Sunday, April 4, 2010

Anaesthesia in dogs and cats - Murdoch Univ Vet Lectures to 4th year students

The following are extracted from the lecture notes from a Murdoch Univ Vet for 4th year vet students and some of my comments as I do use the following drugs in my Toa Payoh Vets,

1. Ketamine must NOT be given alone to horses or dogs because of CNS stimulation and seizure likelihood. Or used as only anaeshetic agent for intraabdominal surgery. Recovery from deep sedation is unsteady to violent.
2. Ketamine is painful on IM and IV injection.

MY COMMENTS: I don't use ketamine alone for dogs as I usually use xylazine IM for the past years. I find that Domitor is great for this purpose. Sometimes my associate vet uses a ketamine/xylazine combination IV is used for pre-anaeshetic induction.

1. xyalzine 1 mg/kg IM or medetomidine up to 20ug/kg IM
2. ketamine 10mg/kg IM about 10 minutes later

Do not give xylazine and ketamine to old dogs or dogs with myocardial weakness or arrhythmias. Never antagonise the action of xylazine in dogs given xylazine and ketamine as seizures are likely. Dogs recovering from anaethesia and suffering from seizures, give diazepam IV.

There was no mention of the use of xylazine and ketamine combination IV for anaesthesia for dogs in the lecture notes.

However there is a mention of using diapepam and ketamine mg in one syringe for pre-anaesthetic induction in dogs. Draw up equal volumes of each such that the combination of each drug per ml is: diazepam 2.5 mg and ketamine 50 mg.


3. The notes mention that ketamine is the drug of choice for sedating viscious cats. Yet the notes mention that sedaion requires doeses up to 30 mg/kg IM or SC and injections are painful. High doses cause violent recoveries. Atropine is advised to prevent salivation.

MY COMMENTS ON INJECTABLE ANAESTHESIAS IN SINGAPORE CATS IN MY PRACTICE: For viscious cats in Singapore and for spay, I will advise xylazine 2% and ketamine 10% (100mg/ml) combination in one syringe IM. For cats less than 2-3 kg, give xylazine 0.1 ml mixed with ketamine 0.4 ml IM. For cats 3-4 kg, xylazine @0.15 ml and ketamine @ 6ml in one syringe IM. For cats 4-6 kg, xylazine @ 0.2ml and ketamine @ 0.8 ml will be sufficient for a duration of 20 - 30 minutes. Less dosage for neuter. Top up with isoflurane gas mask if the dosage is under-estimated. I don't use atropine and have no deaths in cat spays or neuter.

4. The notes mention that anaesthesia is produced from a xylazine and ketamine combination as follows:
xyalzine 1.1 mg/kg IM. This is given first. Wait 10 minutes.
ketamine 10 to 22 mg/kg IM is given. Give a low dose of atropine.
Duration is 20 - 30 minutes. Occasional unexplained deaths and pulmonary oedema have been reported in cats given he aabove combination.

MY COMMENTS: The notes do not mention using xylazine and ketamine in one syringe as I have had written above.


There is a mention of using diapepam and ketamine mg in one syringe for pre-anaesthetic induction in cats. Draw up equal volumes of each such that the combination of each drug per ml is: diazepam 2.5 mg and ketamine 50 mg. The dose of the combination is up to 1 ml/10kg BW IV and give to effect. It has few cardiovascular depressant actions.

6. Tiletamine and ketamine are classified as ANAESTHETICS in the notes. Tiletamne is never used alone due to its CNS stimulation and seizure activity. It is combined with zolazepam and is available as Zoletil. I use it as a sedative in dogs (must give atropine to prevent salivation and head torticollis). I used it as an injectable anaesthetic in hamsters. Sometimes I need isoflurane gas to top up as i is very difficult to know the exact dose for surgical anaesthesia in dwarf and syrian hamsters who may be sedated since they are under-dosed.

7. Xylazine, medetomidine, detomidine and ketamine are classified as SEDATIVE. The drugs listed under sedaaives can produce tranquillisation at low doses. Acepromazine, diazepam, midazolam, morphine, pethidine, mehadone, buprenorphine and butorphanol are classified as tranquilisers.

In conclusion, I hope the 4th year vet students reading this article gets some ideas for dog and cat premedication drugs. They have lots to memorise regarding dosage for bids, horses, sheep, goats and other animals!

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