Pseudomonas-Enterobacter Co-Infection Drives Cellulitis and Lymphangitis in Equines: A Case Report

TL;DR

This case report describes a rare co-infection in a horse that caused severe cellulitis and lymphangitis, highlighting the importance of comprehensive diagnostics and combined treatments.

Contribution

The report introduces a rare Pseudomonas-Enterobacter co-infection and a multifaceted diagnostic and treatment approach for equine cellulitis and lymphangitis.

Findings

Co-infection with Pseudomonas asiatica and Enterobacter hormaechei was confirmed using bacterial culture and genomics.

Combining antimicrobials, anti-inflammatory therapy, and traditional Chinese medicine resolved the infection and restored the horse's health.

Elevated AEAb levels correlated with lymphatic degradation, and imaging identified abnormal lymphatic vessels.

Abstract

Cellulitis/lymphangitis is a common disease in horses. Clinicians diagnose these diseases based on empirical judgement, namely the clinical presentation such as fever, limb swelling and acute lameness. This may lead to misdiagnoses or missed diagnoses or even practice against antibiotic stewardship. However, there are limited published reports focusing on diagnostic tests and integrative treatment regarding cellulitis/lymphangitis. This case report first documented a comprehensive approach using bacterial culture, bacterial genomics analysis and lymphangiograms to confirm the diagnosis.

This case report detailed a rare co-infection of Pseudomonas asiatica and Enterobacter hormaechei in a 9-year-old warmblood mare, leading to severe cellulitis and secondary lymphangitis following traditional hoof blood-letting therapy. The mare exhibited acute limb swelling, fever, cutaneous ulceration, lymphatic dysfunction and unknown anemia. Comprehensive diagnostics, including bacterial culture, whole-genome sequencing, anti-elastin antibody (AEAb) ELISA, and diagnostic imaging, confirmed the pathogens causing cellulitis and secondary lymphangitis. AEAb levels were elevated, correlating with lymphatic degradation, while radiography and lymphangiography ruled out laminitis but identified tortuous lymphatic vessels. The treatment integrated systemic antimicrobials, anti-inflammatory therapy, combined decongestive therapy, and traditional Chinese herbal medicine, resulting in resolution of infection, improved hematological parameters, and restored athletic performance. The therapeutic regimen primarily included gentamicin, enrofloxacin, oxytetracycline, and the Wei Qi Booster. The case highlights the critical role of pathogen-directed antimicrobial selection and the potential benefits of combining conventional and holistic therapies. This report emphasizes the necessity of early, multifaceted interventions to prevent life-threatening complications in equine cellulitis–lymphangitis cases.

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