Lawsonia intracellularis associated equine proliferative enteropathy in Danish weanling foals.

Lawsonia intracellularis, an obligate intracellular bacterium, causes equine proliferative enteropathy, mainly in horses around weaning. This disease is rarely reported in the Scandinavian countries.Five cases of equine proliferative enteropathy were diagnosed between 2008-2016 at the University of Copenhagen Large Animal Teaching Hospital. Cases were Danish Warmbloods and a Friesian horse, aged 6-7 months, presenting with typical clinical signs of lethargy, poor body condition, pyrexia and diarrhea. Clinical pathology was consistent with previous reports of severe hypoalbuminemia and leukocytosis. Diagnosis was confirmed by fecal polymerase chain reaction, serum immunomonolayer peroxidase assay and/or immunofluorescence and fluorescence in situ hybridization performed on formalin-fixed ileum samples. Concurrent intestinal parasitism was present in all five cases. Treatment consisted of antimicrobial therapy, anti-inflammatories, intravenous crystalloids and plasma. Three foals were euthanised due to deterioration and poor response to treatment, one with complications of septic arthritis and Strongylus vulgaris associated intestinal infarct. The other two foals survived and were reported by the owners to be healthy on long-term follow-up.Equine proliferative enteropathy is a disease to consider in young horses presenting with diarrhea and hypoproteinemia in Denmark.