Effect of intracoelomic administration of alfaxalone on the righting reflex and tactile stimulus response of common garter snakes (Thamnophis sirtalis).

OBJECTIVE: To determine the intracoelemic (ICe) dose of alfaxalone required to induce loss of righting reflex (LRR) in garter snakes (Thamnophis sirtalis) and to evaluate the tactile stimulus response in unanesthetized and alfaxalone-anesthetized snakes. ANIMALS: 8 healthy mature garter snakes. PROCEDURES: During the first of 3 phases, snakes received each of 3 doses (10, 20, and 30 mg/kg) of alfaxalone, ICe, with a 2-week washout period between treatments. Times to LRR and return of righting reflex were determined after each dose. During phase 2, unanesthetized snakes underwent tactile stimulation testing with Semmes-Weinstein monofilaments once daily for 3 consecutive days to determine the baseline tactile pressure required to elicit purposeful movement. During phase 3, snakes were anesthetized with alfaxalone (30 mg/kg, ICe), and the tactile pressure required to induce purposeful movement was assessed at predetermined times after LRR. RESULTS: Intracoelomic administration of alfaxalone at doses of 10, 20, and 30 mg/kg induced LRR in 0, 5, and 8 snakes, respectively. For snakes with LRR, median time to LRR following the 30-mg/kg dose (3.8 minutes) was significantly shorter than that following the 20-mg/kg dose (8.3 minutes); median time to return of righting reflex did not differ between the 2 doses. Mean ± SD tactile pressure that resulted in purposeful movement in unanesthetized snakes was 16.9 ± 14.3 g. When snakes were anesthetized, the mean tactile pressure that resulted in purposeful movement was significantly increased from baseline at 10, 20, and 30 minutes after LRR. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested ICe administration of alfaxalone might be effective for anesthetizing garter snakes.

Effects of acepromazine and trazodone on anesthetic induction dose of propofol and cardiovascular variables in dogs undergoing general anesthesia for orthopedic surgery.

OBJECTIVE To compare the doses of propofol required to induce general anesthesia in dogs premedicated with acepromazine maleate or trazodone hydrochloride and compare the effects of these premedicants on cardiovascular variables in dogs anesthetized for orthopedic surgery. DESIGN Prospective, randomized study. ANIMALS 30 systemically healthy client-owned dogs. PROCEDURES 15 dogs received acepromazine (0.01 to 0.03 mg/kg [0.005 to 0.014 mg/lb], IM) 30 minutes before anesthetic induction and 15 received trazodone (5 mg/kg [2.27 mg/lb] for patients > 10 kg or 7 mg/kg [3.18 mg/lb] for patients ≤ 10 kg, PO) 2 hours before induction. Both groups received morphine sulfate (1 mg/kg [0.45 mg/lb], IM) 30 minutes before induction. Anesthesia was induced with propofol (4 to 6 mg/kg [1.82 to 2.73 mg/lb], IV, to effect) and maintained with isoflurane or sevoflurane in oxygen. Bupivacaine (0.5 mg/kg [0.227 mg/lb]) and morphine (0.1 mg/kg [0.045 mg/lb]) were administered epidurally. Dogs underwent tibial plateau leveling osteotomy (n = 22) or tibial tuberosity advancement (8) and were monitored throughout anesthesia. Propofol induction doses and cardiovascular variables (heart rate and systemic, mean, and diastolic arterial blood pressures) were compared between groups. RESULTS The mean dose of propofol required for anesthetic induction and all cardiovascular variables evaluated did not differ between groups. Intraoperative hypotension developed in 6 and 5 dogs of the acepromazine and trazodone groups, respectively; bradycardia requiring intervention developed in 3 dogs/group. One dog that received trazodone had priapism 24 hours later and was treated successfully. No other adverse effects were reported. CONCLUSIONS AND CLINICAL RELEVANCE At the described dosages, cardiovascular effects of trazodone were similar to those of acepromazine in healthy dogs undergoing anesthesia for orthopedic surgery.

Evaluation of serial venous and arterial lactate concentrations in healthy anesthetized sheep undergoing ovariectomy.

OBJECTIVE: To determine if lactate concentrations in jugular venous and auricular arterial blood differ in anesthetized sheep. STUDY DESIGN: Prospective, controlled experimental study. ANIMALS: Twelve healthy adult ewes, 4-7 years and weighing 62-77 kg. METHODS: Jugular venous blood was collected before anesthesia (PreOv ) for measurement of lactate concentration, packed cell volume and total protein. Ewes were administered a standard anesthesia protocol. Jugular venous (IntraOv ) and auricular arterial (IntraOa ) blood samples were obtained 40 minutes after induction of anesthesia, and again in recovery (PostOv and PostOa ). An additional blood sample was drawn 6 weeks post-operatively from non-fasted sheep (NF_Lact). Lactate concentrations were compared among PreOv , IntraOv and IntraOa , PostOv and PostOa , and between PreOv and NF_Lact with paired t-test and repeated measure analyses of variance (anova) with PreOv as a covariate (p ≤ 0.05). RESULTS: IntraOv lactate concentration had decreased from PreOv There were significant differences between arterial and venous IntraO and PostO lactate concentrations. There was no significant difference between IntraO and PostO, or PreOv and NF_Lact. CONCLUSIONS AND CLINICAL RELEVANCE: Lactate concentrations were significantly lower in anesthetized sheep compared to non-anesthetized sheep. Lactate concentrations in venous blood were higher than in arterial blood. Therefore, anesthetic status and sampling site should be considered when interpreting lactate concentrations, and the sampling site should be consistent for repeated measurements.

Comparison of three different inhalant anesthetic agents (isoflurane, sevoflurane, desflurane) in red-tailed hawks (Buteo jamaicensis).

OBJECTIVE: To compare isoflurane, sevoflurane and desflurane for inhalant anesthesia in red-tailed hawks (Buteo jamaicensis) in terms of the speed and characteristics of induction; cardiovascular and respiratory parameters while anesthetized; and speed and quality of recovery. STUDY DESIGN: Prospective, cross over, randomized experimental study. ANIMALS: 12 healthy adult red-tailed hawks. METHODS: Anesthesia was induced with isoflurane, sevoflurane or desflurane in oxygen via face mask in a crossover, randomized design with a 1 week washout period between each treatment. Hawks were tracheally intubated, allowed to breathe spontaneously, and instrumented for cardiopulmonary monitoring. Data collected included heart rate, respiratory rate, end-tidal CO(2) , inspired and expired agent, SpO(2,) temperature, systolic blood pressure, time to intubation and time to recovery (tracking). Recovery was subjectively scored on a 4 point scale as well as a summary evaluation, by a single blinded observer. RESULTS: No significant difference in time to induction and time to extubation was noted with the administration of isoflurane, sevoflurane or desflurane. Time to the ability of the bird to follow a moving object with its eyes (tracking) was significantly faster with the administration of sevoflurane and desflurane. All recoveries were scored 1 or 2 and were assessed as good to excellent. No significant difference was noted in heart rate, blood pressure and temperature among the three inhalants. Administration of isoflurane resulted in lower respiratory rates. CONCLUSIONS AND CLINICAL RELEVANCE: Overall, although isoflurane remains the most common inhaled anesthetic in avian practice, sevoflurane and desflurane both offer faster time to tracking, while similar changes in cardiopulmonary function were observed with each agent during anesthesia of healthy red-tailed hawks.

Comparison of two anesthetic protocols for feline blood donation.

OBJECTIVE: To compare hemodynamic variables during, and recovery quality following, anesthesia for feline blood donation using intramuscular ketamine-midazolam-butorphanol (KMB) versus inhaled sevoflurane in oxygen (SEV). STUDY DESIGN: Prospective blinded, randomized, crossover study. ANIMALS: Twenty healthy, client-owned, mixed breed cats, aged 4-8 years, weighing 5.2-6.4 kg. METHODS: Cats were anesthetized with KMB for one donation and SEV for another. Heart rate (HR), respiratory rate (f(R)), pulse quality, mucous membrane color, capillary refill time, arterial hemoglobin saturation with oxygen (SpO(2)), and noninvasive arterial blood pressure (Doppler) were assessed by a blinded observer every 1 minute during collection. A nonblinded anesthesiologist delivered drugs and responded to hemodynamic changes. Each donation consisted of 55 mL of whole blood drawn via jugular puncture over 5-22 minutes. Donors received 60 mL subcutaneous lactated Ringer's solution before recovery. Donors were monitored for a minimum of 4 hours post-donation, before returning home. Owners, unaware of anesthetic protocol, completed a questionnaire regarding their cat's behavior during the 24 hours following donation. RESULTS: Both protocols provided adequate restraint but were complicated by significant hypotension, requiring intervention in 16 (84%) SEV cats, and eight (42%) KMB cats. KMB cats experienced post-procedure hyperthermia, with body temperatures >103.5 degrees F. All animals responded to symptomatic therapy within 2 hours. Owners noted a significantly faster return to normal behavior at home following SEV. CONCLUSION: All cats experienced hypotension, with many animals requiring intervention. There was no significant difference between protocols in incidence and severity of hypotension. The primary post-procedure complication was hyperthermia with KMB. CLINICAL RELEVANCE: As a result of the potential for hypotension during blood donation, intravenous (IV) access and blood pressure monitoring are recommended for all anesthetized donor cats, regardless of the anesthetic protocol. Post-procedure hyperthermia is a risk with KMB, so temperature monitoring is recommended. Return to normal behavior is faster with SEV.

Development and verification of saphenous, tibial and common peroneal nerve block techniques for analgesia below the thigh in the nonchondrodystrophoid dog.

OBJECTIVE: To document simple and reliable local, infiltrating nerve blocks for the saphenous, tibial and common peroneal nerves in the dog. STUDY DESIGN: Laboratory technique development; in vivo blind, controlled, prospective study. ANIMALS: Twenty canine cadavers and 18 clinically normal, client-owned dogs. METHODS: A peripheral nerve blockade technique of the tibial, common peroneal, and saphenous nerves was perfected through anatomic dissection. Injections were planned in the caudal thigh for the tibial and common peroneal nerves, and in the medial thigh for the saphenous nerve. Cadaver limbs were injected with methylene blue dye and subsequently dissected to confirm successful dye placement. Clinically normal dogs undergoing general anesthesia for unrelated, elective procedures were randomly assigned to treatment (bupivacaine; n = 8) or control (saline; n = 8) nerve blocks of the nerves under study. Upon recovery from general anesthesia, skin sensation in selected dermatomes was evaluated for 24 hours. RESULTS: Cadaver tibial, common peroneal, and saphenous perineural infiltrations were successful in nonchondrodystrophoid dogs (100, 100, and 97%, respectively.) Intraneural injection was rare (1%; 1/105; tibial nerve) in cadaver dogs. In the treatment group of normal dogs, duration of loss of cutaneous sensation in some dermatomes (saphenous, superficial and deep peroneal nerve) was significantly different than control dogs; the range of desensitization occurred for 1-20 hours. No clinical morbidity was detected. CONCLUSIONS: This technique for local blockade of the tibial, common peroneal, and saphenous nerves just proximal to the stifle is easy to perform, requires minimal supplies and results in significant desensitization of the associated dermatomes in clinically normal, nonchondrodystrophoid dogs. CLINICAL RELEVANCE: This technique may be an effective tool for post-operative analgesia to the femoro-tibial joint and distal pelvic limb. Other applications, using sustained-release drugs or methods, may include anesthesia/analgesia in high-risk patients or as a treatment for chronic pelvic limb pain or self-mutilation.

Controlled, clinical trial assessing saphenous, tibial and common peroneal nerve blocks for the control of perioperative pain following femoro-tibial joint surgery in the nonchondrodystrophoid dog.

OBJECTIVE: To determine whether bupivacaine peripheral nerve block of the saphenous, tibial and common peroneal nerves proximal to the femoro-tibial joint reduces peri-operative pain following extracapsular surgical stabilization of cranial cruciate ligament rupture in the nonchondrodystrophoid dog. ANIMALS: Forty-one dogs with naturally acquired femoro-tibial joint instability. Study design Randomized, controlled, clinical trial. METHODS: Dogs diagnosed with suspected cranial cruciate ligament injury based on physical and radiographic evidence were randomly assigned to treatment (bupivacaine) or control (saline) nerve blocks before femoro-tibial joint surgery. Pain scores, skin sensation, pain threshold to incisional pressure, time to first systemic 'rescue' opioid analgesic and total analgesic dose were evaluated for 24 hours. p < 0.05 was considered significant. RESULTS: Treatment dogs had a significantly longer period of cutaneous desensitization than control dogs. There were no significant differences between treatment and control groups for pain score, pain threshold to incisional pressure, or time to first-rescue analgesic. The treatment group received significantly more supplemental analgesics than the control group. CONCLUSIONS: These peripheral nerve blocks were easy to perform and resulted in significant desensitization of the associated nerve autonomous zones, but did not improve post-operative analgesia. CLINICAL RELEVANCE: Clinical benefit was not detected when using this technique for peri-operative pain management following extracapsular cranial cruciate ligament surgical stabilization.

Effects of propofol-induced sedation on intradermal test reactions in dogs with atopic dermatitis.

We compared the effect of propofol and saline control on intradermal test reactions in dogs with atopic dermatitis undergoing outpatient intradermal testing (IDT). Nineteen dogs were used in this clinical study. Patients were randomly allocated to receive either intravenous (IV) propofol or IV 0.9% saline, and IDT was performed on the right or left (randomized) lateral thorax. One investigator, unaware of the treatments, interpreted all IDT results. Injection sites were analysed using a subjective and objective method. A value of P or= 1+ on all dogs, significantly more positive sites were apparent during propofol sedation than during saline administration. In addition, the greater number of individual dogs experiencing more positive reactions >or= 1+ during propofol sedation was significant. When subjectively analysing reactions >or= 2+, the greater number of positive reactions and the greater number of dogs with more positive reactions observed during propofol treatment was not significantly different from the saline control. When analysed objectively, the greater number of positive reactions observed during propofol sedation was not significant. A greater number of dogs had higher subjective scores and larger objective measurements during propofol sedation compared with saline administration. In summary, propofol sedation was associated with an overall greater number of positive IDT reactions compared with the saline control. Although not always significant, this difference should be considered when choosing propofol for skin testing dogs with atopic dermatitis.