Veterinary Services

Glasser’s disease and bacterial meningitis were diagnosed on a unit that experienced five sudden deaths in a pen of 100 eight-week-old weaners over two days. The postmortem findings were typical including fibrinous pleurisy, peritonitis and polysynovitis with isolation of Haemophilus parasuis from the lungs. Additionally, histopathology revealed severe semi-purulent meningitis affecting all areas of the brain and the cranial cervical spinal cord, confirming neurological involvement in this instance.

Meningitis associated with Streptococcus suis serotype 2 was diagnosed on three units. One reported six deaths within the previous three days out of a pen of 100 ten-week-old gilts. Postmortem examination of three pigs showed a combination of pulmonary, joint and neurological lesions associated with the organism.  On an unrelated unit there were three deaths in two days and some affected pigs were reported to have nervous signs. There was grey opacity of the meninges and the diagnosis was confirmed by a combination of bacterial cultures and histopathology. The third incident involved 21-week-old pigs close to slaughter weight. There were seven deaths over a two-day period. Affected pigs were found recumbent and paddling before dying. Of two pigs submitted for postmortem examination, one had a thick layer of fibrin overlying the cerebellum and also some fibrin over the brain stem. The brain was congested and the meningeal vessels were injected. In the second case the meningeal vessels were injected and there was some cloudiness over the brainstem. The diagnosis was confirmed by histopathology and isolation of Streptococcus suis serotype 2. Pasteurella multocida was also isolated in systemic distribution from the second pig.

Another neurological disease incident involved the deaths of 33 finishing pigs over a three day period. The pigs were disorientated, lying and kicking.  A typical 18-week-old pig was euthanased and submitted for postmortem examination. On histopathology the brain showed widespread, severe semi-purulent meningitis with micro-abscesses affecting the cerebrum. A Pasteurella species was isolated in culture from the meninges of this case. As only one carcase was submitted, SAC C VS were unsure that this was truly representative of all the deaths in this outbreak.

A 15-week-old boar carcase was submitted from a unit where there was lameness in two pens of boars with a morbidity of 2.5 per cent. The pigs were reported to be shaking and squealing. There was excess bloody synovial fluid and some fibrin in the right shoulder joint. Both stifles also contained excess bloody synovial fluid with hyperaemic synoviae. Histopathology revealed congestion, oedema and inflammation of the synovial membrane with erosion of surface synovial cells. The inflammatory infiltrate was mixed, with mainly neutrophils and lymphocytes present. Areas of haemorrhage and blood loss from the eroded surface were apparent. No bacteria were evident. However, giemsa-stained sections showed moderate numbers of tiny pleomorphic organisms resembling Mycoplasma species associated with the surface of the synovial membrane. Although no Mycoplasmas were isolated in culture from one of the affected joints, SAC C VS considered the findings were highly suggestive of a Mycoplasma-type synovitis.