A case report of tracheitis in finishing pigs in France

During an outbreak of respiratory disease, pigs suffering of severe and usually fatal respiratory distress can be observed sporadically. During necropsy, oedema and haemorrhage of the mucosa can be observed in the trachea leading to the suspicion of severe tracheitis. However, aetiology of tracheitis remains obscure in pigs. We report here a clinical case of tracheitis in finishing pigs.

This study reports on a 200 sow farrow-to-finish farm located in Brittany, France. Groups of sows farrow every 2 weeks and piglets are weaned at 21 days of age. The farm is free of PRRSV and Actinobacillus pleuropneumoniae. Piglets are vaccinated against Mycoplasma hyopneumoniae (Mhyo) at 8 and 28 days of age. In the nursery, piglets are treated with tilmicosine at 300 ppm and flubendazole at 15 ppm in the first feed during fifteen days. When moved in the finishing phase, pigs are orally treated for five days with tylosin, 25mg/kg/day. In January 2015, an outbreak of respiratory disease due to H1N2 swine influenza virus (SIV) occurred. During that outbreak, chronic coughing of pigs without dyspnoea was observed. In addition, some pigs with severe respiratory distress and tracheitis were also found. A clinical investigation including post-mortem examinations and laboratory analysis was initiated.

Clinical signs were observed on heavy fattening pigs including hard/rough coughing, severe dyspnoea and death of pigs left untreated (marbofloxacine, 2mg/kg and/or dexamethasone, 0.03mg/kg). Dark red lesions and consolidation of the cranial lobes of the lungs were indicative of bronchopneumonia and histology confirmed those as enzootic pneumonia lesions due to Mhyo. A serological profile (ELISA Oxoid) revealed a seroconversion against Mhyo one month before slaughtering. Gross lesions in the trachea showed haemorrhagic lesions, necrotic ulceration, oedema and fibrin, confirmed by histology that revealed as well bacterial infection of the lesions. Streptococcus suis type 4 and Staphylococcus hyicus were recovered from the trachea. During the investigation, parasitic infestation with Ascaris suum was concurrently identified by serology (Serasca®).

Tracheitis clinical signs and lesions were more severe during an outbreak of SIV. In this case, our hypothesis is that tracheitis was triggered by Porcine Respiratory Disease Complex (PRDC), with a cough-associated tracheal damage. Indeed, SIV, Mhyo and Ascaris suum were identified in finishing pigs and after implementation of measures against those pathogens, clinical signs of tracheitis were lowered.

Disclosure of Interest: None Declared.