Comparison of analgesic and tissue effects of subcutaneous perineural injection of liposomal bupivacaine and bupivacaine hydrochloride in horses with forelimb lameness induced via circumferential clamp.

OBJECTIVE: To evaluate the analgesic and tissue effects of liposomal bupivacaine administered SC as an abaxial sesamoid nerve block in horses with experimentally induced lameness. ANIMALS: 6 healthy mature light-breed horses. PROCEDURES: In a randomized crossover study, a circumferential hoof clamp was applied to a forelimb to induce reversible lameness. An abaxial sesamoid nerve block of the lame forelimb was performed by SC perineural injection of 10 mg of liposomal bupivacaine or bupivacaine HCl/site. Quantitative gait data were objectively obtained with a body-mounted inertial sensor system before (baseline) and at 30-minute intervals after treatment. Time to return to 85% of baseline lameness was determined. After a minimum 4-day washout period, procedures were repeated with the alternate limb and treatment. Lastly, the palmar digital nerves and perineural tissues were collected and examined histologically. RESULTS: SC perineural injection of liposomal bupivacaine ameliorated forelimb lameness in 5 of 6 horses. The median duration of analgesia was not significantly different between liposomal bupivacaine (4.5 hours) and bupivacaine HCl (3.0 hours). Histologically, mild inflammation was noted in 3 of 10 sites injected with liposomal bupivacaine and in none of the sites injected with bupivacaine HCl. CONCLUSIONS AND CLINICAL RELEVANCE: SC perineural injection of 10 mg of liposomal bupivacaine/site ameliorated experimentally induced forelimb lameness in some horses. At milligram-equivalent doses, liposomal bupivacaine had a similar duration of analgesia to that of bupivacaine HCl. Further investigation is required before recommending clinical use of liposomal bupivacaine for nerve blocks in horses.

The effect of intravenous maropitant on blood pressure in healthy awake and anesthetized dogs.

OBJECTIVE: To evaluate the effects of intravenous maropitant on arterial blood pressure in healthy dogs while awake and under general anesthesia. DESIGN: Experimental crossover study. ANIMALS: Eight healthy adult Beagle dogs. PROCEDURE: All dogs received maropitant (1 mg kg-1) intravenously under the following conditions: 1) awake with non-invasive blood pressure monitoring (AwNIBP), 2) awake with invasive blood pressure monitoring (AwIBP), 3) premedication with acepromazine (0.005 mg kg-1) and butorphanol (0.2 mg kg-1) intramuscularly followed by propofol induction and isoflurane anesthesia (GaAB), and 4) premedication with dexmedetomidine (0.005 mg kg-1) and butorphanol (0.2 mg kg-1) intramuscularly followed by propofol induction and isoflurane anesthesia (GaDB). Heart rate (HR), systolic (SAP), diastolic (DAP), and mean blood pressures (MAP) were recorded before injection of maropitant (baseline), during the first 60 seconds of injection, during the second 60 seconds of injection, at the completion of injection and every 2 minutes post injection for 18 minutes. The data were compared over time using a Generalized Linear Model with mixed effects and then with simple effect comparison with Bonferroni adjustments (p <0.05). RESULTS: There were significant decreases from baseline in SAP in the GaAB group (p < 0.01) and in MAP and DAP in the AwIBP and GaAB (p < 0.001) groups during injection. A significant decrease in SAP (p < 0.05), DAP (p < 0.05), and MAP (p < 0.05) occurred at 16 minutes post injection in GaDB group. There was also a significant increase in HR in the AwIBP group (p < 0.01) during injection. Clinically significant hypotension occurred in the GaAB group with a mean MAP at 54 ± 6 mmHg during injection. CONCLUSION: Intravenous maropitant administration significantly decreases arterial blood pressure during inhalant anesthesia. Patients premedicated with acepromazine prior to isoflurane anesthesia may develop clinically significant hypotension.

Effects of 2% lidocaine hydrochloride solution as a coinduction agent with propofol on cardiopulmonary variables and administered propofol doses in healthy dogs premedicated with hydromorphone hydrochloride and acepromazine maleate.

OBJECTIVE: To evaluate the effects of lidocaine as a coinduction agent with propofol on cardiopulmonary variables and administered propofol doses in healthy dogs premedicated with hydromorphone hydrochloride and acepromazine maleate and anesthetized with isoflurane. ANIMALS: 40 client-owned dogs (American Society of Anesthesiologists physical status classification I or II and age ≥ 6 months) scheduled to undergo anesthesia for elective procedures. PROCEDURES: In a randomized, blinded, controlled clinical trial, dogs received 2% lidocaine hydrochloride solution (2.0 mg/kg [0.9 mg/lb], IV; n = 20) or buffered crystalloid solution (0.1 mL/kg [0.05 mL/lb], IV; 20; control treatment) after premedication with acepromazine (0.005 mg/kg [0.002 mg/lb], IM) and hydromorphone (0.1 mg/kg, IM). Anesthesia was induced with propofol (1 mg/kg [0.45 mg/lb], IV, with additional doses administered as needed) and maintained with isoflurane. Sedation was assessed, and anesthetic and cardiopulmonary variables were measured at various points; values were compared between treatment groups. RESULTS: Propofol doses, total sedation scores, and anesthetic and most cardiopulmonary measurements did not differ significantly between treatment groups over the monitoring period; only oxygen saturation as measured by pulse oximetry differed significantly (lower in the lidocaine group). Mean ± SD propofol dose required for endotracheal intubation was 1.30 ± 0.68 mg/kg (0.59 ± 0.31 mg/lb) and 1.41 ± 0.40 mg/kg (0.64 ± 0.18 mg/lb) for the lidocaine and control groups, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: No propofol-sparing effect was observed with administration of lidocaine as a coinduction agent for the premedicated dogs of this study. Mean propofol doses required for endotracheal intubation were considerably lower than currently recommended doses for premedicated dogs. (J Am Vet Med Assoc 2020;256:93-101).

Spotlight on the perioperative use of maropitant citrate.

Neurokinin-1 (NK-1) receptors are present in both the central nervous system and peripheral tissues. Substance P (SP) is the major ligand and is involved in multiple processes including pain transmission, vasodilation, modulation of the inflammatory response, as well as the sensory neuronal transmission involved in stress, anxiety, and emesis. The involvement of NK-1 and SP in the vomiting reflex has led to the development of NK-1 antagonists to prevent and treat vomiting in human and veterinary medicine. Maropitant is a potent, selective neurokinin (NK-1) receptor antagonist that blocks the pharmacologic action of SP in the central nervous system. Maropitant is available in both an injectable and tablet formulation and approved for use in dogs and cats for the treatment and prevention of vomiting from a variety of clinical causes and motion sickness. When administered prior to anesthetic premedication, maropitant prevents or significantly decreases the incidence of opioid-induced vomiting and signs of nausea in dogs and cats. Maropitant has also been shown to improve postoperative return to feeding and food intake in dogs. The minimum alveolar concentration of sevoflurage is decreased in both dogs and cats by maropitant, indicating a potential role as an adjunct analgesic, especially for visceral pain. This article will review the background information and literature, including clinical recommendations with respect to the perioperative use of maropitant in canine and feline veterinary patients.

Effects of administration of a synthetic low molecular weight/low molar substitution hydroxyethyl starch solution in healthy neonatal foals.

This study compared the effects of IV administration of isotonic fluid therapy and colloidal fluid therapy in healthy neonatal foals. Fifteen healthy neonatal foals were used in a randomized blinded prospective clinical study. Foals were randomly assigned to receive a bolus of 20 mL/kg of tetrastarch (TES) or balanced crystalloid solution. Vital parameters, colloid osmotic pressure (COP), and various clinicopathologic variables were assessed prior to infusion and at various time points up to 120 h after infusion. The treatment group (TES) had a significant increase in both COP and percentage increase in COP at 1 and 3 h. The COP was significantly lower than baseline at 3 h in the control group. No significant changes were observed in coagulation parameters in either group. Tetrastarch was effective in increasing COP for 3 h after infusion and had no notable adverse clinical effects in this group of healthy foals. Further studies are warranted regarding optimal dosing and effects in clinically ill foals.

Effets de l'administration d'une solution de substitution synthétique d'amidon hydroxyéthylé de faible poids moléculaire/faible molarité chez des poulains néonataux en santé. Cette étude a comparé les effets de l'administration IV d'une fluidothérapie isotonique et d'une fluidothérapie colloïdale chez des poulains néonataux en santé. Quinze poulains néonataux ont été utilisés dans une étude clinique prospective randomisée. Les poulains ont été assignés au hasard pour recevoir un bolus de 20 mL/kg de tétra-amidon (TEA) ou d'une solution cristalloïde équilibrée. Les paramètres vitaux, la pression osmotique colloïdale (POC) et diverses variables clinicopathologiques ont été évalués avant l'infusion et à divers moments jusqu'à 120 heures après l'infusion. Le groupe de traitement (TEA) a subi une hausse importante de la POC et une augmentation du pourcentage de POC à 1 et 3 heures dans le groupe témoin. Aucun changement significatif n'a été observé dans les paramètres de coagulation des deux groupes. Le tétra-amidon a été efficace pour l'augmentation de la POC pendant 3 heures après l'infusion et il n'a pas eu d'effets cliniques négatifs notables dans ce groupe de poulains en santé. De nouvelles études sont justifiées concernant le dosage optimal et les effets chez les poulains cliniquement malades.(Traduit par Isabelle Vallières).

Effect of dosing interval on efficacy of maropitant for prevention of hydromorphone-induced vomiting and signs of nausea in dogs.

OBJECTIVE: To evaluate the effect of dosing interval on the efficacy of maropitant for prevention of opioid-induced vomiting and signs of nausea in dogs. DESIGN: Randomized prospective clinical study. ANIMALS: 50 client-owned dogs that underwent an elective surgical procedure. Procedures: Dogs were randomly assigned to receive maropitant (1 mg/kg [0.45 mg/lb], SC), then hydromorphone (0.1 mg/kg [0.045 mg/lb], IM) at 0 (simultaneously; group 0; n = 10), 15 (group 15; 10), 30 (group 30; 10), 45 (group 45; 10), or 60 (group 60; 10) minutes later. Dogs were monitored for vomiting and signs of nausea for 30 minutes after hydromorphone administration. A historical control group of similar dogs (n = 9) that were administered hydromorphone (0.1 mg/kg, IM) but not maropitant served as the referent for comparison purposes. RESULTS: Vomiting was recorded for 6 dogs in group 0 and 2 dogs in group 15. Signs of nausea were recorded for 10 dogs in group 0, 9 dogs in group 15, 8 dogs in group 30, 6 dogs in group 45, and 1 dog in group 60. Compared with dogs in the historical control group, vomiting was significantly decreased and prevented when maropitant was administered 15 and 30 minutes, respectively, before hydromorphone; signs of nausea were significantly decreased only when maropitant was administered 60 minutes before hydromorphone. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that vomiting was significantly decreased and then prevented when maropitant was administered to dogs 15 and 30 minutes before hydromorphone. However, signs of nausea were significantly decreased only when the dosing interval was 60 minutes.

Efficacy of orally administered maropitant citrate in preventing vomiting associated with hydromorphone administration in dogs.

OBJECTIVE: To evaluate the effectiveness of orally administered maropitant citrate in preventing vomiting after hydromorphone hydrochloride administration in dogs. DESIGN: Randomized, blinded, prospective clinical study. ANIMALS: 40 dogs with American Society of Anesthesiologists status of I or II, > 6 months of age, and weighing between 24 and 58.2 kg (52.8 and 128.04 lb). PROCEDURES: Dogs were randomly selected to receive maropitant (2.0 to 4.0 mg/kg [0.9 to 1.8 mg/lb]) or placebo (lactose monohydrate) orally 2 hours prior to receiving hydromorphone (0.1 mg/kg [0.045 mg/lb], IM). A blinded observer recorded the occurrence of vomiting or signs of nausea (eg, salivation or lip-licking) during a 30-minute period after hydromorphone administration. Two-tailed Fisher exact tests were used to compare the incidences of vomiting and signs of nausea with or without vomiting between treatment groups. Results-Of the 20 dogs receiving maropitant, none vomited but 12 (60%) developed signs of nausea. Of the 20 dogs receiving placebo, 5 (25%) vomited and 11 (55%) developed signs of nausea; overall, 16 of 20 (80%) dogs in the placebo treatment group vomited or developed signs of nausea. Compared with the effects of placebo, maropitant significantly decreased the incidence of vomiting but not signs of nausea in dogs administered hydromorphone. CONCLUSIONS AND CLINICAL RELEVANCE: Among the 40 study dogs, the incidence of vomiting associated with hydromorphone administration was 25%. Oral administration of maropitant prevented vomiting but not signs of nausea associated with hydromorphone administration in dogs.

Efficacy of maropitant in preventing vomiting in dogs premedicated with hydromorphone.

OBJECTIVE: The goal of this study was to evaluate the effectiveness of maropitant (Cerenia(®)) in preventing vomiting after premedication with hydromorphone. STUDY DESIGN: Randomized, blinded, prospective clinical study. ANIMALS: Eighteen dogs ASA I/II admitted for elective orthopedic surgical procedures. The dogs were a mixed population of males and females, purebreds and mixed breeds, 1.0-10.2 years of age, weighing 3-49.5 kg. METHODS: Dogs were admitted to the study if they were greater than 1 year of age, healthy and scheduled to undergo elective orthopedic surgery. Dogs were randomly selected to receive one of two treatments administered by subcutaneous injection. Group M received 1.0 mg kg(-1) of maropitant, Group S received 0.1 mL kg(-1) of saline 1 hour prior to anesthesia premedication. Dogs were premedicated with 0.1 mg kg(-1) of hydromorphone intramuscularly. A blinded observer documented the presence of vomiting, retching and/or signs of nausea for 30 minutes after premedication. RESULTS: All dogs in S vomited (6/9), retched (1/9) or displayed signs of nausea (2/9). None (0/9) of the dogs in M vomited, retched or displayed signs of nausea. Dogs in M had significantly fewer incidences of vomiting (p=0.0090), vomiting and retching (p=0.0023) and vomiting, retching and nausea (p<0.0001) when compared to S. CONCLUSION AND CLINICAL RELEVANCE: Maropitant prevents vomiting, retching and nausea associated with intramuscular hydromorphone administration in dogs.

Physiologic effects of nasopharyngeal administration of supplemental oxygen at various flow rates in healthy neonatal foals.

OBJECTIVE: To evaluate the effects of various flow rates of oxygen administered via 1 or 2 nasal cannulae on the fraction of inspired oxygen concentration (FIO2) and other arterial blood gas variables in healthy neonatal foals. ANIMALS: 9 healthy neonatal (3- to 4-day-old) foals. PROCEDURES: In each foal, a nasal cannula was introduced into each naris and passed into the nasopharynx to the level of the medial canthus of each eye; oxygen was administered at 4 flow rates through either 1 or both cannulae (8 treatments/foal). Intratracheal FIO2, intratracheal end-tidal partial pressure of carbon dioxide, and arterial blood gas variables were measured before (baseline) and during unilateral and bilateral nasopharyngeal delivery of 50, 100, 150, and 200 mL of oxygen/kg/min. RESULTS: No adverse reactions were associated with administration of supplemental oxygen except at the highest flow rate, at which the foals became agitated. At individual flow rates, significant and dose-dependent increases in FIO2, PaO2, and oxygen saturation of hemoglobin (SaO2) were detected, compared with baseline values. Comparison of unilateral and bilateral delivery of oxygen at similar cumulative flow rates revealed no differences in evaluated variables. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that administration of supplemental oxygen via nasal cannulae appeared to be a highly effective means of increasing FIO2, PaO2, and SaO2 in neonatal foals. These findings may provide guidance for implementation of oxygen treatment in hypoxemic neonatal foals.