Dear Editor

We read with interest the recent paper by Broux B, Torfs S, Wegge B et al, “Acute respiratory failure caused by Leptospira spp. in five foals”,[1] and we would like to share our experience with pulmonary hemorrhage in horses seroreactive to leptospirosis in Rio de Janeiro, Brazil.

In tropical areas, members of Icterohaemorrhagiae serogroup (serovars Icterohaemorrhagiae or Copenhageni) are the most frequent serovars causing leptospirosis in horses.[2] Besides the well-known ocular and reproductive manifestations,[3] respiratory disorders associated to leptospirosis, including pulmonary hemorrhage (PH) and pneumonitis, have been described in horses.[4]

Our group recently reported a case of pulmonary hemorrhage in an aborted foal in Rio de Janeiro, Brazil. The diagnosis of leptospirosis was confirmed by PCR of the hemorrhagic thoracic fluid.[5]

In another study, we studied 84 adult training horses, which were tested for anti-Leptospira antibodies and underwent endoscopy. Pulmonary hemorrhage was significantly more common in seroreactive (34.7%) than seronegative (8.6%) (P < .05) horses, and also was more severe in the seroreactive horses. Additionally, it has been demonstrated that seroreactive horses were 4.26 times more likely (odds ratio, [OR]) to present with PH than were seronegative horses.[4]

With regard to the treatment, it was notable that, of 5 studied foals, the authors employed antibiotic therapy (cefquinome), with good results, in only 1 animal (case 2). In our experience, procaine penicillin G combined with streptomycin (Pen & Strep®, Lavizoo, Campinas, SP, Brazil), 25mg/kg was employed in 18 adult seroreactive horses, and substantial improvement in the grade of their hemorrhage was observed.

We agree with the authors that leptospirosis must be considered in the differential diagnosis of acute respiratory distress, not only in the foal, but also in adult horses. It is noteworthy that they reported cases in Belgium. Because incidental infections caused by members of the Icterohaemorrhagiae serogroup are more frequent in tropical than in temperate countries, it is possible that cases of pulmonary distress in horses associated with leptospirosis are neglected and may be more common under tropical conditions, requiring more investigation.


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