Endocrine disorders - The Thyroid Gland: Hypothyroidism

Hypothyroidism

• Deficiency in thyroid hormone

• Most commonly found in dogs

• Usually caused by lymphocytic thyroiditis - autoimmune

• Usually 6-10 years of cages

• Causes inflammation within the thyroid gland

Clinical signs of HypoT4

‘Great impersonator’

• Lethargy - lack of thyroid hormone

• Weight gain

• Symmetrical alopecia - patchy, ‘rat-tail’

• Skin disease - pyoderma, seborrhoea

• Occasionally see cardio and neuro abnormalities

Diagnosis of HypoT4

• Clinical signs

• Routine blood tests - Hypercholesterolemia, Mild non-regenerative anaemia

• Low Total T4

• Raised TSH

Management of HypoT4

• Levo-thyroxine replacement

• Tablet - Thyforon - Recommends trough (pre dose) and peak (3h post)

• Liquid - Leventa - Recommend at peak (4-6h post)

• Monitor serum T4 concentration - ‘post-pill’ (differs with drug)

• Improvement can take 6-8 weeks

Levo-thyroxine

• Identical to endogenous thyroxine

• Binds thyroxine receptors to regulate metabolism, cardiac function and blood flow, lipid and carbohydrate metabolism

Levo-thyroxine - Pharmacology

• Oral administration

• Variable Tmax and half life

• Variable dose frequency recommendation (once or twice daily)

• Consistent with feeding routine

Nursing care for HypoT4

• Care when handling

• Skin care

• Nutrition - weight loss

• Regular diagnostic tests

• Owner support