Lymphatic vessel puncture of the bovine udder

Paratuberculosis or Johne's disease (JD), caused by Mycobacteriumavium subsp paratuberculosis (MAP), is a costly and important disease of ruminants in all developed countries. Diagnosis of paratuberculosis is challenging during the early stages of the disease, and currently available laboratory tests do not have satisfactory sensitivity when used to test MAP-infected cows before the onset of clinical signs. The lymphatic system plays a major role in the defence against infection and is an important part of the immune system. The superficial lymph vessels of the bovine udder are accessible for collection of lymphatic fluid by lymph vessel puncture in lactating cows. The objectives of the study were to: 1) evaluate the feasibility of lymph collection from the bovine udder under field conditions, 2) investigate the potential for detection of MAP in the collected lymphatic fluid of cows infected with MAP, and 3) evaluate lymphatic fluid use as a diagnostic medium for detection of MAP-infected animals in the subclinical stages of JD.