Peritoneopericardial diaphragmatic hernia (PPDH) is a congenital defect allowing communication between the peritoneal cavity and the pericardial sac, through which abdominal organs may herniate into the pericardial space. The condition can be asymptomatic or symptomatic, and if symptomatic, accompanied mostly with non‐specific gastrointestinal or respiratory clinical signs. A 2‐year‐old, male, neutered mixed breed dog was referred due to fever, lethargy and decreased food intake over the last 2 weeks. Abdominal ultrasound was performed and a transposition of abdominal organs into the thoracic cavity was suspected. Further diagnostic imaging confirmed PPDH with herniation of the gall bladder and spleen into the pericardial sac. The dog underwent surgery for hernia repair. Severe pneumopericardium subsequently complicated by pericardial effusion developed postoperatively. Both complications resolved without intervention. The dog never showed signs of haemodynamic instability or cardiac tamponade.

The significance of large multigene families causing high-frequency surface variations in mycoplasmas is not well-understood. Previously, VpmaY and VpmaU clonal variants of the Vpma family of lipoproteins of M. agalactiae were compared via experimental sheep infections using the two corresponding ‘Phase-Locked Mutants’. However, nothing is known about the infectivity of the remaining four Vpma expression variants VpmaX, VpmaW, VpmaZ and VpmaV as they were never evaluated in vivo. Here, in vivo infection and disease progression of all six Vpma expressers constituting the Vpma family of type strain PG2 were compared using the corresponding xer1-disrupted PLMs expressing single well-characterized Vpmas. Each of the six PLMs were separately evaluated using the intramammary sheep infection model along with the control phase-variable wildtype strain PG2. Thorough bacteriological, pathological and clinical examinations were performed, including assessment of milk quality, quantity and somatic cell counts. Altogether, the results indicated that the inability to vary the Vpma expression phase does not hamper the initiation of infection leading to mastitis for all six PLMs, except for PLMU, which showed a defect in host colonization and multiplication for the first 24 h p.i. and pathological/bacteriological analysis indicated a higher potential for systemic spread for PLMV and PLMX. This is the first study in which all isogenic expression variants of a large mycoplasma multigene family are tested in the natural host.