PPID (Cushing's)

Question 1

What is PPID (Cushing’s)?

Answer 1

Pars Pituitary Intermedia Dysfunction, or Equine Cushing’s Disease - most common endocrine disorder in horses; disorder of the pituitary gland; affects both sexes and all breeds equally; occurs in 15-30% of horses and ponies aged 15 or older

Question 2

What happens in the brain of a PPID horse?

Answer 2

Degeneration of the neurons that produce dopamine. Dopamine usually inhibits the pars intermedia portion of the pituitary gland, so then this causes hyperplasia of the pars intermedia and overproduction of its derivatives (namely ACTH, which regulates cortisol secretion)

Question 3

What happens in the rest of the body of a PPID horse?

Answer 3

Excess ACTH, overproduction of cortisol, significant generalized hormonal dysregulation

Question 4

What are some early signs of PPID?

Answer 4

Poor performance, behavior changes or lethargy, delayed shedding (can be subtle), muscle atrophy esp. along topline, regional fat deposits, laminitis

Question 5

What are the advanced signs of PPID?

Answer 5

Long, wavy hair coat with loss of shedding; generalized muscle atrophy; rounded abdomen or pot-belly; abnormal sweating; increased thirst and urination; frequent or chronic infections; reproductive abnormalities; tendon laxity; laminitis

Question 6

How is PPID diagnosed?

Answer 6

Blood work is required to test ACTH levels, but testing is not recommended August to November due to a natural rise in ACTH levels, which can complicate test interpretation

Question 7

How is PPID treated?

Answer 7

There is no cure, but it can be successfully managed with pergolide (Prascend), which is structurally similar to dopamine and acts as its replacement in the pituitary. Retesting is recommended 2-3 months after starting pergolide to assure successful control.