Hyperadrenocorticism

Question 1

What is the common name of Hyperadrenocorticism?

Answer 1

Cushing’s disease

Question 2

What causes Cushing’s disease?

Answer 2

Excessive circulating cortisol due to;
1. Pitutiary Mass: Most likely
2. Adrenal Mass:
3. Identical signs can be caused by topical steriods in dogs

Question 3

What is Cortisol produced by?

Answer 3

Cortisol is produced by the Adrenal Glands

Question 4

How does a pitutary mass cause Cushing’s?

Answer 4

• The pituitary gland secretes ACTH, which signals the adrenals to continue to produce cortisol
  
  • If a pituitary mass is present, causing excess ACTH release, the negative feedback from adrenal cortisol is ineffective. Cortisol secretion continues, leading to Cushing’s

Question 5

What are the 6 clinical signs of Cushing’s Disease?

Answer 5

1. Increased urination and drinking (polyuria and polydipsia or PU/PD)
2. Pot-bellied appearance
3. Hair loss
4. Calcinosis cutis
5. Excessive panting
6. +/- concurrent hypertension

Question 6

What are the labatory signs of Cushing’s?

Answer 6

1. Markedly elevated alkaline phosphatase
2. +/- proteinuria
3. Dilute urine (isosthenuria/hyposthenuria)
4. Prone to urinary tract infections (urine culture and sensitivity is recommended, to look for subclinical UTI)

Question 7

What are the two main tests for Cushing’s? What other tests may be helpful?

Answer 7

1. ACTH stimulation test
2. Low-Dose Dexamethasone Suppression Test
   - May help to differentiate a pituitary cause from an adrenal cause
   - Other tests which may be helpful;
   
   1. Urine cortisol:creatinine ratio
   2. Endogenous ACTH
   3. High-dose dex. suppression test
   4. Abdominal ultrasound

Question 8

What are the two types of treatment?

Answer 8

1. Trilostane (Vetoryl): treatment of choice
   
   • Works by inhibiting steroid synthesis
   • Usually does not cause permanent change in the adrenal gland (but is possible)
2. MItotane (Lysodren)
   
   • Destroys part of the adrenal cortex to prevent cortisol production
   • Lysodren may cause more side effects and causes permanent changes that could lead to hypoadrenocorticism

Question 9

How do horses differ in signs of Cushing’s than dogs?

Answer 9

Many have the same signs
+/- Hirsutism (abnormal long and way haircoat)