A storm in the gut, a flood in the lungs: Pleural effusion associated with astA-positive Escherichia coli in a search-and-rescue dog

Authors: Hosam Shams-Eldin

Ger. J. Vet. Res 2026. vol. 6, Iss. 3 pp:56-64
Doi: https://doi.org/10.51585/gjvr.2026.3.0200

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Abstract:

In this study, a working search-and-rescue dog was evaluated for pleural effusion and thoracic discomfort. Although prominent respiratory signs initially suggested primary pulmonary disease, a thorough history revealed that abdominal pain, bloating, and mild gastrointestinal disturbances preceded the respiratory symptoms. Empirical administration of broad-spectrum antimicrobials, initiated without culture guidance, did not improve the clinical condition and may have contributed to intestinal dysbiosis. Fecal culture revealed significant overgrowth of morphologically atypical Escherichia coli, and molecular analysis identified the astA gene encoding enteroaggregative heat-stable toxin 1 (EAST-1). Antimicrobial susceptibility testing demonstrated reduced efficacy of previously used agents, whereas high in vitro susceptibility to trimethoprim–sulfamethoxazole allowed for targeted therapy. A multimodal treatment strategy incorporating culture-guided antimicrobial therapy, intestinal adsorbents, mucosal support, and dietary modification led to rapid clinical improvement. Subsequent evaluations showed a substantial decrease in astA-positive colonies, resolution of gastrointestinal symptoms, and gradual resolution of pleural effusion. This case suggests a potential association between intestinal dysbiosis and extra-intestinal manifestations such as pleural effusion, emphasizing the need to consider gastrointestinal etiologies in dogs presenting with unexplained thoracic disease. 

Keywords:

Dog, Escherichia coli, astA, EAST-1, Intestinal dysbiosis, Pleural effusion, Splenectomy, Antimicrobial therapy, Gut–lung axis

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