Gastrointestinal nematode (GIN) parasitism is common in Canadian sheep flocks, and managing GIN through the selection of sheep with superior immunity is of growing interest. The CARLA (R) Saliva Test measures salivary IgA against the carbohydrate larval antigen (CarLA) found on third-stage larvae of all GIN species. Salivary anti-CarLA IgA exceeding 1.0 U/ml is associated with 20 - 30 % lower fecal egg counts (FEC) in sheep under New Zealand grazing conditions, but there has been limited application of the CARLA (R) Saliva Test elsewhere. To address this gap, this study explored the utility of the CARLA (R) Saliva Test under Canadian grazing conditions. In Year 1, eighteen sheep farms in Ontario were enrolled and 25 ewe lambs per farm, on average, were randomly selected after grazing pasture for at least 60 consecutive days. The body condition, fecal consistency, FAMACHA (c) score, weight, packed cell volume, FEC, and salivary anti-CarLA IgA level were recorded for each study animal in Year 1. Study animals returned to pasture in Year 2 and were re-sampled 4 weeks after turnout. Multivariable linear regression modeling demonstrated that the salivary anti-CarLA IgA response in Year 1 predicted the salivary anti-CarLA IgA response in Year 2 (beta = 0.213; p < 0.001). In addition, salivary anti-CarLA IgA in Year 1 was negatively associated with FEC in Year 2 (beta = - 0.167; p = 0.025). These data indicate that salivary anti-CarLA IgA measurements may be useful for identifying replacement sheep with superior immune responses to GIN infection in Canada.

Machine learning algorithms have been applied to various animal husbandry and veterinary-related problems; however, its use in Johne’s disease diagnosis and control is still in its infancy. The following proof-of-concept study explores the application of tree-based (decision trees and random forest) algorithms to analyze repeat milk testing data from 1197 Canadian dairy cows and the algorithms’ ability to predict future Johne’s test results. The random forest models using milk component testing results alongside past Johne’s results demonstrated a good predictive performance for a future Johne’s ELISA result with a dichotomous outcome (positive vs. negative). The final random forest model yielded a kappa of 0.626, a roc AUC of 0.915, a sensitivity of 72%, and a specificity of 98%. The positive predictive and negative predictive values were 0.81 and 0.97, respectively. The decision tree models provided an interpretable alternative to the random forest algorithms with a slight decrease in model sensitivity. The results of this research suggest a promising avenue for future targeted Johne’s testing schemes. Further research is needed to validate these techniques in real-world settings and explore their incorporation in prevention and control programs.

Colostrum replacement products (CRP) for use in goat kids are sourced from bovine colostrum and often used by producers to supplement or replace maternal colostrum to prevent infections. To compare the CRP fed on farm to caprine colostrum a cross-sectional study was undertaken. Ontario dairy goat producers were asked to collect first milking colostrum from their goats and samples of the reconstituted commercial replacement product currently in use. The frozen samples were thawed and submitted for testing of fat, protein, and lactose content, IgG1 concentration, and aerobic bacterial culture. Compared with caprine colostrum, the reconstituted replacement products were lower in protein (11.7%), and fat (4.6%) and higher in lactose (5.4%) on average. The average IgG1 concentration in goat colostrum (53.5 g/L; range: 16.6-1,985.8) was significantly higher than in CRP (33.7 g/L; range: 10.7-55.3). The Brix cut point for good quality goat colostrum (50 g/L) was calculated at 23% (sensitivity = 69.6%, specificity = 88.0%) for goat colostrum and 26% for the CRP (sensitivity = 87.5%, specificity = 100%). The average aerobic bacteria count for goat colostrum was lower (2.95 log10 cfu/mL) than the CRP samples that were cultured (3.85 log10 cfu/mL). Further investigation into CRP, including on-farm storage of opened powdered product and mixing and storage of reconstituted product, is warranted. Variability in the levels of IgG1; aerobic bacterial growth; and fat, protein, and lactose content in CRP also requires further exploration to determine their effects on kid health.

ABSTRACT The primary objective of this study was to identify associations between the prepartum teat apex microbiome and the presence of Staphylococcus aureus intramammary infections (IMI) in primiparous cows during the first 5 weeks after calving. We performed a case-control study using shotgun metagenomics of the teat apex and culture-based milk data collected longitudinally from 710 primiparous cows on five organic dairy farms. Cases had higher odds of having S. aureus metagenomic DNA on the teat apex prior to parturition compared to controls (OR = 38.9, 95% CI: 14.84–102.21). Differential abundance analysis confirmed this association, with cases having a 23.8 higher log fold change (LFC) in the abundance of S. aureus in their samples compared to controls. Of the most prevalent microorganisms in controls, those associated with a lower risk of post-calving S. aureus IMI included Microbacterium phage Min 1 (OR = 0.37, 95% CI: 0.25–0.53), Corynebacterium efficiens (OR = 0.53, 95% CI: 0.30–0.94), Kocuria polaris (OR = 0.54, 95% CI: 0.35–0.82), Micrococcus terreus (OR = 0.64, 95% CI: 0.44–0.93), and Dietzia alimentaria (OR = 0.45, 95% CI: 0.26–0.75). Genes encoding for Microcin B17 AMPs were the most prevalent on the teat apex of cases and controls (99.7% in both groups). The predicted abundance of genes encoding for Microcin B17 was also higher in cases compared to controls (LFC 0.26). IMPORTANCE Intramammary infections (IMI) caused by Staphylococcus aureus remain an important problem for the dairy industry. The microbiome on the external skin of the teat apex may play a role in mitigating S. aureus IMI risk, in particular the production of antimicrobial peptides (AMPs) by commensal microbes. However, current studies of the teat apex microbiome utilize a 16S approach, which precludes the detection of genomic features such as genes that encode for AMPs. Therefore, further research using a shotgun metagenomic approach is needed to understand what role prepartum teat apex microbiome dynamics play in IMI risk.

In cattle, colostral maternal immunoglobulins and lymphocytes transfer across the neonate’s intestinal epithelium to provide protection against pathogens. This study aimed to compare repertoires of B cell populations in blood and colostrum in cows for the first time, with an emphasis on ultralong complementarity determining region 3 (CDR3, ≥40 amino acids). Blood mononuclear cells (BMCs, n= 7) and colostral cells (n = 7) were isolated from Holstein-Friesian dairy cows. Magnetic-activated cell sorting was used to capture IgM and IgG B cells from BMCs. Colostral cells were harvested by centrifugation. RNA was extracted and cDNA was produced; IgM and IgG transcripts were amplified using polymerase chain reactions. Amplicons were sequenced using the Nanopore Native barcoding kit 24 V14 and MinION with R10.4 flow cells. In colostrum, there was a significantly greater percentage of IgM B cells with ultralong CDR3s (8.09% ± 1.73 standard error of the mean) compared to blood (4.22% ± 0.70, p = 0.05). There was a significantly greater percentage of IgG B cells in colostrum with ultralong CDR3s (12.98% ± 1.98) compared to blood (6.61% ± 1.11, p = 0.05). A higher percentage of IgM and IgG B cells with ultralong CDR3s in colostrum may be indicative of a potential role in protecting the neonate.

OBJECTIVE To determine clients' preferences for veterinarians' communication during decision-making in relation to 3 clinical contexts: preventive care, general problem (eg, illness or injury), and urgent appointments. METHODS A cross-sectional online questionnaire was distributed by use of snowball sampling to veterinary clients owning a pet. Demographic information was collected, and participants were then randomly assigned to a scenario reflecting one of the following clinical contexts (appointment types): preventive, general problem, or urgent. Discrete choice exercises were used to solicit client preferences for 5 aspects of veterinarians' communication approach to decision- making with clients in clinical contexts: amount of information, presentation of plan (options or a recommendation), communication of value, nature of client involvement, and communication of financial cost. Relative-preference scores were calculated using hierarchical bayesian modeling. RESULTS Responses for 1,614 participants were included in the final analysis. The majority were female, lived in Canada, and were financially stable. Across clinical decision-making contexts, participants preferred to collaborate with the veterinarian, be offered options with a clear recommendation, be informed of present and future costs, and have benefits of any action regarding their pet's health explained to them. For the general-problem context, participants preferred veterinarians' communication to focus solely on concerns; in contrast, in preventive care and urgent contexts, participants preferred that communication include both normal findings and concerns. CONCLUSIONS Irrespective of clinical decision-making context, participants preferred collaborative decision-making with a veterinarian. CLINICAL RELEVANCE Veterinary professionals should consider, when possible, communication that supports a collaborative approach to decision-making with clients.

In Canada, currently no antibiotics are approved for use in lactating dairy goats. Trimethoprim sulfadoxine is indicated for the treatment of bacterial pneumonia, enteric and septicemic colibacillosis and salmonellosis, infectious pododermatitis, and septicemias. The aim of this study was to determine the trimethoprim sulfadoxine withdrawal time and evaluate the test accuracy of the Charm Rapid One Step Assay (ROSA) SULF test (Charm Sciences Inc.) at the individual goat level. The study was conducted on 20 visibly healthy Ontario dairy goats. They received trimethoprim sulfadoxine at a dose of 16 mg/kg i.m. once a day for 5 d as the commercially available preparation trimethoprim sulfadoxine (Borgal, Merck Animal Health). Residue levels were measured using liquid chromatography-tandem mass spectrometry and the Charm ROSA SULF. The withdrawal time was calculated using safe concentration linear regression. The determined milk withdrawal time was 60 h.

The objective of this randomized controlled vaccine field trial was to determine the effectiveness of a commercial respiratory bacterin, Ovipast™ Plus, administered to feedlot lambs at weaning, approximately 8 wk of age, to improve animal health, growth performance, and carcass traits. Lambs were weaned, weighed, and sorted into groups by sex and the previous Ovipast™ Plus vaccination status of their mother, because this is stage 2 of that ongoing trial (Gardner et al., 2023). Lambs born to vaccinated ewes were vaccinated with the Ovipast™ Plus bacterin and revaccinated 3 to 5 wk later. Lambs born to unvaccinated ewes were not vaccinated. During the growing and finishing phases of the trial, vaccination did not reduce pneumonia treatment rates, crude or pneumonia specific mortality rates, or improve growth rates. Vaccinated lambs had a lower carcass fat cover (P < 0.001) and a 1.33 times increased odds of yielding a Grade 1 carcass compared to unvaccinated lambs (P = 0.01). Vaccination reduced carcass fat cover and improved yield grades, but it had no beneficial effect on disease rates or growth performance, suggesting a limited economic benefit of vaccinating lambs post-weaning, which were borne from ewes vaccinated with Ovipast™ Plus during gestation.

Climatic and land use changes have contributed to substantial changes in the abundance, distribution, and activity patterns of ticks in Canada, which have led to an increased risk of tick bites and tick-borne pathogen exposure for companion animals. The objectives of this study were to describe current spatial and temporal patterns of Ixodes spp. on companion animals in Canada and explore the association between tick bites and dog and cat demographic factors. Ticks were collected for one year (April 2019 - March 2020) from 94 veterinary clinics. Included with each submission was a short questionnaire containing owner-reported information on travel history, date of removal and suspected location of tick acquisition, and animal-specific demographic factors. Ticks were identified morphologically using a stereomicroscope, standard keys, and through PCR analyses. Mixed effect multivariable logistic regression models were built to explore the association between an Ixodes scapularis bite and animal demographic factors; veterinary clinic was included as a random effect. Approximately 2300 submissions were received from clinics across Canada, totalling 4425 ticks. The most common Ixodes spp. was I. scapularis (n = 2168), followed by Ixodes pacificus (n = 172) and Ixodes cookei (n = 155). Ixodes scapularis were well distributed in regions across central and eastern Canada. Ixodes cookei was found in eastern Canada, with the greatest numbers from Quebec and New Brunswick. Ixodes pacificus submissions were restricted to British Columbia. Across eastern Canada, dogs of the herding, mixed breed (large and small), sporting, working, terrier, and toy breed groups, and spayed cats were all found to have higher odds of acquiring I. scapularis, compared to other tick species. For the dog model, significant interactions were found between predictor variables age and sex. Regional information on tick distribution, seasonality, and risk factors for acquisition contribute to evidence-based veterinary practices for tick and tick-borne disease control in Canada.

Due to recent climatic and land use changes, Canada has experienced changes in tick populations, leading to an increased risk of tick bites and tick-borne pathogen exposure, especially in eastern Canada. Preventative recommendations for companion animals from veterinary professionals include regular use of tick prevention products and tick checks. Tick checks, specifically, should target regions of an animal's body which are deemed to be high risk for tick attachment. However, tick species-specific infestation patterns on dogs and cats are largely understudied, and additional research is needed to help guide targeted tick checks. The objective of this study was to identify tick species-specific infestation patterns on dogs and cats. Ticks were collected for one year (April 2019 -March 2020) from 94 veterinary clinics across Canada as part of the Canadian Pet Tick Survey. All ticks were identified to species, and data on the location of tick attachment were ascertained with each submission. To examine the association between location of attachment (outcome) and tick species (explanatory variable), specifically Ixodes scapularis and Dermacentor variabilis, mixed effects univariable models were built. Two thousand three hundred and six submissions were received from 1925 dogs and 381 cats across Canada. Of these submissions, 1377 comprised Ixodes scapularis, and 620 comprised Dermacentor variabilis. Clear tick species-specific infestation patterns for dogs were present, with I. scapularis being significantly more likely to be found on the shoulders, and D. variabilis more likely to be found on the ears and neck. Dermacentor variabilis was more likely to be found on the cranial aspect of cats' limbs, compared to I. scapularis. Up-to-date information on infestation patterns can be used to inform veterinary professionals and pet owners of common attachment sites based on established ticks in their region and thus conduct targeted tick checks.

In cattle, maternal immunoglobulins are transferred through colostrum to provide passive immunity to the neonatal calf once they are absorbed into circulation. Cows can be assessed for antibody- and cell-mediated immune responses (AMIR and CMIR, respectively), and through estimated breeding values (EBV) and genomic parent averages (GPA), cows can be classified as having high, average, or low immune response (IR). The objective of this study was to identify associations of colostral IgG concentrations with IR in dairy cows. High IR dairy cows identified by GPA or EBV were hypothesized to produce higher colostral IgG concentrations than cows with average or low IR. Colostrum was collected from Holstein dairy cows from 3 large commercial herds (n = 590) in the United States and 1 research herd at the Ontario Dairy Research Centre (n = 275) in Canada. For the US herds, IR GPA were available through genotyping. For the Canadian herd, IR EBV were available through phenotyping and pedigree information. Colostral IgG concentrations were measured by radial immunodiffusion and analyzed using general linear models in SAS. Based on a prediction equation, cows in US herds with a CMIR GPA of 1 would have colostral IgG concentrations 6.3 g/L higher on average than cows with a CMIR GPA of 0. High CMIR cows produced statistically greater colostral IgG concentrations (least squares mean ± standard error of the mean, 107.5 ± 7.7 g/L) than low CMIR cows (91.4 ± 7.1 g/L), with intermediate values for average CMIR cows (105.1 ± 5.6 g/L). No differences were found among AMIR categories in US cows. The Canadian herd showed a trend for cows with high CMIR EBV (continuous variable) to produce greater colostral IgG. No differences were observed among high, average, and low AMIR EBV classifications in Canadian cows. The findings suggest that selective breeding of Holstein cows to enhance CMIR could contribute to higher-quality colostrum in succeeding generations.

Johne's disease (JD) control is often based on the culling of positive animals and the adoption of management practices that minimize exposure of young stock to the pathogen (Mycobacterium avium ssp. paratuberculosis). Throughout 2010 to 2013, the province of Ontario, Canada, instituted a voluntary Johne's control program consisting of whole-herd testing and risk assessment. The JD risk assessment evaluated 5 management areas to characterize herd JD risk. Using a modified milk ELISA technique with an optical density cut-off of 0.089, province-wide bulk tank milk (BTM) testing was used to assess the prevalence of JD high-risk herds at the end of the control program and again 4 yr after its completion. Approximately 71% of Ontario bulk tanks were classified as positive in 2017 compared with roughly 46% in 2013. In 2019, the same JD risk assessment used in the original program was readministered on 180 Ontario dairy farms. Using this cross-sectional approach, logistic regression models were built using data from the original program risk assessment and follow-up risk assessment as well as the BTM ELISA results to determine management factors associated with the control of JD. We demonstrated that management of the maternity area is an important factor in the control of Johne's disease. Although it is believed that the highest risk group for JD infection is calves under 6 mo, the cleanliness scores of older heifers and their exposure to mature cow manure was significantly associated with JD control; farms with highly contaminated weaned and bred heifers and those that had exposure to mature cow manure were more likely to be unsuccessful in their JD control efforts. Careful management of young calves appears to be important for JD control, and this management should continue even after calves have left the maternity area.

For the control of Johne's disease (JD), management practices to minimize disease transmission must be implemented and maintained. Once infected, animals will enter a latent phase and will typically only manifest clinical symptoms years later. As young calves are the main susceptible group on farm, the observed effects of management practices geared toward minimizing their exposure to infective material may not be realized until years later. This delayed feedback limits the sustained implementation of JD control practices. Although quantitative research methods have demonstrated changes to management practices as well as their association with changes to JD prevalence, dairy farmers can offer insights into the current challenges relating to JD implementation and control. Thus, this study aims to use qualitative methods and in-depth interviews (n = 20) with Ontario dairy farmers who had previously been engaged in a Johne's control program to explore their motivations and barriers to the implementation of JD control practices and general herd biosecurity. A thematic analysis using inductive coding was completed generated the following 4 overarching themes: (1) the hows and whys of Johne's control, (2) barriers to general herd biosecurity, (3) barriers to Johne's control, and (4) overcoming barriers. Farmers no longer believed JD was an issue on their farm. Johne's was low on their list of concerns due to little public discourse, absence of animals displaying clinical signs, and no financial support for diagnostic testing. Producers who were still actively engaged in JD control cited animal and human health as their primary motivations. Financial support, targeted education, and promoting engagement through discourse may help encourage producers to reconsider their participation in JD control. Government and industry collaboration with producers may help to develop more effective biosecurity and disease control programs.

The objective of this narrative review was to compare the results of the 2015 Canadian National Dairy Study and the 2014 US National Animal Health Monitoring System (NAHMS) Dairy Studies, with a specific focus on calf management and welfare, and to interpret these findings within more recent calf health research to describe where we need to go next in the North American dairy industry. Situating results of periodic national studies within the context of past and recent research provides an opportunity to gauge adoption of recommendations and best practices and to help identify persistent and new challenges that the industry is wrestling with to help guide research needs. Through this review of the 2 national studies, we identified several strengths of the Canadian and US dairy industries. In each area of calf health management, improvements relative to previous NAHMS studies and the published literature have been found in the level of mortality, amount of colostrum fed, housing, and the number of producers using pain control for disbudding and dehorning. There were, however, some areas that present clear opportunities for improvement. Specifically, although mortality levels have improved, a large number of calves die at birth, within the first 48 h of life, and during the preweaning period. To improve the health of calves in early life, producers could look at feeding high-quality colostrum at 10% of body weight in the first feeding, as well as feeding a larger amount of milk during the preweaning period. The barriers to making these management changes and improving overall calf health need to be identified in future studies. The majority of preweaning calves in Canada and the United States are housed in individual housing. This represents a clear opportunity for improvement because recent research has identified the positive aspects of group housing. Finally, with respect to pain control, improvements are needed (particularly in the United States) to ensure that pain management is provided when disbudding and dehorning calves. Although the science is clear on pain management, discussions with producers are needed to identify reasons for the lack of uptake.

Understanding how downer cattle are managed allows for the evaluation of strengths and weaknesses in these practices, which is an important step toward improving the care these animals receive. The objective of this cross-sectional study was to analyze factors associated with the care and management of downer cattle by Canadian dairy producers. Data were obtained from the 2015 National Dairy Study, and analysis was limited to the 371 respondents completing the downer cow scenario. The scenario described a downer cow that the producer wanted to keep in their herd but must be moved, and was followed by questions addressing the cow's care and management. Using multivariable logistic regression models, associations between respondent demographics and farm characteristics, and the presence of downer cow protocols, we assessed decisions regarding euthanasia and use of behavioral prognostic indicators. Written downer cow protocols were reported by 18.2% of respondents, 67% indicated that they had a nonwritten protocol, and 14.8% reported that they did not have a protocol (either written or nonwritten). Respondents from western provinces were more likely to have a written protocol than those from Ontario. Nineteen percent of the respondents with a written or unwritten protocol reported veterinary involvement in developing their downer cow protocol, which occurred more commonly on farms with more frequent herd health visits and a good producer-veterinarian relationship. An area to move a downer cow to was present on 88% of farms, with respondents who were farm staff being less likely to report having knowledge of a designated area than respondents who were the farm owner. In addition, approximately half (45%) of respondents reported moving downer cattle with hip lifters as their most common method. Behavioral prognostic indicators chosen by respondents were associated with the respondent's geographic region, age, farm size, and education. Most notably, older respondents were more likely to use appetite, and less likely to use attitude, as a prognostic indicator compared with younger respondents. Using perceived pain as a prognostic indicator was more common among respondents from western and Atlantic provinces compared with respondents from Ontario, and more common among respondents with a college or university education. These results highlighted herd and farmer demographics that were associated with how Canadian dairy producers managed downer cattle in 2015 and could be used as a benchmark for evaluating how these management practices compare with those currently implemented.

Cryptosporidium is a zoonotic protozoan parasite that is distributed globally and impacts both human and animal health. There are over 40 species of Cryptosporidium described to date, of which four (C. parvum, C. bovis, C. ryanae and C. andersoni) are routinely reported in cattle. The goal of this study was to identify the Cryptosporidium species infecting dairy cattle from across Canada using cow fecal samples and post-weaned calf rectal swabs obtained through the Canadian National Dairy Study. A total of 353 cattle samples (117 pooled rectal fecal swabs from post-weaned calves and 236 cow fecal samples) from 175 herds across the 10 Canadian provinces were analysed by targeting Cryptosporidium's small subunit ribosomal RNA (SSU rRNA or 18S) gene. Herd prevalence of Cryptosporidium was 27.4% nationally, ranging from 0% in Saskatchewan (SK) to 62% in Prince Edward Island (PE). The national prevalence of Cryptosporidium cattle infections was 15.4% in pooled rectal fecal swab samples from post-weaned calves and 16.1% in adult cows. Sanger sequence analysis of the SSU rRNA gene target revealed that C. bovis, C. andersoni and C. ryanae occurred in both adults and post-weaned calves, with C. bovis as the predominant species detected in pooled fecal swab samples of post-weaned calves (9/18, 50%) and C. andersoni as the predominant species in cows (25/38, 66%). Cryptosporidium parvum was not observed in any of the pooled rectal swab samples from post-weaned calves but was observed in one mixed infection of C. bovis/C. parvum in an adult cow. The fifth species identified in this study was C. muris and was present in two adult cows. Low concentrations of oocyst equivalents, as measured by quantitative real-time PCR (qPCR) of the SSU rRNA gene copy number, were observed in a subset of cattle samples. Cryptosporidium andersoni concentrations varied from province to province, with the widest range and highest counts in cows from PE. In conclusion, oocysts from Cryptosporidium species observed in this study are shed into the environment, contributing to the environmental load. However, the Cryptosporidium species in the post-weaned calves and cows found in this study pose a lower risk to the dairy cattle than if they were infected with C. parvum. Similarly, these Cryptosporidium species pose only a small risk to public health as the three species are infrequently reported in humans globally and have not been reported in Canadians to date.