Filaroidosis Infection in an Immunocompetent Adult Dog from France

Abstract

A dog from Paris (France) was referred with a 2-week history of dry cough, intermittent acute onset of dyspnoea, and acute abdominal pain. A generalised bronchoalveolar infiltrate with a patchy distribution was observed at chest x-rays and computed tomography (CT) scans. Negative results were obtained through several faecal examinations for cardiorespiratory nematodes by using the Baermann technique and at two blood analysis with a commercially available test for the detection of A. vasorum antigen (the first one at the first visit and second one at the control visit, one month later). PCR methods for the identification of A. vasorum and C. vulpis were also accomplished. At the control visit, nematode L1s were found during direct microscopic examination of bronchoalveolar lavage fluid (BALF). Thus, a different antigen-based assay for the detection of A. vasorum was performed with a positive result. Moreover, based on morphology, isolated larvae were identified as Filaroides hirthi. The dog was treated with fenbendazole (50 mg/kg per os once daily) for two consecutive weeks. After five months, the dog was referred again for the intermittent acute onset of dyspnoea and was found to be still positive for F. hirthi larvae at BALF examination. A 15-day treatment regimen with fenbendazole in combination with three subcutaneous injections of ivermectin (0.4 mg/kg, once every two weeks), was then performed. No larvae were detected at two BALF microscopical examinations performed one month apart. Results from this case report underline the importance of including F. hirthi infections in the differential diagnosis of dog bronchopneumonia.

Keywords: Filaroides hirthi; France; canine verminous bronchopneumonia.

Fig. 1

Right lateral (on the left) and ventrodorsal (on the right) thoracic radiographs of the examined dog showing an extensive broncho-alveolar infiltrate and consolidated areas with a patchy distribution. Lesions are more severe in the right hemithorax.

Fig. 2

Transverse computed tomographic images of the lungs of the dog. (A) Pulmonary lesions at clinical presentation, showing a large consolidated area (black thick arrow) with formation of air bronchograms (black thin arrow), surrounded by diffuse zones of ground-glass opacification (red thin arrow). Lesions are more severe in the right hemithorax (B) Moderate improvement in pulmonary lesions after few days of treatment. (C) Improvement in pulmonary lesions 15 days after starting treatment with oral fenbendazole. Consolidated areas have almost disappeared.

Fig. 3

Filaroides hirthi first stage larva detected at the microscopic examination of the BALF (40x magnification). Note the straight tail with a single slight dorsal indentation (thick arrow), ending into a lance-like shape (thin arrow), consistent with F. hirthi.