Functional Thyroid Gland Adenoma in a Dog Treated with Surgical Excision Alone

Abstract

ABSTRACT. An 11-year-old male Golden Retriever presented with progressive weight loss, tachycardia, hyperthermia, polyuria and polydipsia. A freely movable mass, 4.5 × 4 cm in size, was palpated at the cranioventral cervical region. Hormonal study revealed high levels of serum thyroid hormones, and a tentative diagnosis of hyperthyroidism due to a thyroid tumor was made. The tumor was removed surgically and diagnosed histopathologically as thyroid gland adenoma. Serum thyroid hormone levels decreased after surgery with improved clinical signs. At 12 months after surgery, the dog maintained a good physical condition with no evidence of recurrence. KEY WORDS: canine, hyperthyroidism, thyroid gland adenoma.J. Vet. Med. Sci. 69(1): 61-63, 2007 Thyroid gland tumors represent 1.2 to 4% of all canine tumors [5,8]. Most are described as carcinomas, of which less than 10% secrete thyroid hormones [2,3,5,8,10]. Benign thyroid adenomas are clinically rare, usually discovered at necropsy as incidental findings consisting of nonfunctional small nodules [3,5]. In contrast, most thyroid tumors in cats are functional adenomas that result in hyperthyroidism, but are often successfully treated with thyr o i d e c t o m y a l o n e [ 3 ] . S u r g i c a l t r e a t m e n t o f hyperthyroidism due to thyroid adenoma has been reported in a dog with only 5 weeks post-surgical follow-up [6], but to our knowledge, no similar canine case reports have yet to be reported. The present report describes a canine case of functional thyroid adenoma treated with surgical excision alone, with clinical and hormonal improvements 12 months after surgery.An 11-year-old male Golden Retriever was presented for evaluation of progressive weight loss. The dog was active and had a good appetite without any gastrointestinal signs, but his body weight was 22.9 kg compared to 31.7 kg 15 months before presentation. The owner noticed signs of polyuria and polydipsia about 1 month prior to presentation. The dog's heart rate was 160 beats per min and the rectal temperature was 40.6°C. A firm, freely movable subcutaneous mass, 4 × 4.5 cm in size, was palpated in the left cranioventral cervical region. Ultrasonographic examination of the lesion revealed a well-demarcated mass without invasion to the surrounding tissues. The mass was aspirated for cytology under ultrasound guidance, revealing clusters of mononuclear cells suggestive of a thyroid gland tumor. The owner did not consent to further examination.Two weeks later, the dog was readmitted because of frequent vomiting for 24 hr, and the owner requested close examination. The movable, cervical mass remained, and progression of weight loss (20.8 kg), tachycardia (180 beats per min), and hyperthermia (39.7°C) with a panting breath (120 breaths per min) were noted. Thoracic radiography revealed no evidence of metastasis or cardiac enlargement and regional lymph nodes showed no swelling on palpation.Results of hematological and biochemical examination were almost normal except for mild bilirubinemia (0.7 mg/dl)...

Thyroid papillary cist adenoma in dog (Canis familiaris)

“…O adenoma do presente trabalho foi classificado como sendo não funcional devido à ausência de alteração dos níveis padrões dos hormônios TSH, T3 e T4 (Tilleu & Smith, 2003;Mooney, 2005). Segundo Nelson & Couto (2001) e Mooney (2005), o aumento dos níveis de TSH, T3 e T4 em associação com tumores funcionais da tireoide é mais comum em humanos e em gatos, e menos comum em cães (Itoh et al, 2007).…”

Alimentäre Thyreotoxikose bei zwei Hunden

“…Hierbei kommt es zu einer übermäßigen Hormonproduktion, die zu einer erhöhten Konzentration der peripheren Schilddrüsenhormone bei gleichzeitig erniedrigter Konzentration des Thyreoidea-stimulierenden Hormons (TSH) führt (24). Rund 10 % der Schilddrüsentumoren bei Hunden sind hormonell aktiv (14). Symptome einer Hyperthyreose finden sich vorwiegend bei autonomen Schilddrüsenkarzinomen (22,24), während es zu hormonproduzierenden Schilddrüsenadenomen beim Hund lediglich einzelne Kasuistiken gibt (14,20).…”

“…Rund 10 % der Schilddrüsentumoren bei Hunden sind hormonell aktiv (14). Symptome einer Hyperthyreose finden sich vorwiegend bei autonomen Schilddrüsenkarzinomen (22,24), während es zu hormonproduzierenden Schilddrüsenadenomen beim Hund lediglich einzelne Kasuistiken gibt (14,20). Bei den meisten Hunden mit einer Schilddrüsenneoplasie lässt sich klinisch eine Umfangsvermehrung im Bereich des Halses feststellen, die mit oder ohne Symptome einer Hyperthyreose vorliegen kann (23).…”

Hyperthyroidism in dogs caused by consumption of thyroid-containing head meat

“…Canine hyperthyroidism is exceptionally rare and typically results from thyroid carcinomas producing excessive amounts of thyroid hormones (Mooney and Jones, 2004). Sporadic cases associated with a functional adenoma have been reported (Lawrence et al, 1991;Itoh et al, 2007). Elevations of thyroid hormones are usually modest and clinical signs are mild (Meuten, 2002).…”