Effects of doxapram HCl on laryngeal function of normal dogs and dogs with naturally occurring laryngeal paralysis

OBJECTIVES: To compare the effects of IV doxapram on glottic size and arytenoid motion in normal dogs and in dogs with laryngeal paralysis. STUDY DESIGN: Prospective experimental and clinical trials. ANIMALS: Six healthy dogs weighing 24.5 +/- 3.9 kg and six dogs weighing 27.4 +/- 11.5 kg suspected of having laryngeal paralysis. METHODS: Dogs were pre-medicated with acepromazine and butorphanol, and a light plane of anesthesia was induced with isoflurane by mask. Videoendoscopic examination of laryngeal function was recorded before (baseline) and after IV doxapram administration. Normalized glottal gap area (NGGA) at maximal inspiration and expiration, and percentage change in height, width, area, and NGGA were calculated with measurements from digitized images of the glottal gap. RESULTS: Active arytenoid motion was present in all normal dogs at baseline. After doxapram administration, depth of respiration appeared greater, but arytenoid motion, as measured by percentage change in NGGA, and in area and width, did not significantly increase in normal dogs. No arytenoid motion was detected in dogs with laryngeal paralysis at baseline; however, rima glottidis NGGA of dogs with laryngeal paralysis was greater at inspiration and expiration than normal dogs. After doxapram administration, dogs with laryngeal paralysis developed paradoxical arytenoid motion and significant, negative percentage change in area (-61%) and NGGA (-145%) because of inward collapse of the arytenoids during inspiration. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of doxapram during laryngeal examination is useful for differentiating normal dogs from dogs with laryngeal paralysis. Dogs with laryngeal paralysis may suffer extreme glottic constriction with vigorous respirations, and may require intubation during examination.     

Chemical immobilization of Weddell seals (Leptonychotes weddellii) by ketamine/midazolam combination

ObjectiveTo provide reliable, effective immobilization for Weddell seals under extreme field conditions using an injectable ketamine/midazolam combination.Study designObservational study.AnimalsThirty adult Weddell seals (12 male, 18 female) in Erebus Bay, Antarctica, body mass (mean ± SD) 412 ± 47 kg, aged 9–27 years.MethodsSeals were immobilized with a target dose of 2 mg kg^?1 ketamine hydrochloride and 0.1 mg kg^?1 midazolam hydrochloride (IM), based on visually estimated body mass. When required, maintenance doses were administered at a target of 0.5 mg kg^?1 ketamine hydrochloride and 0.025 mg kg^?1 midazolam hydrochloride (IV).ResultsComplete immobilization was achieved in 33 of 40 injections (14 of which were repeat events on the same individual). Time to immobilization averaged 12 ± 4 minutes, with a duration of initial immobility of 38 ± 19 minutes. Total immobilization time varied by handling protocol, including condition assessment and muscle biopsy (Protocol 1, 60 ± 13 minutes), condition assessment and instrument attachment (Protocol 2, 154 ± 13 minutes), and condition assessment, muscle biopsy and instrument retrieval (Protocol 3, 48 ± 8 minutes). Overall, a total immobilization time of 114 ± 60 minutes was accomplished with 4 ± 4 maintenance doses, and an average recovery time of 36 ± 17 minutes. Most effects of the anesthetic combination were unrelated to mass, age, sex or total body fat. However, leaner seals had longer duration of initial immobility (% and kg total body fat) and recovery times (kg fat). Apnea events were uncommon and treated effectively with doxapram. No animals died.Conclusions and clinical relevanceReliable and effective field immobilization of Weddell seals was accomplished with a low dose of ketamine hydrochloride and midazolam hydrochloride, utilizing IM injection initially and IV maintenance methods.