This text describes the processes of how a vet
diagnoses & treats a case of oral tumours with
tooth root abscess and oro-nasal fistula in an
older Chihuahua. These processes form part of
the Standard Operating Procedures at Toa Payoh
Owner noticed that the dog had swelling on the
right side of the cheek for more than two weeks
and later brought the dog to Toa Payoh Vets.
The patient: Chihuahua, Male, 10 years old,
was swelling on the right side of the cheek
however the appetite was still normal. The
swelling had been there for more than two weeks.
It seems like the old dog had oro-nasal fistula
and tooth root abscess.
has not ended for this old dog as it was given a
second chance by its owner. He had once been
abandoned and later he found home with this kind
hearted Singaporean who flew him all the way
from Australia. He had journey far to reach his
home sweet home.
dog’s mouth is seldom examined by most dog
owners and bad breath is usually tolerated by
many Singaporean dog owners. They also seldom
pay attention to the mouth part of their pet as
long as the dog is eating without a problem.
check up is not usually done and tartar will
usually build up and rotten teeth fall off. Many
owners are not bothered or are ignorant that
dogs also need to have regular dental check up
and dental care. However, the younger generation
of Singaporeans are better educated and more
concerned about the welfare of the old pets.
to my case.
One fine day on late January 2013, the owner
of a male, 10-year-old Chihuahua noticed a
swelling on the right cheek and brought it
to Toa Payoh Vets.
At Toa Payoh Vets, Dr Daniel Sing was on
duty. I was present.
“This looks like a case of tooth root
abscess as you can see that the teeth are
rotten and filled with tartar. There may
also be oro-nasal fistula. It is an abnormal
communication between the oral and nasal
cavities involving the soft palate, hard
palate, premaxilla, or the lip” said Dr.
it a case of tooth root abscess and
“So what are the treatment options
available?” asked the owner.
“For this case, we would recommend to go
through surgery to remove all the affected
teeth and clean the abscess” explained Dr.
“But then how would my dog eat without
teeth” the owner said.
“Don’t worry, the dog can eat soft canned
food or even boiled chicken breast and
The financial costs and risk must be
explained fully before any operation is
done. But the owner must give his consent
and that is where personality and financial
conflicts come in. He must also be aware of
the risk involve especially in older dogs.
Health screening is strongly advised before
anaesthesia and surgery for all patients,
esp. in the older dog.
Anaesthetic risks are much higher in old
dogs. There is always the possibility that
the older dog may die on the operating
table. When the owner hears that the dog may
die on the operating table, he may decide
not to get the surgery done. Some deem the
vet incompetent and consulted another vet. A
health screening should be suggested by the
vet to let the owner knows whether the risks
are high or not.
"I advise a blood test to screen the health
of the Chihuahua," Dr Daniel said. The
owners must consent to take the anaesthetic
risk if they give permission for the surgery
as in this case. No surgeon can guarantee
zero risk in any anaesthesia, whether in
people or animal.
The total WBC 16.6 (normal 6.0-17.0).
Neutrophils 50.8%, Lymphocytes 19.2%,
Monocytes 24.6%, Eosinophils 1.1%, Basophils
4.2%. The platelets count is 520 which is
slightly above normal (normal 200-500)
This blood test indicates that the liver and
kidneys were functioning normally.
"OK," the owner consented to the surgery.
Antibiotics were given to the dog.
IV anaesthesia without Intubation.
Anaesthesia. What type? IV, gas or both? IV
anaesthesia is shorter acting than gas
anaesthesia. Intubation (a breathing tube
connects anaesthetic gas and oxygen to the
dog) is usually done in dental extraction.
After the dog had been anaesthetised, I discover
that there was a big tumour about the size of
palm size dough growing from the soft palate.
This tumour occupied the whole oral cavity and
the plan now had changed. We had to remove the
tumour and the teeth as well. Therefore we can’t
intubate the dog as the tumour is obstructing
the endotracheal tube.
“Call the owner and inform him about the tumour
and the plan to remove it and ask for his
consent." The owner gave his permission to
proceed and the surgery continued.
Dormitor IV at 25% of calculated dosage for
young healthy dog was sufficient for
electro-surgical excision. Dental extraction was
done after that.
The old dog survived the anaesthesia and that
was what mattered most for the owner. It is not
always possible for every old dog to survive
anaesthesia during surgery. Therefore it is
wiser to remove the tumour when it is smaller
and when the dog is younger.
“Is the soft palate tumour cancerous or not?”
the owner asked.
“Nobody can tell from the physical appearance,”
I said. “The tumour needs to be analysed by the
laboratory and the tumour cells can be seen
under the microscope if there are any. This is
the process of histology. Do you wish to get the
tumour sent for histology?”
It is best to get the owner’s permission to send
the tumour for histology to determine its state,
as some owners may have budget constrain or do
not wish to spend more money.
It is unprofessional to give medication to the
owner to treat the oral tumour as some owners
may insist on having them as an alternative to
the high risk of anaesthesia during surgery as
it will not disappear.
Electro-surgical excision of the soft palate
tumour including extraction of molar teeth.
“The tumour can be removed from its stalk by
using electro-cauterized to avoid losing too
much blood,” said Dr. Daniel. Then after
removing the tumour, the dog started to wake up
from anaesthesia, so it had to be gassed with
Isoflurane. When it was down, Dr. Daniel
proceeded with dental extraction of the molar
and drainage of the pus.
Histology Lab Result
The result of the histology came out and the
nodule is covered by squamous epithelium with
overlying parakeratosis. At the centre, there
were irregularly-shaped trabeculae of woven and
lamellar bone. There is no evidence of
malignancy. So this is good news for the owner
is it was not cancerous.
The final diagnosis from the histology is
ossifying fibroma mass, with tooth root abscess
and oro-nasal fistula. The dog was put on
antibiotic and two days after surgery it was
BE KIND TO YOUR OLDER DOG. EXAMINE YOUR OLDER
DOG'S MOUTH WEEKLY FOR ORAL TUMOURS. SMALL
TUMOURS ARE EASIER TO REMOVE AND THERE IS A MUCH
LOWER ANAESTHETIC RISK.
Tips & Advices:
Post surgical management.
Owner need to come back for review every 3
months for the next 12 months. Owner needs to be
advised and reminded by the vet but this is
seldom done by me.
mouth of older dogs must be checked by the owner
daily and any mouth tumour can be removed when
it is small. In this case, the whole oral cavity
had been filled with the tumour. It could have
existed for some months without the owner seeing
old and unhealthy dogs (>5 years) must be given
25-50% of the calculated dosage of IV
anaesthesia for younger dogs to lessen risks of
Er Erica Chai Hui Ling
COMMENTS BY DR SING KONG YUEN
4th-year veterinary student wrote the above case
study as part of internship requirements.
Interns learn and remember much more when they
write case studies. In this article, the 25% of
domitor and ketamine was actually 50%. The high
% of monocytes in the blood test indicated a
chronic inflammatory condition. This would
likely to be due to the growing inflamed mouth
tumour of the old dog. Surprisingly, there was
no increase in total white cell count although
the mouth was badly infected and the ossifying
fibroma was occupying almost the entire oral
cavity for a long time. A "spell check" is best
done before submission of the article to me.
The article is at the blog:
A report written by me is at: