Bovine Viral Diarrhoea Virus (BVDV) in Dairy Cattle: A Matched Case-Control Study.

Bovine viral diarrhoea virus (BVDV) causes one of the most important diseases of cattle in terms of economic costs and welfare. The aims were to estimate herd prevalence and to investigate the factors associated with antibodies in bulk tank milk (BTM) in dairy herds through a matched case-control study. To estimate herd prevalence, BTM samples were randomly selected (n = 314) from a population (N = 1604). The true prevalence of BVDV was 24.3% (CI 95% = 20.1-29.3%). For the case-control study, BVDV antibody-positive herds (high antibody titres) were classified as cases (n = 21) and matched (n = 63) by milk production with herds presenting low antibody titres (ratio of 1 : 3). Three multivariable models were built: 1) full model, holding all 21 variables, and two models divided according to empirical knowledge and similarity among variables; 2) animal factor model; and 3) biosecurity model. The full model (model 1) identified: age as a culling criteria (OR = 0.10; CI 95% = 0.02-0.39; P < 0.01); farms that provided milk to other industries previously (OR = 4.13; CI 95% = 1.17-14.49; P = 0.02); and isolation paddocks for ill animals (OR = 0.14; CI 95% = 0.01-0.26; P = 0.02). The biosecurity model revealed a significant association with the use of natural mating (OR = 9.03; CI 95% = 2.14-38.03; P < 0.01); isolation paddocks for ill animals (OR = 0.06; CI 95% = 0.05-0.83; P = 0.03); years providing milk for the same industry (OR = 0.94; CI 95% = 0.91-0.97; P = 0.02); and direct contact over fences among cattle of neighbouring farms (OR = 5.78; CI 95% = 1.41-23.67; P = 0.04). We recommend the application of grouping predictors as a good choice for model building because it could lead to a better understanding of disease-exposure associations.

Seroprevalence of Brucella ovis in rams and associated flock level risk factors in the state of Rio Grande do Sul, Brazil.

A cross-sectional study based on a planned probabilistic sampling was carried out to estimate animal and flock prevalence of Brucella ovis in rams, as well as to determine risk factors at the flock level. Data regarding the flocks were collected by means of a questionnaire applied on 705 farms in the state of Rio Grande do Sul, Brazil, using one-stage cluster sampling. From the 705 flocks, 20 (2.5%, CI95%: 2.0-3.1%) had at least one positive ram. At the animal level, out of 1800 rams, 52 were positive (2.89%, CI95%: 0.4-5.3%). Statistical analysis identified the following as risk factors: average age of rams in the flocks (PR: 1.99, CI95%: 1.19-3.32); farms larger than 5 km(2) (500 ha) on extension area (PR: 7.46CI95%: 2.03-27.43); and the lack of lambing paddocks (PR: 5.56, CI95%: 1.70-18.11). This study provided relevant information for authorities to elaborate plans for the first Brazilian state based B. ovis disease control and eradication program. To the authors' knowledge, this is the first study that shows the importance of lambing paddocks in order to keep pre-lambing and lambing ewes away from the rest of the flock, the lack of this infrastructure was considered an important risk factor for B. ovis.

Herd-level risk factors for bovine viral diarrhea virus infection in dairy herds from Southern Brazil.

A cross-sectional study was carried out to identify risk factors for bovine viral diarrhea virus (BVDV) infection in 300 randomly selected dairy herds which were tested for antibodies in bulk tank milk (BTM) using a commercial indirect ELISA kit (SVANOVA). Results from the analysis were interpreted according to the Swedish BVDV control scheme. The testing revealed 129 (43%) BTM BVDV antibody-positive herds. Use of artificial insemination (AI) and herd size were significantly associated with BVDV serological status (P<0.05). Dairy herds that use AI had 2.82 increased odds of BVDV-seropositivity (95% CI: 1.02-7.24). Since the semen used in the studied population come from known selected sires, it was hypothesized that AI technicians should represent an important risk factor because the increasing number of visitors in the farm can introduce the virus through the clothes, shoes and contaminated equipment.

Giant cell glioblastoma in the cerebrum of a Pembroke Welsh corgi.

A 6-year-old, neutered female Pembroke Welsh corgi was presented with a 1-month history of ataxia and panting. The clinical signs progressed until the dog became anorexic, obtunded and exhibited circling to the left. At necropsy examination, a mass was detected in the left forebrain, impinging on the cribriform plate. Microscopically, the mass was composed of sheets of round to pleomorphic neoplastic cells with vacuolated cytoplasm. Nuclear atypia, anisocytosis and anisokaryosis were common. Numerous bizarre, multinucleated giant cells containing 60 or more nuclei and giant mononuclear cells were present. The matrix contained abundant reticulin. Immunohistochemistry revealed the neoplastic cells uniformly to express vimentin, and a small number of neoplastic cells expressed glial fibrillary acid protein. A diagnosis of giant cell glioblastoma was made. Although well recognized in man, this tumour has been documented rarely in the veterinary literature.

Eimeria maxima: a comparison of two laboratory strains with a fresh isolate.

Oocysts of the Weybridge and Houghton strains of Eimeria maxima and a fresh field isolate were similar and measured on average 30-9 X 22-4 mum. The Weybridge strain and the field isolate produced similar pathogenic effects in 6-week-old chickens, high doses causing 50-80% mortality and severe weight loss. The Houghton strain was slightly less pathogenic and few birds died but more oocysts were produced. With each strain, a single dose gave complete immunity to a light challenge with the homologous strain. Two or 3 immunizing doses gave complete immunity to a heavy homologous challenge but were not sufficient to protect against heterologous challenge.