The effects of two intramuscular sedation protocols on echocardiographic variables in cats following sedation and blood donation.

OBJECTIVE: To compare effects of 2 IM sedation protocols, alfaxalone-butorphanol (AB) versus dexmedetomidine-butorphanol (DB), on echocardiographic (ECHO) variables in cats following sedation and blood donation. DESIGN: Experimental randomized, blinded crossover study. SETTING: University teaching hospital. ANIMALS: Eleven client-owned healthy cats. INTERVENTIONS: Cats received a baseline ECHO without sedation prior to their first donation. Cats were sedated intramuscularly with AB (alfaxalone, 2 mg/kg, and butorphanol, 0.2 mg/kg) for 1 donation and DB (dexmedetomidine, 10 µg/kg, and butorphanol 0.2, mg/kg) for another, with a minimum 6 weeks between donations. A post-sedation, post-donation ECHO was performed after each blood donation. MEASUREMENTS AND MAIN RESULTS: Eight cats completed the study. Compared to baseline, DB combined with blood donation decreased heart rate (-84/min; P < 0.0001), fractional shortening (-16.5%; P < 0.0001), ejection fraction (-21.0%; P = 0.0002), and cardiac output (-292 mL/min, P = 0.0001); AB combined with blood donation increased heart rate (+45/min; P = 0.0003) and decreased left ventricular end diastolic volume (-1.57 mL; P < 0.0001). Compared to AB, DB decreased heart rate (-129/min; P < 0.0001) and fractional shortening (-21.6%; P < 0.0001) and increased left ventricular end-systolic (+1.14 mL; P = 0.0004) and diastolic volumes (+1.93 mL; P < 0.0002). Cats administered DB had a significant increase in regurgitant flow across mitral, aortic, and pulmonic valves following blood donation (P < 0.05). One cat administered DB developed spontaneous echo contrast in the left ventricle following donation. CONCLUSIONS AND CLINICAL RELEVANCE: Compared to AB, DB had more pronounced effects on ECHO variables in cats following IM sedation and blood donation. Due to its minimal impact on ECHO variables, AB may be a more desirable sedation protocol in this population of cats.

Iatrogenic ocular trauma associated with infraorbital block performed for rhinoscopy in a cat: case report and preliminary imaging findings.

OBJECTIVES: This paper describes a case of endophthalmitis in a feline patient caused by globe penetration during an infraorbital block performed to provide analgesia during rhinoscopy, and presents additional imaging and dissection data demonstrating risk of iatrogenic ocular trauma during infraorbital blocks in cats when the infraorbital canal is entered. METHODS: Case records and accompanying histopathologic reports were reviewed for the feline patient. Separately, two feline cadavers were imaged using CT following placement of 5/8" 25 G needles or 1" 22 G over the needle catheters in the infraorbital canal. Infraorbital blocks with injection of trypan blue dye followed by dissection were performed in two further feline cadavers to assess the potential for globe penetration and to provide preliminary information regarding the potential efficacy of infraorbital blocks for analgesia during rhinoscopy. RESULTS: Clinical and histopathologic findings support inadvertent globe penetration during infraorbital block as the cause for endophthalmitis in the feline patient described. CT imaging and dye injection studies further demonstrate the risks involved with this local anesthetic technique in cats. CONCLUSIONS AND RELEVANCE: Further study is needed to assess the safety and efficacy of infraorbital blocks performed for rhinoscopy in cats. Catheters may be safer anesthetic delivery devices than needles. Extreme caution should be used when entering the infraorbital canal in cats.

Comparison of liposomal bupivacaine and 0.5% bupivacaine hydrochloride for control of postoperative pain in dogs undergoing tibial plateau leveling osteotomy.

OBJECTIVE: To compare liposome-encapsulated bupivacaine (LEB) and (nonliposomal) 0.5% bupivacaine hydrochloride (0.5BH) for control of postoperative pain in dogs undergoing tibial plateau leveling osteotomy (TPLO). ANIMALS: 33 client-owned dogs. PROCEDURES: In a randomized clinical trial, dogs undergoing TPLO received LEB (5.3 mg/kg [2.4 mg/lb]) or 0.5BH (1.5 mg/kg [0.68 mg/lb]) by periarticular soft tissue injection. All dogs received carprofen (2.2 mg/kg [1 mg/lb], SC, q 12 h) beginning at extubation. Signs of pain were assessed at extubation and predetermined times up to 48 hours later with the Colorado State University-Canine Acute Pain Scale and Glasgow Composite Pain Scale-Short Form. A pressure nociceptive threshold device was used at the affected stifle joint before surgery and at 5 postoperative time points. Methadone (0.1 mg/kg [0.05 mg/lb], IV) was administered if the Colorado State University pain scale score was ≥ 2 (scale, 0 to 4). Surgical variables; pain scores; pressure nociceptive thresholds; times to first administration of rescue analgesic, first walk, and first meal consumption; and total opioid administration were compared between treatment groups. RESULTS: 28 dogs completed the study. Dogs administered LEB were less likely to require rescue analgesia and received lower amounts of opioids than dogs administered 0.5BH. There were no significant intergroup differences in other measured variables. CONCLUSIONS AND CLINICAL RELEVANCE: The LEB appeared to provide adequate analgesia after TPLO with lower requirements for opioid treatments, which may allow dogs to be discharged from the hospital earlier than with traditional pain management strategies.

Comparison of two intramuscular sedation protocols on sedation, recovery and ease of venipuncture for cats undergoing blood donation.

OBJECTIVES: The aim of this study was to compare the quality of sedation and recovery, and ease of venipuncture following sedation for feline blood donation using two intramuscular (IM) sedation protocols: alfaxalone/butorphanol (AB) and dexmedetomidine/butorphanol (DB). METHODS: This was an experimental randomized, blinded, crossover study. Ten client-owned healthy cats were recruited to participate in the study. Cats were sedated with AB (alfaxalone 2 mg/kg and butorphanol 0.2 mg/kg) for one donation and DB (dexmedetomidine 10 µg/kg and butorphanol 0.2 mg/kg) for another. Reaction to injection, quality of sedation and quality of recovery were assessed by a blinded observer. Time to lateral recumbency, number of venipuncture attempts, time required for blood collection and time to return to sternal recumbency were recorded. Cats were monitored for evidence of gastrointestinal distress. Each donation consisted of a maximum of 53 ml whole blood drawn over 3-22 mins. Donors received 100 ml subcutaneous lactated Ringer's solution in recovery. Owners, unaware of sedation protocol, were asked to complete a questionnaire evaluating their cat's behavior following sedation. RESULTS: IM injections were well tolerated by both treatment groups. There was no significant difference between treatment groups in sedation scores for posture ( P = 0.30) or behavior ( P = 0.06). Cats sedated with DB had significantly higher muscle relaxation scores ( P = 0.03) compared with AB. There was no significant difference between treatment groups in time to lateral recumbency ( P = 0.12), number of venipuncture attempts ( P = 0.91) and time for blood draw ( P = 0.29). There was no difference in quality of recoveries between treatment groups based on simple descriptive scores ( P = 0.18) and owner evaluation 24 h following sedation. One cat vomited following administration of DB. CONCLUSIONS AND RELEVANCE: Alfaxalone is a suitable alternative to dexmedetomidine when combined with butorphanol and used as part of an IM sedation protocol for cats undergoing blood donation.