Pyelonephritis in slaughter pigs and sows: Morphological characterization and aspects of pathogenesis and aetiology

<p>Abstract</p> <p>Background</p> <p>Pyelonephritis is a serious disease in pig production that needs to be further studied. The purpose of this study was to describe the morphology, investigate the pathogenesis, and evaluate the aetiological role of <it>Escherichia coli </it>in pyelonephritis in slaughtered pigs by concurrent bacteriological, gross and histopathological examinations.</p> <p>Methods</p> <p>From Danish abattoirs, kidneys and corresponding lymph nodes from 22 slaughtered finishing pigs and 26 slaughtered sows with pyelonephritis were collected and evaluated by bacteriology and pathology. Based on gross lesions, each kidney (lesion) was grouped as acute, chronic, chronic active, or normal and their histological inflammatory stage was determined as normal (0), acute (1), sub-acute (2), chronic active (3), or chronic (4). Immunohistochemical identification of neutrophils, macrophages, T-lymphocytes, B-lymphocytes, plasma cells, <it>E. coli </it>and Tamm-Horsfall protein (THP) in renal sections was performed. The number of <it>E. coli </it>and the proportion of immunohistochemically visualized leukocytes out of the total number of infiltrating leukocytes were scored semi-quantitatively.</p> <p>Results</p> <p>Lesions in finishing pigs and sows were similar. Macroscopically, multiple unevenly distributed foci of inflammation mostly affecting the renal poles were observed. Histologically, tubulointerstitial infiltration with neutrophils and mononuclear cells and tubular destruction was the main findings. The significant highest scores of L1 antigen⁺neutrophils were in inflammatory stage 1 while the significant highest scores of CD79αcy⁺B-lymphocytes, IgG⁺and IgA⁺plasma cells were in stage 3 or 4. Neutrophils were the dominant leukocytes in stage 1 while CD3ε⁺T-lymphocytes dominated in stage 2, 3 and 4. Interstitially THP was seen in 82% and 98% of kidneys with pyelonephritis from finishing pigs and sows, respectively. <it>E. coli </it>was demonstrated in monoculture and/or identified by immunohistochemistry in relation to inflammation in four kidneys from finishing pigs and in 34 kidneys from sows.</p> <p>Conclusions</p> <p><it>E. coli </it>played a significant role in the aetiology of pyelonephritis. Neutrophils were involved in the first line of defence. CD3ε⁺T-lymphocytes were involved in both the acute and chronic inflammatory response while a humoral immune response was most pronounced in later inflammatory stages. The observed renal lesions correspond with an ascending bacterial infection with presence of intra-renal reflux.</p

Impact of a killed PRRSV vaccine on sow longevity in a PRRSV infected swine herd

In porcine reproductive and respiratory syndrome virus (PRRSV)-infected farms, there is an increase in the female culling rate, mainly due to reproductive problems and culling of young females. This has significant economic importance, as the low female culling rate is an important management factor. In the present study, in a farrow-to-finish farm with 1100 sows, all gilts and sows were vaccinated with a PRRS killed virus (PRRS KV) vaccine (PROGRESSIS (R)/Merial SAS, France) for a period of 18 months. For each gilt and sow, reproductive data were collected starting from 1-year prior until 18 months after the start of vaccination. Culling rate and the causes of culling (reproductive failure, death, old age, locomotor problems and other) were recorded. Blood samples from non-vaccinated animals were collected prior and after the start of vaccination. The purpose of this field study was to evaluate the sow longevity in a PRRSV-infected farm after their long-term vaccination with a PRRSV KV vaccine. The results indicated that the vaccination leads to a significant reduction (P<0.001) of culling rate due to reproductive failure 1.5 years after the start of vaccination and an increase of old age (P<0.001) totally 1.5 years after the start of vaccination. Eventually, culling rates due to deaths (P = 0.066), locomotor problems (P = 0.264) and other causes (P = 0.894) did not significantly differ per semester and totally prior and after the start of vaccination. In conclusion, the long-term vaccination of breeding stock with a PRRSV KV vaccine can lead to decrease of culling rate due to reproductive failure and improvement of the sow longevity