Lysosomal storage disease in Sida carpinifolia toxicosis: an induced mannosidosis in horses.
Authors: Loretti A P, Colodel E M, Gimeno E J, Driemeier D
Journal: Equine veterinary journal
Summary
# Editorial Summary: Lysosomal Storage Disease from *Sida carpinifolia* Toxicosis in Horses A previously undocumented neurological syndrome emerged in ponies on a southern Brazilian farm following exposure to pasture heavily infested with *Sida carpinifolia*, prompting investigation into whether the plant induced an acquired lysosomal storage disease. When three of eleven recently introduced ponies died within 15–20 days of exposure, displaying progressive stiff gait, muscle tremors, abdominal pain and ultimately death, the researchers conducted detailed clinical monitoring and histopathological examination including specialised lectin staining of nervous tissue. Microscopically, widespread cytoplasmic vacuolisation was evident throughout the central and peripheral nervous systems—including neurones in the brain, cerebellum, spinal cord, autonomic ganglia (trigeminal and coeliac), and enteric plexuses—as well as in renal proximal tubular cells; lectin histochemistry of cerebellar and ganglionic tissue demonstrated a staining pattern consistent with mannosidosis and indistinguishable from that seen in swainsonine toxicosis. The findings align with documented *Sida carpinifolia* poisoning in goats and resemble toxicoses from related plants (*Swainsona*, *Oxytropis* and *Astragalus* species), suggesting a shared mechanism of glycoprotein accumulation. Clinicians evaluating equine neuropathies with progressive neurological decline and gastrointestinal signs should now consider *Sida carpinifolia* exposure in their differential diagnosis, particularly in endemic regions, and consider pasture assessment as a preventive strategy.
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Practical Takeaways
- •Add Sida carpinifolia to differential diagnosis for horses with progressive neurological disease, especially in southern Brazil and regions with this plant
- •If ponies are introduced to new pasture and develop stiff gait, tremors, and abdominal pain within 2-3 weeks, consider plant toxicosis and inspect for Sida carpinifolia infestation
- •No specific treatment mentioned; prevention through pasture management and avoiding introduction to contaminated paddocks is essential
Key Findings
- •Three of 11 ponies died 15-20 days after exposure to Sida carpinifolia-infested pasture
- •Neurological signs included stiff gait, muscle tremors, and abdominal pain
- •Histopathology revealed cytoplasmic vacuoles in neurons of brain, cerebellum, spinal cord, autonomic ganglia, and intestinal plexuses
- •Lectin histochemistry pattern suggests mannosidosis similar to swainsonine toxicosis