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Canine Premedication and Sedation "Cheat Sheet"

Posted in Guest Blogger @ Nov 17th 2016 - By Jen Davis BVMS Masters Vet Anaes. MANZCVS (Anaesthesia and Critical Care) DipECVAA
Canine Premedication And Sedation Cheat Sheet

Another useful tool thanks to Dr Jen Davis, specialist veterinary anaesthetist....

Originally published on the Vet Anaesthesia Blog 28 June 2016: Canine Premedication and Sedation "Cheat Sheet"

One of the most common requests that I hear, as a specialist veterinary anaesthetist, from vets and nurse in general practice is for a premedication / sedation “cheat sheet”.

Ideally choice of drug(s) and dose should be tailored to each individual animal, with decisions being influence by factors such as temperament, age, breed, pre-existing conditions and the procedure to be performed.

Before sharing with you my version of a “cheat sheet” (link to pdf. at bottom of page), I want to make a few important notes.

  • Avoid using the same sedation/premedication “recipe” for all animals. Even ASA 1 dogs should be individually assessed with careful history taking and a full physical examination.
  • Consider the aims of premedication when determining what drug combination to use for a particular animal:
    • calming/anxiolytic effect
    • improvement in ease of animal handling
    • provision of analgesia
    • reduction in dose of induction/maintenance agent
  • Be aware of the onset of action of the drugs you are using, and time administration appropriately. It may not be appropriate to mix two drugs with a very different onset time in the same syringe, they may be better given separately at different times.As a guide, onset of maximal sedation following IM administration is: ACP up to 45 minutes, medetomidine 15-20 minutes, methadone/morphine 20-30 minutes, butorphanol 10-20 minutes.
  • Be aware of how long the opioid you have used at premedication will last. If not using any additional intra-operative analgesia you may have to repeat the opioid dose during surgery to ensure the dog has adequate analgesia on board. For example, methadone and morphine last up to 4 hours when administered IM.
  • Ensure that you use premedication doses if you intend to follow the drug administration with general anaesthesia. These are generally lower doses than if sedation only is to be used, because adverse cardiorespiratory effects are usually exacerbated when combined with other anaesthetic agents.
  • I frequently refer to the use of methadone. Morphine may be used instead of methadone and at the same doses, however it frequently causes vomiting when used for premedication, and be aware of the risk of histamine release if used IV
  • Here in Australia the a2-adrenoceptor agonist we use mainly for small animals is medetomidine, so I refer to that drug most frequently.If you use dexmedetomidine, the dose given for medetomidine should be halved.
  • I do not recommend the routine use of atropine as part of a premedication. Historically, atropine was included to reduce effects including hypersalivation and bradycardia that occurred with inhalants such as diethyl ether. Modern anaesthetics much less effect on the autonomic nervous system, and unnecessary use of atropine may produce unwanted effects such as tachycardia and tachyarrhythmias. I prefer to use this drug only when bradycardia is present and problematic (e.g. causing hypotension). Atropine should never be used with medetomidine or dexmedetomidine.

Finally, the drug combinations and doses that I recommend are based on a combination of personal experience and published literature. There are endless potential combinations of drugs/doses that can be used, and opinion of the “best” combinations will differ between anaesthetists.

Without further ado, here is the three page pdf “cheat sheet”: Vet Anaesthesia Tips - Small animal sedation / Premedication

I’d love to hear comments below regarding how you find the sheet to use, and whether there is any information missing that you would like.

About Jen

Dr Jen Davis (@Dr GasVet) is a European Specialist in Veterinary Anaesthesia and Analgesia. She is currently undertaking a PhD at Murdoch University, investigating the early diagnosis of acute kidney injury induced by anaesthesia-related hypotension.

Jen also works part-time as registrar in veterinary anaesthesia at The Animal Hospital at Murdoch University, where she administers sedation, anaesthesia, and analgesia to all species of animal, as well as teaching undergraduate students and resident vets studying to become anaesthesia specialists.

A summary of Jen’s research, and open access to her published work can be found on ResearchGate.

For more excellent posts on veterinary anaesthesia vist Jen's blog: Vet Anaesthesia Tips and register to receive notifications of new posts by email

You can also follow Jen on:

Twitter: Vet Anaesthesia Tips  |  Facebook: Veterinary Anaesthesia Tips

Comments

Scott Snellgrove @ Nov 25th 2016 3:14pm
Any recommendations for premeds for Caesarians generally or for brachycephalic Caesars?. Thanks
Dr Jen Davis @ Nov 28th 2016 9:51pm
Hi Scott, thanks for reading the blog. Those are trickier ones... I usually find that caesareans don't need premedication as they are tired from labour. I place a catheter while pre-oxygenating, then use a co-induction technique (e.g. midazolam then propofol). Line block for analgesia, and wait to give opioid once pups out. If I feel she needs an opioid prior I would use low dose fentanyl as it is short acting so less likely to affect pups, but still can - they may require naloxone. Brachycephalics I usually stick to an opioid alone for premed, avoiding ACP or medetomidine. If non-painful procedure I would use butorphanol 0.2-0.4 mg/kg IM (nice sedation and anti-tussive), if for surgery I would use methadone 0.25 - 0.5 mg/kg IM. If dog is very worked up though and I'm concerned that risk of obstruction due to anxiety is higher than associated with sedation, I would add a small dose of ACP 0.01-0.02mg/kg IM. With brachycephalics its a balancing act between too much sedation and stress/anxiety of hospitalisation - both can lead to obstruction. Never leave them unobserved after premed, put in a kennel in same room as you, or keep on lead near where you are working. Ideally get an IV catheter in as soon a possible, so you are ready if obstruction does occur. And don't forget to pre-oxygenate before induction. Hope that helps!
Scott Snellgrove @ Nov 30th 2016 8:55am
Much appreciated Jen

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