3. What anaesthesia I use in the sterilisation of cats in Toa Payoh Vets for the past 5 years. I find the following combination in one syringe given by IM safe and effective

INJECTABLE ANAESTHETICS IM General guideline at Toa Payoh Vets for xylazine + ketamine IM anaesthesia in domestic cats, with isoflurane gas top up if necessary: 1. The combination dosage is not dependent on weight directly. 2. It is given for a range of weights as follows:   4-5 kg cat - xylazine 0.2 + ketamine 0.8 ml IM in one syringe for a cat spay without the need to top up isoflurane gas. 2-4 kg cat - xylazine 0.15 + ketamine 0.6 ml IM in one syringe for a cat spay without the need to top up isoflurane gas. For cat neuter, the dosage can be reduced. For example, 2-4 kg cat neuter, xylazine 0.1 + ketamine 0.4 ml IM in one syringe can be effective.  Surgery is to be done around 5-10 minutes after the injection. No delays, otherwise top up with isoflurane gas is necessary.

INJECTABLE ANAESTHESIA IM Male cat, 6 months, 4.2 kg Xylazine 2% @ 0.15ml + Ketamine 0.6 ml IM Surgery: 10 minutes after injection. Excellent surgical anaesthesia Neuter 10 minutes after injection to get the best surgical anaesthetic effect Female cat, 6 months, 3.0 kg Xylazine 2% @ 0.1 ml + Ketamine 0.4 ml IM Surgery: 20 minutes after injection as there was some delay by my assistant in the clipping of hair and cleaning of the surgical area. The cat was awake by then. There is no problem as isoflurane gas by mask at 5% for around 60 seconds and to effect provided excellent surgical anaesthesia.

The combination dosage for this cat should be similar to the one in the male cat if isoflurane gas top up is not needed.

4. Cat cats be sterilised at 3 months of age or younger?
I am aware that cat-control activists and shelters spay them as early as 3-4 months to prevent unwanted pregnancies. On one website, one "vet" working for an animal shelter said that anaesthesia is safe for such age groups as anaesthesia nowadays are better than those in the 1960s. She did not give the % of deaths or type of anaesthesia used.

5. Will my cat's left ear tip be cut off after sterilisation?
No. I don't do it, even in stray cats, unless the owner requests it to be done. Many owners actually dislike seeing their cats being "disfigured" but stray cat activists do get such surgeries done.

6. Can vaccinations be done at the same time?
Yes. However, I don't advise it as the cat is under stress of anaesthetic drugs, pain-killer drugs and antibiotics. But some owners don't have time. So, vaccination is done. Usually there are no adverse effects.

SHARING KNOWLEDGE ON INJECTABLE ANAESTHESIA IN THE STERILISATION OF CATS AT TOAPAYOHVETS, SINGAPORE - PART 2

INJECTABLE ANAESTHETICS IM
Observations of one cat neutered by me recently and in the past. I find the following combination effective as one IM injection. For example, I spayed a Ragamuffin, female, 1 year. 3 kg using injectable anaesthetic. Xylazine 0.15 ml + Ketamine 0.6 ml in one syringe IM. Duration of surgical anaesthesia was 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.

In a 5 kg cat. I have used xylazine 0.2 ml and ketamine 0.8 ml IM without the need of isoflurane gas top up.

INJECTABLE ANAESTHETICS IV 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. FOR EXAMPLE 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. 5-kg cat. Xylazine 0.1 ml + 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 if it is not necessary. Always give incremental dose and observe the depth of surgical anaesthesia. In the IM method, the vet can also give incremental dosage of 0.05 ml IM as there is no IV catheter being used. This method prolongs the spay procedure and this increase in operating time usually pose no problems. However, the shorter the anaesthesia, the better the chances of survival for the patient.

MY CONCLUSIONS
I prefer the IM method for ease of administration and permitting me to focus on surgery. I do give isoflurane gas by mask for a few seconds to top up if necessary. This is very effective. I have seen an animal shelter practitioner topping up with IM injectable anaesthetics when required and he is comfortable with this practice. He has no gas anaesthetic machine which is costly to buy and to maintain.

The IV or IM top-up method is excellent if there is no 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 mask for cat spay. Now, I don't use it as I find the IM method extremely effective in healthy cats if surgery is performed within 10 minutes after injection. Also the duration of surgery should be less than 10 minutes (if possible, in a spay).

In the IV top up method, an IV catheter has to be used and this seems to be less efficient in my opinion. Every time the analgesia is insufficient by observation of the painful movement or cries, the IV anaesthetic is injected by increments to effect. This method is important in countries where the gas anaesthetic machine and isoflurane gas are costly.

For me, a whiff of the isoflurane gas by mask for a few seconds seems more efficient and quieter. Obviously, the vet has to be vigilant on the signs of surgical anaesthesia in both the IV and gas top up. The cat under my regime wakes up earlier than those using IV and I prefer to see a cat up and about as soon as surgery ends.