Page 2743 - Cote clinical veterinary advisor dogs and cats 4th

Hyperthyroidism: Treatment 1428.e1

Hyperthyroidism: Treatment
VetBooks.ir Increased T4

CBC, biochemistry, urinalysis, and BP ±thoracic If present, treat concurrent disease (e.g.,
radiographs to establish baseline and assess for congestive heart failure, hypertension)
concurrent disease

Mild or absent clinical signs Recognized clinical signs
Owner preference
Good clinical
Iodine restricted Methimazole: response Recheck T4, CBC, renal New or Reduce dose with
diet (e.g., Hill’s yd) 2.5 mg/CAT q profile, USG @ 4 and 8 worsened azotemia goal of minimizing
12h or 5 weeks; adjust dose as signs of thyroid and
mg/CAT PO q Adverse effects: necessary to achieve low renal disease
24 h PO or TD adjust dose or normal T4 without T4 normal and renal
Recheck T4, renal route,* or choose adverse effect function stable
profile, USG @ alternative tx
4 and 8 weeks Owner preference

T4 within reference range I131 treatment: Thyroidectomy (scintigraphy Continue methimazole
• Usually curative to r/o ectopic tissue): rechecks q 4-6 months:
yes no • Few adverse effects • May or may not be curative • Never curative
• Requires special • Anesthetic and surgical • Lifetime medication ±
facilities risks side effects
Continue strict diet; Strict diet • Period of isolation • Hypothyroidism and • Effective therapy
recheck T4 and adherence • High upfront costs hypoparathyroidism • Low upfront costs but
renal profile ≈q 4 confirmed? but low long-term common postoperatively high long-term costs
months costs
• Associated with
longest survival
times
*Common GI effects often respond to reduced dose or TD route; more serious BP, Blood pressure; TD, transdermal; USG, urine specific gravity;
adverse effects (e.g., facial excoriation, anemia) warrant change in therapy. tx, treatment; r/o, rule out.
AUTHOR & EDITOR: Leah A. Cohn, DVM, PhD, DACVIM

Clinical Algorithms

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