Occurrence of Mycoplasma hyorhinis infections in fattening pigs and association with clinical signs and pathological lesions of Enzootic Pneumonia

We found no evidence that M. hyorhinis alone can lead to similar lung lesions as seen by an infection with M. hyopneumoniae in fattening pigs. In addition, a simultaneous infection with both M. hyorhinis and M. hyopneumoniae did not aggravate the observed lung lesions. Moreover, the presence of M. hyorhinis showed no clinical effect in terms of coughing at least at the end of the fattening phase. However, different levels of virulence of M. hyorhinis isolates as well as interactions with viral pathogens like porcine reproductive and respiratory syndrome virus (PRRSV) or porcine circovirus type 2 (PCV2) were reported in the literature and need to be further investigated.