Veterinary Services

Nutritional and metabolic disorders

Mulberry heart disease was diagnosed in a two-month-old pig found dead. Gross examination revealed free fluid in the abdomen, thorax and pericardial sac with fibrin strands over the viscera. The pleura appeared thickened and the lungs mottled. The myocardium had obvious red and white striations. Histopathological examination of the heart showed changes typical of acute degenerative cardiomyopathy and the liver showed acute periacinar degeneration consistent with secondary acute hypoxia.

Generalised and systemic conditions

Three pigs were submitted from a unit reporting ten "sudden deaths" in a group of 300 three-month-old growers following an accommodation change one week previously. All three pigs were in a reasonable body condition and showed signs of cyanosis. Gross post mortem examination revealed signs suggestive of septicaemia in two of the pigs (Streptococcus suis serotype 1/2 was isolated from internal organs of both pigs) and an extensive acute polyserositis in the third animal (no significant bacteria isolated). Histopathological examination of lymphoid tissues revealed marked lymphoid depletion and histiocytic infiltration consistent with post-weaning multisystemic wasting syndrome (PMWS). Lesions of acute bacterial pneumonitis were also present in the two pigs with streptococcal septicaemia. Although both S. suis problems and PMWS had been experienced for a number of years, this was the first time that PMWS appears to have been associated with an increase in streptococcal septicaemia in older pigs on this unit.

PMWS was confirmed for the first time on one farrow-to-finish unit following examination of one eight-week-old pig. There had been five deaths from a group of 70, with a further eight pigs showing signs of poor growth. Glässer's disease was confirmed as the cause of death (Haemophilus parasuis was isolated) and histopathological lesions in lymphoid tissues confirmed the involvement of PMWS.

Erysipelothrix rhusiopathiae was isolated from a large vegetative endocarditis lesion on the left atrio-ventricular valve of a seven-month-old Gloucester Old Spot pig found dead in good body condition, one of a litter of eight that had been reared outdoors. There was no history of acute erysipelas amongst the litter which had not been vaccinated against E. rhusiopathiae (vaccination is not generally considered to be effective in preventing chronic forms of the disease, although by reducing the incidence of acute septicaemias, it may possibly reduce the incidence of such endocarditis cases).

Three slaughter pigs were received from a finishing unit reporting an increase in cases of "sudden death". Post mortem examination revealed bacterial-type meningitis and septicaemia and Streptococcus dysgalactiae equisimilis was isolated from both brain and liver. Although this organism is part of the normal skin and tonsillar flora, ulceration/infection of adventitious hock bursae may have been significant as a source of the septicaemia in this sporadic case. The finding of intestinal torsion in the other two pigs examined was thought likely to be more representative of the herd problem reported. There was no evidence of other underlying health problems in these two pigs.

Alimentary tract disorders

Two piglets were submitted from an outdoor breeding unit where facial swelling affecting 20 litters of piglets at around one week of age had been reported. Six of the piglets had subsequently died. Examination of the pigs revealed gingival abscessation adjacent to clipped teeth and cellulitis in surrounding tissues. No significant bacteria were isolated from the lesions, perhaps as a consequence of previous antibiotic therapy, although mixed gram-negative cocci and filamentous organisms were observed in histological sections. There was no apparent involvement of the tooth roots or bones. Damage to the gingiva at the time of tooth clipping was suspected.

Respiratory tract diseases

An upsurge in coughing among growing pigs on a unit that had undergone a partial depopulation (segregated disease control) programme in 2004 to eliminate enzootic pneumonia (EP), swine dysentery and porcine reproductive and respiratory syndrome (PRRS), raised concerns of an EP breakdown. Examination of three sacrificed three-month-old pigs revealed no significant lung lesions in two of the pigs and consolidation of anteroventral areas in one pig. Lesions consistent with subacute viral-type pneumonia and bacterial bronchiolitis were noted on histopathological examination, together with evidence of PMWS in lymphoid tissues examined. No evidence suggestive of EP was detected. However recent serological examinations have shown that PRRS virus infection is present on the unit and infection with this virus, perhaps together with porcine circovirus 2 involvement in PMWS, may underlie the complex pneumonic lesions observed. Recent reports suggest that the clinical situation on the unit has improved.

Nervous system disorders

Meningitis due to S. suis serotype 1/14 was diagnosed as the cause of death of two 25-day-old recently weaned pigs that had shown neurological signs prior to death. Parenteral treatment with penicillin had been successful in treating 15 of the 20 cases recognised on the unit which has a history of problems with this particular serotype.