Effects of Buprenorphine Added to Bupivacaine Infraorbital Nerve Blocks on Isoflurane Minimum Alveolar Concentration Using a Model for Acute Dental/Oral Surgical Pain in Dogs.

Bupivacaine appears to have a duration of action longer than previously reported. Results of this study demonstrate that the addition of buprenorphrine may enhance the analgesic duration of effect for bupivacaine regional nerve blocks. In addition, the use of bupivacaine alone may have analgesia that exceeds 24 hours in many cases. Although not statistically significant based on sample size, 50% of dogs receiving the bupivacaine/buprenorphine regional anesthetic block demonstrated a decreased anesthetic requirement 48 hours postadministration when compared to 25% of dogs receiving the bupivacaine anesthetic. No adverse cardiorespiratory effects were noted secondary to either local anesthetic treatment. Use of bupivacaine may have analgesic effects extending greater than 24 hours (24-72) when used in regional anesthetic blocks in veterinary dental patients with acute dental pain. The addition of buprenorphine to bupivacaine may extend the duration of analgesia (48-96 h). The limited sample size, in addition to patient variability in response to medications, may account for the fact that no differences were detected between the treatments administered.

Comparison of anesthesia with a morphine-lidocaine-ketamine infusion or a morphine-lidocaine epidural on time to extubation in dogs.

OBJECTIVE: To evaluate and compare the time to extubation in two commonly used methods of analgesia in dogs undergoing elective pelvic limb orthopedic procedures. STUDY DESIGN: Prospective, randomized, double-blinded clinical study. ANIMALS: Twenty-five adult, client-owned, healthy dogs aged 4.4 ± 1.6 years and weighing 38.5 ±3.5 kg. METHODS: All dogs were premedicated with dexmedetomidine (5-10 µg kg(-1)) intramuscularly (IM) and anesthesia was induced with propofol (2-6 mg kg(-1)) intravenously (IV). Atipamazole (0.05-0.1 mg kg(-1)) was administered IM after instrumentation. Anesthesia was maintained with isoflurane in oxygen. Dogs were randomly assigned to one of two groups. In one group, morphine (0.1 mg kg(-1)) and lidocaine (2% lidocaine added to a total volume of 0.2 mL kg(-1)) were administered epidurally and a saline placebo constant rate infusion (CRI) was administered IV (group EPI). In the other group (group MLK), morphine (4 µg kg(-1) minute(-1)), lidocaine (50 µg kg(-1) minute(-1)) and ketamine (10 µg kg(-1) minute(-1)) were administered as an IV CRI and a saline placebo was administered by epidural injection. Temperature at the discontinuation of isoflurane, temperature at extubation, time to extubation, duration of inhalation anesthesia and duration of surgery were recorded. RESULTS: No significant differences between the groups were found in time to extubation, temperature at the end of surgery, temperature at extubation and total surgical time. Total anesthesia time was significantly longer in group EPI. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of MLK at the doses reported in this study did not prolong the time to extubation in comparison with a morphine-lidocaine epidural nerve block. The results indicate that concern over prolonging the time to extubation is not a reason to avoid the administration of MLK.

General anesthesia in horses on fluid and electrolyte therapy.

The purpose of this article is to update the community of veterinarians performing general anesthesia in horses on fluid therapy. The rationale behind intraoperative fluid therapy, fluid dynamics, and various fluid options (crystalloids, hypertonic saline, colloids) is discussed. Additionally, electrolytes (calcium, potassium, and sodium) are included in the discussion in relation to general anesthesia and intraoperative fluid management.

Effect of mepivacaine in an infraorbital nerve block on minimum alveolar concentration of isoflurane in clinically normal anesthetized dogs undergoing a modified form of dental dolorimetry.

OBJECTIVE: To evaluate the effects of a routinely used infraorbital nerve block, performed for dental procedures, on the anesthetic requirement for isoflurane in dogs. DESIGN: Prospective controlled study. ANIMALS: 8 healthy adult Beagles. PROCEDURES: Dogs were anesthetized with isoflurane, and the minimum alveolar concentration (MAC) of isoflurane was established. A modification of a well-established method of stimulating the dental pulp, dental dolorimetry, was used to deliver a noxious stimulus (electrical stimulation) for isoflurane MAC determination. Once the isoflurane MAC was established, an infraorbital nerve block was performed with mepivacaine. The isoflurane MAC was then determined with the addition of the nerve block. Measurements of heart rate and mean arterial blood pressure were obtained at specified time points (baseline and prevention and elicitation of purposeful movement) during the determination of MAC and in response to the noxious stimulus. RESULTS: The mean ± SD isoflurane MAC without an infraorbital nerve block was 1.12 ± 0.13%. Isoflurane MAC with the regional mepivacaine anesthesia was 0.86 ± 0.11%. A significant reduction in isoflurane MAC (23%) was seen after the infraorbital nerve block, compared with results before the nerve block. With the exception of baseline measurements, no significant differences were found between treatments (isoflurane alone vs isoflurane with regional mepivacaine anesthesia) in heart rate or mean arterial blood pressure before or after the noxious stimulus. CONCLUSIONS AND CLINICAL RELEVANCE: The significant reduction in MAC of isoflurane supported the practice of the addition of regional anesthesia for painful dental procedures to reduce the dose-dependent cardiorespiratory effects of general anesthesia.

The effects of lactated Ringer's solution (LRS) or LRS and 6% hetastarch on the colloid osmotic pressure, total protein and osmolality in healthy horses under general anesthesia.

OBJECTIVE: To investigate changes in colloid osmotic pressure (COP), total protein (TP) and osmolality (OSM) during anesthesia in horses given intravenous lactated Ringer's solution (LRS) or LRS and hetastarch (HES). STUDY DESIGN: Prospective, clinical trial. ANIMALS: Fourteen horses presented for surgery. Mean age 8.3 ± 1.9 years; mean weight 452 ± 25 kg. METHODS: Horses were premedicated with xylazine intravenously (IV); anesthesia was induced with ketamine and diazepam IV, and maintained with sevoflurane. Butorphanol was administered IV with pre-medications or immediately after induction. Xylazine was administered IV for recovery if necessary. LRS was administered IV to all horses with a target rate of 5-10 mL kg(-1) hour(-1). Half of the horses also received 6% HES, 2.5 mL kg(-1) over 1 hour in addition to LRS. Horses that received LRS only were considered the LRS group. Horses that received both LRS and HES were considered the LRS/HES group. Blood was drawn pre- and post-anesthesia, immediately following induction, and every 30 minutes throughout anesthesia. COP, TP and OSM were measured. RESULTS: COP and TP significantly decreased at similar rates for both treatment groups from pre-anesthetic values. Pre-anesthetic COP was significantly greater in the LRS group when compared to the LRS/HES group pre-, post- and throughout anesthesia. In the LRS group post-anesthetic OSM was significantly different than the pre-anesthesia value and that for the LRS/HES group. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of IV HES (2.5 mL kg(-1), over 1 hour) in combination with LRS does not attenuate the decrease in COP typically seen during anesthesia with crystalloid administration alone. Based on these results, administration of HES at this rate and total volume would not be expected to prevent fluid shifts into the interstitium through its effects on COP.

Ultrasound-guided transversus abdominis plane block in the dog: an anatomical evaluation.

OBJECTIVE: To describe the ultrasound-guided technique to the transversus abdominis plane (TAP) block in the dog and evaluate the spread of a local anesthetic/methylene blue solution. STUDY DESIGN: Prospective experimental trial. ANIMALS: Ten adult Beagle cadavers weighing 11.1 ± 1.1 kg (mean ± SD). METHODS: Transversus abdominis plane (TAP) blocks were performed bilaterally by a single trained individual on unpreserved cadaver dogs using 10 mL of methylene blue/bupivacaine solution per site. Dissection of the abdominal wall was performed within 15-55 minutes of block to determine distribution of injectate and nerve involvement in the transversus abdominis fascial plane. RESULTS: The transversus abdominis fascial plane was adequately visualized via ultrasound and injected in twenty hemi-abdominal walls. Segmental branches of T11, T12, T13, L1, L2, and L3 were adequately stained in 20%, 60%, 100%, 100%, 90%, and 30% of injections, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: This anatomical study suggests that the transversus abdominis plane (TAP) block would provide adequate regional anesthesia of the abdomen, potentially extending to the cranial and caudal limits of the abdomen. This supports the clinical potential of this block in veterinary medicine.

Validity and client use of information from the World Wide Web regarding veterinary anesthesia in dogs.

OBJECTIVE: To determine the validity of the information on the World Wide Web concerning veterinary anesthesia in dogs and to determine the methods dog owners use to obtain that information. DESIGN: Web-based search and client survey. SUBJECTS: 73 Web sites and 92 clients. PROCEDURES: Web sites were scored on a 5-point scale for completeness and accuracy of information about veterinary anesthesia by 3 board-certified anesthesiologists. A search for anesthetic information regarding 49 specific breeds of dogs was also performed. A survey was distributed to the clients who visited the University of Georgia Veterinary Teaching Hospital during a 4-month period to solicit data about sources used by clients to obtain veterinary medical information and the manner in which information obtained from Web sites was used. RESULTS: The general search identified 73 Web sites that included information on veterinary anesthesia; these sites received a mean score of 3.4 for accuracy and 2.5 for completeness. Of 178 Web sites identified through the breed-specific search, 57 (32%) indicated that a particular breed was sensitive to anesthesia. Of 83 usable, completed surveys, 72 (87%) indicated the client used the Web for veterinary medical information. Fifteen clients (18%) indicated they believed their animal was sensitive to anesthesia because of its breed. CONCLUSIONS AND CLINICAL RELEVANCE: Information available on the internet regarding anesthesia in dogs is generally not complete and may be misleading with respect to risks to specific breeds. Consequently, veterinarians should appropriately educate clients regarding anesthetic risk to their particular dog.