Pituitary pars intermedia dysfunction (Cushing’s syndrome) associated with pituitary adenoma in a mare
Authors: Paula Da Costa Rodrigues Ana, Camargo Góss Geórgia, Damasceno Nunes dos Santos Matheus, Schorn Isabela, Leite dos Anjos Bruno, da Silva Azevedo Marcos
Journal: Acta Veterinaria Brasilica
Summary
# Editorial Summary: Pituitary PPID in an Equine Case Study A Crioulo mare presented with the classic constellation of clinical signs associated with pituitary pars intermedia dysfunction (PPID)—progressive weight loss, polydipsia, hirsutism, muscle wasting in the lumbar and gluteal regions, and neurological signs including incoordination—prompting diagnostic investigation via low-dose dexamethasone suppression testing. The mare's post-19-hour cortisol concentration of 4.6 µg/dL above baseline confirmed PPID diagnosis, and initial treatment with cyproheptadine (a serotonin antagonist) yielded clinical improvement sufficient for discharge after 10 days. Although the owner reported continued improvement on the farm, the mare developed severe respiratory complications within 10 days post-discharge and died three days later; necropsy revealed a pituitary pars intermedia adenoma confirming the PPID diagnosis, along with diffuse granulomatous pneumonia as an unexpected concurrent finding. This case underscores the importance of recognising PPID's variable presentation and the potential for serious secondary complications, including opportunistic infections that may compromise immune function—practitioners should remain vigilant for respiratory signs in PPID patients and consider underlying immunosuppression when atypical infections emerge despite appropriate endocrine management. The fatal pneumonia raises questions about whether cyproheptadine monotherapy provided sufficient disease control in this individual, and whether additional diagnostics or monitoring protocols might have identified the respiratory compromise earlier.
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Practical Takeaways
- •PPID presentation includes progressive weight loss, incoordination, excessive thirst, and characteristic hirsute/long coat; low-dose DST is reliable diagnostic confirmation tool
- •Cyproheptadine can provide symptomatic improvement in PPID cases, but close monitoring is essential as immunosuppression may predispose to secondary infections like pneumonia
- •Consider infectious complications during and after PPID treatment; animals may require extended management and farm-based monitoring even after discharge
Key Findings
- •A Crioulo mare presented with progressive weight loss, incoordination, polydipsia, and hirsute coat appearance consistent with PPID
- •Low-dose dexamethasone suppression test confirmed PPID diagnosis with post-treatment cortisol level of 4.6 µg/dL above baseline after 19 hours
- •Cyproheptadine treatment resulted in clinical improvement over 10 days hospitalization, but animal developed fatal respiratory complications post-discharge
- •Necropsy confirmed pituitary pars intermedia adenoma as underlying cause and revealed severe diffuse granulomatous pneumonia as cause of death