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Objective: To determine the prevalence of Mycobacterium avium spp. paratuberculosis (MAP) in cow-calf herds located in the prairie provinces of Alberta, Saskatchewan, and Manitoba using a serum ELISA test., Animals: Study herds were recruited from the Western Canadian Cow-calf Surveillance Network (WC 3 SN) designed to monitor factors related to the health and productivity of cow-calf herds. Overall, 1791 cows from 92 herds were included in the study., Procedure: Blood samples were collected from 20 cows per herd in a systematic random fashion by private veterinarians in the fall of 2014. A serum ELISA (IDEXX, Westbrook, Maine, USA) test was used for the detection of MAP antibodies in the blood samples., Results: The cow level seroprevalence across all 3 provinces was 1.5%. Alberta had the lowest cow seroprevalence (1.3%) followed by Saskatchewan (1.7%), and Manitoba (2.1%). Herd level data showed that 24% of herds had at least 1 positive animal and 5% had at least 2 positive animals. Seroprevalence estimates varied between geographical regions within each province and with herd size., Conclusions: The apparent prevalence of MAP in prairie cow-calf herds remains low and similar to past estimates for the region. However, controlling the spread of Johne's disease in the western Canadian cow-calf herd should be considered an important discussion point in the beef industry., Clinical Relevance: Ongoing surveillance of Johne's disease in western Canadian beef herds is necessary for mitigating disease spread before it becomes a disease of major concern within the industry., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

This study determined whether mineral concentrations in the hooves of cattle with toe tip necrosis syndrome (cases) differed from those of cattle dying of all other causes (controls). Samples were collected over a 2-year period from 16 different feedlots and analyzed for 8 minerals [cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), selenium (Se), and zinc (Zn)]. Mineral concentrations in the hoof wall and solar horn of the same hoof were poorly correlated; Se was the most correlated (ρ = 0.865; P < 0.001), while Mg (ρ = 0.465; P < 0.001) and Zn (ρ = 0.157; P = 0.053) were the least correlated. The cases had significantly lower Mg concentrations in both the hoof wall and solar horn tissue compared to the control subjects. For every 10 ppm decrease in Mg, the odds of a diagnosis of toe tip necrosis syndrome (TTNS) increased by 1.13 times for the hoof wall ( P = 0.002) and 1.21 times for solar horn ( P < 0.001).

The Canadian prairie provinces of Manitoba, Saskatchewan, and Alberta have reported the highest human incidence of clinical cases of West Nile virus (WNV) infection in Canada. The primary vector for WVN in this region is the mosquito Culex tarsalis. This study used constructed models and biological thresholds to predict the spatial and temporal distribution of Cx. tarsalis and WNV infection rate in the prairie provinces under a range of potential future climate and habitat conditions. We selected one median and two extreme outcome scenarios to represent future climate conditions in the 2020 (2010-2039), 2050 (2040-2069) and 2080 (2070-2099) time slices. In currently endemic regions, the projected WNV infection rate under the median outcome scenario in 2050 raised 17.91 times (ranged from 1.29-27.45 times for all scenarios and time slices) comparing to current climate conditions. Seasonal availability of Cx. tarsalis infected with WNV extended from June to August to include May and September. Moreover, our models predicted northward range expansion for Cx. tarsalis (1.06-2.56 times the current geographic area) and WNV (1.08-2.34 times the current geographic area). These findings predict future public and animal health risk of WNV in the Canadian prairie provinces.

The Canadian prairie provinces of Alberta, Saskatchewan, and Manitoba have generally reported the highest human incidence of West Nile virus (WNV) in Canada. In this study, environmental and biotic factors were used to predict numbers of Culex tarsalis Coquillett, which is the primary mosquito vector of WNV in this region, and prevalence of WNV infection in Cx. tarsalis in the Canadian prairies. The results showed that higher mean temperature and elevated time lagged mean temperature were associated with increased numbers of Cx. tarsalis and higher WNV infection rates. However, increasing precipitation was associated with higher abundance of Cx. tarsalis and lower WNV infection rate. In addition, this study found that increased temperature fluctuation and wetland land cover were associated with decreased infection rate in the Cx. tarsalis population. The resulting monthly models can be used to inform public health interventions by improving the predictions of population abundance of Cx. tarsalis and the transmission intensity of WNV in the Canadian prairies. Furthermore, these models can also be used to examine the potential effects of climate change on the vector population abundance and the distribution of WNV.

The study objectives were to investigate Salmonella prevalence, serovar distribution, and risk factors for shedding in 10 purposively selected farrow-to-finish farms in Saskatchewan and Alberta. Pooled fecal samples from the breeding and grow-finish phases and individual fecal samples from breeding, nursery, and grow-finish pigs were cultured for Salmonella; serotyping of isolates was performed. Pig and pen characteristics were recorded for each pig and pen sampled.Overall, 407/1143 (36%) of samples were Salmonella positive; within-farm prevalence ranged from 1% to 79%. Sows, nursery, and grow-finish pigs accounted for 43%, 29%, and 28% of positive samples, respectively. More Salmonella were detected in pooled pen than individual pig samples (P < 0.001). Among 418 Salmonella isolates, there were 19 distinct serovars; the most common were S. Derby (28.5%), S. Typhimurium, var. Copenhagen (19.1%), S. Putten (11.8%), S. Infantis (6.8%), and S. Mbandaka (6.1%). Sows were more likely to shed Salmonella than nursery or grow-finisher (OR 2.9, P < 0.001) pigs. Pelleted feed (OR 8.2, P < 0.001) and nose-to-nose pig contact through pens (OR 2.2, P = 0.005) were associated with increased Salmonella prevalence. Significant differences in serovar distribution were detected among production phases. The use of pooled pen samples is recommended as a more efficient means for accurate evaluation of Salmonella status in different phases of pig production. The breeding herd might be an important source of Salmonella persistence within farrow-to-finish farms and should be targeted in control efforts. The latter might also apply to the use of pelleted feed, which remains the most consistently reported significant risk factor for Salmonella shedding in pigs.

This fecal prevalence study targeted cattle from 7 large (10,000 to > 40,000 head) commercial feedlots in Alberta as a means of establishing Campylobacter levels in cattle just prior to animals entering the food chain. Overall, 87% [95% confidence interval (CI) = 86-88] of 2776 fresh pen-floor fecal samples were culture positive for Campylobacter species, with prevalences ranging from 76% to 95% among the 7 feedlots. Campylobacter spp. prevalence was 88% (95% CI = 86-90) in the summer (n = 1376) and 86% (95% CI = 85-88) in the winter (n = 1400). In addition, 69% (95% CI = 66-71) of 1486 Campylobacter spp. positive samples were identified as Campylobacter jejuni using hippurate hydrolysis testing. Of those, 64% (95% CI = 58-70) of 277 and 70% (95% CI = 67-72) of 1209 Campylobacter isolates were identified as C. jejuni in winter and summer, respectively. After accounting for clustering within pen and feedlot, feedlot size and the number of days on feed were associated with Campylobacter spp. isolation rates. The high isolation rates of Campylobacter spp. and C. jejuni in feedlot cattle feces in this study suggest a potential role for feedlot cattle in the complex epidemiology of campylobacters in Alberta.

Feedlot cattle in Alberta, Canada, have been identified as reservoirs for Campylobacter jejuni, an important human pathogen. Oligonucleotide DNA microarrays were used as a platform to compare C. jejuni isolates from feedlot cattle and human clinical cases from Alberta. Comparative genomic hybridization (CGH) analysis was performed on 87 isolates (46 bovine, 41 human) obtained within the same geographical regions and time frame. Thirteen CGH clusters were obtained based on overall comparative genomic profile similarity. Nine CGH clusters contained human and cattle isolates, three contained only human isolates, and one contained only cattle isolates. The study isolates clustered regardless of temporal or geographical frameworks. In addition, array genes (n = 1,399) were investigated on a gene-by-gene basis to see if any were unequally distributed between human and cattle sources or between clusters dominated by either human or cattle isolates ("human enriched" versus "cattle enriched"). Using Fisher's exact test with the Westfall and Young correction for these comparisons, a small number of differentially distributed genes were identified. Our findings suggest that feedlot cattle and human C. jejuni strains are very similar and may be endemic within Alberta. Further, the common distribution of human clinical and bovine C. jejuni isolates within the same genetically based clusters suggests that dynamic and important transmission routes between cattle and human populations may exist.

A survey of monthly average concentrations of sulfur dioxide (SO2) and hydrogen sulfide (H2S) at rural locations in western Canada (provinces of Alberta, British Columbia, and Saskatchewan) was conducted in 2001-2002, as part of an epidemiological study of the effects of oil and gas industry emissions on the health of cattle. Repeated measurements were obtained at some months and locations. We aimed to develop statistical models of the effect of oil and gas infrastructure on air concentrations. The regulatory authorities supplied the information on location of the different oil and gas facilities during the study period and, for Alberta, provided data on H2S content of wells and flaring volumes. Linear mixed effects models were used to relate observed concentrations to proximity and type of oil and gas infrastructure. Low concentrations were recorded; the monthly geometric mean was 0.1-0.2 ppb for H2S, and 0.3-1.3 ppb for SO2. Substantial variability between repeated measurements was observed. The precision of the measurement method was 0.005 ppb for both contaminants. There were seasonal trends in the concentrations, but the spatial variability was greater. This was explained, in part, by proximity to oil/gas/bitumen wells and (for SO2) gas plants. Wells within 2 km of monitoring stations had the greatest impact on measured concentrations. For H2S, 8% of between-location variability was explained by proximity to industrial sources of emissions; for SO2 this proportion was 18%. In Alberta, proximity to sour gas wells and flares was associated with elevated H2S concentrations; however, the estimate of the effect of sour gas wells in the immediate vicinity of monitoring stations was unstable. Our study was unable to control for all possible sources of the contaminants. However, the results suggest that oil and gas extraction activities contribute to air pollution in rural areas of western Canada.

A disease syndrome characterized by hemolysis, methemoglobinemia, methemoglobinuria, and death was observed in a herd of purebred Limousin beef cattle grazing on pasture in November in Alberta. Improper disposal of the nonselective herbicide, sodium chlorate, was identified as the causal agent. Highly variable blood methemoglobin levels reflected differences in herbicide consumption.

Oil sands mining is steadily expanding in Alberta, Canada. Major companies are planning reclamation strategies for mine tailings, in which wetlands will be used for the bioremediation of water and sediments contaminated with polycyclic aromatic hydrocarbons and naphthenic acids during the extraction process. A series of experimental wetlands were built on companies' leases to assess the feasibility of this approach, and tree swallows (Tachycineta bicolor) were designated as upper trophic biological sentinels. From May to July 2004, prevalence and intensity of infestation with bird blow flies Protocalliphora spp. (Diptera: Calliphoridae) were measured in nests on oil sands reclaimed wetlands and compared with those on a reference site. Nestling growth and survival also were monitored. Prevalence of infestation was surprisingly high for a small cavity nester; 100% of the 38 nests examined were infested. Nests on wetlands containing oil sands waste materials harbored on average from 60% to 72% more blow fly larvae than those on the reference site. Nestlings on reclaimed sites suffered mean parasitic burdens about twice that of those on the reference site; and for comparable parasitic load, they exhibited greater pathologic effects (e.g., decreased body mass) than control nestlings. The heavy blow fly infestation on oil sands-impacted wetlands suggests that oil sands mining disturbs several components of the local ecosystem, including habitat characteristics, blow fly predators, and host resistance to parasites.

Vertical fissures (sandcracks) affect approximately 20% of adult beef cattle in western Canada. The risk factors associated with the formation of these lesions are not well understood. This paper describes a case-control study that identifies the role of increased claw size (claw volume > 390 cm3, odds ratio 7.8) in the formation of the lesion. No connection was found between vertical fissures and horn hydration status. However, horn hydration was found to vary significantly between samples collected in the summer and winter, the latter samples having significantly reduced moisture content. The importance of these findings and the implications for the prevention of fissure formation are discussed.

A study was conducted in Alberta to determine the seroprevalence of Neospora caninum in feedlot calves purchased from various auction markets throughout western Canada. Four feedlots (1 feedlot from each of the Airdrie and High River areas and 2 feedlots from the Strathmore area) were selected for sampling. At each feedlot, a random 10% sample of feedlot steer and bull calves entering the feedlot from September 2001 to December 2001 were enrolled in the study until there were a maximum of 500 animals enrolled per feedlot. Blood samples were collected from 1976 male animals at the time of entry to the 4 study feedlots. The animals represented 375 groups purchased from 70 sale points throughout British Columbia, Alberta, Saskatchewan, and Manitoba. Of the 1976 animals tested, 128 animals tested positive for antibodies to N. caninum. The prevalence and adjusted 95% confidence limits for N. caninum in beef calves on entrance to the feedlot in western Canada were 6.5% (95% CI, 5.1 to 8.2). There were no significant (P > or = 0.05) associations between the risk of treatment, the risk of designation as "chronic," and the risk of death and antibodies to N. caninum either before or after adjusting for feedlot, entry weight, entry date, and clustering of disease within lots at each feedlot. In addition, there was no significant (P > or = 0.05) association between serological status and feedlot entry weight or average daily gain. Note that there was no information available on feed conversion because the calves were mixed within existing commercial feedlot pens and the actual feed intake of each animal could not be determined. Adjustment for the concentration of antibodies to bovine viral diarrhea virus on arrival did not change any of the examined associations between N. caninum status and calf health or performance. The results of this study demonstrated that the prevalence of N. caninum in feedlot calves in western Canada was less than the prevalence reported in the United States. Additional studies are required to determine whether the inferior rate of gain and feed efficiency observed in the southern United States with animals testing positive for antibodies to N. caninum also occurs under the management conditions used in western Canada.

Beef cows sometimes are pastured close to oil- and gas-production and processing facilities. We measured the health and productivity of cow-calf herds with differing exposure to sour-natural-gas processing facilities in western Canada. In seven cow-calf herds, the numbers of eligible mature females included in the study for the breeding seasons beginning in 1993, 1994, and 1995 were 1177, 1251, and 1236, respectively. Outcomes included pregnancy status, calving interval, and the occurrence of twins, abortions, stillbirths, and neonatal mortality. Information also was collected on other risk factors known to influence beef-herd health and productivity. Monthly measurements from a network of passive air-monitoring devices were used to estimate exposure. Total sulfation and H2S deposition were used as markers for the complex mixture of compounds found in emissions from sour-gas processing plants and sour flares. Most herds were managed in multiple pasture groups. Cumulative exposure assessments were made from records of individual-animal movements between pastures. Generalized estimating equations were used to evaluate the association between exposure and outcome and to adjust for potential confounders and clustering of binomial outcomes within herd. No consistent associations were found between either total sulfation or H2S deposition and productivity parameters across the cow-calf production cycles. There were, however, five examples of significant associations between increasing cumulative exposure to total sulfation and decreased productivity in the 18 models examined.

From the fall of 1992 through calving 1996, detailed cow breeding outcome records were maintained actively for seven large cow-calf herds in western Canada. The numbers of mature females in the study for the breeding seasons beginning in 1992, 1993, 1994, and 1995 were 1122, 1177, 1251, and 1236, respectively. Outcomes included pregnancy status, calving interval, and the occurrence of twins, abortions, stillbirths, and neonatal mortality. Information also was collected on other risk factors known to influence beef-herd health and productivity. Detailed maps of active and inactive oil and natural-gas sites, batteries, compressor stations and processing plants were verified. Records of flaring activity at each facility were obtained from the government regulatory agency. Each flaring site then was classified as sour or sweet based on the presence or absence of hydrogen sulfide in the flared gas. A detailed inventory was prepared itemizing the type and number of facilities within 1.6 km (1 mile) of the center of each quarter section used for pasture. The total volume of gas flared within 1.6 km of the center of each pasture was determined for each month of the study. Appropriate risk periods where specified for each outcome and a cumulative exposure calculated for each breeding female (using detailed individual-animal records of cow movements between pastures and herd-management groups). Generalized estimating equations were used to evaluate the association between exposure and outcome and to adjust for potential confounders and clustering of binomial outcomes within herd. Increased risk of non-pregnancy was sometimes associated with exposure to one or more of the following facility types: sour-gas flaring battery facilities, all battery-flaring sites, active gas wells, and larger field facilities. The associations were not, however, consistent among years or even among risk periods for the same year. Facility proximity and flaring were not associated with increased abortion risk. Volume of flared sour gas from battery sites was associated with increased risk of stillbirth. Finally, sour-gas flaring was associated with increased calf-mortality risk for the 1992-1993 calf crop. Several examples of associations between exposure and increased productivity also were found (most of which involved either oil wells or all well sites).

This study examines the long-term impact of a Neospora caninum-associated abortion outbreak in a large cow-calf herd in northern Alberta. Blood samples were collected 4 times from all bred females and heifer calves born during the spring before the outbreak: (1) at the time of the outbreak, (2) the following spring, (3) the subsequent fall, and, finally, (4) the second spring after the outbreak. The samples were analyzed using a commercially available enzyme-linked immunosorbent assay for N. caninum. Calves born immediately following the outbreak were also monitored. Individual calving or abortion records were available from all cows for 2 calving seasons. All cows and heifers were pregnancy tested after the 2 subsequent breeding seasons. At the time of the abortion outbreak in 1997, 81% of all bred females and 87% of the heifer calves were serologically positive. In spring 1998, 49% of the cows and 47% of the heifer calves remained positive. In fall 1998, 48% of the remaining cows and heifers were serologically positive. After the first breeding season following the outbreak (1998), 13.5% of the heifers and 22.2% of the cows were open (not pregnant). Animals that were serologically positive in the spring were more likely to be open in the fall (odds ratio, 2.0; 95% confidence interval, 1.1 to 3.7). No subsequent associations with increased risk of abortion, stillbirth, or nonpregnancy were identified.

Blood samples were collected from 1806 pregnancy-tested cows from 174 herds at a northern Alberta auction mart in the fall of 1998. One hundred sixty-two (9.0%) of these samples were positive for antibodies to N. caninum. Thirty-five of 260 samples (13.5%) collected from the same region in the 1980s were also serologically positive for N. caninum.

Objective: To determine seroprevalence of Neospora caninum infection in beef herds and the association between serologic status and rate of abortion, stillbirth, calf mortality, and reproductive failure., Design: Longitudinal study., Animals: 419 cows from 8 beef herds in central Alberta., Procedure: 1,391 serum samples from a serum bank were analyzed, using ELISA, and results were compared, using logistic regression, with productivity data on individual cows obtained from a database established during a 4-year period., Results: 30% of cows were seropositive at some point during the 4-year period. Risks of abortion (odds ratio [OR], 5.7) and stillbirth (OR, 2.8) in seropositive cows were significantly greater than in seronegative cows. Risks of being culled for any reason (OR, 1.9) or for reproductive failure (OR, 2.5) in seropositive cows were also significantly greater than in seronegative cows. Changes in titer with time in individual cows and a lack of association between serologic status of dam versus daughter suggest that postnatal transmission was possible in these herds. However, horizontal transmission did not appear to play a substantial role in abortions that occurred in these herds., Clinical Implications: Neosporosis should be investigated as a potential source of economic loss to the beef industry.