Pituitary Pars Intermedia Dysfunction (PPID)

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Pituitary Pars Intermedia Dysfunction (PPID)

• Bonnie Brenseke, DVM
• Anatomic Pathology Resident
• Virginia Maryland Regional
• College of Veterinary Medicine
• Authors Bonnie Brenseke, Tanya LeRoith, and
  Geoff Saunders
• Contributors Mark Crisman and Jamie Wearn

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Kibbles
not really Kibbles, hoofcare.blogspot.com
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For the washer/dryer and free trip to Hawaii

• Classic case of PPID/Equine Cushings 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

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www.hawaiiguide.com
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Anatomy
Banks, William. Applied Veterinary Histology.
Baltimore, MD Williams Wilkins, 1981.
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Pathogenesis
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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)

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Clinical signs contd

• 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
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Diagnostics

• CBC/Chem/UA
• Dexamethasone Suppression Test (DST)-fail to
  suppress cortisol (gt 1µg/dl)
• ACTH levels- gt50pg/ml in horses and gt27pg/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

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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
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Necropsy findings
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Histopathology
Pituitary Adenoma
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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.
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Ultrastructural Findings
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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 Cushings 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 Cushings Disease). Equine
• Internal Medicine. Ed. Liz Fathman. St.
  Louis, MN Saunders, 2004. 1327-1338.

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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 Baber

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QUESTIONS?
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