Cushing's dz/syndrome

Question 1

Steroidogenesis

Answer 1

• Adrenal cortisol synthesis begins with cholesterol
  
  • intermediate steps => Cortisol, aldosterone, testosterone, estradiol

Question 2

Pathophysiologic effects of excess cortisol

Answer 2

Body is catabolic!

• inc gluconeogenesis
• proteolysis
• bone demineralization
• inc gastric secretion => ulcers
• immunosuppressions
• inc renal plasma blood flow => inc GFR
• irritability
• inc mature nuets, platelets, monocytes
  
  • dec lymphocytes, eosinophils

Question 3

Breed/age incidence

Answer 3

• common in dogs, not common in cats
• toys and minis more prevalent
  
  • poodles and dashchunds
• age 3-13 yo (ave 8 yrs)

Question 4

Types of cushings

Answer 4

• Endogenous
  
  • Pituitary: ACTH blood levels high
  • Adrenal: ACTH blood levels low
• Exogenous
  
  • iatrogenic

Question 5

Calcinosis cutis

Answer 5

• redness and skin infection in axilla and inguinal area
  
  • yellowed areas of skin from mineralization of Ca deposit
    
    • don’t give topical steroids!
• Can happen in cushnoid dogs

Question 6

Other clinical findings of Cushings

Answer 6

• Lethargy
• Polyphagia
• Muscle weakness
• Hyperpigmentation of skin and hair
• Calcinosis
• cutis
• Keratin plugging of hair follicles
• Testicular atrophy
• Hepatomegaly
• pulmonary calcification
• prothrombotic tendency
• hypertension
• proteinuria
• glomerulopathy (can be permanent)

Question 7

pathologic calcification

Answer 7

• can be caused by cortisol and manifests in different tissues (irreversible)

Question 8

Endocrine DX

Answer 8

1. Urine cortisol/Cr ratio
   
   • normal test => rules out cushings
   • not very specific
2. ACTH stim test (w/abdominal ultrasound)
3. Low dose dex suppression test (normal dogs suppress below 1.7)
4. High dose dex suppression test
5. plasma ACTH
   
   • high with pituitary cushings
   • low with adrenal tumor

Question 9

Cushing’s TX

Answer 9

• Surgery: adrenalectomy, hypophysectomy
• Medical:
  
  • OPDDD (dogs)
    
    • cytotoxic to Glom, Fasc, Ret
  • Trilostane (dogs and cats)
    
    • inhibits steroidogenesis
• Iatrogenic: Stop the steroids

Question 10

Lysodren objectives

Answer 10

• leave a little
• signs abate
• ACTH stim: 2-5 mg/dL
  
  • if > 10 => reload

Question 11

Side effects of OpD’D’D

Answer 11

1. Drug toxicity (depression, weakness, vomiting, diarrhea, anorex)
   
   • stop drug until signs stop
   • restart at lower dose
2. Addison’s disease
   
   • discontinue OpDDD, treat new dz
3. Pituitary tumor growth
   
   • Nelson’s

Question 12

Cushing’s cats

Answer 12

• Hi-dose dex test better than Lo-dose
• ACTCH stim has poor sensitivity
• Many are diabetic => treat this
• TX
  
  • surgery
  • Trilostane