What is a pterygium? It is an invasive
proliferative fibrovascular growth.
Excision of the pterygia was requested
by the owner as the dog had difficulty seeing in the right eye and kept
rubbing the right eye.
Excision was by electro-surgery under general anaesthesia. In human
medicine, there are various sophisticated surgical methods used
I find that many old dogs can survive if the surgery and anaesthesia can
be done under 15 minutes. Provided there is care in the anaesthesia and
knowledge of emergency resuscitation. The anaesthetic time would be
prolonged as there were two pterygia to be excised.
The Divine Powers above threw in an ear haematoma to be operated too. That
meant a much longer anaesthetic time.
The longer the anaesthesia, the higher the chances of the old dog dying on
the operating table.
This dog needed over 60 minutes of surgery. Would his cornea rupture? That
would increase the anaesthetic time.
The dog did not wake up within 2 minutes at the end of anaesthesia.
An antidote (Antisedan) woke him up. He recovered smoothly on Domitor
pre-anaesthetic dose, isoflurane gas maintenance and Antisedan anti-dote.
He woke up quietly as if he had a good nap.
Fortunately, the mission was accomplished with excellent anaesthesia. This
story had a happy ending for everyone. Further info is as follows:
In March 20, 2003, I saw a Shih Tzu
puppy with a growth on the right eye for the first time. Was this a rare
case of a pterygium? No. It was a Dermoid as it had hairs and was of a
different colour. See:
Mar 20 03. The Shih Tzu puppy has a
7 years had passed since I saw the
afore-mentioned Shih Tzu puppy with the Dermoid. A real case of pterygium
surfaced in February 2010.
She was more knowledgeable than me in specific area affecting
this very gentle X-bred dog, as she correctly stated:
"My dog has a pterygium," when she first consulted me. She
requested me to excise the two bulging growths on the cornea of her dog.
The dog also had glaucoma. She was old.
There was a big risk that the cornea might rupture. The bigger risk was
death on the operating table as this old dog would be a high anaesthetic
risk. Every old dog under anaesthesia is a big risk and deaths from anaesthesia
very unpleasant for the vet as the whole family never forgets nor forgives when the outcome is a dead body. I
was very apprehensive that this well cared for and loved family member
would die on the operating table as anaesthesia would take a long time to
excise two pterygia. As if my worries were not sufficient, the dog also
had a right ear haematoma to be operated upon. That meant that the surgery
would take over an hour!
The longer the operation, the higher the chances of deaths on the
"Why do you want the pterygia removed?" I asked the determined owner.
"My dog walked towards her left when the pterygia started to grow
fast towards the centre of the cornea. She cannot see from her right eye
as the pterygium had obstructed her vision." the owner said. "In addition,
she keeps scratching her right eye."
"If the cornea ruptures during excision, I will have to remove the whole eyeball," I said.
"Yes," the lady consented. There was this understanding and
awareness of the high risk of the cornea bursting when I excise the
pterygium when the intraocular pressure was very high. One pterygium was
already worrisome. But this dog had two big ones.
"Have you considered enucleation (eyeball removal)?" I asked as glaucoma
can be a very painful condition and treatment using eye drops must be given
regularly and drug control may become ineffective over time. I don't know
much about its glaucoma formation as it was treated by another vet.
Glaucoma was controlled by eye drops.
"The other vet has recommended it," she said. "But my family does not want
the dog to lose his eye." So enucleation was out of question.
As to what caused such a rapid growth of the pterygia in this beloved dog,
it is hard to say. In people, pterygium is said to be caused by
ultra-violet light exposure.
It was fortunate that the old dog survived the anaesthesia and went home.
"Take good care of her glaucoma," I said to the happy lady as I discovered
that the old e-collar was no more worn. I had asked whether she still had
the e-collar and she said it was worn out and disposed. "That means that
she must wear the e-collar all the time for many weeks and stay out of the
sunlight and wind." 7 days later, I would need to review this case.