Onchocerca sp. in an imported Zangersheide gelding causing suspensory ligament desmitis.
Authors: Brown Kara A, Johnson Amy L, Bender Susan J, Nolan Thomas J, Pfisterer Bianca, Slack JoAnn, Willis Elinor, Rule Emily K
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Onchocerca sp. in an Imported Zangersheide Gelding Causing Suspensory Ligament Desmitis A 5-year-old imported Zangersheide gelding presented with subcutaneous swellings over both forelimbs and lameness localised to the distal metacarpus, prompting investigation into an unusual parasitic aetiology affecting performance horses. Ultrasound imaging revealed verminous granulomas within the subcutaneous tissues alongside linear hyperechoic foci within the suspensory ligament branches bilaterally—findings suggestive of parasitic infiltration—with diagnosis confirmed via biopsy and subsequently by necropsy, which demonstrated Onchocerca sp. (most likely O. reticulata) within both subcutaneous eosinophilic granulomas and degenerative suspensory ligament tissue. Despite treatment with ivermectin and a tapering dexamethasone protocol, the gelding's condition deteriorated to the point of euthanasia. This case is particularly significant for practitioners working with European Warmblood imports, as onchocerciasis warrants inclusion in the differential diagnosis when multifocal suspensory ligament desmitis is paired with characteristic sonographic changes and subcutaneous masses, distinguishing parasitic causes from more common inflammatory or degenerative aetiologies that might otherwise direct management toward less effective interventions.
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Practical Takeaways
- •Consider onchocerciasis in the differential diagnosis for imported European Warmbloods presenting with multifocal suspensory ligament desmitis paired with subcutaneous masses
- •Ultrasound showing hyperechoic foci within suspensory ligament branches alongside verminous granulomas should raise suspicion for Onchocerca sp. infection
- •Biopsy of subcutaneous lesions may be necessary to confirm diagnosis, as medical management with ivermectin alone may not be curative in advanced cases
Key Findings
- •A 5-year-old imported Zangersheide gelding presented with subcutaneous masses and lameness caused by Onchocerca sp. (likely O. reticulata) infection
- •Ultrasound revealed hyperechoic foci within suspensory ligament branches bilaterally, consistent with parasitic infiltration
- •Necropsy confirmed eosinophilic granulomas with intralesional nematodes in both subcutaneous tissue and degenerative suspensory ligament
- •Treatment with ivermectin and dexamethasone did not prevent progression to euthanasia