Severe (grade IV) hypersensitivity to iodinated contrast agent in an anesthetized dog.

An 8-year-old female Labrador dog was anesthetized for contrast-enhanced computed tomography. The dog was sedated with dexmedetomidine and butorphanol and anesthetized with propofol and isoflurane. Upon IV injection of iohexol 350 mg/mL (72 mL), tachycardia, hypotension, and lower airway obstruction developed. Severe hypersensitivity to the contrast agent was suspected. Bronchospasm was treated successfully with epinephrine. Phenylephrine was used for pressure support. While rare, severe hypersensitivity to iodinated contrast agents can occur without evidence of prior exposure.

Hypersensibilité grave (grade IV) à un agent de contraste iodé chez une chienne anesthésiée. Une chienne Labrador âgée de 8 ans a été anesthésiée pour une tomodensitométrie avec contraste. La chienne a été mise sous sédation avec de la dexmédétomidine et du butorphanol et anesthésiée avec du propofol et de l'isoflurane. Au moment de l'injection par voie IV de l'iohexol 350 mg/mL (72 mL), de la tachycardie, de l'hypotension et une obstruction des voies respiratoires inférieures se sont développées. Une grave hypersensibilité à l'agent de contraste a été soupçonnée. Les bronchospasmes ont été traités avec succès avec de l'épinéphrine. La phényléphrine a été utilisée pour le soutien à la tension. Quoique rare, l'hypersensibilité aux agents de contraste iodés peut se produire sans preuve d'exposition antérieure.(Traduit par Isabelle Vallières).

A randomized, blinded, controlled trial of the antiemetic effect of ondansetron on dexmedetomidine-induced emesis in cats.

OBJECTIVE: To determine the effect of ondansetron on the incidence of vomiting in cats pre-medicated with dexmedetomidine and buprenorphine. STUDY DESIGN: Randomized, blinded, controlled trial. ANIMALS: Eighty-nine female domestic shorthair cats, aged 3-60 months (median, 12 months) and weighing 1.2-5.1 kg. METHODS: Each cat received dexmedetomidine (40 µg kg(-1)) plus buprenorphine (20 µg kg(-1)), intramuscularly as pre-anesthetic medication. Cats were assigned to three treatment groups: ondansetron (0.22 mg kg(-1), intramuscular [IM]), either 30 minutes before the pre-anesthetic medication (ONDA group, n = 31) or with the pre-anesthetic medication (OPM group, n = 30) mixed with the pre-anesthetic medications in the same syringe, or not to receive the antiemetic (control group, n = 28). Emesis was recorded as an all-or-none response. The number of episodes of emesis and the time until onset of the first emetic episode were recorded for each cat. Clinical signs of nausea were recorded whenever they occurred, and a numerical rating scale was used to quantify these signs. Data were analyzed using Kruskal-Wallis and Chi-square test; a Bonferroni correction was made for six comparisons; thus, the two-sided p for significance was 0.05/6 = 0.008. RESULTS: There was a significant reduction in the number of cats vomiting, in the episodes of vomiting/cat, the time elapsed between the premedication and the first vomiting and the severity of nausea in the OPM group compared to the ONDA and control groups. CONCLUSIONS AND CLINICAL RELEVANCE: In cats, the administration of ondansetron (0.22 mg kg(-1)) ameliorates and reduced the severity of dexmedetomidine-induced nausea and vomiting only when it was administered in association with this drug.

Sedative and cardiorespiratory effects of dexmedetomidine and buprenorphine administered to cats via oral transmucosal or intramuscular routes.

OBJECTIVE: To determine if buprenorphine plus dexmedetomidine administered via the oral transmucosal route produces sufficient sedation in cats so that students can insert intravenous catheters. STUDY DESIGN: Prospective, randomized, blinded, clinical trial. ANIMALS: Eighty-seven shelter-owned female cats aged 4-48 months, weighing 1.1-4.9 kg. METHODS: Cats were randomly allocated to two treatment groups based on route of drug administration: oral transmucosal (OTM), or intramuscular (IM). Buprenorphine (20 microg kg(-1)) plus dexmedetomidine (20 microg kg(-1)) were administered as pre-medicants via one of these two routes. Prior to and 20 minutes after drug administration, heart and respiratory rates, systolic arterial pressure, and posture were measured and recorded. Twenty minutes after drug administration the same variables plus each cat's response to clipper sound, clipping, and restraint were recorded; higher scores indicated more sedation. RESULTS: There were no significant differences between the two groups prior to pre-medication. Within each treatment group heart rate was significantly lower 20 minutes after treatment, but it did not differ significantly between the two groups. Twenty minutes after treatment, respiratory rate was significantly less in the OTM group, but did not differ significantly between the two groups. Systolic arterial pressure did not differ within or between the two groups at either time. Scores for posture increased significantly within both groups, and cats in the IM group had higher scores after treatment. Twenty minutes after treatment, cats in the IM group had higher scores for clipping and restraint than OTM cats. Ketamine (IM) was necessary to facilitate catheterization in 25% and 16% of cats in the OTM and IM groups, respectively, but this was not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of dexmedetomidine plus buprenorphine by the OTM route is easy to perform, but produces less sedation than the IM route for IV catheterization in cats.