Feline Hyperthyroidism Flashcards
What is the most common endocrine disease in the cat?
Hyperthyroidism
When would you suspect a cat has hyperthyroidism?
Clinical signs and presence of a palpably enlarged gland
Is hyperthyroidism in cats generally benign or malignant?
Benign
What are the clinical signs of hyperthyroidism in a cat?
Maybe essentially clinically “silent”
Palpable thyroid mass
Weight loss
Polyphagia
Hyperactivity
PU/PD
Vomiting
Diarrhea and increased fecal volume
Hair coat changes
Respiratory changes
What is the proposed causes of feline hyperthyroidism?
Associated with a change in how we interact with cats
Dietary iodine
Soy-based isoflavones in the diet
Thyrotoxic substances in the environment
What would the expected serum chemistry changes in a cat with hyperthyroidism?
Liver enzymes are increased
BUN and creatinine should be within reference range - if not might have CKD
Cholesterol is usually normal
Glucose is usually normal
What would confirm the diagnosis of hyperthyroidism in a cat?
Increased tT4 in an older cat with appropriate signs
Which test should never be used as a sole screening test?
fT4
What should be done before radiation therapy in a cat with hyperthyroidism?
Thyroid scintigraphy
What medication is used to manage hyperthyroidism in cats?
Methimazole
What is the MOA of methimazole?
Inhibits synthesis of hormones by blocking oxidation of iodine and coupling of iodothronines to form T3 and T4
What are the side effects of methimazole?
Anorexia, vomiting, neutropenia, thrombocytopenia, hepatotoxicity, extreme facial pruritus
What is the monitoring schedule when using methimazole?
Monitor tT4, CBC, and chem every 14 days for 3 visits then every 3-6 months after tT4 and clinical signs have normalized
What is the risk of long term use of methimazole?
Malignant transformation
What are the cons to a hill’s y/d diet?
No treats
Not curative
Questionable efficacy
Multi-cat household not feasible
Not palatable
When performing a thyroidectomy what is recommended?
Bilateral even if only one side is enlarged
What are the main risks of performing a thyroidectomy?
Close to very important structures
Anethesia complications
What are the post-surgical complications associated with thyroidectomies?
Hypocalcemia
Horner’s syndrome
Hypothyroidism
What is widely regarded as the optimal treatment for hyperthyroidism in a cat?
Radioactive iodine treatment
What test could you run to see if a cat has concurrent CKD with hyperthyroidism?
SDMA
What are the two causes of hyperthyroidism in a dog?
Functional thyroid carcinoma
Diet-induced hyperthyroidism
