1. If your pet ingests thyroxine or is given an obvious overdose, contact your veterinarian immediately.
  2. Your veterinarian may instruct you to induce vomiting, however, do not induce vomiting unless instructed to.

OTHER NAMES

Levotabs, Soloxine, THyro-tabs, Thyrozine , Nutrived, Synthroid , Levothroid, Levo-T, Levoxyl, Eltroxin, Synthroid)

TOXICITY

MILD

CLINICAL SIGNS

Clinical signs of acute overdose develop within 1-9 hours post ingestion in animals. However, depending on the specific drug ingested, clinical signs may develop in a shorter amount of time.

Acute overdose:

  • Vomiting
  • Diarrhoea
  • Hyperactivity or lethargy
  • Increased heart rate (tachycardia)
  • Increased breathing rate (tachypnoea)
  • Difficulty breathing (dyspnoea)
  • Abnormal heart rhythm (arrhythmia)
  • Tremors
  • Seizures

Chronic overdose: signs of hyperthyroidism

  • Increased heart rate (tachycardia)
  • Increased appetite (polyphagia)
  • Weight loss
  • Excessive thirst (polydipsia)
  • Excessive urination (polyuria)
  • Nervousness/aggressiveness
  • Panting

EFFECTS OF TOXICITY

Thyroxine increases oxygen consumption, temperature, heart rate and enzyme activity and also affects protein, fat and carbohydrate metabolism.

TREATMENT

None.

Prognosis for full recovery is good if the clinical signs are managed and thyroid hormone concentrations are monitored closely until they return back to normal.

REFERENCES

Plumb DC (2011) Plumb’s Veterinary Drug Handbook 7thEdn. Iowa, USA:Wiley-Blackwell

DeClementi C (2001) Acute Thyroid Hormone Supplement Overdose. Veterinary Medicine. 96(6)