Schmallenberg virus in Dutch dairy herds: potential risk factors for high within-herd seroprevalence and malformations in calves, and its impact on productivity.

In November 2011, the new orthobunyavirus Schmallenberg virus (SBV) was identified in dairy cows that had induced fever, drop in milk production and diarrhoea in the Netherlands (Muskens et al., 2012. Tijdschrift voor Diergeneeskunde 137, 112-115) and a drop in milk production in cows in Northwestern Germany (Hoffmann et al., 2012. Emerging Infectious Diseases 18 (3), 469-472), in August/September 2011. This study aimed at quantifying risk factors for high within-herd prevalence of SBV and SBV-induced malformations in newborn calves in dairy herds in the Netherlands. Additionally, the within-herd impact of SBV infection on mortality rates and milk production was estimated. A case-control design was used, including 75 clinically affected case herds and 74 control herds. Control herds were selected based on absence of malformations in newborn calves and anomalies in reproductive performance. SBV-specific within-herd seroprevalences were estimated. Risk factors for high within-herd SBV seroprevalence (>50%) and the probability of malformed newborn calves in a herd were quantified. In addition, within-herd impact of SBV with regard to milk production and mortality was estimated. Animal-level seroprevalence was 84.4% (95% confidence interval (CI): 70.8-92.3) in case herds and 75.8% (95% CI: 67.5-82.5) in control herds. Control herds that were completely free from SBV were not present in the study. Herds that were grazed in 2011 had an increased odds (OR 9.9; 95% CI: 2.4-41.2)) of a high seroprevalence (>50%) compared to herds that were kept indoors. Also, when grazing was applied in 2011, the odds of malformations in newborn calves tended to be 2.6 times higher compared to herds in which cattle were kept indoors. Incidence of malformations in newborn calves at herd level was associated with both within-herd seroprevalence and clinical expression of the disease in adult cattle. The rate of vertical transmission of SBV to the fetus once a dam gets infected seemed low. A total of 146 stillborn or malformed calves were submitted by 65 farmers during the study period, of which 19 were diagnosed as SBV-positive based on pathological investigation and/or RT-qPCR testing of brain tissue. Based on these results combined with calving data from these herds we roughly estimated that at least 0.5% of the calves born between February and September 2012 have been infected by SBV. A drop in milk production was observed between the end of August 2011 and the first half of September (week 35-36), indicating the acute phase of the epidemic. During a 4-week period in which SBV infection was expected to have occurred, the total loss in milk production in affected dairy herds was around 30-51 kg per cow. SBV had no or limited impact on mortality rates which was as expected given the relatively mild expression of SBV in adult cows and the low incidence of malformations in newborn calves.

[Assessment of animal welfare aspects in extreme breeds of pet animals]. / Zur Beurteilung von Tierschutzaspekten bei Extremzuchten von kleinen Heimtieren.

In a review based on literature searches animal welfare related characteristics in extreme breed types of small mammals, ornamental birds, reptiles and ornamental fish are summarized. Animal welfare aspects are assessed and measures for improvement are described.

Assessment of environmental stressors potentially responsible for malformations in North American anuran amphibians.

Several species of anuran amphibians from different regions across North America have recently exhibited an increased occurrence of malformations, predominantly of the hindlimb. Research concerning the potential causes of these malformations has focused extensively on three stressors: chemical contaminants, ultraviolet (UV) radiation, and parasitic trematodes. In this overview of recent work with each of these stressors, we assess their plausibility as contributors to the malformations observed in field-collected amphibians. There is as yet little evidence that chemical contaminants are responsible for the limb malformations. This includes chemicals, such as the pesticide methoprene, that could affect retinoid-signaling pathways that are critical to limb development. Exposure to UV radiation also seems to be an unlikely explanation for hindlimb malformations in amphibians. Although solar UV can cause hindlimb deficiencies in amphibians, a probabilistic assessment based on empirical dose-response and exposure data indicates that UV exposures sufficient to induce limb defects would be uncommon in most wetlands. Results of controlled studies conducted with some affected species and field-monitoring work suggest infection by digenetic trematodes as a promising explanation for the malformations observed in anurans collected from many field sites. Controlled experimentation with additional species and monitoring across a broader range of affected sites are required to assess fully the role of trematodes in relation to other stressors in causing limb malformations. If trematode infestations are indeed related to the recent increases in malformed amphibians, then the question remains as to what alterations in the environment might be causing changes in the distribution and abundance of the parasites.

Assessment of the risk of solar ultraviolet radiation to amphibians. I. Dose-dependent induction of hindlimb malformations in the northern leopard frog (Rana pipiens).

A number of environmental stressors have been hypothesized as responsible for recent increases in limb malformations in several species of North American amphibians. The purpose of this study was to generate dose-response data suitable for assessing the potential role of solar ultraviolet (UV) radiation in causing limb malformations in a species in which this phenomenon seemingly is particularly prevalent, the northern leopard frog (Rana pipiens). Frogs were exposed from early embryonic stages through complete metamorphosis to varying natural sunlight regimes, including unaltered (100%) sunlight, sunlight subjected to neutral density filtration to achieve relative intensities of 85%, 75%, 65%, 50%, and 25% of unaltered sunlight, and sunlight filtered with glass or acrylamide to attenuate, respectively, the UVB (290-320 nm) and UVB plus UVA (290-380 nm) portions of the spectrum. The experiments were conducted in a controlled setting, with continual monitoring of UVB, UVA, and visible light to support a robust exposure assessment. Full sunlight caused approximately 50% mortality of the frogs during early larval development; no significant treatment-related mortality occurred under any of the other exposure regimes, including 100% sunlight with glass or acrylamide filtration. There was a dose-dependent (p < 0.0001) induction of hindlimb malformations in the frogs, with the percentage of affected animals ranging from about 97% under unaltered sunlight to 0% in the 25% neutral density treatment. Malformations were comprised mostly of missing or truncated digits, and generally were bilateral as well as symmetrical. Filtration of sunlight with either glass or acrylamide both significantly reduced the incidence of malformed limbs. The estimated sunlight dose resulting in a 50% limb malformation rate (ED50) was 63.5%. The limb ED50 values based on measured sunlight intensities corresponded to average daily doses of 4.5 and 100 Wh x m(-2) for UVB and UVA, respectively. Exposure to sunlight also resulted in increased eye malformations in R. pipiens, however, the dose-response relationship for this endpoint was not monotonic. The results of this study, in conjunction with measured or predicted exposure data from natural settings, provide a basis for quantitative prediction of the risk of solar UV radiation to amphibians.

Assessment of the risk of solar ultraviolet radiation to amphibians. III. Prediction of impacts in selected northern midwestern wetlands.

Solar ultraviolet radiation, especially UVB (280-320 nm), has been hypothesized to be at least partially responsible for adverse effects (e.g., declines and malformations) in amphibian species throughout the world. Evaluation of this hypothesis has been limited by the paucity of high-quality UV dose-response data and reliable estimates of typical UV doses that occur in amphibian habitats. In this preliminary risk assessment for effects of UV radiation on amphibians, dose-response relationships quantified in outdoor experiments were compared with UV exposure estimates for 26 wetlands in northern Minnesota and Wisconsin. A comparison of wetland doses, derived from model prediction, historical data, and dissolved organic carbon (DOC) characterization, with experimental effects levels for green (R. clamitans), northern leopard (R. pipiens), and mink (R. septentrionalis) frogs indicated that the risk of mortality and malformations due to UV exposure is low for the majority of wetlands evaluated. Wetland UV dose, averaged over the entire breeding season, exceeded effects doses for mortality for all three species in two of the 26 wetlands examined and for one species in an additional wetland. On the basis of evidence that shorter term doses caused mortality in amphibian larvae, 3-day doses were also evaluated. In three of the wetlands examined, 3-day doses in excess of 85% of full sunlight (the level that appeared to trigger effects in controlled experimentation) occurred at frequencies ranging 22-100% for all three species and at frequencies ranging from 15% to 58% for R. pipiens and R. septentrionalis in three additional wetlands. Risk of malformation in R. pipiens was apparent in five of the 26 wetlands evaluated. Overall, estimated UVB doses in 21 of the wetlands never exceeded experimental effects doses for mortality or malformations. These results suggest that most amphibians are not currently at significant risk for UVB effects in northern Minnesota and Wisconsin wetlands. However, continued reduction of ozone and other global climate change effects may increase UV doses in wetlands, suggesting that the risk of UV to amphibians should continue to be monitored and studied.

Ultrasonographic assessment of abnormal pregnancy.

Ultrasonographic imaging is widely used in small animal practice for the diagnosis of pregnancy and the determination of fetal number. Ultrasonography can also be used to monitor abnormal pregnancies, for example, conceptuses that are poorly developed for their gestational age (and therefore are likely to fail), and pregnancies in which there is embryonic resorption or fetal abortion. An ultrasound examination may reveal fetal abnormalities and therefore alter the management of the pregnant bitch or queen prior to parturition. There are, however, a number of ultrasonographic features of normal pregnancies that may mimic disease, and these must be recognized.

Racing performance after hemicircumferential periosteal transection for angular limb deformities in thoroughbreds: 199 cases (1987-1989).

Racing records of 199 Thoroughbred foals with angular limb deformities surgically treated by hemicircumferential periosteal transection and elevation (HCPT) from 1987 through 1989 (principals) were compared with records of their 1,017 siblings (controls) for starting status; 2-, 3-, and 4-year-old starts; earnings and earnings per start; and starts percentile ranking number (SPR). Principals had a slightly lower percentage of horses starting a race (45 vs 55%), fewer 2-year-old starts (1.06 vs 1.72), and lower SPR (33.49 vs 49.18), compared with those of controls (P < 0.05). Starting status was significantly (P < 0.05) affected by surgery and the horse's sex, but not by anatomic site treated. Fillies were 1.74 times less likely to start than were colts, regardless of surgery, whereas principal fillies were 2.63 times less likely to start than were control colts. Difference was not detected between principals and controls in 3- or 4-year-old starts; 2-, 3-, or 4-year-old earnings, or earnings per start. Horses treated with distal metacarpal/metatarsal HCPT had fewer 2-year-old starts (1.09 vs 2.19), but did not have a significantly different SPR or lower starting percentage, compared with values for controls. Horses treated with distal radial HCPT had lower starting percentage (48 vs 55%), fewer 2-year-old starts (1.22 vs 1.70), and lower SPR (32.53 vs 53.32), compared with those of controls.(ABSTRACT TRUNCATED AT 250 WORDS)

The cost of premature death in young rabbits.

The costs of death in a model 100-doe commerical rabbit unit were calculated on the basis of two levels of breeding (7.5 and 10.0 litters per doe per year) and two levels of feeding, (ad lib and controlled). Although the cost of individual deaths from stillbirth and other perinatal and neonatal deaths was half or two-thirds the cost of an individual death later in the rabbit's life, the total cost of these early deaths was three times the total cost of the later deaths. Early death thus plays a major part in the profitability of a commercial rabbitry.