Plus-Hex CLINICAL
Materials and methods
The study analysed the body temperature change in dogs admitted to Wear Referrals Small Animal Hospital( part of the Linnaeus Veterinary Group) for general anaesthesia and MRI investigations. Cases were logged retrospectively from 22 August 2022 to 7 December 2022, by analysing and gaining data from the general anaesthesia monitoring record of each patient.
A total of 99 dogs undergoing MRI for neurological investigations at the multidisciplinary referral centre were enrolled on the study. They consisted of 33 breeds, and small, medium and large crossbreeds; ages ranged from 4 months to 12 years and weights ranged from 3.6 kg to 60 kg. Client consent was obtained through the practice ' s general consent form, which contains a section for owners to consent to their animal contributing to clinical research within the Linnaeus Group.
The data collected included:
• Species
• Breed
• Weight
• BCS
• Sex and neuter status
• Age( years and months)
• Presenting problem
• Positioning in scanner
• Body temperature at admission
• Premedication agent, dose, and time and route of administration
• Induction agent, dose, and time of administration
• Body temperature before entering the MRI suite
• Body temperature after leaving the MRI suite
• Temperature change during scan
• Heating aids used
• Scan time( minutes).
A summary of the timeline of events is shown in Figure 1, which includes the points at which body temperature was measured and recorded. All temperatures were taken rectally using a digital thermometer.
Anaesthetic plans were individual to each patient. Premedication choices were combinations of opioids, alpha-2( α2)-agonists, acepromazine, midazolam, lidocaine and ketamine, administered either intramuscularly or intravenously. Induction agents were either propofol or alfaxalone, and all patients were maintained under anaesthesia on isoflurane in oxygen.
All patients in the study were anaesthetised for an MRI scan of either the brain, spine or shoulder( or a combination of the three), and were positioned in either sternal, dorsal or lateral recumbency, respectively, dependent on which area was being imaged. They were placed on an MRI-safe heat pad( ConRad MRI Thermal Blankets) and then covered with one or more blankets. It was not recorded what, if any, additional warming techniques were used during the scan.
Data were collected in a Microsoft Excel spreadsheet and processed before analyses. Processing involved removing any data deemed unnecessary for final analysis and providing groups of data with a numerical code so the SPSS statistical software could interpret / analyse the data.
The groups of data chosen for analysis of their effect on body temperature during MRI investigations were:
• BCS
• Patient age
• Recumbency during scan
• Premedication
• Scan time( minutes).
See Appendix 1( via link on page 49) for full details of the method.
Ethical approval
The study was approved by the Nottingham Trent University School of Animal, Rural and Environmental Science ethics committee.
Figure 1. Timeline of events for patients, from admission to the end of the magnetic resonance imaging( MRI) procedure. IV, intravenous.
Volume 40( 6) • December 2025
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