Endocrine Disorder , Small Animals (hypothyroidism) Flashcards
(22 cards)
What are the primary causes of hypothyroidism in dogs?
Lympohocytic thyroiditis
Idiopathic atrophy
Neoplastic destruction
Iatrogenic ( surgery, radioactive iodine , drugs like sulfamethoxazole)
What causes congenital hypothyroidism?
Thyroid dysgenesis ( aplasia/hypoplasia)
Dyshormonogenesis ( iodine organification defect )
Dietary iodine deficiency
5 metabolic signs of hypothyroidism in dogs
Lethargy
Weight gain
Cold intolerance
Mental dullness
Inactivity
Name 3 dermatological manifestations (hypothyroidism)
Endocrine alopecia
Dry, brittle hair coat
Hyperpigmentation
Ocular manifestations in hypothyroidism
Uveitis
Corneal ulceration
Corneal lipid deposits
Cardiovascular signs in hypothyroidism in dogs
Bradycardia
Cardiac arrhythmia
Decreased contractility
Reproductive signs in dogs of hypothyroidism
Loss of libido
Stillbirths
Gynecomastia
Prolonged estrual bleeding
Testicular atrophy
Give examples of a etiology of tertiary hypothyroidism in dogs and cats
Congenital hypothyroidism
Deficient dietary iodine intake
Congenital hypothalamic malformation
Acquired destruction of hypothalamus
What is the first screening test for hypothyroidism
Serum T4 ( low T4 suggests hypothyroidism;normal T4 rules it out )
Why is TSH testing alone insufficient?
High false positive / false negative rates
Must pair with T4/fT4
Which drugs falsely lower T4?
Glucocorticoid
Phenobarbital
Sulfonamides
What is the drug of choice for hypothyroidism?
Synthetic levothyroxine (T4)
0.01-0.02 mg/kg q12h
How is treatment in hypothyroidism monitored ?
TSH should normalize within 4-8 weeks
Check serum T4 4-6hours post pill
What are signs of thrytoxicosis?
Tachycardia, panting , weight loss
Polyuria , polydipsia, aggression
What is cretinism
Congenital hypothyroidism causing dwarfism , mental dullness and goiter
How does iodine deficiency present?
Goiter + hypothyroidism treat with iodide supplementation
Is primary hypothyroidism common in cats ?
No (rare) usually secondary to iodine deficiency or iatrogenic causes
What is the most common endocrine disorder in cats?
Hyperthyroidism
Gastrointestinal manifestations of hypothyroidism
Constipation
Anemia
Oesophageal hypomotility
Hematologic
What are neuromuscular manifestations of hypothyroidism?
Ataxia
Seizures
Exercise intolerance
Skeletal muscle wasting
Weakness
Potential reasons for poor clinical response to sodium levothyroxine
Incorrect diagnosis of hypothyroidism
Inspo levothyroxine dose
Use of inactivated/outdated product
Poor bioavailability
Compliance issues
Treatment of thyrotoxicosis
Adjust dose or frequency of administration of levothyroxine
Supplementation should be discontinued for a few days if clinical signs are severe
Signs should resolve in 1-3 days if due to medication
