“When you hear hoofbeats, don’t look for zebras.” This notion was drilled into our consciousness during the clinical years at veterinary school. This is usually true in dentistry, but thanks to modern imaging and diagnostics, there are surprises we call zebras. You do not know what you are going to find unless you take the time to open the mouth and examine each tooth using periodontal probes, explorers, test strips, and imaging.
Some zebra examples are as follows:
1. Skin lesions that are more than skin deep
Figure 1A shows presentation of apparent ventral neck skin lesions. Differential diagnosis included bite wounds from a dog, cat, snake, or spider. In Figure 1B, skin lesions are prepped. In Figure 1C, a mouth examination revealed advanced periodontal disease, the proximate cause of the skin lesions, which were extensions of dental disease. A radiograph of the right mandible revealed marked periodontal disease affecting the right and left mandibular first and second molars. Figure 1D shows the right mandibular first and second molars extracted. Figure 1E presents the left mandibular first and second molars and fourth premolar affected by advanced periodontal disease.
2. Uncomplicated tooth fractures
Dogs and cats often fracture some of the enamel and dentin on their teeth after chewing on antlers, bones, nylon toys, or rocks. Unless the pulp is exposed, we do not pay much attention. Anatomically, there are tubules that travel from the pulp through the dentin ending below the enamel. When the dentin layer is breached, these tubules may communicate discomfort from pressure and cold or hot temperatures. They may also act as a path for oral bacteria to infect the pulp. All fractured teeth must be radiographed and monitored.
Figure 2A shows uncomplicated right mandibular first molar fractures. Figure 2B presents intraoral radiograph of the right mandible with periapical lucencies.
3. The “routine” dentistry
There is rarely a routine dental procedure in clinical practice compared to human dentistry where patients present with clean teeth to have them cleaned more thoroughly. Our veterinary dental patients are presented by caregivers who are uncomfortable with oral malodor. Halitosis is a sign of a condition in the mouth that commonly occurs secondary to periodontal pockets that hold malodorous decomposing food and oral debris. In some zebra cases, comorbidities such as kidney disease and diabetes promote the progression of advanced periodontal disease.
Figure 3A shows the left mandible of an older dog with moderately elevated levels of blood urea nitrogen, creatinine, symmetric dimethylarginine, and serum phosphorus as well as moderate plaque and tartar that were presented for routine dentistry. Figure 3B presents intra-oral imaging of the rostral left mandibular canine and first, second, and third molars with little periodontal support. Figure 3C shows a left mandibular fourth premolar and first molar. 3D picture presents a left maxilla, mandible, and cranium consistent with renal secondary hyperparathyroidism with fibrous osteodystrophy. Therapy for this pet included multiple extractions, phosphorus binders, and renal support.
4. Breed-related gingival hyperplasia
Gingival hyperplasia is relatively common in the boxer, golden retriever, English bulldog, and rottweiler breeds. When it presents in a different breed, it is time to think about zebras. Medication-induced gingival enlargement can occur from the administration of cyclosporine, phenytoin derivatives, and calcium channel blockers. Gingivectomy to decrease the depth of pseudopockets and replacement of calcium channel blockers with hydralazine can be effective in resolving gingival hyperplasia.
Figure 4A shows medication-induced gingival enlargement affecting the left maxilla in a dog being treated with amlodipine. Figure 4B medication-induced gingival enlargement affecting the rostral maxilla. Figure 4C shows immediate appearance of the rostral maxilla post gingivectomy.
5. Swollen face and slab fracture/periapical abscess
Look for zebras when some signs do not fit a common diagnosis, especially if those signs appear in addition to a swollen face, protruding third eyelid, or firm swelling.
In Figure 5Aa swollen right face and protruding third eyelid are shown. Figure 5B presents a crown root fracture of the right maxillary fourth premolar. Figure 5C shows an intraoral radiograph revealing abnormal increased densities apical to the fourth premolar. Figure 5D presents surgical exposure of oral mass for histopathology, which revealed osteosarcoma.
Diagnosis aids to discover zebras
- Williams periodontal probe
- Explore diagnostic instrument
- OraStripdx–a diagnostic test strip for the measurement of dissolved thiol levels can be used as an examination room indicator of gingival health and periodontal status even when periodontal disease does not appear clinically. The original OraStrip test became unavailable a few years ago, but the newer OraStripdx is easier to use and more economical.
- Figure 6A shows an OraStripdx test. Figure 6B shows a test strip placed on a cat’s gingiva in the exam room. Figure 6C presents a reading consistent with periodontal disease.
- Intraoral imaging
I would love to see and share some of your dental zebras. Please email them to me at email@example.com
Jan Bellows, DVM, DAVDC, DABVP, FAVD received his undergraduate training at the University of Florida and his doctorate in veterinary medicine from Auburn University in 1975. After completing an internship at the Animal Medical Center in New York, New York, he returned to South Florida, where he practices companion animal medicine surgery and dentistry at All Pets Dental in Weston. He has been certified by the American Board of Veterinary Practitioners (canine and feline) since 1986 and American Veterinary Dental College (AVDC) since 1990. He was president of the AVDC from 2012 to 2014 and is currently president of the Foundation for Veterinary Dentistry.