Endocarditis-associated brain lesions in slaughter pigs.

Left-sided valvular endocarditis (LSVE) is a common finding in slaughter pigs. The lesion is often associated with renal thromboembolism, but information on embolization to other organs is sparse. This study focuses on the presence and type of endocarditis-associated brain lesions (EABLs). The brains of 20 slaughter pigs with spontaneously arising LSVE and 11 controls were examined by sectioning half of a formalin-fixed brain into 4mm slices for histological examination. The aetiology of the endocarditis was determined by bacteriological and, in some cases, by fluorescence in-situ hybridization examinations. These examinations identified 11 cases of Streptococcus suis, six cases of Erysipelothrix rhusiopathiae, one Streptococcus spp. and two cases that remained aetiologically undetermined. One of the S. suis cases had a dual infection with S. suis in the aortic valve lesions and Streptococcus dysgalactiae subsp. equisimilis in the atrioventricular valve lesions. Renal infarcts were present in eight cases. Focal encephalitis was found in 12 cases, with the number of lesions ranging from one to 11. Most pigs had less than four microscopical lesions. Acute lesions were characterized by focal microabscesses without observable bacteria. Chronic lesions were characterized by astrocytosis and focal accumulation of mononuclear leucocytes. An infarct was observed in one animal. Perivascular inflammation was seen in 14 cases, mostly as two or three lesions, while focal leptomeningitis was found in eight cases. EABLs are therefore common in slaughter pigs with LSVE. The number of lesions per animal is small, which may explain the limited attention paid to this sequela of LSVE. EABLs have rarely been reported in domestic animals and mostly in patients with neurological signs. The frequent occurrence of EABLs in slaughter pigs suggests that this pathology should be investigated in other animal species with LSVE.

Case study: chronic erysipelas of the sow--a subclinical manifestation of reproductive problems.

Systemic infections with Erysipelothrix rhusiopathiae are usually associated with skin lesions, vegetative endocarditis and arthritis, but they can also cause reproductive symptoms such as abortion, increased stillbirths, and smaller litter size. In a large Hungarian breeding unit that had ceased to vaccinate the sows against erysipelas, an increased incidence of pre- and post-partal vulval discharge, increased weaning-to-oestrus intervals, decreased farrowing rates, and reductions in total number of pigets born and live-born litter size were reported. Anterior vaginal swabs were obtained from 64 sows shortly before parturition and they all yielded heavy growths of E. rhusiopathiae. A vaccination programme with a killed vaccine was reinstated and subsequently the incidence of vulval discharge and weaning-to-oestrus intervals were decreased and total born and live-born litter size were increased. In the absence of a control group definitive conclusions can not be made regarding the effect of vaccination against E. rhusiopathiae on sow fertility. However, it is not unreasonable to suggest that the aetiology of the reduced sow fertility in the present herd did involve E. rhusiopathiae and that appropriate vaccinations subsequently protected the sows from the disease.

[Enzyme, enzyme-histochemical and immunohistological studies in chronic erysipelas polyarthritis of swine]. / Enzymatische, enzymhistochemische und immunhistologische Untersuchungen bei der chronischen Rotlaufpolyarthritis des Schweines.

The chronic Erysipelas-polyarthritis in pigs has been considered an animal model resembling human rheumatoid arthritis. Fifteen specifically pathogenfree (SPF) pigs 45 days old were experimentally infectec with strain T 28 of Erysipelothrix rhusiopathiae-bacteria. During the subsequent 32 weeks several enzymatic, immunohistological and microbiological parameters were monitored. Compared to 5 age and sex matched healthy controls the infected pigs showed increased activity of plasma acid phosphatase starting 4 weeks after the infection. Acid phosphatase activity was usually enhanced in synovial fluid of chronically ill animals. Histochemically increased activity of acid phosphatase, beta-glucuronidase and beta-acetylglucosaminidase was found in lining cells and fibroblasts of the synovial membrane of chronically diseased joints. Immunohistochemically Erysipelas-antigen was demonstrated in the synovial membrane even of those inflamed joints from which no living bacteria had been isolated. The microbiological and immunohistochemical results correlated positively with the enzymehistochemical data. The release of lysosomal enzymes from cells of the synovial membrane in chronically diseased joints due to the influence of Erysipelas-bacteria and the possible implications of persistent bacteria on the perpetuation of chronic Erysipelas-polyarthritis are discussed.