10 weeks ago - two massive perineal hernias were presented and repaired. Neutering was advised so as to reduce urine-marking straining of the pelvic muscles. Three images are presented (top row). The left perineal hernia recurs but not in a massive size as before. See pictures of the dog 10 weeks after surgery below. A Tardak injection had been given after neutering. The owner prefers to wait and see if the hernia develops to a bigger size.
10 weeks ago, I was surprised that the dog would still be alive with such a large bilateral perineal hernia. The operation took around 2.5 hours
10 weeks after hernia repair, the owners are happy with the outcome. The dog passed blood in the stools twice and I was consulted.
Still urine-marking obsessively. The owners agreed to the neutering.

The first approach will be to neuter the dog. Incredibly, around 12 hours after neutering, the perineal hernia had gone down by 80% in swelling when I saw him at 8 pm. He was neutered at 9.30 am on Thursday Sep 28, 2011. I could not believe it. The hernia had softened as the intestines and probably bladder had gone back into the abdomen on its own accord. I will have to wait and see.

ANAESTHESIA
6.4 kg. Domitor 0.1 + Ketamine 0.1 = 0.2 ml IV with normal saline 0.2 ml. This is much below my guideline of Domitor 0.4 + Ketamine 0.5 ml IV for a healthy 10 kg dog.

Isoflurane gas for 2 minutes
Intubated and given isoflurane gas
The dog stopped breathing and emergency measures were performed. I did cardiac massage and blowing into the endotracheal tube for around 5 minutes. The heart started beating and the dog started breathing.

Thereafter, isoflurane gas top up by mask was given in short doses of less than 30 seconds by mask. As the dog woke up from Stage 4 and made crying noises, my assistant gave the isoflurane gas by mask for less than 30 seconds at less than 3%. Using 5% is tempting but is much risky as the old dog's heart may stop beating. 

As part of my mentoring, I gave a tip to my assistant Mr Min to monitor the depth of anesthesia using the eye blinking reflex when the dog is masked and given isoflurane gas directly. Observe the eyelid blinking by tapping the eyelids. Once the blinking reflex has ceased and the eye white rolls downwards, the dog is progressing into the Stage 4 which is surgical anaesthesia. The dog closed his eyes too.  

In this case, the endotracheal tube had been taken out as the dog did give a "vomiting" reflex earlier. Patience, focus on isoflurane effects and a longer time was needed to neuter this dog. The dog woke up immediately after the last stitch of 2/0 absorbable PDS to close the skin wound. Therefore there was no need for Antisedan reversal of domitor. He was on the Stage 3 and Stage 4 anaesthesia and therefore woke up immediately since the dosage was slightly under.

As to what caused the cessation of breathing 5 minutes after intubation and on isoflurane + oxygen maintenance, it is hard to say. It could be the heart being sensitive to isoflurane at more than 1%.

The dog's blood test was normal but he might have lung or other internal health problems, being an old dog. No x-rays of the lungs were done as the owner wished to have the lowest veterinary cost as possible. The dog had a 2.5 hour anaesthesia earlier to repair his massive perineal hernia with no anaesthetic problems.

Anaesthesia in old dogs is always a big risk. The left perineal hernia should be repaired as it was half the size of an orange. Otherwise the blood in the stools would present again as the intestines get trapped inside the hernia. If neutering stops further enlargement of the hernia, then no more repair would be done. We would wait and see as we don't want to take the anaesthetic risk in a well beloved old dog. I gave a Tardak 1.3 ml SC injection and the dog would go home on day 2 after neuter. The dog is much loved by the patriarch and he is such a happy friendly Silkie Terrier that can win the hearts of everyone. And the love of its owners.