Sedating the critical dog: a safe emergency protocol

Question

10-year-old Labrador with haemoabdomen from a suspected splenic mass. After initial fluid therapy its heart rate is 130 bpm, systolic pressure 95 mmHg and lactate still raised. It is restless and you need to sedate it for ultrasound and abdominocentesis.

Which sedation protocol is the most appropriate?

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A. Acepromazine with butorphanol, the usual consulting room protocol

Acepromazine causes vasodilation and hypotension, lasts for hours and is not reversible. It is contraindicated in a hypovolaemic or bleeding patient.

B. An opioid (butorphanol or methadone) with midazolam, intravenously at low doses, titrated to effect

Correct. Opioids and benzodiazepines have minimal cardiovascular effects, can be titrated and are reversible (naloxone and flumazenil). In critical patients midazolam usually does sedate, unlike in young healthy dogs.

C. Dexmedetomidine, because it can be reversed with atipamezole if there are problems

Although reversible, alpha-2 agonists cause vasoconstriction, bradycardia and a marked fall in cardiac output. In a patient with compromised perfusion they are not a good choice.

D. Reduced-dose propofol without intubation, because its effect is brief

Propofol is an anaesthetic induction agent that causes hypotension and apnoea. Without intubation and airway control it is not safe sedation in an unstable patient.

lightbulb Key takeaway

In critical patients, choose drugs with few cardiovascular effects, short action and reversibility: opioids and benzodiazepines. Use low intravenous doses titrated to effect, because sick patients need much less. Before sedating, have oxygen, intubation equipment and venous access ready.

Which sedation protocol is the most appropriate?

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