Top 4 Canine Endocrine Disorders

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Canine endocrine disorders can get confusing…PU/PD, lethargy, they all start to blend together.

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There are some key differences in presentation, diagnostics, and therapeutics of the top canine endocrine disorders.

Here are Zuku’s top 4 canine endocrine conditions to know for NAVLE® success:
  1. Hypothyroidism
    • Classic case: Middle-aged mid-to-large breed dog with dullness, weight gain, lethargy, hypothermia, dry coat, bilaterally symmetric nonpruritic alopecia with rat tail; rare - myxedema with “tragic” facial expression or stupor; signs can be vague and variable
    • Dx: Screen and see lowered serum total T4; measure lowered free T4 and increased TSH in dogs; TSH stimulation test rare; thyroid imaging; RULE OUT nonthyroidal illness syndrome; routine labs show ­increased cholesterol, mild nonregenerative anemia
    • Rx: Oral T4 (levothyroxine); IV T4 if in myxedema coma
    • Pearls: Congenital is rare, see disproportionate dwarfism etc. at birth; prognosis for adult-onset is good to excellent; euthyroid sick = other diseases lead to low total T4; HYPERthyroidism is RARE in dogs & common in cats

  2. Diabetes Mellitus
    • Classic case: Polyuria/polydipsia/polyphagia, weight loss; if diabetic ketoacidosis (DKA) – vomiting, inappetence, lethargy
    • Dx: Elevated serum fructosamine; routine labwork shows hyperglycemia, +/- ­increased ALP; urinalysis shows glucosuria +/- low USG and ketonuria
    • Rx: At home – long-acting insulin, dietary changes; if ketoacidosis – regular insulin and IV fluid therapy with electrolytes in hospital
    • Pearls: Fructosamine estimates blood glucose over previous 2 weeks if concerned the hyperglycemia is stress-induced; good prognosis

  3. Hyperadrenocorticism (HAC, Cushing’s Disease)

    Cushingoid Dachshund with potbelly and cutaneous atrophy

    • Classic case: The 4 P’s – polyuria, polydipsia, polyphagia, and panting; truncal alopecia, pot-bellied appearance, thin skin; can be iatrogenic, adrenal-dependent (ADH), or pituitary-dependent (PDH)
    • Dx: Depends on type of HAC; low- or high-dose (for PDH) dexamethasone suppression test; ACTH stimulation test (r/o iatrogenic), urine cortisol-to-creatinine ratio, endogenous ACTH (­increased with PDH); routine labwork shows stress leukogram, ­increased ALP and cholesterol; adrenal ultrasound
    • Rx: For PDH – trilostane, lysodren, or surgical hypophysectomy or bilateral adrenalectomy; for ADH – trilostane, lysodren, or bilateral adrenalectomy
    • Pearls: Can be difficult to differentiate between PDH and ADH; good prognosis with medical Rx for PDH; variable for ADH

  4. Hypoadrenocorticism (Addison’s Disease)
    • Classic case: Young adult female dog with loss of condition, recurrent gastroenteritis, poor response to stress; acute circulatory collapse and renal failure when “early” signs go unnoticed
    • Dx: History and clinical signs with hyperkalemia, hyponatremia, acidosis, azotemia, and normocytic normochromic anemia; ACTH stimulation test
    • Rx: Acute crisis – IV saline +/- dextrose, steroids for shock; long-term mineralocorticoid replacement with desoxycorticosterone pivalate (DOCP)
    • Pearls: Acute Addisonian crisis is an emergency! Most commonly due to autoimmune failure of the adrenal cortex

Images courtesy Gopal 1035 (dog drinking), Caroldermoid (Cushing’s), Caroldermoid (hypothyroidism), Foixet Fabien (badminton dog) and Carterse (dog catching bubble).