Infertility in dairy cows – Possible bacterial and viral causes

Abstract

In this research uterine swab and biopsy samples were collected from 40 infertile dairy cows kept at five dairy cattle farms in Hungary. Samples were tested for bacteria including Coxiella burnetii chlamydiae, Mycoplasma and Ureaplasma, and for the viruses Bovine herpesvirus 1 (BoHV-1) and Bovine viral diarrhoea virus (BVDV). Chlamydiaceae DNA was detected by real-time PCR in 22/40 (55%) samples. Coxiella burnetii DNA was detected in 3/40 (7.5%) cases by real-time PCR. Mycoplasma and Ureaplasma DNA was found in 2/40 (5%) and 4/40 (10%) cows, respectively. BVD and BoHV-1 DNA was not detected in any samples. Escherichia coli as a recognised uterine pathogen was found in two cases. The following potential uterine pathogens were found: Bacillus licheniformis (one case), non- haemolytic streptococci (five cases), Histophilus somni (two cases) and Candida krusei (two cases). Blood samples were collected at same time as swab samples from all 40 cows, and their examination for C. burnetii antibodies by ELISA revealed seropositivity in 26/40 cows (65%). Histological examination of the uterine biopsy samples showed the presence of mild lympho-histiocytic infiltration in the mucosain 22 cases (59%). Moderatelympho-histiocytic infiltration of the endometrium was evident in 13 cases (35%), while in two cases (6%) severe inflammatory cell infiltration of the endometrium with lympho-histiocytes and neutrophil granulocytes was found. Although no statistical correlation could be demonstrated between the severity of histological lesions of the endometrium and the uterine pathogenicity of the bacteria (P = 0.8555), endometritis of a certain severity grade and/or a recognised or potential uterine pathogen were found in all samples. The latter may play a role in the development of infertility either collectively or independently.