Pituitary Pars Intermedia Dysfunction (PPID)

Bonnie Brenseke, DVMAnatomic Pathology ResidentVirginia Maryland Regional

College of Veterinary Medicine

Authors: Bonnie Brenseke, Tanya LeRoith, and Geoff SaundersContributors: Mark Crisman and Jamie Wearn

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

“Kibbles”

*not really “Kibbles”, hoofcare.blogspot.com

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

For the washer/dryer and free trip to Hawaii…

• Classic case of PPID/Equine Cushing’s Syndrome

• Common endocrine disorder of aged horses and ponies

• Etiology and pathophysiology?

-primary lesion of the pituitary gland

-loss of dopaminergic inhibition on the pars intermedia

www.hawaiiguide.com

www.saatchi-gallery.co.uk

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Anatomy:

Banks, William. Applied Veterinary Histology. Baltimore, MD: Williams & Wilkins, 1981.

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Pathogenesis:

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Clinical Signs due to hormone dysregulation & to space-occupying effects

• Hypertrichosis (Hirsutism)- almost pathognomonic

• Hyperhydrosis

• Laminitis

• Polyuria/Polydipsia

• Polyphagia

• ↑’ed susceptibility to infections (skin, lung, parasites)

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Clinical signs cont’d

• Behavioral changes-docility, lethargy, narcolepsy

• Muscle wasting- pendulous abdomen, sway back

• Fat redistribution- bulging supraorbital fat pads, cresty neck, fat accumulation around tailhead

• Infertility

www.lazyhorserescue.org Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Diagnostics:

• CBC/Chem/UA• Dexamethasone Suppression Test (DST)-fail to

suppress cortisol (> 1μg/dl)• ACTH levels- >50pg/ml in horses and >27pg/ml

in ponies supports diagnosis

• Baseline cortisol concentrations• Urinary corticoid/creatinine ratio• ACTH stimulation test• Combined DST and ACTH stimulation test• Thyrotropin-releasing hormone (TRH) stimulation test• Combined DST and TRH stimulation test• Resting insulin concentrations• Glucose tolerance test• Insulin tolerance test• Imaging

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Treatment:

• Dopamine agonists Pergolide and Bromocriptine

• Serotonin antagonist Cyproheptadine

• Supplements Magnesium & chromium picolinate Vitex (chasteberry extract, V. agnus-castus)

*Treat all pathologic conditions (i.e., laminitis & infections)

www.smartpakequine.com

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Necropsy findings:

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Pituitary Adenoma

Histopathology:

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Miller, M.A., I.D. Pardo, L.P. Jackson, G.E. Moore and J.E. Sojka. “Correlation of Pituitary Histomorphometry with Adrenocorticotrophic Hormone Response to Domperidone Administration in the Diagnosis of Equine Pituitary Pars Intermedia Dysfunction.” Veterinary Pathology 45 (2008): 26- 38.

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Ultrastructural Findings:

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

References:

1. Banks, William. Applied Veterinary Histology. Baltimore, MD: Williams & Wilkins, 1981.

2. Capen, Charles. “Tumors of the Endocrine Glands.” Tumors in Domestic Animals. Ed. Donald Meuten. Ames, IA: Iowa State Press, 2002. 616-620.

3. McFarlane, D., M.T.Donaldson, T.M. Saleh and A.E. Cribb. “The Role of Dopaminergic Neurodegeneration in Equine Pituitary Pars Intermedia Dysfunction (Equine Cushing’s Disease).” Proceedings of the 49th Annual Convention of the American Association of Equine Practitioners, New Orleans, Louisiana, USA, 21-25 November 2003. Internet Publisher: International Veterinary Information Service.

4. Miller, M.A., I.D. Pardo, L.P. Jackson, G.E. Moore and J.E. Sojka. “Correlation of Pituitary Histomorphometry with Adrenocorticotrophic Hormone Response to Domperidone Administration in the Diagnosis of Equine Pituitary Pars Intermedia Dysfunction.” Veterinary Pathology 45 (2008): 26- 38.

5. Toribio, Ramiro. “Pars Intermedia Dysfunction (Equine Cushing’s Disease).” Equine Internal Medicine. Ed. Liz Fathman. St. Louis, MN: Saunders, 2004. 1327-1338.

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

BIG Thanks to:• Pathologists: Drs. Tanya LeRoith &

Geoff Saunders

• Equine Clinicians: Drs. Mark Crisman & Jamie Wearn

• Resident Mates: Drs. Natalie Durrett, Anya Hawthorn, & Ron Tyler

• Histology Laboratory Technicians: Barbara Wheeler, Jill Songer, & Luther Vest

• Morphology Laboratory Manager: Kathy Lowe

• Media: Jerry BaberPresented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only

Go Pack! Go Hokies!

QUESTIONS?

Presented at SEVPAC 2008 – Permission granted for use on

SEVPAC website only