Deitz K. and Gilmour L.

Conference Proceedings, (2012). American College of Veterinary Internal Medicine, New Orleans:

Computed tomography is often used to help determine the treatment approach to canine thyroid tumors. This study was undertaken to describe the computed tomographic features of canine thyroid tumors. Nineteen dogs with computed tomographic images of a histo- pathologically confirmed thyroid tumor were identified. Each CT scan was evaluated by 3 clinicians for various characteristics, independently and then by consensus.
There were 17 carcinomas and 2 adenomas. Tumor consis- tency was heterogeneous in 16/19 (84%). Most (12/19) had internal mineralization, although in 2 there was extensive bone destruction which made the presence of tumor mineralization difficult to determine. Sixteen tumors (84%) were unilateral. Of these, 11/16 were left-sided, and 5/16 were right-sided. The remaining 3 were considered bilateral or ventral. All tumors had some degree of contrast enhancement. Eighteen had heteroge- neous enhancement, with 7/19 having more contrast enhance- ment peripherally than centrally. Most (16/19) had well-defined margins post-contrast. Location of tumors compared to bony structures was variable, with most having their cranial margin somewhere along the level of the second cervical vertebra (13/ 19) or at the junction of the second and third cervical vertebra (1/19). Some were much more cranially located, with the cranial margin at the level of the temporomandibular joint (1/19) or bulla (4/19). The caudal extent was variable, and was anywhere from mid C1 to caudal C5. Common CT features of canine thyroid tumors include unilat- eral location in the neck anywhere from the temporomandibular joint to C5, with heterogeneous consistency, internal mineraliza- tion, and heterogeneous contrast enhancement with well-defined margins.