Please enable JavaScript.
Coggle requires JavaScript to display documents.
Equine Cushing's Disease - Pituitary Pars Intermedia Dysfunction…
Equine Cushing's Disease - Pituitary Pars Intermedia Dysfunction (PPID)
general info
neurodegenerative
dysregulation of POMC hormones
disease of age
incurable but manageable
primary dysfunction of hypothalamus
secondary pituitary gland dysfunction
POMC = pro-opiomelanocortin
precursor hormone from which several peptide hormones are processed
pathophysiology
increased secretion of ACTH and POMC hormones by melanotropes in intermediate pituitary
hypothalamic neurons that produce dopamine degenerate and lose function
progressive loss of
inhibition
leads to oversecretion of POMC
gradual onset
CS
advanced disease
hypertrichosis
laminitis
acute
chronic
muscle atrophy
neck and topline
pot-bellied appearance
caabolic state due to excessive cortisol secretion
PU/PD
reduced produced of ADH from posterior pituitary
osmostic diuresis from persistent hyperglycemia (severe IR)
inappropriate sweating
IR +/- hyperglycemia
insulin dysregulation
reduced responsiveness to insulin
impaired glucose uptake into tissues
increased insulin secretion
hyperinsulinemia
laminitis risk
screening is recommended
immunosuppression
higher parasite loads
tooth root abscesses sinusitis
pneumonia
hepatitis
pitonitis
dermatitis
cellulitis
infertility
lactation
diagnostics
:forbidden: measurement of resting [cortisol], useless
endogenous [ACTH]
blood measurement
healthy horses
normal = <30pg/mL
= < 50 pg/mL in fall
PPID horse
PPID >50 pg.mL
= >100 pg.mL in fall
rises in fall (mid-July to Nov)
stress and pain may be confounding!
TRH-stimulation test
2 sample modification of the endogenous ACTH test
improved sensitivity
in early cases
method
draw blood for ACTH (T0)
give 1mg TRH IV
draw blood again 10 min later (t10)
expected results
normal horse will have <30pg/mL t0 and <110pg/mL t10
t10 >200 pg/mL is consistent with PPID
advanced disease is easy to diagnose, early is not
results can be influenced by season, pain, stress
if in doubt, implement a rial course of therapy and assess the response
test for insulin resistance
treatment
pergolide mesylate
most effective agent
D2 receptor agonist
mimics fxn of dopaminergic neurons in hypothalamus
resotres inhibition of POMC secretion
dosing
range of 1-3mg posid
takes 4-8w to start seeing clinical response
lifelong treatment
higher doses required overtime
supportive care
clip haircoat
preventative care
treat infections promptly
parasite control
limit dietary starch and sugar