Granu lomatous mastitis is a common disease in sow herds maintained on straw bedding and in group housing, and it has negative effects on sow productivity. A thorough description of the clinical appearance of the disease and the identification of risk factors should contribute to development of relevant control measures.

Chronic mastitis in sows is a common disease that has a negative influence on productivity. Results indicate that certain management practices and environmental factors influenced the development of mastitis, which may contribute to the development of methods useful for controlling the disease.

An unusual Actinomyces-like bacterium originating from a pig with mastitis was subjected to a polyphasic taxonomic investigation. The morphological and biochemical characteristics of the organism were consistent with its preliminary assignment to the genus Actinomyces but it did not appear to correspond to any recognized species. PAGE analysis of whole-cell proteins confirmed the phenotypic distinctiveness of the bacterium and 16S rRNA gene sequence analysis demonstrated that it represents a hitherto unknown sub-line amongst a cluster of Actinomyces species which embraces Actinomyces canis, Actinomyces georgiae, Actinomyces hyovaginalis, Actinomyces meyeri, Actinomyces odontolyticus, Actinomyces radingae and Actinomyces turicensis. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium isolated from pig mastitis be classified as Actinomyces suimastitidis sp. nov. The type strain of Actinomyces suimastitidis is CCUG 39276 T (l CIP 106779 T ).

Summary The main objective of this study was to obtain data about the frequencies of teat injuries, udder skin lesions and abnormal palpatory findings of the mammary glands at the day of weaning and 7 days after weaning. Milk samples were collected from mammary glands and teats without clinical changes and from glands and teats showing abnormal clinical appearance. Bacteriological examination was performed and evaluated. The total cell content (TCC) and the polymorphonuclear leucocytes (PMNLs) were counted and used as indicators of inflammatory response. Sixty per cent of the lactations showed teat injuries and (or) udder skin lesions irrespective of lactation number. The prevalence of palpable changes increased gradually from the first to the second and subsequent lactations (15%, 30% and 60%), the increase from the first to the second and from the first to the third and subsequent lactations being significant or highly significant (P < 0.05 and P < 0.001). The average number of teats injured per ‘lactation with teat injuries’ showed a numerical but not significant decrease (3.0, 3.2 and 2.4, respectively). The average number of palpable changes per ‘lactation with palpable changes’ varied from 1.7 to 2.5. The teat injuries were numerically more frequent within the two thoracic and first three abdominal teat pairs, varying from 11% to 16%. The clinical appearance of the teat injuries and palpatory changes subsided rapidly, 76% and 49% being scored as clinically normal when the reexamination was performed 7 days after weaning. Irrespective of clinical group, the milk collected at the day of weaning yielded non‐ as well as α‐ and β‐haemolytic streptococci. The β‐haemolytic streptococci turned out to be more frequently isolated from milk collected from clinically abnormal glands and teats. The limited number of secretion samples obtained and cultured 7 days after weaning yielded staphylococci and Actinomyces pyogenes, which indicated a bacterial flora known to cause infectious mastitis. A cytological comparison between milk from clinically normal and abnormal mammary glands and teats revealed almost significantly or significantly increased levels of TCC and PMNLs (12.17 vs. 17.76 × 106 cells/ml and 1.40 vs. 2.77 × 106 cells/ml). A comparison between levels of TCC and PMNLs in milk collected from the two clinical groups of sows, but where the bacteriological growth turned out to be negative, also revealed significant increases in the levels of the two cell parameters emanating from clinically abnormal glands and teats. The individual sow, but not herd or lactation, showed a significant influence on the variation of TCC.

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