History and Physical Examination
A 2-year-old sexually intact male Labrador Retriever weighing 34.6 kg (76.12 lb) was evaluated because of unilateral right-sided nasal discharge of approximately 3 days' duration. Head trauma as a result of a fight with a larger dog was reported at approximately 1 week of age, resulting in the eventual enucleation of the Labrador Retriever's right eye at 4 months of age. There was extensive soft tissue damage to the orofacial region, including trauma to the oral cavity at the level of the gums and surrounding mucosa. It was unknown whether the dog's deciduous right maxillary canine tooth had ever erupted; however, as noted on subsequent physical examinations, its permanent right maxillary canine tooth never erupted. The dog was reportedly healthy until 7 months prior to evaluation. At that time, halitosis was noticed and extraction of a necrotic right maxillary fourth premolar (carnassial) tooth was performed. Treatment with trimethoprim-sulfamethoxazole after extraction temporarily resolved the halitosis. An episode of right-sided epistaxis and a low platelet count (16,000 platelets/μL) were documented at that time; therefore treatment with the antimicrobial was discontinued. The platelet count returned to within reference range 1 week later. Approximately 5 days later, the dog developed right-sided green nasal discharge of mucoid consistency.
Oral examination revealed absence of the right maxillary fourth premolar and right maxillary canine teeth. No swelling or signs of pain were associated with the area of these missing teeth. Because of the persistent nasal discharge, CT of the head was performed (Figure 1).
Computed tomographic images of the head of a 2-year-old Labrador Retriever with unilateral nasal discharge. A—Transverse CT image obtained at the level of the second premolar tooth and displayed in a bone window (slice thickness, 2 mm). B—Reformatted sagittal CT image of the skull.
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Computed tomographic images of the head of a 2-year-old Labrador Retriever with unilateral nasal discharge. A—Transverse CT image obtained at the level of the second premolar tooth and displayed in a bone window (slice thickness, 2 mm). B—Reformatted sagittal CT image of the skull.
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Computed tomographic images of the head of a 2-year-old Labrador Retriever with unilateral nasal discharge. A—Transverse CT image obtained at the level of the second premolar tooth and displayed in a bone window (slice thickness, 2 mm). B—Reformatted sagittal CT image of the skull.
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Diagnostic Imaging Findings and Interpretation
On CT images, an empty right maxillary canine tooth alveolus and the presence of a structure resembling an apparently fully developed canine tooth within the nasal cavity, predominantly in the ventral aspect of the conchae, are evident (Figure 2). The maxillary right fourth premolar tooth is absent. The vomer bone and nasal septum are partially deformed and displaced to the left.
Same transverse CT image as in Figure 1. Notice the apparently fully developed canine tooth within the right nasal cavity, predominantly in the ventral aspect of the conchae (asterisk). Notice the left deviation (arrows) of the vomer bone and nasal septum by the intranasally located tooth.
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Same transverse CT image as in Figure 1. Notice the apparently fully developed canine tooth within the right nasal cavity, predominantly in the ventral aspect of the conchae (asterisk). Notice the left deviation (arrows) of the vomer bone and nasal septum by the intranasally located tooth.
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Same transverse CT image as in Figure 1. Notice the apparently fully developed canine tooth within the right nasal cavity, predominantly in the ventral aspect of the conchae (asterisk). Notice the left deviation (arrows) of the vomer bone and nasal septum by the intranasally located tooth.
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Computed tomographic images were obtained before and after IV administration of contrast medium. On postcontrast CT evaluation of the head, there was mild contrast enhancement of the soft tissue surrounding the aberrant right maxillary canine tooth (Figure 3).
Pre- (A) and postcontrast (B) transverse CT images of the head of the same dog in Figure 1 (slice thickness, 2 mm) obtained at the level of the second premolar tooth. Notice the mild contrast enhancement of tissue surrounding the intranasally located tooth (arrows).
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Pre- (A) and postcontrast (B) transverse CT images of the head of the same dog in Figure 1 (slice thickness, 2 mm) obtained at the level of the second premolar tooth. Notice the mild contrast enhancement of tissue surrounding the intranasally located tooth (arrows).
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Pre- (A) and postcontrast (B) transverse CT images of the head of the same dog in Figure 1 (slice thickness, 2 mm) obtained at the level of the second premolar tooth. Notice the mild contrast enhancement of tissue surrounding the intranasally located tooth (arrows).
Citation: Journal of the American Veterinary Medical Association 240, 10; 10.2460/javma.240.10.1165
Comments
A rhinotomy was performed, and the right maxillary canine tooth, which was embedded on the dorsal aspect of the hard palate, was extracted with minimal difficulty. Although complete histologic examination was not performed, the tooth was a normal fully developed adult canine tooth (containing a central pulp cavity, cementum, and dentin) with a vascular supply and alveolar bone attachment to the hard palate.
The patient was treated after surgery for pain with tramadol. No further nasal discharge or complications were noted 6 months after surgery.
The tooth bud is formed from the ectoderm and is organized into 3 parts: the enamel organ, dental papilla, and dental follicle.1 The traumatic episode as a 1-week-old puppy may have resulted in the dorsal displacement of the tooth bud, forcing embryonic ectoderm through the hard palate and into the nasal cavity. The hard palate mucosa, which resembles gingival tissue,2 may have then allowed for the tooth germ and dental follicle and their differentiating components to develop into a normal mature adult canine tooth within the nasal cavity. The mucosa of the oral cavity developed normally, with no evidence of a defect where the canine tooth should have been. It is not uncommon to be unable to view impacted teeth, especially if they are deeply embedded in the sinus tissue.3 In humans in which teeth are found in sites other than their normal dental environment, there are many suggested etiologies, including trauma, infection, pathological conditions (dentigerous cysts), crowding, and developmental abnormalities.4
Computed tomography of the head is indicated in cases of chronic nasal discharge and helped elucidate the origin of the nasal discharge in the dog of this report. The fully developed maxillary canine tooth within the nasal cavity was acting as a foreign body and therefore causing the nasal discharge. The postcontrast images demonstrated mild enhancement, suggesting an inflammatory process in the tissue surrounding the tooth. Minimal contrast enhancement and absence of a mass helped rule out concomitant processes such as tumor. In addition, the CT image displayed in the bone window also demonstrated the nasal septum deviation caused by the tooth, the absence of other osseous lesions, and the absence of other foreign bodies in the nasal cavity that could be contributing to the nasal discharge.
- 1.↑
Gracis M. Orodental anatomy and physiology. In: Tutt C, Deeprose J, Crossley D, eds. BSAVA manual of canine and feline dentistry. Quedgeley, Gloucester, England: British Small Animal Veterinary Association, 2007;1–21.
- 2.↑
Kertesz P. Dental anatomy. In: A colour atlas of veterinary dentistry and oral surgery. Aylesbury, Buckinghamshire, England: Wolfe Publishing, 1993;31–33.
- 3.↑
Shipp AD, Fahrenkrug P. Anatomy of the tooth and supporting structures. In: Practitioners' guide to veterinary dentistry. Glendale, Calif: Griffin Printing Inc, 1992;1–14.
- 4.↑
Reghoebar GM, Boering G, Vissink A, et al. Eruption disturbances of permanent premolars: a review. J Oral Pathol Med 1991; 20:159–166.
