Evaluation of suspected pituitary pars intermedia dysfunction in horses with laminitis.
OBJECTIVE
To determine prevalence and clinical features of pituitary pars intermedia dysfunction (PPID) in horses with laminitis.


METHODS
Case series.


METHODS
40 horses with laminitis.


METHODS
Horses with laminitis that survived an initial episode of pain and were not receiving medications known to alter the hypothalamic-pituitary-adrenal axis were tested for PPID by evaluation of endogenous plasma ACTH concentration. Signalment, suspected cause, month of onset and duration of laminitis, Obel grade of lameness, pedal bone rotation, physical examination findings, results of endocrine function tests, treatment, outcome, and postmortem examination findings were recorded.


RESULTS
Prevalence of PPID as defined by a single high plasma ACTH concentration was 70%. Median age of horses suspected of having PPID (n = 28) was 15.5 years, and median age of horses without PPID (12) was 14.5 years. Laminitis occurred most frequently in horses with and without suspected PPID during September and May, respectively. Chronic laminitis was significantly more common in horses suspected of having PPID. In horses suspected of having PPID, the most common physical examination findings included abnormal body fat distribution, bulging supraorbital fossae, and hirsutism. Five horses suspected of having PPID had no clinical abnormalities other than laminitis. Seventeen horses suspected of having PPID that were treated with pergolide survived, and 3 horses that were not treated survived.


CONCLUSIONS
Evidence of PPID is common among horses with laminitis in a primary-care ambulatory setting. Horses with laminitis may have PPID without other clinical signs commonly associated with the disease.
Donaldson
Mark T
MT
Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA.
Jorgensen
Alec J R
AJ
Beech
Jill
J
D000273:Adipose Tissue / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D005260:Female; D005534:Foot Diseases / Q000150:complications / Q000453:epidemiology / Q000662:veterinary*; D006628:Hirsutism / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary; D006724:Hoof and Claw; D006734:Horse Diseases / Q000453:epidemiology* / Q000473:pathology; D006736:Horses; D007249:Inflammation / Q000662:veterinary; D007794:Lameness, Animal; D008297:Male; D010900:Pituitary Diseases / Q000150:complications / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D015995:Prevalence; D011379:Prognosis; D012621:Seasons
D000324:Adrenocorticotropic Hormone