July 2006
Dr Gerhard Steenkamp

A 5 year-old Dachshund is presented as a, second opinion ,with a draining fistula of the right maxilla, ventral to the eye.  This dog started with a similar lesion 6 months ago and was then treated by a veterinarian for a carnassial tooth (108) abscess.  The treatment consisted of an extraction of the carnassial tooth (108) as well as antibiotic treatment.  The dog recovered, and the initial swelling ventral to the eye disappeared.  After 2 months the lesions appeared again and the dog was presented to the same veterinarian who anaesthetised the dog and found no apparent cause for the condition on oral examination.  A further course of antibiotics was prescribed the lesions disappeared for a short while after it reappeared again. 

d carnassial fistula.jpg

a) What would your differential diagnosis (dd’s) be for a swelling ventral to the eye?
b) How would you confirm the presence of abscense of your dd’s in (a)?
c) What would be the treatment of choice in this particular case?

a) Tooth root abscess, root remnants, foreign body, trauma (bite wounds),  tumour.

b) Tooth root abscess – History,oral examination (see if tooth has fractures or not, or if there are severe periodontal disease surrounding the tooth), radiographs.
Root remnants – History, oral examination and radiography as above.
Foreign body – History, extra-and intraoral examination, ultrasound examination, radiography (with or without contrast).
Trauma – History, extra-and intraoral examination and possibly radiography (if the dog was bitten there may be underlying bone pathology).
Tumour – History, intra-and extraoral examination, radiography (possibly CT[computed tomography]) and biopsy.

c)  From the history an infectious cause seems most likely, as the patient responded very well to antibiotic treatment.  Peri-tumour necrosis and infection may sometimes respond to antibiotic treatment but then the swelling will decrease by a small amount initially, if at all.  However, the swelling will not disappear and carry on enlarging as the tumour grows.  Radiography revealed the rostral 2 roots of the 108 which was not extracted by the referring veterinarian.    Tooth root abscesses results from endodontic or periodontic infection that reaches the root tip (apex).  Regardless of the route of entry the entire pulp will be infected, and in a tooth with multiple roots (3 in the case of 108) all the canals with pulp will be infectious.  It is therefore imperative to fully remove all the roots of such a tooth.  Any fragment that is left behind does have pulp and will therefore perpetuate the infection.  If a clinician is uncertain if all the roots have been removed totally after extracting such a tooth, radiography of the area is indicated to make sure there are no more pieces of tooth left behind.