ISSN 2398-2985      

Hypothyroidism

6guinea pig

Introduction

Hypothyroidism is rare in guinea pigs, so more common causes of weight gain, alopecia and lethargy should be considered.
  • Cause: unknown.
  • Signs: obesity, lethargy, hair loss, bradycardia, weight loss in chronic cases.
  • Diagnosis: TSH stimulation testing.
  • Treatment: oral treatment with levothyroxine.
  • Prognosis: good with treatment if not presented in late stages.
  • Hypothyroidism is characterized by impaired production or secretion of thyroid hormones by the thyroid gland, resulting in a decreased concentration of circulating thyroid hormone and associated clinical signs.
  • Although the disease is one of the most common endocrine diseases seen in dogs, hypothyroidism is poorly described and documented in guinea pigs.

Pathogenesis

Etiology

  • Currently unknown.
  • In dogs, primary hypothyroidism resulting from either immune-mediated lymphocytic thyroiditis or idiopathic thyroid atrophy, is most common. On rare occasions, primary or metastatic neoplasia may also cause hypothyroidism. In cats, hypothyroidism is most commonly iatrogenic, resulting from treatment for hyperthyroidism.
  • In guinea pigs, neoplasia can destroy the thyroid gland architecture leading to a reduction in circulating thyroid hormone.
  • Other causes of iatrogenic hypothyroidism could include post thyroidectomy, over-supplementation of treatment for hyperthyroidism Hyperthyroidism, post radioactive iodine treatment. Iatrogenic damage to the thyroid gland can occur during submandibular abscess surgery.

Pathophysiology

  • Neoplastic lesions can destroy thyroid tissue leading to a reduced function. In dogs, lymphocytic thyroiditis can cause hypothyroidism but there is insufficient evidence of this is in guinea pigs. Other causes in other species include congenital or TSH deficiencies but there is insufficient evidence of this in guinea pigs.
  • Other causes include radioactive iodine treatment for hyperthyroidism Hyperthyroidism, iatrogenic over-supplementation of anti-thyroid medication or thyroidectomy.

Timecourse

  • Usually, a slow chronic onset over weeks to months.

Epidemiology

  • Hypothyroidism is rare in guinea pigs.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Thorson L (2014) Thyroid diseases in rodent species. Vet Clin North Am Exotic Anim Pract 17 (1), 51-67 PubMed.
  • Mayer J, Wagner R, Mitchell M A & Fecteau K (2013) Use of recombinant human thyroid-stimulating hormone for evaluation of thyroid function in guinea pigs (Cavia porcellus). JAVMA 242 (3), 346-349 PubMed.
  • Mayer J, Wagner R & Taeymans O (2010) Advanced diagnostic approaches and current management of thyroid pathologies in guinea pigs. Vet Clin North Am Exot Anim Prac 13, 509-523 PubMed.
  • Müller K, Müller E, Klein R & Brunnberg L (2009) Serum thyroxine concentrations in clinically healthy pet guinea pigs (Cavia porcellus). Vet Clin Pathol 38 (4), 507-510 PubMed.

Other sources of information

  • Ewringmann A & Glockner B (2012) Leitsymptome bei Meerschweinchen, Chinchilla und Degu. In: Diagnostischer Leitfaden und Therapie (Kleintier konkret). 2nd edn. Enke Publishing, Germany.
  • Rosenthal K L & Wyre N R (2012) Endocrine Diseases. In: Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery. 3rd edn. Eds: Quesenberry K E & Carpenter J W. Elsevier, USA. pp 86-102.
  • Keeble E & Meredith A (2009) Eds BSAVA Manual of Rodents and Ferrets. BSAVA, UK.
  • Ewringmann A & Glockner B (2005) Leitsymptome bei Meerschweinchen, Chinchilla und Degu. In: Diagnostischer Leitfaden und Therapie. Enke Publishing, Germany.

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