Suspected anaphylactoid reaction following intravenous administration of a gadolinium-based contrast agent in three dogs undergoing magnetic resonance imaging.

OBSERVATIONS: Anaphylactoid reactions were suspected in three dogs following the intravenous administration of the contrast agent gadobenate dimeglumine 0.05 mmol kg(-1) (Multihance). Case 1: A 14 kg 6-year-old atopic female dog was anaesthetized for brain magnetic resonance imaging (MRI). All monitored parameters remained stable during the procedure. Fifteen minutes following MR completion; facial, peri-orbital and sublingual oedema were noted. Resolution of the oedema was rapid and uneventful following treatment of clinical signs over 2 hours. Case 2: A 16 kg 10-month-old male dog was anaesthetized for brain and neck MRI. Ten minutes after MR contrast intravenous (IV) injection; heart rate (HR) increased (85-120 beats minute(-1)), mean arterial blood pressure (MAP) decreased (from 70 to 43 mmHg) and PE'CO(2) decreased (from 4.66 to 3.19 kPa). Labial, periorbital and lingual oedema were noted. Clinical signs responded to fluid bolus administration. The dog vomited in recovery but oedema resolved within one hour. Case 3: A 34 kg 2-year-old atopic male dog was anaesthetized for head MRI. Within 5 minutes of MR contrast IV injection; the dog suffered severe cardiovascular collapse. MRI procedure was aborted and administration of anaesthetics discontinued. Aggressive IV fluid resuscitation and IV epinephrine administration were necessary to re-establish cardiovascular stability. Some periorbital and labial oedema were noted. The dog vomited once and had soft faeces but made a complete recovery. CONCLUSIONS: The administration of contrast medium may result in mild to severe anaphylactoid reactions.

The sedative effects of low-dose medetomidine and butorphanol alone and in combination intravenously in dogs.

OBJECTIVE: To evaluate the sedative effects of intravenous (IV) medetomidine (1 microg kg(-1)) and butorphanol (0.1 mg kg(-1)) alone and in combination in dogs. STUDY DESIGN: Prospective, blinded, randomized clinical trial. ANIMALS: Sixty healthy (American Society of Anesthesiologists I) dogs, aged 6.2 +/- 3.2 years and body mass 26 +/- 12.5 kg. METHODS: Dogs were assigned to four groups: Group S (sodium chloride 0.9% IV), Group B (butorphanol IV), Group M (medetomidine IV) and Group MB (medetomidine and butorphanol IV). The same clinician assessed sedation before and 12 minutes after administration using a numerical scoring system in which 19 represented maximum sedation. Heart rate (HR), respiratory rate, pulse quality, capillary refill time and rectal temperature were recorded after each sedation score assessment. Sedation scores, sedation score difference (score after minus score before administration) and patient variables were compared using one-way anova for normally distributed variables and Kruskal-Wallis test for variables with skewed distributions and/or unequal variances. Where significance was found, further evaluation used Bonferroni multiple comparisons for pair-wise testing. RESULTS: Breed, sex, neuter status, age and body mass did not differ between groups. Sedation scores before substance administration were similar between groups (p = 0.2). Sedation scores after sedation were significantly higher in Group MB (mean 9.5 +/- SD 5.5) than in group S (2.5 +/- 1.8) (p < 0.001), group M (3.1 +/- 2.5) (p < 0.001) and group B (3.7 +/- 2.0) (p = 0.003). Sedation score difference was significantly higher in Group MB [7 (0-13)] than in Group S [0 (-1 to 4)] (p < 0.001) and Group M [0 (0-6)] (p < 0.001). HR decreased significantly in Groups M and MB compared with Group S (p < 0.05). CONCLUSION AND CLINICAL RELEVANCE: Low-dose medetomidine 1 microg kg(-1) IV combined with butorphanol 0.1 mg kg(-1) IV produced more sedation than medetomidine or butorphanol alone. HR was significantly decreased in both medetomidine groups.

Alfaxalone in cyclodextrin for induction and maintenance of anaesthesia in ponies undergoing field castration.

OBJECTIVE: To evaluate the induction and maintenance of anaesthesia using alfaxalone following pre-anaesthetic medication with romifidine and butorphanol in ponies undergoing castration in the field. STUDY DESIGN: Prospective clinical study. ANIMALS: Seventeen male ponies weighing 169 +/- 29 kg. METHODS: The ponies were sedated with romifidine and butorphanol intravenously (i.v.). Induction time was recorded following administration of alfaxalone 1 mg kg(-1) and diazepam 0.02 mg kg(-1) i.v.. If movement during surgery occurred, alfaxalone 0.2 mg kg(-1) was administered i.v.. The quality of anaesthetic induction, and recovery were scored on a subjective scale of 1 (good) to 5 (poor). The number of attempts to attain sternal recumbency and standing, quality of recovery and times from induction to end of surgery, first head lift, sternal recumbency and standing were recorded. RESULTS: Induction quality was good [median score (range) 1 (1-3)] with a mean +/- SD time of 29 +/- 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 +/- 9 minutes, 31 +/- 9 minutes, 33 +/- 9 minutes and 34 +/- 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1-1) and to attain standing was 1(1-2). Quality of recovery was good, with a recovery score of 1(1-2). CONCLUSIONS AND CLINICAL RELEVANCE: Alfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies.