Effect of Leptospira interrogans serovar hardjo infection on progesterone concentrations in heifers

Abstract

THERE is evidence that Leptospira interrogans serovar hardjo localises in the genital tract of cattle (Ellis and others 1986). Uterine infections, such as bovine viral diarrhoea and Actinomyces pyogenes, alter the length of the oestrous cycle and cause embryonic death (Fredriksson and others 1988, Semambo and others 1992), but it is unknown whether hardjo is similarly pathogenic.In cattle, hardjo infection has been associated with subfertility which improves after vaccination (Hanson and others 1972, Dhaliwal and others 1996). Infection may have a direct effect on fertilisation and/or early embryonic signalling to the dam, or may interfere with corpus luteum function. The present study was designed to investigate progesterone concentrations during interoestrus intervals and early pregnancy in heifers infected experimentally with hardjo.Oestrus in 14 normally cyclic heifers, seronegative to hardjo, was synchronised using ear implants containing 6 mg norgestomet and 5 mg oestradiol valerate (Crestar; Intervet) for 10 days and an intramuscular injection of 25 mg prostaglandin F2a (Lutalyse; Upjohn) 24 hours before implant removal. At the synchronised oestrus, and on the following day, eight heifers were inoculated with 105 hardjo organisms diluted in 1 ml culture medium (Tween/80/40/lactalbumen hydrolysate) into the body of the uterus. Six control heifers were similarly inoculated with culture medium alone. All the heifers were observed for at least two hours daily for signs of oestrus and occasionally animals were examined manually per rectum for confirmation. All heifers were inseminated with antibiotic-free semen during the subsequent oestrus period (18 to 22 days later). Those returning to oestrus during the experimental period were reinseminated.Following inoculation (day 0), duplicate blood samples were collected from all heifers, with and without heparin for plasma and serum, respectively. Blood samples were taken on alternate days until day 60 of pregnancy; thereafter weekly samples were taken for a further four weeks or until the end of the experiment, whichever was earlier. Plasma was separated after centrifugation at 3000 g for 15 minutes and stored at -20°C pending hormone assay. Serum samples were collected at weekly intervals and kept at -20°C until assayed for hardjo antibodies.Plasma progesterone concentrations were estimated using

Laboratory Diagnosis of Bovine Abortions Caused by Non-Maintenance Pathogenic Leptospira spp.: Necropsy, Serology and Molecular Study Out of a Belgian Experience

“…Hence, it is a concern for public and animal health management. The management and diagnosis of infections due to L. borgepetersenii serovar Hardjobovis and L. interrogans serovar Hardjoprajitno in cattle are supported by numerous experimental and epidemiological studies [ 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. L. borgepetersenii serovar Hardjobovis and L. interrogans serovar Hardjoprajitno have been shown to be causes of reproductive losses worldwide [ 25 , 26 , 27 ].…”