¹³¹treatment in dogs with hyperthyroidism caused by a non‐resectable ectopic thyroid tumour: 5 cases (2008‐2019)

Abstract

Objectives This study aimed to describe the clinical and diagnostic characteristics, as well as outcomes of radioiodine treatment in dogs with hyperthyroidism caused by a non‐resectable ectopic thyroid tumour. Materials and Methods This retrospective study reviewed the medical records between 2008 and 2018 of dogs diagnosed with hyperthyroidism secondary to a non‐resectable ectopic thyroid tumour and treated with radioiodine. Results Five dogs were included in the study. Three dogs had sublingual ectopic tumours, of which one also had a unilateral cervical thyroid tumour. The remaining two dogs were diagnosed with an ectopic thyroid tumour at the level of the caudal pharynx and the heart base, respectively. All cases were treated with radioiodine. The size of the ectopic masses decreased after radioiodine treatment. Total thyroxine concentrations returned to reference ranges in all dogs. Further, clinical signs of hyperthyroidism disappeared after treatment in all patients. One dog developed myelosuppression secondary to radioiodine treatment. The dog with metastasis had a very short survival compared to the four dogs without metastasis (3 months compared to 7, 36, 50 and 24 months, respectively) and succumbed most likely to thyroid‐related problems. In the remaining four dogs, their quality of life improved. They died due to diseases unrelated to the ectopic thyroid tumour. Clinical Significance Radioiodine therapy should be considered as a treatment option in dogs diagnosed with hyperthyroidism due to a non‐resectable ectopic thyroid tumour.

Response of canine thyroid carcinomas to radioiodine

“…All dogs with functional tumours became euthyroid following 131 I. A recent study of five dogs with ectopic functional thyroid carcinomas treated with 131 I also described normalization of T4 in all dogs 32 . This raises a question around the importance of achieving a measurable response.…”

“…A recent study of five dogs with ectopic functional thyroid carcinomas treated with 131 I also described normalization of T4 in all dogs. 32 This raises a question around the importance of achieving a measurable response. Turrel et al found no difference in the MST of dogs treated with 131 I that had subsequent tumour resection compared with 131 I alone, postulating no benefit in reducing tumour burden.…”

Reporte de caso clínico: Carcinoma anaplásico de tiroides en paciente canino de 9 años

“…De igual forma la radioterapia con yodo en un estudio denominado "Treatment with hyperthyroidism caused by a non-resectable ectopic thyroid tumour: 5 cases (2008-2019)" y realizado por (Lyssens et al, 2021), demostró una diminución del tamaño de las masas ectópicas en tanto que las concentraciones totales de tiroxina volvieron a los rangos de referencia en todos los perros.…”

“…Vol.8-N° 1, 2024, pp. 3922-3940 Journal Scientific MQRInvestigar 3928 mejorar el diagnóstico, la estadificación y la planificación del tratamiento del carcinoma de tiroides humano (Lyssens et al, 2021).…”