SHARING KNOWLEDGE ON INJECTABLE ANAESTHESIA IN THE SPAY OF A CAT
I find the following combination effective as one IM injection
1.1. 3 kg cat. Today, I spayed a raggamuffin, female, 1 year. 3 kg using injectable anaesthetic.
Xylazine 0.15 ml Ketamine 0.6 ml in one syringe IM
Duration of anaesthesia around 20 minutes in this case. I don't need isoflurane gas top up. This is the ideal situation as it means less operating time.
1.2 5 kg cat. I have used xylazine 0.2 ml and ketamine 0.8 ml IM without side effects.
I don't use IV as I find it time consuming but it is one vet's favourite mode of administration and he following simple formula, easy to remember is shared with vets.
2.1 3-kg cat. xylazine 0.1 ml, ketamine 0.2 ml in one syringe, totalling 0.3 ml. Inject 0.1 ml IV first, then another 0.1 ml to effect.
2.2 5-kg cat. xylazine 0.1 ml and ketamine 0.4 ml, totalling 0.5 ml.
Note that you give 0.2 ml IV first. Then increase by 0.05 ml doses to effect. You don't need to use all 0.5 ml.
3. MY CONCLUSIONS
I prefer the IM method for ease of administration and permitting me to focus on surgery. I give isoflurane gas by mask for a few seconds to top up if necessary. However, the IV top-up method is excellent if you don't have isoflurane facilities. The cat is shaved 5 minutes after IM and I operate 10 minutes after injection. Many years ago, I used xylazine IM and then isoflurane gas for cat spay. Now, I don't use it as I find the IM method extremely effective in healthy cats.