Pheochromocytoma

Question 1

Canine Pheochromocytoma

Answer 1

• Rare
• 50% benign/50% malignant
• usually arises from adrenal medulla
• Catecholamine secretion or postcaval obstruction

Question 2

Clinical signs pheochromocytoma in dogs

Answer 2

1. Paroxysmal anxiety, mental depression, restlessness and panting
2. Paroxysmal blanching and flushing
3. Tachycardia +/- VPC’s, tachyarrhythmias, +/- CHF
4. Paroxysmal weakness and/or collapse
5. Ascites associated with postcaval invasion by tumor

Question 3

Norepinephrine

Answer 3

• pressor
  
  • raises BP

Question 4

Epinephrine

Answer 4

• various effects on smooth m.
  
  • stim heart rate
  • bronchodilitation
  • neurostimulant
• doesn’t raise BP like norepi

Question 5

Pheo DDX

Answer 5

• Hypoglycemia
• Cardiac disease
• Cerebral dysfunction
• Hyperthyroidism

Question 6

Dx of Canine Pheo

Answer 6

• Imaging
• Elevated urinary normetanephrine
• HX
• PE
• Imaging
• BP

Question 7

sx on pheos

TEST QUESTION

Answer 7

• Use alpha adrenergic antagonists for spikes in BP
  
  • phenoxybenzamine => lowers BP

Question 8

Treating Pheo’s

Answer 8

• surgery
• Medical
  
  • Phenoxybenzamine: alpha blocker PO
  • Regitine (phentolamine): alpha blocker Parenteral
  • Propranolol: beta blocker

*Always alpha block before you beta block to avoid hypertensive swing

Question 9

Phenoxybenzamine

Answer 9

• alpha adrenergic blocker
• better surgical survival if started 2 weeks before surgery

Question 10

Pheo take home messages

Answer 10

1. Signs from episodic symphathetic surges or postcaval obstruction
2. Abdominal rads, ultrasound, and CT scan assist diagnosis
3. Monitor for hypertension and tachyarrhythmias
4. Use phenoxybenzamine
5. Alpha before Beta