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Home / Equine Research Bank / Vet Sci / Thyroid Disease in Horses-Retrospective Case Series on Patie...
Veterinary sciences2025; 12(12); 1127; doi: 10.3390/vetsci12121127

Thyroid Disease in Horses-Retrospective Case Series on Patients Examined for Thyroid Disease in an Equine University Clinic (2009-2024).

Abstract: Thyroid diseases in horses are rare and pose challenges for veterinarians due to the complexity of clinical and diagnostic approaches. This retrospective case series describes cases of equine thyroid disease in a referral hospital population. Files of horses examined for suspected thyroid disease at an equine university clinic between 2009 and 2024 were reviewed. Data from nine horses examined for suspected thyroid disease, including signalment, clinical presentation, laboratory results, imaging findings, fine needle aspirates, biopsies, diagnoses, and treatments, were summarised. Diagnoses included thyroid adenoma ( = 6), multiple thyroid cysts (possibly thyroid adenoma ( = 1)), non-thyroidal illness syndrome (NTIS, = 1), and iodine deficiency goitre ( = 1). Diagnostic modalities varied, with, besides manual palpation performed in every patient, basal thyroid hormone measurement and ultrasonography being the most common. Low serum iodine concentrations were noted in four horses, yet iodine supplementation was inconsistently applied. Hemithyroidectomy was performed in four horses, enabling histopathological diagnosis (three out of four). Despite being rare, thyroid diseases in horses require consistent and thorough diagnostic approaches, including imaging, laboratory, and histopathological examinations. Improved screening tools and research could enhance the diagnostic accuracy and management of equine thyroid disorders.
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Publication Date: 2025-11-27 PubMed ID: 41472107PubMed Central: PMC12737595DOI: 10.3390/vetsci12121127Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study reviews nine cases of thyroid disease in horses examined over 15 years at a university veterinary clinic.
  • It highlights the challenges in diagnosing and managing these rare equine thyroid conditions and emphasizes the need for thorough diagnostic procedures and better screening methods.

Introduction to the Study

  • Thyroid diseases in horses are uncommon and difficult to diagnose due to complex clinical signs and the need for multiple diagnostic tools.
  • The study is a retrospective case series, meaning it looked back at medical records of horses examined between 2009 and 2024 for thyroid issues at a referral equine university clinic.
  • The aim was to summarize key clinical features, diagnostic findings, and treatment outcomes to improve understanding of these diseases.

Case Population and Data Collection

  • A total of nine horses suspected of having thyroid disease were identified from clinic records.
  • Information was gathered on:
    • Signalment (age, breed, sex)
    • Clinical presentation (symptoms and physical examination findings)
    • Laboratory results (e.g., thyroid hormone levels, serum iodine)
    • Imaging results (primarily ultrasonography)
    • Fine needle aspirates and biopsies when available
    • Definitive diagnoses and treatments administered

Diagnoses Observed

  • Thyroid adenoma was the most common diagnosis, found in 6 horses.
  • One horse presented with multiple thyroid cysts, which were possibly related to thyroid adenoma.
  • One case was diagnosed with non-thyroidal illness syndrome (NTIS), a condition where thyroid function appears abnormal due to another illness rather than primary thyroid disease.
  • One horse had iodine deficiency goitre, a condition resulting from insufficient iodine leading to thyroid gland enlargement.

Diagnostic Modalities

  • All horses underwent manual palpation of the thyroid gland as a preliminary assessment.
  • Basal thyroid hormone measurements and ultrasonography were the most commonly used diagnostic tests.
  • Fine needle aspiration and surgical biopsies were performed in some cases, providing tissue samples for histopathological examination — key for confirming diagnosis.
  • Low serum iodine concentrations were detected in four horses, implicating iodine deficiency in their thyroid disease; however, iodine supplementation was not consistently implemented in treatment protocols.

Treatment and Outcomes

  • Four horses underwent hemithyroidectomy (surgical removal of one thyroid lobe), which allowed for direct histopathological diagnosis in three horses.
  • Other forms of treatment, such as iodine supplementation, were applied inconsistently across cases.
  • The rarity of thyroid disease in horses means that treatment plans often rely on a combination of diagnostic findings rather than standardized protocols.

Conclusions and Implications

  • Equine thyroid diseases, although rare, necessitate comprehensive diagnostic approaches combining clinical examination, laboratory tests, imaging, and histology for accurate diagnosis.
  • Current diagnostic methods vary, and the inconsistent use of treatment options (e.g., iodine supplementation) indicates a need for clearer guidelines.
  • Developing improved screening tools and conducting further research could enhance diagnostic accuracy and optimize management strategies for thyroid disorders in horses.
  • This study provides valuable insights into the spectrum of thyroid conditions seen in horses and underscores the complexity and importance of thorough evaluation in referral hospital settings.

Cite This Article

APA
Stoeckle SD, Stage HJ, Gehlen H. (2025). Thyroid Disease in Horses-Retrospective Case Series on Patients Examined for Thyroid Disease in an Equine University Clinic (2009-2024). Vet Sci, 12(12), 1127. https://doi.org/10.3390/vetsci12121127

Publication

Veterinary sciences
ISSN: 2306-7381
NlmUniqueID: 101680127
Country: Switzerland
Language: English
Volume: 12
Issue: 12
PII: 1127

Researcher Affiliations

Stoeckle, Sabita Diana
  • Equine Clinic: Surgery and Radiology, Freie Universität Berlin, 14163 Berlin, Germany.
Stage, Hannah Julia
  • Equine Clinic: Surgery and Radiology, Freie Universität Berlin, 14163 Berlin, Germany.
Gehlen, Heidrun
  • Equine Clinic: Surgery and Radiology, Freie Universität Berlin, 14163 Berlin, Germany.

Conflict of Interest Statement

The authors declare no conflict of interest.

References

This article includes 62 references
  1. Toribio R.E.. Thyroid Gland. 2017;pp. 1058–1069.
  2. Breuhaus B.A.. Disorders of the equine thyroid gland. Vet. Clin. N. Am. Equine Pract. 2011;27:115–128.
    doi: 10.1016/j.cveq.2010.12.002pubmed: 21392657google scholar: lookup
  3. Wissdorf H., Gerhards H., Huskamp B., Deegen E. Praxisorientierte Anatomie und Propädeutik des Pferdes. M&H Schaper; Hannover, Germany: 2010.
  4. Hilderbran A., Breuhaus B., Refsal K.. Nonthyroidal illness syndrome in adult horses. J. Vet. Intern. Med. 2014;28:609–617.
    doi: 10.1111/jvim.12274pmc: PMC4857970pubmed: 24417524google scholar: lookup
  5. Frank N., Sojka J.E., Latour M.A., McClure S.R., Polazzi L.. Effect of hypothyroidism on blood lipid concentrations in horses. Am. J. Vet. Res. 1999;60:730–733.
    doi: 10.2460/ajvr.1999.60.06.730pubmed: 10376902google scholar: lookup
  6. Thompson F.N., Caudle A.B., Kemppainen R.J., Nett T.M., Brown J., Williams D.J.. Thyroidal and prolactin secretion in agalactic mares. Theriogenology 1986;25:575–580.
    doi: 10.1016/0093-691X(86)90141-Xpubmed: 16726148google scholar: lookup
  7. Schwarz B.C., Sallmutter T., Nell B.. Keratoconjunctivitis sicca attributable to parasympathetic facial nerve dysfunction associated with hypothyroidism in a horse. J. Am. Vet. Med. Assoc. 2008;233:1761–1766.
    doi: 10.2460/javma.233.11.1761pubmed: 19046036google scholar: lookup
  8. Stanley O., Hillidge C.J.. Alopecia associated with hypothyroidism in a horse. Equine Vet. J. 1982;14:165–167.
    doi: 10.1111/j.2042-3306.1982.tb02378.xpubmed: 7084203google scholar: lookup
  9. Waldron-Mease E.. Hypothyroidism and myopathy in racing Thoroughbreds and Standardbreds. J. Equine Med. Surg. 1979;3:124–128.
  10. Stephen J.O., Baptiste K.E., Townsend H.G.. Clinical and pathologic findings in donkeys with hypothermia: 10 cases (1988–1998). J. Am. Vet. Med. Assoc. 2000;216:725–729.
    doi: 10.2460/javma.2000.216.725pubmed: 10707690google scholar: lookup
  11. Lowe J.E., Baldwin B.H., Foote R.H., Hillman R.B., Kallfelz F.A.. Equine hypothyroidism: The long term effects of thyroidectomy on metabolism and growth in mares and stallions. Cornell Vet. 1974;64:276–295.
    pubmed: 4826263
  12. Alberts M.K., McCann J.P., Woods P.R.. Hemithyroidectomy in a horse with confirmed hyperthyroidism. J. Am. Vet. Med. Assoc. 2000;217:1051–1054.
    doi: 10.2460/javma.2000.217.1051pubmed: 11019715google scholar: lookup
  13. Tan R., Davies S., Crisman M., Coyle L., Daniel G.. Propylthiouracil for treatment of hyperthyroidism in a horse. J. Vet. Intern. Med. 2008;22:1253-8.
    doi: 10.1111/j.1939-1676.2008.0169.xpubmed: 18691365google scholar: lookup
  14. Chen C.L., Riley A.M.. Serum thyroxine and triiodothyronine concentrations in neonatal foals and mature horses. Am. J. Vet. Res. 1981;42:1415–1417.
    doi: 10.2460/ajvr.1981.42.08.1415pubmed: 7294478google scholar: lookup
  15. Irvine C.H.G.. Thyroxine secretion rate in the horse in various physiological states. J. Endocrinol. 1967;39:313–320.
    doi: 10.1677/joe.0.0390313pubmed: 4169346google scholar: lookup
  16. Irvine C., Evans M.J.. Postnatal changes in total and free thyroxine and triiodothyronine in foal serum. J. Reprod. Fertil. 1975;23:709–715.
    pubmed: 1060870
  17. Irvine C., Evans M.J.. Hypothyroidism in foals. N. Z. Vet. J. 1977;25:354.
    doi: 10.1080/00480169.1977.34452pubmed: 276738google scholar: lookup
  18. Malinowski K., Christensen R.A., Hafs H.D., Scanes C.G.. Age and breed differences in thyroid hormones, insulin-like growth factor (IGF)-I and IGF binding proteins in female horses. J. Anim. Sci. 1996;74:1936–1942.
    doi: 10.2527/1996.7481936xpubmed: 8856448google scholar: lookup
  19. Irvine C.. Hypothyroidism in the foal. Equine Vet. J. 1984;16:302–306.
    doi: 10.1111/j.2042-3306.1984.tb01932.xpubmed: 6383812google scholar: lookup
  20. Motley J.. Use of radioactive triiodothyronine in the study of thyroid function in normal horses. Vet. Med. Small Anim. Clin. 1972;67:1225–1228.
    pubmed: 4484974
  21. Pirrone A., Panzani S., Govoni N., Castagnetti C., Veronesi M.C.. Thyroid hormone concentrations in foals affected by perinatal asphyxia syndrome. Theriogenology 2013;80:624–629.
    doi: 10.1016/j.theriogenology.2013.06.003pubmed: 23849257google scholar: lookup
  22. Panzani S., Comin A., Galeati G., Romano G., Villani M., Faustini M., Veronesi M.C.. How type of parturition and health status influence hormonal and metabolic profiles in newborn foals. Theriogenology 2012;77:1167–1177.
    doi: 10.1016/j.theriogenology.2011.10.023pubmed: 22153270google scholar: lookup
  23. Himler M., Hurcombe S.D.A., Griffin A., Barsnick R.J., Rathgeber R.A., Macgillivray K.C., Toribio R.E.. Presumptive nonthyroidal illness syndrome in critically ill foals. Equine Vet. J. 2012;44:43–47.
    doi: 10.1111/j.2042-3306.2011.00480.xpubmed: 22594025google scholar: lookup
  24. Breuhaus B.. Thyroid function and dysfunction in term and premature equine neonates. J. Vet. Intern. Med. 2014;28:1301–1309.
    doi: 10.1111/jvim.12382pmc: PMC4857961pubmed: 24934827google scholar: lookup
  25. Komosa M.A., Flisinska-Bojanowska A., Gill J.. Development of diurnal rhythm in some metabolic parameters in foals. Comp. Biochem. Physiol. A Comp. Physiol. 1990;95:549–552.
    doi: 10.1016/0300-9629(90)90737-Dpubmed: 1971544google scholar: lookup
  26. De Martin D.. Study on the thyroid function of male and female Thoroughbred horses in different times after winning races at the Hippodrome Cidade Jardin, with the use of “in vitro” 125 I–T 3 and 125 I–T 3 tests. Rev. Fac. Med. Vet. Zootec. Univ. S. Paulo. 1977;14:199–203.
  27. Fazio E., Medica P., Cravana C., Bruschetta G., Ferlazzo A.. Seasonal thyroid and lipid profiles in Thoroughbred pregnant and nonpregnant mares (Equus caballus). Theriogenology 2016;85:1582–1589.
    doi: 10.1016/j.theriogenology.2016.01.017pubmed: 26920797google scholar: lookup
  28. Messer N.T., Ganjam V.K., Nachreiner R.F., Krause G.F.. Effect of dexamethasone administration on serum thyroid hormone concentrations in clinically normal horses. J. Am. Vet. Med. Assoc. 1995;206:63–66.
    doi: 10.2460/javma.1995.206.01.63pubmed: 7744665google scholar: lookup
  29. Abraham G., Allersmeier M., Schusser G.F., Ungemach F.R.. Serum thyroid hormone, insulin, glucose, triglycerides and protein concentrations in normal horses: Association with topical dexamethasone usage. Vet. J. 2011;188:307–312.
    doi: 10.1016/j.tvjl.2010.05.033pubmed: 20594877google scholar: lookup
  30. Morris D.D., Garcia M.. Thyroid-stimulating hormone: Response test in healthy horses, and effect of phenylbutazone on equine thyroid hormones. Am. J. Vet. Res. 1983;44:503–507.
    doi: 10.2460/ajvr.1983.44.03.503pubmed: 6682298google scholar: lookup
  31. Breuhaus B.A.. Thyroid--stimulating hormone in adult euthyroid and hypothyroid horses. J. Vet. Intern. Med. 2002;16:109–115.
    pubmed: 11822799
  32. Harris P., Marlin D., Gray J.. Equine thyroid function tests: A preliminary investigation. Br. Vet. J. 1992;148:71–80.
    doi: 10.1016/0007-1935(92)90069-Dpubmed: 1551018google scholar: lookup
  33. Group E.E.. Recommendations on Diagnosis and Management of Thyroid Disease and the Use of Thyroxine in Horses. 2023.
  34. Dalefield R., Palmer D.. The frequent occurrence of thyroid tumours in aged horses. J. Comp. Pathol. 1994;110:57–64.
    doi: 10.1016/S0021-9975(08)80270-8pubmed: 8040373google scholar: lookup
  35. Cubillos V., Norambuena L., Espinoza E.. Cell growth and neoplasms of the thyroid gland in horses. Zentralblatt Vet. Reihe A. 1981;28:201–208.
    doi: 10.1111/j.1439-0442.1981.tb01182.xpubmed: 6792830google scholar: lookup
  36. Hopper L.D., Kennedy G.A., Taylor W.A.. Diagnosing and treating thyroid adenoma in a horse. Vet. Med. 1987;82:1252.
  37. Elce Y.A., Ross M.W., Davidson E.J., Tulleners E.P.. Unilateral thyroidectomy in 6 horses. Vet. Surg. 2003;32:187–190.
    doi: 10.1053/jvet.2003.50017pubmed: 12692764google scholar: lookup
  38. Schlotthauer C.F.. The Incidence and Types of Disease of the Thyroid Gland of Adult Horses. J. Am. Vet. Med. Assoc. 1931;78:211–218.
  39. Scharner D., Kappe A.. Einseitige Thyreoidektomie bei 5 Pferden mit Tumoren der Schilddrüse. Pferdeheilk. 2009;25:444–450.
    doi: 10.21836/PEM20090501google scholar: lookup
  40. Troillet A., Brehm W., Scharner D.. Thyroid Gland Tumours in the Horse: Clinical Diagnostic, Treatment and Histological Characterisation. Equine Vet. J. 2014;46:7.
    doi: 10.1111/evj.12323_14google scholar: lookup
  41. Troillet A., Böttcher D., Brehm W., Scharner D.. Retrospective Evaluation of Hemithyroidectomy in 14 Horses. Vet. Surg. 2016;45:949–954.
    doi: 10.1111/vsu.12540pubmed: 27598400google scholar: lookup
  42. Åsvold B.O., Vatten L.J., Bjøro T.. Changes in the prevalence of hypothyroidism: The HUNT Study in Norway. Eur. J. Endocrinol. 2013;169:613–620.
    doi: 10.1530/EJE-13-0459pubmed: 23975540google scholar: lookup
  43. Aoki Y., Belin R.M., Clickner R., Jeffries R., Phillips L., Mahaffey K.R.. Serum TSH and total T4 in the United States population and their association with participant characteristics: National Health and Nutrition Examination Survey (NHANES 1999–2002). Thyroid 2007;17:1211–1223.
    doi: 10.1089/thy.2006.0235pubmed: 18177256google scholar: lookup
  44. Canaris G.J., Manowitz N.R., Mayor G., Ridgway E.C.. The Colorado thyroid disease prevalence study. Arch. Intern. Med. 2000;160:526–534.
    doi: 10.1001/archinte.160.4.526pubmed: 10695693google scholar: lookup
  45. Madariaga A.G., Palacios S.S., Guillén-Grima F., Galofré J.C.. The incidence and prevalence of thyroid dysfunction in Europe: A meta-analysis. J. Clin. Endocrinol. Metab. 2014;99:923–931.
    doi: 10.1210/jc.2013-2409pubmed: 24423323google scholar: lookup
  46. Hollowell J.G., Staehling N.W., Flanders W.D., Hannon W.H., Gunter E.W., Spencer C.A., Braverman L.E.. Serum TSH, T4, and thyroid antibodies in the United States population (1988 to 1994): National Health and Nutrition Examination Survey (NHANES III). J. Clin. Endocrinol. Metab. 2002;87:489–499.
    doi: 10.1210/jcem.87.2.8182pubmed: 11836274google scholar: lookup
  47. O’nEill D.G., Khoo J.S.P., Brodbelt D.C., Church D.B., Pegram C., Geddes R.F.. Frequency, breed predispositions and other demographic risk factors for diagnosis of hypothyroidism in dogs under primary veterinary care in the UK. Canine Med. Genet. 2022;9:11.
    doi: 10.1186/s40575-022-00123-8pmc: PMC9552398pubmed: 36217196google scholar: lookup
  48. Gulzar S., Khurana R., Agnihotri D., Aggarwal A., Narang G.. Prevalence of hypothyroidism in dogs in Haryana. Indian J. Vet. Res. 2014;23:1–9.
  49. Wakeling J., Elliott J., Syme H.. Evaluation of Predictors for the Diagnosis of Hyperthyroidism in Cats. J. Vet. Intern. Med. 2011;25:1057–1065.
    doi: 10.1111/j.1939-1676.2011.00790.xpubmed: 21985139google scholar: lookup
  50. Foster D.J., Thoday K.L., Arthur J.R., Nicol F., Beatty J.A., Svendsen C.K., Labuc R., McConnell M., Sharp M., Thomas J.B.. Selenium status of cats in four regions of the world and comparison with reported incidence of hyperthyroidism in cats in those regions. Am. J. Vet. Res. 2001;62:934–937.
    doi: 10.2460/ajvr.2001.62.934pubmed: 11400853google scholar: lookup
  51. Edinboro C.H., Scott-Moncrieff J.C., Janovitz E., Thacker H.L., Glickman L.T.. Epidemiologic study of relationships between consumption of commercial canned food and risk of hyperthyroidism in cats. J. Am. Vet. Med. Assoc. 2004;224:879–886.
    doi: 10.2460/javma.2004.224.879pubmed: 15070058google scholar: lookup
  52. Bertin F., Frank N., Breuhaus B.A., Schott H.C., Kritchevsky J.E.. Diagnosis and management of thyroid disorders and thyroid hormone supplementation in adult horses and foals. Equine Vet. J. 2024;56:243–252.
    doi: 10.1111/evj.13981pubmed: 37533378google scholar: lookup
  53. Slovis N.M., Watson J.L., Couto S.S.. Marsupialization and iodine sclerotherapy of a branchial cyst in a horse. J. Am. Vet. Med. Assoc. 2001;219:338–340, 324–325.
    doi: 10.2460/javma.2001.219.338pubmed: 11497048google scholar: lookup
  54. Deandrea M., Mormile A., Veglio M., Motta M., Pellerito R., Gallone G., Grassi A., Torchio B., Bradac R., Garberoglio R.. Fine-needle aspiration biopsy of the thyroid: Comparison between thyroid palpation and ultrasonography. Endocr. Pract. 2002;8:282–286.
    doi: 10.4158/EP.8.4.282pubmed: 12185993google scholar: lookup
  55. Cesur M., Corapcioglu D., Bulut S., Gursoy A., Yilmaz A.E., Erdogan N., Kamel N.. Comparison of palpation-guided fine-needle aspiration biopsy to ultrasound-guided fine-needle aspiration biopsy in the evaluation of thyroid nodules. Thyroid 2006;16:555–561.
    doi: 10.1089/thy.2006.16.555pubmed: 16839257google scholar: lookup
  56. Renshaw A.A., Pinnar N.. Comparison of thyroid fine-needle aspiration and core needle biopsy. Am. J. Clin. Pathol. 2007;128:370–374.
    doi: 10.1309/07TL3V58337TXHMCpubmed: 17709309google scholar: lookup
  57. Lucke V.M., Lane J.G.. C--cell tumours of the thyroid in the horse. Equine Vet. J. 1984;16:28–30.
    doi: 10.1111/j.2042-3306.1984.tb01843.xpubmed: 6714201google scholar: lookup
  58. Saulez M.N., Viljoen A., Kafka U., Rubio-Martinez L., van Wilpe E., Steyl J.. The use of nuclear imaging for a mixed C cell microfollicular carcinoma of the thyroid gland in a mature horse. Equine Vet. Educ. 2013;25:118–125.
    doi: 10.1111/j.2042-3292.2012.00405.xgoogle scholar: lookup
  59. Wehr U., Englschalk B., Kienzle E., Rambeck W.A.. Iodine Balance in Relation to Iodine Intake in Ponies. J. Nutr. 2002;132:1767S–1768S.
    doi: 10.1093/jn/132.6.1767Spubmed: 12042521google scholar: lookup
  60. Mochizuki M., Hayakawa N., Minowa F., Saito A., Ishioka K., Ueda F., Okubo K., Tazaki H.. The concentration of iodine in horse serum and its relationship with thyroxin concentration by geological difference. Environ. Monit. Assess. 2016;188:1–6.
    doi: 10.1007/s10661-016-5221-7pubmed: 26972926google scholar: lookup
  61. Lopez-Rodriguez M.F., Cymbaluk N.F., Epp T., Laarveld B., Thrasher M., Card C.E.. A Field Study of Serum, Colostrum, Milk Iodine, and Thyroid Hormone Concentrations in Postpartum Draft Mares and Foals. J. Equine Vet. Sci. 2020;90:103018.
    doi: 10.1016/j.jevs.2020.103018pubmed: 32534782google scholar: lookup
  62. Lopez-Rodriguez M.F., Cymbaluk N., Epp T., Laarveld B., Recalde E.C.S., Simko E., Card C.. Effects of the Glucosinolate Sinigrin in Combination with a Noniodine Supplemented Diet on Serum Iodine and Thyroid Hormone Concentrations in Nonpregnant Mares. J. Equine Vet. Sci. 2020;91:103110.
    doi: 10.1016/j.jevs.2020.103110pubmed: 32684255google scholar: lookup

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