Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Dentigerous Cyst

Synonyms: Follicular Cyst, Ear Fistula, Ear Tooth, Heterotopic Polyodontia, Temporal Cyst or Odontoma


Dentigerous cysts are firm non-painful bumps that usually develop near the base of the ear, but can also be found in other locations on the head. They are more commonly seen in young horses.

They result from imperfect embryonic development, the failure of closure of one of the branchial pouches. The result is dental tissue and cystic lining (fluid producing tissue) ending up in an abnormal location.

These cysts may be loose or firmly attached to the underlying bone, and many contain one or more teeth (dental tissue). They usually ooze dark golden, amber or pale, pus-colored discharge. The discharge may emanate from the base of the ear or pinna (upright part of the ear itself), or it may come from further down the side of the face or behind the jaw.

Ultrasound and radiography (x-ray) may be used to determine the nature and depth of the condition, whether there is bone or dental tissue within the cyst, and whether the cyst is attached to underlying bone.

Treatment is surgical removal of the cyst but removal of the dental tissue and any bone growth must be done with care.

my vet's role


The prognosis is good with surgical excision, but any surgical approach must be very cautious. Some of these are attached firmly to the skull.

If bone or dental tissue is broken loose from the skull, it can result in life-threatening fracture.

my role

Questions To Ask Your Vet:
  • Is the cyst attached to underlying bone and, if so, will this make removal risky?
  • How successful is surgical treatment?
  • Are there any other treatments you might recommend?

Author: Doug Thal DVM Dipl. ABVP