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Subclinical hypocalcemia (SCH), a reduction in blood calcium concentrations without apparent clinical signs of milk fever, occurs in 25 to 50 % of early-postpartum dairy cows. Compared to their normocalcemic counterparts, these cows have an increased risk of subsequent disease developments, reduced milk production, and poorer reproductive performance. Due to the absence of an economical and accurate on-farm test, the mainstay of individual cow testing and herd-level monitoring is done through total calcium (tCa) analysis performed at regional laboratories or veterinary clinics. Due to practicality reasons, this often results refrigeration of whole blood for various lengths of time prior to centrifugation or prolonged storage of frozen plasma or serum. In order to provide bovine practitioners and researchers with the optimal method of handling samples for tCa testing, our objective was to examine the effect of storage time and temperature on tCa concentrations in bovine blood., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2019

There is currently no efficient and inexpensive method for field measurement of blood calcium concentrations. Ionized calcium (iCa) is the homeostatic form of the mineral and is thought to have greater biological relevance over that of total calcium. The objective of this study was to evaluate the linearity and precision of a prototype cow-side instrument (Horiba, Japan) for measuring blood iCa concentrations., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2015

As a consequence of lagging dry matter intake and increased energy demands, nonesterified fatty acid (NEFA) is released into the bloodstream from adipose tissue to be used as a source of energy in dairy cows in early lactation. Nonesterified fatty acid is used for milk fat synthesis, ketone production (e.g., -hydroxybutyrate; BHBA) and liver triglyceride accumulation. Nonesterified fatty acid and BHBA can be used as markers of negative energy balance (NEB) and elevated concentrations in the transition period have been associated with an increased risk of developing disease. The multiple pathways available for NEFA may result in a non-linear relationship between NEFA and BHBA concentrations. Additionally, the ratio between these two metabolites may differ in sub populations, e.g., subclinically ketotic (SCK) cows, and cows with elevated NEFA. Hence, the ratio of these metabolites may be a useful parameter for further understanding the biological mechanisms of adaption or maladaptation to NEB. The objectives of this study were to evaluate the R2 coefficient of determination between NEFA and BHBA in apparently healthy cows three to 14 DIM, and to estimate the association between the ratio of NEFA to BHBA and the subsequent development of displaced abomasum (DA), clinical ketosis (CK), or metritis (MET)., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2012

Cows normally visit a state of negative energy balance (NEB) during the transition period in response to decreased dry matter intake and increased energy demands early in lactation. Energy balance is commonly measured with non-esterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB) concentrations, and several studies have shown that excessive NEB is associated with detrimental health, reproduction, and production effects at the cow-level. The objectives of this study were to determine the herd alarm level for the proportion of sampled cows with elevated metabolites resulting in herd-level effects, and to describe the herd-level prevalence of elevated metabolite concentrations., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2009

Large increases in demands for energy and nutrients occur as dairy cows transition from the last weeks of pregnancy to the first weeks of lactation. If excessive, negative energy balance (NEB) in the pre-partum period and subclinical ketosis (SCK) in the post-partum period may be associated with poor reproductive and milking performance, as well as increased incidence of metabolic (e.g. DA) and infectious diseases (e.g. mastitis). Published research suggests that SCK is the most costly disorder of dairy cows in Ontario. The objective of this study was to measure the occurrence of NEB and SCK in a large sample of progressive dairy herds to determine if there is opportunity for better management of this critical time in a cow's life., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2007

Over a 5-year period (1988-92), von Willebrand factor antigen (vWf:Ag) assays were performed on plasma samples from 207 Scottish Terriers. Based on these tests, 47 dogs (23%) had vWf:Ag concentrations < 50 canine units (CU)/dL and were classified as heterozygous carriers of the von Willebrand's disease (vWD) gene, while 9 (4%) had concentrations below the sensitivity of the assays and were classified as homozygous. There was thus an overall prevalence of 27% for the vWD gene in the Scottish Terriers tested. The homozygous dogs (median age 0.6 years at diagnosis) consisted of 7 males and 2 females. Eight of these had haemorrhage attributable to the disease, mostly spontaneous and from the oral mucosa. Other signs included haemorrhage induced by trauma or surgery, easy bruising and epistaxis. Many haemorrhagic episodes were severe enough to warrant therapeutic intervention and there was a single fatality. Pedigree analysis, possible in 7 of the dogs, revealed that each was the progeny of a mating between dogs with vWf:Ag concentrations < 50 CU/dL, which supported an autosomal recessive mode of inheritance. A single heterozygous carrier suffered haemorrhage after surgery that, in contrast to the homozygotes, was mild and did not require therapy. The data indicate that vWD is a significant problem in Scottish Terriers in Australia. Accordingly, we recommend that steps be taken to reduce the prevalence of the disease and thereby the number of clinically affected dogs, such as the establishment of a national testing scheme to determine the vWD status of all breeding dogs.