AN EVIDENCE-BASED APPROACH TO BALANCED ANAESTHESIA IN SMALL ANIMALS

Dr. Maria Bellei BVSc, DipACVAA

Which structures are most likely to be found in the lumbosacral epidural space of adult dogs?

a) Cerebrospinal fluid and the caudal sections of the spinal cord

b) It is comprised by the bony structures of the spinal canal and nothing else

c) The sacral hiatus and sacrococcygeal membrane

d) Fat, connective tissue, blood vessels and the cauda equina

e) Intervertebral discs

You perform an epidural block with bupivacaine and morphine at standard recommended doses in a mature, healthy dog anaesthetized for a cruciate repair. The dog received 0.3mg/kg of Methadone and 0.02mg/kg of Acepromazine subcutaneously followed by 2mg/kg of Alfaxan and 2% isoflurane. Approximately 30 minutes after induction and 10-15 minutes after injecting your epidural agents, you notice the patient’s mean arterial blood pressure has dropped from 90mmHg to 55mmHg. What is the most likely explanation for this?

a) The patient was likely hypovolaemic but pre-operative blood tests didn’t show this

b) Sympathetic blockade from the local anaesthetic administered epidurally can cause hypotension in healthy patients

c) Changes in blood pressure like the one described above are common and expected during anaesthesia

d) It is likely because the nurses moved the dog from sternal to lateral recumbency

e) The morphine administered epidurally is likely to be causing the low blood pressure described in this patient

When choosing your agent for a constant rate infusion for an ASA IV patient undergoing splenectomy, which of the drugs below is known to provide a decrease in anaesthetic requirements AND an anti-arrhytmic effect for treatment of premature supraventricular beats?

a) Lignocaine

b) Ketamine

c) Morphine

d) Bupivacaine

e) Fentanyl

4. In regards to ketamine administration as an intra-operative constant-rate infusion, which statement is CORRECT?

a) Ketamine constant rate infusions can be used in dogs but should NOT be used in cats intra-operatively

b) Severe bradycardia and hypertension are commonly observed in cats during the administration of ketamine as a constant-rate infusion

c) One disadvantage of ketamine as a constant-rate infusion if that is cannot be combined with other injectable agents such as lignocaine or fentanyl

d) Best inhalant-sparing effects are seen intra-operatively if ketamine is administered as boluses instead of as a constant-rate infusion

e) Studies have shown that dogs receiving ketamine intra-operatively have significantly lower pain scores after surgery