (2 mg/kg i.v.), or diazepam (0.25 mg/kg i.v.) prior to propofol i.v. until loss of jaw tone was achieved (up to a maximum of 8 mg/kg). Propofol was followed by 0.3 mg/kg atracurium i.v. Direct arterial blood pressures and heart rates were recorded before premedication, induction, and intubation. No statistically significant differences were found among the groups for cardiovascular measurements or for the propofol dose required for intubation.     

A comparison of cardiopulmonary and anesthetic effects of an induction dose of alfaxalone or propofol in dogs

ObjectiveTo compare the physiological parameters, arterial blood gas values, induction quality, and recovery quality after IV injection of alfaxalone or propofol in dogs.Study designProspective, randomized, blinded crossover.AnimalsEight random-source adult female mixed-breed dogs weighing 18.7 ± 4.5 kg.MethodsDogs were assigned to receive up to 8 mg kg^?1 propofol or 4 mg kg^?1 alfaxalone, administered to effect, at 10% of the calculated dose every 10 seconds. They then received the alternate drug after a 6-day washout. Temperature, pulse rate, respiratory rate, direct blood pressure, and arterial blood gases were measured before induction, immediately post-induction, and at 5-minute intervals until extubation. Quality of induction, recovery, and ataxia were scored by a single blinded investigator. Duration of anesthesia and recovery, and adverse events were recorded.ResultsThe mean doses required for induction were 2.6 ± 0.4 mg kg^?1 alfaxalone and 5.2 ± 0.8 mg kg^?1 propofol. After alfaxalone, temperature, respiration, and pH were significantly lower, and PaCO₂ significantly higher post-induction compared to baseline (p < 0.03). After propofol, pH, PaO₂, and SaO₂ were significantly lower, and PaCO₂, HCO₃, and PA-aO₂ gradient significantly higher post-induction compared to baseline (p < 0.03). Post-induction and 5-minute physiologic and blood gas values were not significantly different between alfaxalone and propofol. Alfaxalone resulted in significantly longer times to achieve sternal recumbency (p = 0.0003) and standing (p = 0.0004) compared to propofol. Subjective scores for induction, recovery, and ataxia were not significantly different between treatments; however, dogs undergoing alfaxalone anesthesia were more likely to have ≥1 adverse event (p = 0.041). There were no serious adverse events in either treatment.Conclusions and clinical relevanceThere were no clinically significant differences in cardiopulmonary effects between propofol and alfaxalone. A single bolus of propofol resulted in shorter recovery times and fewer adverse events than a single bolus of alfaxalone.     

The effects of extubation with an inflated versus deflated endotracheal tube cuff on endotracheal fluid volume in the dog

Objective The purpose of this study was to investigate the effect of extubation with the endotracheal tube (ETT) cuff inflated versus deflated on endotracheal fluid volume in normal canine cadavers. Study Design Prospective randomized blinded controlled cadaver study. Animals Sixteen adult Beagle cadavers weighing 10.7 ± 1.7 kg (mean ± SD) and <2 years of age. Methods Cadavers were orotracheally intubated in lateral recumbency, and the ETT cuffs were inflated to a closing pressure of 20 cm H₂O before barium was introduced orad to the cuff. The dogs were randomly assigned to an ETT cuff extubation condition of deflated or unchanged from the original closing pressure. After extubation, lateral thoracic radiographs of the cadavers were obtained and scored by three independent blinded reviewers. Each reviewer ordered all 16 lateral radiographs from most to least intratracheal contrast and also estimated residual intratracheal contrast volume. Results Dogs extubated with a deflated ETT cuff had a median rank of 13 and dogs extubated with an inflated ETT cuff had a median rank of 4.5 (p < 0.0001). Dogs extubated with a deflated ETT cuff had an estimated intratracheal volume of fluid of 1.8 mL ± 0.7 mL (mean ± SD) and dogs extubated with an inflated ETT cuff had an estimated volume of 0.9 mL ± 0.5 mL (p < 0.0001). Fleiss Kappa for agreement among evaluators was 0.875. Conclusions and clinical relevance Extubation with the cuff inflated removed more liquid contents from the trachea than extubation with the cuff deflated and may assist in the prevention of pulmonary aspiration when fluid is present in the proximal trachea. The technique did not remove all fluid so the potential for pulmonary damage remains.     

Effect of body position on cranial migration of epidurally injected methylene blue in recumbent dogs

OBJECTIVE: To determine the relationship between different body positions during recumbency on the cranial migration of epidurally injected methylene blue in canine cadavers. SAMPLE POPULATION: 21 fresh cadavers of clinically normal adult female mixed-breed dogs. PROCEDURE: Dogs were randomly assigned to the following 3 groups: dogs remaining in right lateral recumbency (n = 7), dogs rotated from left to right lateral recumbency (7), and dogs rotated from dorsal to right lateral recumbency (7). Each dog received an epidural injection of 0.05% methylene blue (0.1 mL/kg) at the lumbosacral space. A dorsal laminectomy of the vertebral column was made, and cranial extent of methylene blue in 4 quadrants (right lateral, left lateral, ventral, and dorsal) was determined by examining dura mater staining. RESULTS: No significant difference was found among groups in regard to body weight or body condition score. Epidural cranial migration of methylene blue in the right lateral quadrant was significantly greater in dogs that remained in right lateral recumbency than in dogs that were rotated from left to right lateral recumbency. No significant difference was found within groups for epidural cranial migration of methylene blue between each quadrant. No significant relationship was found between body weight or body condition score and epidural cranial migration of methylene blue. CONCLUSIONS AND CLINICAL RELEVANCE: Body positioning and amount of recumbency time influence cranial migration of epidurally injected methylene blue. If greater cranial migration of an epidurally administered drug is desired, placing the patient in lateral recumbency with the surgical site on the dependent side may precede surgery.