Equine pituitary pars intermedia dysfunction (Equine Cushing's disease)
Authors: Menzies Nicola
Journal: Companion Animal
Summary
# Editorial Summary: Equine Cushing's Disease in Nondomestic Equids Pituitary pars intermedia dysfunction (PPID), commonly recognised in aged domestic horses and ponies, has rarely been documented in wild equid species until now. This case series examined clinical presentation, diagnostic findings, and pathological changes in six nondomestic equids—one Chapman's zebra and five Przewalski's horses—with confirmed PPID, using basal ACTH testing for diagnosis and pergolide mesylate for treatment. Gross and histopathological examination of pituitary tissue in four cases revealed adenomas or adenomatous hyperplasia consistent with those seen in domestic equids, confirming that PPID shares the same underlying pathology across equid species. All animals showed clinical improvement following pergolide treatment, with reduced basal ACTH concentrations and resolution of clinical signs. Given the increasing lifespan of captive zoo equids resulting from improved management and veterinary care, practitioners should implement routine PPID screening protocols—particularly basal ACTH testing—in middle-aged and older nondomestic equids, as early detection and treatment can prevent secondary complications such as laminitis, muscle atrophy, and immune dysfunction that substantially compromise welfare.
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Practical Takeaways
- •Clinicians working with zoological equids should screen for PPID routinely, particularly in aging populations, as improved care is extending lifespans in captive settings
- •Basal ACTH testing is a reliable diagnostic and monitoring tool for PPID in nondomestic equids; pergolide mesylate is an effective treatment option
- •Early diagnosis and treatment of PPID in zoo equids can prevent painful sequelae and improve welfare outcomes
Key Findings
- •PPID was identified in 7 zoological equids (1 Chapman's zebra, 5 Przewalski's horses, and reference to 1 onager), expanding known species affected beyond domestic equids
- •Basal ACTH testing successfully diagnosed PPID and monitored treatment response in nondomestic equids
- •Pergolide mesylate reduced basal ACTH concentrations and clinical signs in treated cases
- •Gross and histopathological examination of 4 pituitary glands revealed adenomas or adenomatous hyperplasia consistent with domestic equine PPID pathology