Chronic caprine mastitis in Nigerian goat breeds: microbiological flora and histopathological findings

In a study involving lactating does with normal-sized and enlarged pendulou s udders, 85.5% of milk samples obtained from does with unilateral udder en largement and 84.8% of samples from bilaterally enlarged udders indicated t he presence of intramammary inflammation based on results of the modified W hiteside test. In contrast, only 47.6% of milk samples obtained from normal -sized udders showed evidence of intramammary inflammation. Bacterial cultu res were performed on all milk samples which showed evidence of intramammar y inflammation. 16 species of bacteria and other microorganisms were cultur ed from these samples. Bilaterally enlarged udders collectively yielded 13 different microbial isolates, while unilaterally enlarged udders yielded 11 , and normal-sized udders yielded 9. The most frequent isolates in all grou ps were Staphylococcus spp. and Corynebacterium spp. On histopathologic exa mination, severe pathological changes in the teat and udder tissues of enla rged pendulous udders were observed. Lesions in parenchymatous tissues show ed mild to severe inflammation with involution of the parenchyma of glands. This led to shrinkage of the alveoli and in severe cases, their complete d isappearance and replacement by fibrous connective tissue which was observe d to have a high degree of proliferation. Sections of non-pendulous udder t issue showed proper arrangement of alveoli with hypertrophic epithelial cel ls, indicating active secretory activity. The results provide some definiti ve evidence that enlarged pendulous udder development in some Nigerian bree ds of goats is not spontaneous but occurs largely as a result of incursion of the mammary glands by pathogenic organisms which may cause mastitis resu lting in progressive dysfunction of mammary tissue. In chronic cases, there is severe atrophy of glandular tissue leading to fibrosis. (C) 2000 Publis hed by Elsevier Science B.V. All rights reserved.