Pedro Boscan

Surgical time and severity of postoperative pain in dogs undergoing laparoscopic ovariectomy with one, two, or three instrument cannulas

OBJECTIVE To determine whether number of instrument cannulas is associated with surgical time or severity of postoperative pain in dogs undergoing laparoscopic ovariectomy. DESIGN Randomized clinical trial. ANIMALS 18 healthy dogs. PROCEDURES Dogs were randomly assigned to undergo laparoscopic ovariectomy with 1, 2, or 3 instrument cannulas. Surgical time and intraoperative and postoperative complications were recorded. Severity of pain was monitored 2, 4, 8, 12, and 24 hours after surgery by means of pain scoring with a modified Melbourne Pain Scale and palpation of surgical sites with variably sized von Frey filaments. Owner-assessed postoperative comfort was also evaluated. RESULTS Surgical time was significantly longer with 1 cannula (mean ± SD, 29.7 ± 5.6 minutes) than with 2 cannulas (18.2 ± 4.4 minutes) or 3 cannulas (19.3 ± 3.4 minutes). Intraoperative complications included splenic puncture (2 dogs), pedicle hemorrhage (1 dog), and SC emphysema (1 dog); complication rates were not significantly different among groups. Total pain score was significantly lower for dogs with 2 cannulas than for dogs with 3 cannulas; total pain score for dogs with 1 cannula did not differ significantly from scores for dogs with 2 cannulas or 3 cannulas. Owner assessments of postoperative comfort and number of days pain medications were administered did not differ among groups. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that laparoscopic ovariectomy with 2 instrument cannulas, rather than with 1, resulted in shorter surgical times without increasing severity of postoperative pain.

Effect of maropitant, a neurokinin 1 receptor antagonist, on anesthetic requirements during noxious visceral stimulation of the ovary in dogs

OBJECTIVE To determine the anesthetic-sparing effect of maropitant, a neurokinin 1 receptor antagonist, during noxious visceral stimulation of the ovary and ovarian ligament in dogs. ANIMALS Eight 1-year-old female dogs. PROCEDURES Dogs were anesthetized with sevoflurane. Following instrumentation and stabilization, the right ovary and ovarian ligament were accessed by use of laparoscopy. The ovary was stimulated with a traction force of 6.61 N. The minimum alveolar concentration (MAC) was determined before and after 2 doses of maropitant. RESULTS The sevoflurane MAC value was 2.12 ± 0.4% during stimulation without treatment (control). Administration of maropitant (1 mg/kg, IV, followed by 30 μg/kg/h, IV) decreased the sevoflurane MAC to 1.61 ± 0.4% (24% decrease). A higher maropitant dose (5 mg/kg, IV, followed by 150 μg/kg/h, IV) decreased the MAC to 1.48 ± 0.4% (30% decrease). CONCLUSIONS AND CLINICAL RELEVANCE Maropitant decreased the anesthetic requirements during visceral stimulation of the ovary and ovarian ligament in dogs. Results suggest the potential role for neurokinin 1 receptor antagonists to manage ovarian and visceral pain.

REFLEXLY EVOKED COACTIVATION OF CARDIAC VAGAL AND SYMPATHETIC MOTOR OUTFLOWS: OBSERVATIONS AND FUNCTIONAL IMPLICATIONS

1 The purpose of the present review is to highlight the pattern of activity in the parasympathetic and sympathetic nerves innervating the heart during their reflex activation. 2 We describe the well‐known reciprocal control of cardiac vagal and sympathetic activity during the baroreceptor reflex, but point out that this appears to be the exception rather than the rule and that many other reflexes reviewed herein (e.g. peripheral chemoreceptor, nociceptor, diving response and oculocardiac) involve simultaneous coactivation of both autonomic limbs. 3 The heart rate response during simultaneous activation of cardiac autonomic outflows is unpredictable because it does not simply reflect the summation of opposing influences. Indeed, it can result in bradycardia (peripheral chemoreceptor, diving and corneal), tachycardia (nociceptor) and, in some circumstances, can predispose to malignant arrhythmias. 4 We propose that this cardiac autonomic coactivation may allow greater cardiac output during bradycardia (increased ventricular filling time and stronger contraction) than activation of the sympathetic limb alone. This may be important when pumping blood into a constricted vascular tree, such as is the case during the peripheral chemoreceptor reflex and the diving response.

Evaluation of the sedative and cardiovascular effects of intramuscular administration of dexmedetomidine with and without concurrent atropine administration in dogs.

OBJECTIVE To evaluate degree of sedation and cardiovascular, respiratory, acid-base excess, and electrolyte variables in response to IM administration of dexmedetomidine or dexmedetomidine with atropine. DESIGN Randomized crossover study. Animals-5 healthy 1- to 2-year-old sexually intact male Treeing Walker Coonhounds. PROCEDURES Dogs were instrumented with catheters placed in the dorsal pedal artery and lateral saphenous vein. All dogs received dexmedetomidine (10 μg/kg [4.5 μg/lb], IM) or dexmedetomidine with atropine (0.02 mg/kg [0.009 mg/lb], IM). Variables were measured at baseline (time 0) and 5, 15, 30, and 60 minutes after drug administration. RESULTS In all dogs, lithium dilution cardiac output decreased from a mean ± SD baseline value of 5.07 ± 1.0 L/min to 2.1 ± 0.9 L/min. Cardiac output was not different between dexmedetomidine group dogs and dexmedetomidine-atropine group dogs. Mean arterial pressure increased from baseline in both groups but was significantly higher in dexmedetomidine-atropine group dogs, compared with dexmedetomidine group dogs. Heart rate in dexmedetomidine group dogs decreased from 110 ± 14.2 beats/min to 49.4 ± 10.4 beats/min by 15 minutes. No differences were seen in blood gas values, electrolyte concentration, or hemoglobin values over time or between groups. Arrhythmias were detected in dexmedetomidine-atropine group dogs and included atrioventricular block, ventricular premature contractions, and ventricular bigeminy. CONCLUSIONS AND CLINICAL RELEVANCE Administration of atropine at 0.02 mg/kg, IM, with dexmedetomidine at 10 μg/kg, IM, resulted in an increase in mean arterial blood pressure and heart rate; deleterious cardiac arrhythmias were also observed. Use of atropine with dexmedetomidine is not recommended in dogs.

Neurokininergic Mechanism within the Lateral Crescent Nucleus of the Parabrachial Complex Participates in the Heart-Rate Response to Nociception

We wanted to ascertain whether the lateral parabrachial nucleus was involved in mediating the heart-rate response evoked during stimulation of somatic nociceptors. Reversible inactivation of the lateral parabrachial nucleus, using a GABAA agonist, reduced the reflex tachycardia evoked during noxious (mechanical) stimulation of the forelimb by ∼50%. The same effect was observed after blockade of neurokinin 1 receptors within the lateral parabrachial nucleus, indicating a possible involvement for substance P as a neurotransmitter. Immunocytochemistry revealed a strong expression of substance P-immunoreactive fibers and boutons in all lateral subnuclei, but they were particularly dense in the lateral crescent subnucleus. Histological verification showed that the most effective injection sites for attenuating the noxious-evoked tachycardia were all placed in or near to the lateral crescent nucleus of the lateral parabrachial complex. Many single units recorded from this region were activated by high-intensity brachial nerve stimulation. The brachial nerve evoked firing responses of some of these neurons was reversibly reduced after local delivery of a neurokinin 1 receptor antagonist. However, only a minority of these neurons followed a paired-pulse stimulation protocol applied to the spinal cord, suggesting a predominance of indirect projections from the spinal cord to the parabrachial nucleus. We conclude that the cardiac component of the response to somatic nociception involves indirect spinal pathways that most likely excite neurons located in the lateral crescent nucleus of the parabrachial complex via activation of neurokinin 1 receptors.

Comparison of Surgical Variables and Pain in Cats Undergoing Ovariohysterectomy, Laparoscopic-Assisted Ovariohysterectomy, and Laparoscopic Ovariectomy

Laparoscopy is an established modality in veterinary medicine. To date, laparoscopy in feline surgery is rarely reported. The objectives of this study were to compare surgical time, complications, and postoperative pain in a group of cats undergoing laparoscopic ovariectomy (LOVE), laparoscopic-assisted ovariohysterectomy (LAOVH), and ovariohysterectomy via celiotomy (COVH). Eighteen healthy cats were randomly assigned to undergo LOVE, LAOVH, or COVH. Severity of pain was monitored 1, 2, 3, and 4 hr after surgery. Surgical time was significantly longer for LAOVH (mean ± standard deviation [SD], 51.6 ± 7.7 min) compared to COVH (mean ± SD, 21.0 ± 7.1 min) and LOVE (mean ± SD, 34.2 ± 11.2 min). There were no major intraoperative complications, although minor complications were more common in both laparoscopic groups. Cats sterilized via laparoscopy (LOVE and LAOVH) were statistically less painful than cats spayed via celiotomy (COVH) 4 hr following surgery. Results suggested that LOVE in cats is safe, can be performed in a comparable amount of time as COVH, and may result in less postoperative discomfort.

Evaluating Femoral-Sciatic Nerve Blocks, Epidural Analgesia, and No Use of Regional Analgesia in Dogs Undergoing Tibia-Plateau-Leveling-Osteotomy

This is a retrospective study evaluating femoral-sciatic nerve blocks (FSBs), epidural analgesia, and non-regional analgesia (NRA) in dogs undergoing tibia-plateau-leveling-osteotomy surgery. Thirty-five records met the criteria for each of the FSB and epidural analgesia groups. Seventeen anesthesia records met the criteria for the NRA or control group. The parameters reported were: isoflurane vaporizer setting, rescue analgesia/anesthesia drugs received, heart rate, systolic blood pressure, and recovery quality (0-4, with 0 being poor and 4 being good). Rescue analgesia-anesthesia during surgery was performed with either fentanyl, ketamine, or propofol. A larger percentage of dogs in the NRA group required rescue analgesia during surgery. The FSB group had a higher recovery quality with median (95% confidence interval of four (±0.3) when compared to two (±0.8) in NRA (p < 0.01). No difference between groups was observed on any other parameter reported. As part of a multimodal analgesia approach for tibia-plateau-leveling-osteotomy surgery, the use of femoral and sciatic nerves blocks with bupivacaine appears to be an alternative technique to help with analgesia and anesthesia during surgery.

Effect of hospitalization on gastrointestinal motility and pH in dogs

OBJECTIVE To determine the effect of hospitalization on gastrointestinal motility and pH in healthy dogs. DESIGN Experimental study. ANIMALS 12 healthy adult dogs. PROCEDURES A wireless motility capsule (WMC) that measured pressure, transit time, and pH within the gastrointestinal tract was administered orally to dogs in 2 phases. In the first phase, dogs received the WMC at the hospital and then returned to their home to follow their daily routine. In the second phase, dogs were hospitalized, housed individually, had abdominal radiography performed daily, and were leash exercised 4 to 6 times/d until the WMC passed in the feces. All dogs received the same diet twice per day in both phases. Data were compared between phases with the Wilcoxon signed rank test. RESULTS Data were collected from 11 dogs; 1 dog was excluded because the WMC failed to exit the stomach. Median gastric emptying time during hospitalization (71.8 hours; range, 10.7 to 163.0 hours) was significantly longer than at home (17.6 hours; range, 9.7 to 80.8 hours). Values of all other gastric, small bowel, and large bowel parameters (motility index, motility pattern, pH, and transit time) were similar between phases. No change in gastric pH was detected over the hospitalization period. High interdog variability was evident for all measured parameters. CONCLUSIONS AND CLINICAL RELEVANCE Hospitalization of dogs may result in a prolonged gastric emptying time, which could adversely affect gastric emptying of meals, transit of orally administered drugs, or assessments of underlying motility disorders.

Assessing the Efficacy of Maropitant Versus Ondansetron in the Treatment of Dogs with Parvoviral Enteritis

Antiemetics are commonly prescribed during the treatment of canine parvoviral enteritis. This blinded, randomized prospective study compared the quality of clinical recovery and duration of hospitalization in canine parvoviral dogs receiving either maropitant (1 mg/kg [0.45 mg/lb] IV q 24 hr, n = 11) or ondansetron (0.5 mg/kg [0.23 mg/lb] IV q 8 hr, n = 11). All dogs were treated with IV fluids, cefoxitin, and enteral nutrition. Frequency of vomiting and pain scoring were recorded twice daily. Rescue analgesics and antiemetics were administered as dictated by specific pain and vomiting criteria. Clinical severity scoring, body weight, and caloric intake were monitored daily. When comparing dogs receiving maropitant versus ondansetron, respectively, there were no differences in duration of hospitalization (3.36 ± 0.56 versus 2.73 ± 0.38 days, P = .36), requirement of rescue antiemetic (3/11 versus 5/11 dogs, P = .66), duration of vomiting (5 versus 4 days, P = .65), or days to voluntary food intake (2 versus 1.5 days, P = 1.0). Results of this study suggest that maropitant and ondansetron are equally effective in controlling clinical signs associated with parvoviral enteritis.

Evaluation of ultrasound-guided vascular access in dogs: Ultrasound-guided vascular access in dogs

Objective To describe the technique and determine the feasibility, success rate, perceived difficulty, and time to vascular access using ultrasound guidance for jugular vein catheterization in a cardiac arrest dog model. Design Prospective descriptive study. Setting University teaching hospital. Animals Nine Walker hounds. Measurements and Main Results A total of 27 jugular catheterizations were performed postcardiac arrest using ultrasound guidance. Catheterizations were recorded based on the order in which they were performed and presence/absence of a hematoma around the vein. Time (minutes) until successful vascular access and perceived difficulty in achieving vascular access (scale of 1 = easy to 10 = difficult) were recorded for each catheterization. Mean time to vascular access was 1.9 minutes (95% confidence interval, 1.1–3.4 min) for catheterizations without hematoma, versus 4.3 minutes (1.8–10.1 min) for catheterizations with hematoma (P = 0.1). Median perceived difficulty was 2 of 10 (range 1–7) for catheterizations without hematoma, versus 2 of 10 (range 1–8) for catheterizations with hematoma (P = 0.3). A learning curve was evaluated by comparing mean time to vascular access and perceived difficulty in initial versus subsequent catheterizations. Mean time to vascular access was 2.5 minutes (1.0–6.4 min) in the initial 13 catheterizations versus 3.3 minutes (1.5–7.5 min) in the subsequent 14 catheterizations (P = 0.6). Median perceived difficulty in the first 13 catheterizations (3, range 1–8) was significantly greater (P = 0.049) than median perceived difficulty in the subsequent 14 catheterizations (2, range 1–6). Conclusions Ultrasound-guided jugular catheterization is associated with a learning curve but is successful in obtaining rapid vascular access in dogs. Further prospective studies are warranted to confirm the utility of this technique in a clinical setting.OBJECTIVE To describe the technique and determine the feasibility, success rate, perceived difficulty, and time to vascular access using ultrasound guidance for jugular vein catheterization in a cardiac arrest dog model. DESIGN Prospective descriptive study. SETTING University teaching hospital. ANIMALS Nine Walker hounds. MEASUREMENTS AND MAIN RESULTS A total of 27 jugular catheterizations were performed postcardiac arrest using ultrasound guidance. Catheterizations were recorded based on the order in which they were performed and presence/absence of a hematoma around the vein. Time (minutes) until successful vascular access and perceived difficulty in achieving vascular access (scale of 1 = easy to 10 = difficult) were recorded for each catheterization. Mean time to vascular access was 1.9 minutes (95% confidence interval, 1.1-3.4 min) for catheterizations without hematoma, versus 4.3 minutes (1.8-10.1 min) for catheterizations with hematoma (P = 0.1). Median perceived difficulty was 2 of 10 (range 1-7) for catheterizations without hematoma, versus 2 of 10 (range 1-8) for catheterizations with hematoma (P = 0.3). A learning curve was evaluated by comparing mean time to vascular access and perceived difficulty in initial versus subsequent catheterizations. Mean time to vascular access was 2.5 minutes (1.0-6.4 min) in the initial 13 catheterizations versus 3.3 minutes (1.5-7.5 min) in the subsequent 14 catheterizations (P = 0.6). Median perceived difficulty in the first 13 catheterizations (3, range 1-8) was significantly greater (P = 0.049) than median perceived difficulty in the subsequent 14 catheterizations (2, range 1-6). CONCLUSIONS Ultrasound-guided jugular catheterization is associated with a learning curve but is successful in obtaining rapid vascular access in dogs. Further prospective studies are warranted to confirm the utility of this technique in a clinical setting.