Thyroid Carcinoma

Thyroid carcinoma is the most common endocrine malignancy in dogs, typically affecting middle-aged to older individuals of any breed. While it often arises unilaterally, bilateral involvement is possible without significant prognostic implications. Clinically, surgically amenable tumors are round, ovoid, discrete, and freely movable. Without detectable metastasis, survival post-surgery ranges from 1 to 4 years. Metastatic disease is present in approximately 38% of dogs at diagnosis and up to 90% by death. Despite high metastatic potential, canine thyroid carcinomas exhibit either rapid, aggressive growth or indolent progression. Metastasis may not manifest until 12–18 months post-surgery, with variable survival times post-diagnosis. Clinical presentations vary from incidental findings to symptoms like dysphagia, vocalization changes, and dyspnea. Rarely, functional tumors cause hyperthyroidism. Diagnostic evaluation includes physical exams, lymph node palpation, and imaging. Treatment options include surgery, methimazole for functional tumors, and targeted therapies like tyrosine kinase inhibitors. Prognosis depends on metastasis presence and tumor behavior, with surgery offering long-term survival in non-metastatic cases. Adjuvant therapies and genetic profiling may guide treatment decisions. Retinoids, natural or synthetic derivatives of vitamin A, play a crucial role in epithelial differentiation and cellular homeostasis.