Friday, May 28, 2010
82. 6-month-old cat neuter and spay
SHARING KNOWLEDGE ON INJECTABLE ANAESTHESIA IN THE STERILISATION OF CATS AT WWW.TOAPAYOHVETS.COM, SINGAPORE - PART 1
Frequently Asked Questions For Dr Sing
1. Best time to spay my female cat?
If cats are home-based and not permitted to stray outdoors, it is best to spay at 6 months of age as their private parts (vulva) will be be able to develop into adult size.
2. Best time to neuter my male cats?
I advise 6 months of age. However, if there is a male and female sibling cats living in the same apartment, the male will be much interested in the female at 6 months of age. Get them sterilised when interest is shown or neuter the male at 5 months.
One case study
Two domestic short haired cats were adopted as kittens.
At 6 months of age, the male was very interested in the female cat at 6 months.
During sterilisation, the female cat's ovaries were enlarge and blood vessels were very red and big, indicating the cat was on heat. However she was not pregnant. The owner stopped water and food at 10 pm the previous night. One website claims that cats can still be given water prior to surgery. I don't agree with this.
3. What anaesthesia I use in the sterilisation of cats in 2010?
I find the following combination in one syringe given by IM safe and effective
INJECTABLE ANAETHESIA IM
Male cat 4.2 kg
Xylazine 2% @ 0.15ml + Ketamine 0.6 ml IM
Surgery: 10 minutes after injection.
Female cat 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 analgesia.
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 websigte, 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 WWW.TOAPAYOHVETS.COM, SINGAPORE - PART 2
1. Observations of one cat neutered by me
I find the following combination effective as one IM injection
1.1. 3 kg cat. Today, 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 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 do give isoflurane gas by mask for a few seconds to top up if necessary. This is very effective.
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.
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 isolfurane 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.