Equine Carcinoma Hemithyroidectomy


  • Alessandra Mayer Coelho Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP
  • Brenda Valeria dos Santos Oliveira Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP
  • Diana Villa Verde Salazar Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP
  • Karin Elisabeth Rodrigues Borba Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP
  • Lais Maria Gomes Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP
  • Manuela Cristine Camargo Lambert Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP
  • Renata Gebara Sampaio Dória Faculdade de Zootecnia e Engenharia de Alimentos FZEA/USP




Background: In horses, the thyroid gland is located slightly caudal to the larynx and dorsolaterally between the third and sixth tracheal ring, adjacent to the thyroid, there are four small glands called parathyroid glands. In the clinical routine of horses, thyropathies are difficult to be diagnosed, as they have a silent evolution. Thyroid neoplasia is the most common finding in horses, usually unilateral and normally present in older animals. The present study reports a case of equine thyroid carcinoma and its systemic clinical effects, which was successfully treated by means of hemitieroidectomy. 

Case: A 12-year-old male mixed breed horse weighing 436 kg, was admitted to the Veterinary Medical Teaching Hospital of the FZEA/USP    with the main complaint of volume increase in the right ventrolateral region of the neck, difficulty in swallowing, significant weight loss and weakness of the pelvic limbs. On inspection, there was an increase in volume in the topographic region of the thyroid gland and on palpation, there was a firm mass, with delimited edges, with a smooth, mobile surface, without increasing the temperature and without pain. The animal was sent for ultrasound examination, which revealed a delimited mass, with an apparent capsule around it, differentiated and disorganized cellularity with small hypoechoic points of liquid inside the structure, with no apparent vascularization inside the mass. These findings, associated with the anatomical location of the mass, were consistent with thyroid tissue. The clinical signs commonly observed in thyroid neoformations are respiratory stridor, decreased performance, difficulty in swallowing and suffocation. As there was a compromised diet and weight gain, as well as athletic performance, he chose to have a hemithyroidectomy. After surgery, histopathology of the tissue was performed and thyroid carcinoma was diagnosed. Postoperatively, the animal was medicated with antibiotics, anti-inflammatory and anti-tetanus serum, after 10 days the stitches were removed and the animal was discharged. 

Discussion: Neoplasia is the most frequent cause of progressive thyroid growth and in case of suspicion of thyroid disorders, thin needle aspiration (FNAB) is recommended and, later, histopathological examination, which is considered the gold standard for diagnosis pathologies of the thyroid gland. In the present case, no FNAB or preoperative histopathological examination was performed due to the time required to obtain the result, associated with difficulty in swallowing and significant weight loss, which required immediate removal of the mass. Considering that the ultrasound examination revealed the absence of noble structures or important vascularization very close to or adhered to the mass, its removal prior to the histopathological examination was indicated. As there was compromised feeding and weight gain, he opted for hemithyroidectomy, the recommended treatment for unilateral tumors in horses. When performing a hemithyroidectomy, it should be remembered that the parathyroid glands accompany the thyroid and are located in its posterior portion, in the pre tracheal region, with its variable final position. With this variation in topography, the identification of parathyroid glands becomes challenging and, consequently, after thyroidectomy, a portion of parathyroid glands stops operating, and this fact is marked clinically by hypocalcemia and its consequences. In this case described, in which the animal had a tumor in thyroid tissue, possibly the parathyroid functions were also altered, which probably reflected in the lameness in the pelvic limbs. It is concluded that partial hemithyroidectomy in horses is an easy procedure to perform and has favorable results in relation to prognosis and quality of life. 

Keywords: carcinoma, hemithyroidectomy, thyroid. 

Título: Hemitireoidectomia por carcinoma em equino

Descritores: carcinoma, hemitireoidectomia, tireóide. 


Download data is not yet available.


Breuhaus B.A. 2011. Disorders of the equine thyroid gland. Veterinary Clinics of North America: Equine Practice. 27(1): 115-28.

Budras K.D., Sack W.O. & Rock S. 2008. Head. In: Budras K.D., Sack W.O. & Rock S. (Eds). Anatomy of the Horse. 5th edn. Hannover: Schlütersche, pp.38-50.

Cheng S.Y., Leonard J.L. & Davis P.J. 2010. Molecular aspects of thyroid hormone actions. Endocrine Reviews. 31(2): 139-170.

De Marco V. & Larsson C.E. 2006. Hipotireoidismo na espécie canina: avaliação da ultrassonografia cervical como metodologia de diagnóstico. Brazilian Journal of Veterinary Research and Animal Science 43(6): 177-179.

Elce Y.A., Ross M.W., Davidson E.J. & Tulleners E.P. 2003.Unilateral thyroidectomy in 6 horses. Veterinary Surgery. 32(2): 187-190.

Frank N., Sojka V.M.D. & Messer N.T. 2002. Equine thyroid dysfunction. Veterinary Clinics of North America: Equine Practice. 18(2): 305-319.

Galloway J.W., Sardi A., Deconti R.W., Mitchell W.T. & Bolton J.S. 1991. Changing trends in thyroid surgery 38 years’ experience. The American Surgeon. 57(1): 18-20.

Giuffrida G.K. & Gharib H. 1995. Controversies in the management of cold, hot and occult thyroid nodules. American Journal of Medicine. 99(6): 642-650.

Grodski S. & Serpell J. 2008. Evidence for the role of perioperative PTH measurement after total thyroidectomy as a predictor of hypocalcemia. World Journal of Surgery. 32(7): 1367-1373.

Hani H., von Tscharner C. & Straub R. 1979. Thyroid carcinoma with bone metastases in the horse. Schweizer Archiv für Tierheilkunde. 121: 413-420.

Harris A.S., Prades E., Tkachuk O. & Zeitoun H. 2016. Better consenting for thyroidectomy: who has an increased risk of postoperative hypocalcaemia? European Archives of Oto-Rhino-Laryngology. 273(12): 4437-4443.

Hillidge C.J., Sanecki R.K. & Theodorakis M.C. 1982. Thyroid carcinoma in a horse. Journal of American Veterinary Medical Association. 18(7): 711-714.

Joyce J.R., Thompson R.B., Kyzar J.R. & Hightower D. 1976. Thyroid carcinoma in a horse. Journal of American Veterinary Medical Association. 168: 610-612.

Kemppainem R.J. & Behrend E.N. 2000. Update: Interpretation of endocrine diagnostic test results for adrenal and thyroid disease. In: Bonagura J.D. & Kirk R.W. (Eds). Current Veterinary Therapy - Small Animal Practice. Philadelphia: Saunders, pp.321-323.

Lappas D., Noussios G., Anagnostis P., Adamidou F., Chatzigeorgiou A. & Skandalakis P. 2012. Location, number and morphology of parathyroid glands: results from a large anatomical series. Journal Anatomical Science International. 87(3) :160-164.

Lo C.Y. & Lam K.Y. 1998. Postoperative hypocalcemia in patients who did or did not undergo parathyroid autotransplantation during thyroidectomy: a comparative study. Surgery. 124(6): 1081-1086.

Lucke V.M. & Lane L.G. 1984. C-cell tumors of the thyroid in the horse. Equine Veterinary Journal. 16(1): 28-30.

Messer N.T., Johnson P.J., Ganjam V.K., Thompson Jr. D.L., Refsal K.R., Loch W.E. & Ellersiek M.R. 2003. Effects of propylthiouracil and bromocryptine on serum concentrations of thyrotrophin and thyroid hormones in normal female horses. Equine Veterinary Journal. 35(3): 296-301.

Montironi R., Braccismi A., Scarpelli M., Matera G. & Alberti R. 1991. Value of quantitative nucleolar features in the preoperative cytological diagnosis of follicular neoplasias of the thyroid. Journal of Clinical Pathology. 44: 509.

Novo A.C.M.P., Carvalho C.B. & Alves R.B.M. 2009. Ultrassonografia das glândulas tireóideas em cães. Jornal Brasileiro de Ciência Animal. 2(3): 135-149.

Olson Jr. J.A., Debenedetti M.K., Baumann D.S. & Wells Jr. S.A. 1996. Parathyroid autotransplantation during thyroidectomy:results of long-term follow-up. Annals of Surgery. 223(5): 472-80.

Ramsey I.K., Evans H. & Herrtage M.E. 1997.Thyroid-stimulating hormone and total thyroxine concentrations in euthyroid, sick euthyroid and hypothyroid dogs. Journal of Small Animal Practice. 38(12): 540-545.

Reed S.M., Bayly W.M. & Sellon D.C. 2018. Disorders of calcium and phosphorus. In: Toribio R.E. & Duckett W.M (Eds). Equine Internal Medicine. 4th edn. St. Louis: Saunders, pp.1277-1291.

Ritter K., Elefenbein D., Schneider D.F., Chen H. & Sippel R.S. 2015. Hypoparathyroidism after total thyroidectomy: incidence and resolution. Journal of Surgical Research. 197: 348-353.

Scharner D. & Kappe A. 2009. Unilateral thyroidectomy in horses with thyroid tumors. Pferdeheilkunde Equine Medicine. 25: 444-450.

Schulz S.L., Seeberger U. & Hengstmann J.H. 2003. Color Doppler sonography in hypothyroidism. European Journal of Ultrasound. 16: 183 -189.

Shoback D. 2008. Clinical practice. Hypoparathyroidism. The New England Journal Medicine. 359(4): 391-403.

Souza P.M., Mamprim M.J. & Vulcano L.C. 2012. Diagnóstico ultrassonográfico de nódulo em tireoide em cão: relato de caso. Veterinária e Zootecnia. 19(1): 63-64.

Suwannasarn M., Jongjaroenprasert W., Chayangsu P., Suvikapakornkul R. & Sriphrapradang C. 2016. Single measurement of intact parathyroid hormone after thyroidectomy can predict transient and permanent hypoparathyroidism: a prospective study. Asian Journal of Surgery. 40(5): 350-356.

Toribio R.E. & Duckett W.M. 2004. Thyroid gland. In: Reed S.M., Bayly W.M. & Sellon D.C. (Eds). Equine Internal Medicine. 2nd edn. St. Louis: Saunders, pp.1340-1356.

Troillet A., Bottcher D., Brehm W. & Scharner D. 2016. Retrospective evaluation of hemithyroidectomy in 14 horses. Veterinary Surgery. 45(7): 949-954.

Turk J.R., Nakata Y.J., Leathers C.W. & Gallina A.M. 1983. Ultimobranchial adenoma of the thyroid gland in a horse. Veterinary Pathology. 20(1): 114-117

Ueki H., Kowatari Y., Oyamada T., Oikawa M. & Yoshikawa H. 2004. Non-functional C-cell adenoma in aged horses. Journal of Comparative Pathology. 131(2-3): 157-165.

Venzke W.G. 1986. Endocrinologia. In: Sisson S. & Grossman J.D. (Eds). Anatomia dos Animais Domésticos. 5.ed. Rio de Janeiro: Guanabara Koogan., pp. 516-520.

Venzke W.G. 1975. Equine endocrinology. In: Sisson S. & Grossman J.D. (Eds). The Anatomy of the Domestic Animals. 5th edn. Philadelphia: Saunders, pp.550-553.

Wisner E.R. & Nyland T.G. 1998. Ultrasonography of the thyroid and parathyroid glands. Veterinary Clinics of North America: Small Animal Practice. 28(4): 973-991.



How to Cite

Coelho, A. M., Oliveira, B. V. dos S., Salazar, D. V. V., Borba, K. E. R., Gomes, L. M., Lambert, M. C. C., & Dória, R. G. S. (2021). Equine Carcinoma Hemithyroidectomy. Acta Scientiae Veterinariae, 49. https://doi.org/10.22456/1679-9216.111619

Most read articles by the same author(s)