The collection of lymphatic fluid from the bovine udder and its use for the detection of Mycobacterium avium subsp. paratuberculosis in the cow.

The objective of the current study was to evaluate the feasibility of lymph collection from the bovine udder and to investigate if the lymphatic fluid might be of diagnostic value in cows infected with Mycobacterium avium subsp. paratuberculosis (MAP), the etiologic agent of paratuberculosis. Lymph fluid collection was attempted from 58 cows, and the reactions of the cows as well as the level of difficulty of the procedure were recorded in 56 animals. Lymph samples (51 in total) were tested for the presence of MAP by nested polymerase chain reaction. Collection of the lymphatic fluid caused no or mild signs of discomfort in 94.6% of the cows; in 51.8% of cows, lymphatic fluid was attained on the first attempt, while sample collection was unsuccessful in 12.1%. Mycobacterium avium subsp. paratuberculosis was detected in 43.1% of all lymph samples. The bacterium was present in 66.7% of cows with clinical Johne's disease, in 42.8% of asymptomatic cows with a positive or suspicious enzyme-linked immunosorbent assay (ELISA) result in blood, and in 38.7% of cows with a negative ELISA result in blood. The present study shows that the procedure was well tolerated by most cows and can easily be performed on farm. The current report of the isolation of MAP from lymph fluid suggests that the present approach could be used for the early detection of Johne's disease in cattle.