Many Malaysian vets I meet during continuing education talks have found the following effective for injectable general anaesthesia. Here is one from a helpful vet in Johor Bahru.
Hi there Dr. Sing,
For me, in terms of injectable zoletil most of us vets here uses the TKX mixture. here is how you do it:
1. take zoletil 100
2. discard the water diluent
3. mix 2 ml of xylazine 100mg/ml
4. mix 8 ml of ketamine 100mg/ml
then you will have 10ml of TKX (zoletil plus ket plus xylazine) where 0.1ml of this tkx should knock down an animal about 3kg for a decent 15-20 minutes. very good for short procedures and also the muscles are quite relaxed unlike those if you use in pure zoletil.
i personally use my own concoction of 3ml xylazine and 7 ml ketamine and i find that this mixture gives me a knock down of 20-25 minutes and the animal 'sleeps' longer. i maintain my animals on gas if the procedure takes any longer than 15 minutes. the only worry is the chance of hypotension (due to xylazine) and we should be mindful of older animals or those with cardiac insufficiency.
I have seen the above TKX used effectively in cat spays in NANAS, an animal shelter in Johor some 2 years ago. It is said to be safe.