ABSTRACT
Case history:
Medical records from 2009 to 2021 from a private equine referral hospital in Rochester, NH, USA were analysed for cases that underwent general anaesthesia for low-field MRI of the distal limb. These were used to determine peri-anaesthetic morbidity and mortality.
Clinical findings and outcome:
Two hundred and forty-three anaesthetic episodes were recorded in horses undergoing low-field MRI. The peri-anaesthetic complication rate prior to discharge was 6.2% (15/243). No patients experienced a fatal complication. Ninety two of the 243 patients had multiple sites imaged, 90/243 received pre-anaesthetic dantrolene, 134/243 received intra-anaesthetic dobutamine, and 15/243 were positioned in dorsal recumbency. Complications included: abdominal discomfort (“colic”; 9/243), myopathy (4/243), hyphaema (1/243) and carpal fracture (1/243). At the time of discharge, 14/15 complications had resolved. Of 135 horses for which data were available 55 became hypotensive during the procedure (lowest mean arterial pressure < 65 mmHg). Median body weight was 553 (min 363, max 771) kg. Horses were anaesthetised for a median of 150 (min 45, max 210) minutes. There was no evidence of an association between higher body weight (p = 0.051) or longer duration of anaesthesia (p = 0.421) and development of an anaesthetic complication. For categorical variables (dantrolene administration pre-anaesthesia, dobutamine administration during anaesthesia, hypotension (mean < 65 mmHg) during anaesthesia, dorsal vs. lateral recumbency, and imaging of single vs. multiple sites), the 95% CI for the OR included 1, indicating a lack of effect of the variable on the odds of complication.
Clinical relevance:
The cases included in this series suggest that low-field MRI under general anaesthesia is a viable option for diagnostic imaging in otherwise healthy horses. Complications occur, but most resolve before discharge.
Acknowledgements
We thank technicians Kathryn Wakeman and Sophie Shulman for their contributions to data collection.
Disclosure statement
No potential conflict of interest was reported by the author(s).