"Oro-nasal fistula also known as malar abscess or carnaissal abscess," I said to the two interns very confidently as this was a common problem in old dogs that seldom if ever was sent for dental check ups or scaling.

I was 50% correct. There was a large oral tumour shaped like an oval elongated tumour! Veterinary medicine throws surprising oral tumours to me even after 40 years of practice! The dog was eating food under this tumour which expanded to fit the length and width and height of the oral cavity. The length of this tumour was estimated to be 10.5 cm long. I doubt I will ever see another case similar to this.

Dr Daniel operated to remove this "hamburger" tumour using electro-surgery. I was present for a few seconds during surgery as this was his case and I had confidence he would be able to perform this surgery.

"There was a lot of bleeding," he told me when I audited this case on Feb 12, 2013 (yesterday) and phoned the owner as well. He packed the back of the mouth with gauze swabs to prevent inhalation of blood into the lungs. Around 90% of the length of the tumour was excised electrically and then the remnants.  He electro-coagulated the bleeders in the remnants so that there would be no more bleeding.  Electro-cautery was effective in preventing bleeding.
 

The 50% calculated dosage of domitor and ketamine IV anaesthesia was just sufficient for surgery, with top up of isoflurane gas via the mask. This formula is now used by the vets for IV anaesthesia. It took some time to convince vets that this is a safe and effective formula as all vets have their own judgments and preferences of using various anaesthetics. Stocking a variety of anaesthetics is very costly as they expire and so I don't permit associate vets to order their favourite or their vet professors' choice. A veterinary surgery must be able to sustain its profitability and most associate vets don't bother with this aspect as they are not accountable for the bottom line.    

Histology confirmed it is non-cancerous. It is known as a ossifying fibroma, originating from the soft palate according to the operating vet. There was also oro-nasal fistula which I diagnosed on first visual inspection and the rotten teeth black teeth as you can see from the image, were also extracted.  Blood test had not shown any abnormal findings and so this dog was fit for anaesthesia and survived without any problems.  In this case, the profuse bleeding from the excised tumour could be inhaled into the lungs and cause death by asphyxiation if electro-cautery had not been used to seal all bleeders successfully.

From my phone call, the gentleman owner of this dog is most happy. As far as the dog owner is concerned, his old Chihuahua is OK and eating and that surgical outcome is what matters in the final analysis. "How long has this tumour exist?" I asked him. "I don't know as I don't look inside the mouth," he said. This is a very rare case of a "hamburger" oral tumour.

Yearly dental check up of your dog over 3 years of age with your vet will prevent most oral tumours and rotten loose teeth.

MY COMMENTS ON MANAGEMENT OF THIS CASE:
1.  Electro-surgery was the correct choice.
2.  IV anaesthesia with top up IV would be the choice in this case as isoflurane gas use by mask was not practical. However, the IV anaesthesia at 50% had lasted a sufficient amount of time to complete 90% of the surgery and isoflurane gas top up was effective in this case.

IV anaesthesia top up, the drugs would be injected with the IV drip or the syringe with the drugs would be attached to the IV catheter.  

This webpage:
http://www.bekindtopets.com/dogs/20130214ossifying_fibroma_oral_dog_toapayohvets.htm

Case report written by a vet intern:
Oro-nasal fistula report written by an intern