Oral pathology quiz

A tech's guide to oral pathology

HALIFAX, NS – Using your eyes, ears, nose, and sense of touch to check for any external abnormalities is the first step to identifying oral/dental disease. Judy Rochette, DVM, FAVD, Dipl AVDC, while presenting at the Atlantic Provinces Veterinary Conference, said that any variation that exists should be considered abnormal until proven otherwise. Examining the inside of the pet’s mouth, and assessing the diagnostic reports, history, its breed, etc. will help to determine the pet’s oral pathology, and are key to getting and keeping patients healthy.

Conducting an external assessment
Even before looking inside a pet’s mouth, indications of oral/dental disease can often be suspected. For example, facial asymmetry, ocular or nasal discharge, pain on opening the mouth, bumps, head type or occlusion, may suggest a problem. “Although you may not see a lesion, you might hear a ‘click’, smell an odour, or palpate an unexpected lump or change in texture”, said Dr. Rochette.

She said that to assess symmetry, stand directly behind the animal and look along the midline of the skull and along the nose. See if the nose is straight, whether there is dental interlock, a genetically controlled wry occlusion, or facial trauma that has affected growth. Check whether the muscle mass is equal, because atrophy can result from disuse resulting from an undiagnosed fracture, be neurogenic secondary to trauma, or result from the autoimmune condition masticatory muscle myositis.

She added that unexplained lumps or bumps might indicate tooth abscesses or swelling of the sinuses. Nasal discharge or history of sneezing or coughing in a young animal may suggest a palatal defect, whereas an adult may have deep periodontal pockets, a nasal foreign body, nasal infection, or a tumour.

Inspecting the dental soft tissues
The soft tissues, teeth, and hard tissues of the jaws should be assessed, in that order, as well as the number, location, orientation, and health of the teeth. Gingivitis and/or periodontal disease is the most frequently encountered soft tissue pathology, which may result in bad breath, inflammation, soft tissue edema and bleeding, gingival recession, gingival hyperplasia, attachment loss, furcation exposure, tooth mobility, and abscesses.

Dr. Rochette noted that lesions on or around the nose might indicate an autoimmune disease. Oral “lumps” can be benign, locally invasive, metastatic, and occasionally contagious, and can only be diagnosed by biopsy.

Squamous cell carcinoma is the most common tumour in cats and is almost always fatal due to aggressive local reoccurrence. In the dog, depending on location, it can be surgically excised and cured. Fibrosarcomas tend to be found in the palatal and nasal areas and are extremely locally invasive. Osteosarcoma may be cured with surgical excision, but chemotherapy is recommended, as this tumour will metastasize, especially to the lungs. Lymphoma and mast cell cancers depend on surgical debulking and controlling the primary tumours.

Surgical excision cures dentigerous cysts, which can form around impacted teeth, and radicular cysts, which form from the area of a non-vital tooth root when the Rests of Malassez "re-awaken".
Other potential findings include acanthomatous ameloblastomas, which are locally aggressive jaw tumours that arise from the subgingival tissues and will invade bone; they have a high propensity for recurrence.

Gingival hyperplasia is an inflammatory reaction, usually to plaque, that results in accumulation of gingival tissues, which will require excision.

Papillomas (warts) are more common in young dogs, and can be contagious to other dogs. Dr. Rochette said recent research suggests older animals with severe, recurring infections usually have an underlying disease, and lymphoma is often the cause.

Eosinophilic granulomas, which can be raised masses, flat plaques, or diffusely thickened tissues, are more common in the cat than the dog, and can be controlled by removing substances that stimulate the immune system (e.g. fleas, food proteins) in combination with immunomodulation.

Cheek, or tongue, chewer's "granulomas" are accumulations of scar tissue from chronic trauma.

Dr. Rochette said that last but not least, the tongue must be examined for ulcers, fungal plaques, foreign bodies, cancer, etc.

The teeth
Too many teeth can cause displacement of other teeth, and crowding can lead to periodontal disease.

The location and orientation of a tooth can be considered together. Variations from normal occur when a tooth bud is displaced or rotated, or if the developing tooth erupts abnormally. Teeth that are in the normal location but rotated need treatment to relieve a malocclusion, or periodontal disease if it is present, or is likely to develop. Teeth that are tipped will need treatment to alleviate the resulting malocclusion and/or soft tissue trauma.

Crowded teeth are usually a result of breed specifications. Dr. Rochette said that if the crowding doesn't cause a malocclusion it usually results in periodontal disease.

A healthy tooth should be white and shiny. A diffusely discoloured tooth with normal enamel can occur from pulpitis (pink, purple), tooth death (yellow, grey, brown), tetracycline/doxycycline staining (yellow), porphyrin accumulation (fluoresce with UV light), or teeth that look bluish may have a dentinal developmental defect. Any fractured tooth with pulp exposure that the explorer can penetrate should be considered non-vital (dark chocolate or black).

Dr. Rochette noted that true caries lesions are rare in animals; if found the most common site is the occlusal surface of a molar, which will be brownish and “sticky” to probe.

Resorptive lesions occur in cats and dogs, and may be external or internal. They are very painful once there is exposure to the oral environment, and require extraction.

Ankylosis occurs when the periodontal ligament and space are lost, and the cementum of the tooth bonds with the bone of the jaw. This can occur along with tooth resorption, following an avulsion, or with advanced age.

Hypercementosis is the proliferation of cementum, so that an adjacent root, often of another tooth, is bonded to the first tooth.

Examining the bones of the oral cavity
The bone of the mandible, maxilla, and temperomandibular joints is the last thing to consider during an oral examination, and radiographs will be necessary to determine the extent of a lesion. A bony lump can be benign or cancerous, or arise from osteomyelitis. Benign lumps can result from "space occupying lesions" such as dentigerous cysts or odontomas.

Bone cancers include osteosarcoma and chondrosarcomas, which may manifest as either bony proliferation, or can be destructive. Osteomyelitis can look very similar, so a biopsy is always indicated to distinguish between radiographic lesions.

A generalized decrease in density may suggest systemic disease such a hyperparathyroidism. Fractures and dislocations are possible.

Finally, radiographs of the temperomandibular joint can be important for diagnosing fractures, dislocations, or deformities. Jaw shifting/malocclusion, pain and/or crepitus on opening, bruising, soft tissue tears, inability to close the mouth, etc. are all indications for radiographs.

Dr. Rochette concluded by saying that the first step in diagnosing an abnormality is recognizing that it is an abnormality. She stressed that any lesion that persists should indicate further investigation, by taking every opportunity to help your patients. CVT