OBJECTIVE To evaluate changes in behavior and surfactant protein (SP) A and D concentrations in serum and bronchoalveolar lavage fluid (BALF) samples of calves experimentally infected with Mannheimia haemolytica.
ANIMALS Twelve 4- to 5-month-old Holstein steers.
PROCEDURES Calves were divided into 2 treatment groups and instrumented with a data logger to collect behavioral data. After 10 days of acclimation, calves were experimentally inoculated with 3 × 109 CFUs to 5 × 109 CFUs of M haemolytica suspended in approximately 5 mL of PBS solution (infected calves; n = 6) or 5 mL of PBS solution without M haemolytica (control calves; 6) through a catheter into the right accessory lung lobe. Calves were clinically evaluated twice daily for 7 days after inoculation. Blood and BALF samples were collected from all calves at predetermined times for determination of serum and BALF SP-A and SP-D concentrations. Serum and BALF concentrations of SP-A and SP-D and behavioral data were evaluated over time and between treatment groups.
RESULTS Compared with control calves, infected calves spent more time lying in general and more time lying on the right side during the 24 hours and 6 days after inoculation, respectively. Mean rectal temperature for infected calves (41.3°C) was significantly greater than that for control calves (39.2°C) 12 hours after inoculation. Mean respiratory rate for infected calves (52.5 breaths/min) was significantly greater than that for control calves (45.4 breaths/min) throughout the observation period.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated continuous behavioral monitoring may improve detection of calves with respiratory tract disease.
To compare pregnancy-associated glycoprotein 1 (PAG1) concentrations in maternal (jugular vein) and fetal (uterine vein) circulations and amniotic fluid samples between pregnant ewes that were and were not experimentally infected with bovine viral diarrhea virus (BVDV).
11 healthy pregnant yearling ewes.
Before study initiation, all ewes were naïve to BVDV and confirmed pregnant by transabdominal ultrasonography at approximately 60 days of gestation. At 65 days of gestation, ewes were intranasally inoculated with a noncytopathic BVDV type 1b strain (concentration, 107 TCID50/mL; 2 mL/nostril; n = 6) or an equal volume of BVDV-free viral culture medium (control; 5). A blood sample was collected for measurement of PAG1 concentration before inoculation. At 80 days of gestation, each ewe was anesthetized and underwent an ovariohysterectomy. While sheep were anesthetized, blood samples from the jugular and uterine veins and an amniotic fluid sample were collected for measurement of PAG1 concentration. Fetal tissues underwent real-time PCR analysis for BVDV RNA, and placental specimens underwent histologic evaluation and immunohistochemical staining for BVDV antigen.
At 80 days of gestation, BVDV RNA in fetal tissues and mild placentitis were detected in 5 of 6 BVDV-inoculated ewes. Mean PAG1 concentrations in the maternal and fetal circulations of BVDV-inoculated ewes were significantly less than those in control ewes. Mean amniotic fluid PAG1 concentration did not differ significantly between the 2 groups.
CONCLUSIONS AND CLINICAL RELEVANCE
Concentration of PAG1 in the maternal circulation may be a useful biomarker for determining placental health in sheep after viral infection of the reproductive tract.