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Two adult female bison, housed in an outdoor research facility and observed daily, died suddenly three days apart. Minimal coordination and behavioral changes were observed in one animal the evening before being found in a moribund state. Malignant catarrhal fever was suspected in both bison due to a recent confirmed MCF case with similar course. The cause of death was not apparent from necropsy, but brains of both animals were strongly positive for rabies virus antigen by fluorescent antibody and/or immunohistochemical tests. Minimal to mild encephalitis with Negri bodies was observed on histopathology. The bison were located in an area that had not been endemic for skunk rabies; however, a case of rabies in a skunk had been discovered 1.6 km north of the bison paddock two months prior to the bison cases.

The objective of the study was to determine the efficacy of modified-live virus (MLV) BVDV type la (BVDV1a) vaccine against BVDV type 2 (BVDV2) or type 1b (BVDV1b) virus in fetal calves. The experimental vaccine administered to the cows and heifers had a minimum antigen load dose of MLV BVDV1a and a full (commonly marketed) antigen dose of infectious bovine rhinotracheitis (IBR), parainfluenza-3 (PI3), bovine respiratory syncytial virus (BRSV), and Leptospira serovars canicola, grippotyphosa, hardjo, icterohaemorrhagiae and pomona (Lepto-CGHIP) bacterin. In Trial A, 25 pregnant vaccinated cows and heifers and 10 pregnant unvaccinated controls were challenged with BVDV2. In Trial B, 25 pregnant vaccinated cows and heifers and eight pregnant unvaccinated controls were challenged with BVDV1b. In both trials, fetuses were obtained by Cesarean section, which was performed after ?150 days of gestation (range 148-174 days), and the presence or absence of fetal BVDV infection was determined. All control fetuses were infected with BVDV. In Trial A, all fetuses (n=25) of vaccinated dams were free of BVDV infection. In Trial B, one cow did not have a fetus at 150 days of gestation, and out of the 24 fetuses, 23 were negative and one fetus was positive for BVDV. These results suggest that vaccination with MLV BVDV1a vaccine significantly reduce fetal infection following challenge with BVDV2., The Bovine Practitioner, Vol. 41, No. 1 (2007 Spring)

This study was conducted to determine the effect of removing cattle persistently infected (PI) with bovine viral diarrhoea virus (BVDV) on seroprevalence and prevalence of PI calves in an endemically infected beef herd in Colorado, USA. The prevalence of PI animals and the serum neutralizing (SN) titres of heifers, bulls and calves were determined for three cow-calf herds in a beef cattle ranch over a period of 2 years [date not given]. In the first year, identified PI animals were removed from the herd within 3 weeks of identification. Five PI animals of 2921 (0.171%) cattle tested were identified in the first year. One PI animal was a yearling heifer and the remaining 4 were calves. Three of the 4 PI calves identified were removed prior to the breeding season, when the calves averaged 2 months of age. One PI animal was not identified until weaning at 6 months of age, and was present in the herd during the breeding season. The percentage of animals with high SN titres (?1:512) were 20.6% (367/1784) to type I BVDV and 44.8% (799/1784) to type II BVDV. In year 2, PI calves were not identified and the percentage of calves with high SN titres to BVDV type I and type II decreased to 5.91 (58/981) and 18.04% (177/981), respectively. Removal of PI animals in the first year reduced transmission of BVDV as evidenced by a significant decrease in the prevalence of high BVDV SN titres and the absence of PI animals the following year. These findings support the use of PI animal identification and removal as an effective BVDV control strategy in beef herds., The Bovine Practitioner, Vol. 38, No. 2 (2004 June)

Twenty-one heifers vaccinated with a modified live virus (MLV) type la BVDV vaccine (Pyramid MLV 4) and eight unvaccinated control heifers were bred between 28 and 53 days post-vaccination., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2002

Serum neutralizing (SN) antibody titres to cytopathic (cp) type 1a, type 1b and type 2 bovine viral diarrhoea viruses (BVDV) were determined for yearling, crossbred beef heifers immunized with a modified live cytopathic type 1a BVDV vaccine, or experimentally infected with a noncytopathic (ncp) type 1b or a ncp type 2 BVDV. The results indicate that type-specific and cross-reactive SN titres are usually found to all three test viruses in an individual animal, with the highest SN titres to the same genotype of BVDV as the challenge or vaccine virus. Exceptions to this trend were found in individual animals, however, emphasizing the importance of comparing the SN titres for several animals in a herd. Determining SN titres to the three BVDV genotypes may help veterinarians distinguish the BVDV genotype involved in a herd infection from antibody titres due to vaccination., The Bovine Practitioner, Vol. 35, No. 2 (2001 June)

Bovine viral diarrhea virus (BVDV) is the most common infectious cause of abortions, stillbirths and weak calves in western range beef herds. A variety of vaccines containing a BVDV component are used by producers to prevent the consequences of fetal BVDV infections. In spite of vaccination, BVDV "wrecks" occur annually. This study examined the impact of BVD-associated disease in vaccinated beef herds., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2000