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Abstract Background Hypocalcemia is a relatively common complication after parathyroidectomy for treatment of primary hyperparathyroidism. Objectives To retrospectively evaluate clinical variables in dogs with primary hyperparathyroidism to determine whether or not an association exists between pre-surgical variables and the development of post-surgical hypocalcemia. Animals One hundred three dogs diagnosed with primary hyperparathyroidism and treated by parathyroidectomy in seven referral hospitals between 2010 and 2021. Material and Methods Data collected from medical records included signalment, physical examination findings, concurrent illnesses, ongoing medications, and clinicopathologic test results (including serum ALP activity, iCa, plasma phosphate and PTH concentrations). Dogs were assigned into groups based on lowest iCa post-surgery: Group1 ≥ 1.1 mmol/L, Group2 < 1.1 mmol/L. The Mann–Whitney U test assessed associations between several variables of interest and the occurrence of post-surgery hypocalcemia. ROC analyses were performed to identify variables that had the potential to predict the development of hypocalcemia after surgery. Results The median plasma PTH concentration pre-surgery in dogs which developed hypocalcemia after surgery was significantly higher (232 pg/mL {[IQR] 108–421}) than in dogs which did not develop hypocalcemia after surgery (81.5 pg/mL {IQR 58.5–145.0}; p < 0.001). Plasma PTH concentration had a fair to good ability to predict the development of post-surgery hypocalcemia, with AUC being 0.78 [95% confidence interval 0.67–0.89]. Using a cut-off of ≥ 75 pg/mL, pre-surgery plasma PTH concentration had a sensitivity of 96.6% and specificity of 42.3% for the development of post-surgery hypocalcemia. Dogs that developed hypocalcemia after surgery were older and had lower body weights. Conclusion Pre-surgery plasma PTH concentrations might be helpful in predicting those dogs at risk of developing hypocalcemia after parathyroidectomy.

The diagnosis of milk fever or hypocalcemia in lactating cows has a significant economic impact on the dairy industry. It is challenging to identify asymptomatic subclinical hypocalcemia (SCH) in transition dairy cows. Monitoring subclinical hypocalcemia in milk samples can expedite treatment and improve the health, productivity, and welfare of dairy cows. In this study, an attomolar-sensitive sensor is developed using extrusion-based 3D-printed sensing structures to detect the ratio of ionized calcium to phosphate levels in milk samples. The unique geometries of the lateral structure of 3D-printed sensors, along with the wrinkled surfaces, provide a limit of detection down to the attomole (138 a m ) concentration of the target analyte. The calcium-to-phosphate ratio in milk samples not only provides early disease indications but also enables on-site testing. This highly selective test is validated using real milk and blood samples, and the results are compared with those of commercial meters. This fast response (~10 s) low-cost sensor opens a promising tool for the farm-side diagnostic of dairy cows that can promote best practice management of dairy cows. A 3D-printed sensor with surface-wrinkled structures detects subclinical hypocalcemia in dairy cows by measuring the calcium-to-phosphate ratio in milk. With attomolar sensitivity and rapid results, it enables early treatment, improving cow health and productivity.

Abstract Background The incidence of subclinical hypocalcemia (iSCH) based on blood ionized calcium (iCa < 1.00 mmol/L) has not been investigated in Holsteins fed an anionic diet (AD) and non-AD prepartum and treated or not treated with calcium bolus (CB) around the time of calving. Hypothesis Anionic diets supported with CB at 12 h after calving should increase iCa and reduce iSCH better than AD + non-CB and non-AD + CB. Animals One hundred Holsteins were allocated to 4 groups: Group 1 (AD + CB), group 2 (AD + non-CB), group 3 (non-AD + CB) and group 4 (non-AD and non-CB). Methods The animals were randomly selected according to calving order. The iCa and iSCH were analyzed at calving before CB application on postpartum days (PPD) 1, 3, and 10. Urine pH was analyzed at calving and PPD1. Results Urine pH (6.43 ± 0.26), iCa (0.90 ± 0.16 mmol/L) and iSCH (50%) were significantly different in the combined AD groups compared to the non-AD groups at calving. Multiparous cows in combined AD groups had higher iCa and lower iSCH at calving. Group 1 had a higher iCa than groups 3 and 4. Group 2 had a higher iCa than Group 4 at PPD3. The iSCH of group 1 at PPD3 and 10 was lower than that of other groups. The iSCH decreased from 50% (PPD1) to 17% (PPD3) and 4% (PPD10) in group 1. Group 4 showed milk fever of 12%, 4%, and 4% at PPD1, 3, and 9, respectively. Conclusion Group 1 was the most appropriate protocol to increase iCa, reduce iSCH, and prevent milk fever.

Periparturient hypocalcemia is a complex metabolic disorder that occurs at the onset of lactation because of a sudden irreversible loss of Ca incorporated into colostrum and milk. Some cows are unable to quickly adapt to this demand and succumb to clinical hypocalcemia, commonly known as milk fever, whereas a larger proportion of cows develop subclinical hypocalcemia. The main goal of this study was to identify causative mutations and candidate genes affecting postpartum blood calcium concentration in Holstein cows. Data consisted of blood calcium concentration measured in 2513 Holstein cows on the first three days after parturition. All cows had genotypic information for 79 k SNP markers. Two consecutive rounds of imputation were performed: first, the 2513 Holstein cows were imputed from 79 k to 312 k SNP markers. This imputation was performed using a reference set of 17,131 proven Holstein bulls with 312 k SNP markers. Then, the 2513 Holstein cows were imputed from 312 k markers to whole-genome sequence data. This second round of imputation used 179 Holstein animals from the 1000 Bulls Genome Project as a reference set. Three alternative phenotypes were evaluated: (1) total calcium concentration in the first 24 h postpartum, (2) total calcium concentration in the first 72 h postpartum calculated as the area under the curve; and (3) the recovery of total calcium concentration calculated as the difference in total calcium concentration between 72 and 24 h. The identification of genetic variants associated with these traits was performed using a two-step mixed model-based approach implemented in the R package MixABEL. The most significant variants were located within or near genes involved in calcium homeostasis and vitamin D transport ( GC ), calcium and potassium channels ( JPH3 and KCNK13 ), energy and lipid metabolism ( CA5A , PRORP , and SREBP1 ), and immune response ( IL12RB2 and CXCL8 ), among other functions. This work provides the foundation for the development of novel breeding and management tools for reducing the incidence of periparturient hypocalcemia in dairy cattle.

Abstract Background Acute pancreatitis (AP) is associated with a high death rate in dogs, but accurate predictors of early death are still lacking. Objectives To develop a scoring system for prediction of short-term case fatality in dogs with AP. Animals One hundred sixty-nine dogs with AP including 138 dogs in the training cohort and 31 dogs in the validation cohort. Methods Multicenter, retrospective cohort study. Survival analysis was used to assess the associations with short-term death (within 30 days after admission). Independent predictors of death were identified by a stepwise selection method and used for the score calculation. Results Death rate within 30 days after admission was 33% in the training cohort. Four independent risk factors for short-term death were identified in the training cohort: presence of systemic inflammatory response syndrome, coagulation disorders, increased creatinine and ionized hypocalcemia. Canine Acute Pancreatitis Severity (CAPS) score was developed to predict short-term death, integrating these 4 factors in a weighted way. A simplified version of CAPS score (sCAPS) including respiratory rate instead of SIRS was also assessed. The area under the receiver-operating characteristic curve (AUC) of CAPS and sCAPS scores was 0.92 in the training cohort with an optimal cutoff of 11 (sensitivity, 89%; specificity, 90%) and 6 (sensitivity, 96%; specificity, 77%), respectively. CAPS and sCAPS score were validated in the validation cohort with respective AUC of 0.91 and 0.96. Conclusions and Clinical Importance We propose 2 scoring systems that allow early and accurate prediction of short-term death in dogs with AP.

Abstract Background Data on the factors affecting blood ionized calcium concentration (ciCa2+) and diagnostic performance of serum total calcium concentration (ctCa) measurements to detect abnormal blood iCa2+ status are lacking in sick adult cattle. Objective Assess the association of ciCa2+ with venous blood pH, plasma concentrations of chloride (cCl), sodium (cNa), and potassium (cK), and ctCa, and total protein, albumin, and globulin concentrations in sick adult cattle. Animals Two-hundred and sixty-five adult cattle (≥1-year-old) with different diseases. Methods Prospective study. Whole blood pH, ciCa2+, cNa, cK, and cCl were measured using a blood gas and electrolyte analyzer, whereas ctCa, and total protein, and albumin concentrations were determined using an autoanalyzer. The relationship between ciCa2+ and venous blood pH, plasma cCl, cNa, cK, and ctCa, and total protein, albumin, and globulin concentrations was investigated. Sensitivity and specificity were calculated for ctCa for diagnosis of abnormal ciCa2+. Results Sensitivity of ctCa measurements to detect abnormal ciCa2+ was 66.0% whereas specificity of ctCa measurements was 72.3%. Serum total calcium concentration measurements accounted for 42% of adjusted blood ionized calcium (iCa2+7.40) concentration variance. Plasma cCl, and cK had explanatory power of ciCa2+7.40, accounting for an additional 21% and 9% of the variance, respectively. Conclusions and Clinical Importance Serum tCa measurements failed to accurately predict blood iCa2+ status in ill adult cattle. Serum tCa concentrations and plasma cCl were the strongest predictors of ciCa2+ in sick adult cattle.

Calcium homeostasis is crucial for the normal function of the organism. Parathyroid hormone, calcitriol and calcitonin play critical roles in the homeostatic regulation of calcium. Serotonin and prolactin have also been shown to be involved in the regulation of calcium homeostasis. In modern dairy cows, the endocrine pathways controlling calcium homeostasis during non-lactating and non-pregnant physiological states are unable to fully support the increased demand of calcium required for milk synthesis at the onset of lactation. This review describes different endocrine systems associated with the regulation of calcium homeostasis in mammalian species around parturition with special focus on dairy cows. Additionally, classic and novel strategies to reduce the incidence of hypocalcemia in parturient dairy cows are discussed.

Background A better comprehension of the redox status during the periparturient period may facilitate the development of management and nutritional solutions to prevent subclinical hyperketonemia (SCHK) and subclinical hypocalcemia (SCHC) in dairy goats. We aimed to evaluate the variation in the redox status of dairy goats with SCHK and SCHC during their periparturient periods. Guanzhong dairy goats (n = 30) were assigned to SCHK (n = 10), SCHC (n = 10), and healthy (HEAL, n = 10) groups based on their blood β-hydroxybutyrate (BHBA) and calcium (Ca) concentrations. Blood were withdrawn from goats every week from 3 weeks before the expected parturition date to 3 weeks post-kidding. On the same day, the body condition scores (BCS) were evaluated, and the milk yield was recorded for each goat. The metabolic profile parameters and the indicators of oxidative status were determined by using the standard biochemical techniques. Results In comparison with the HEAL goats, SCHK and SCHC goats presented with a more dramatic decline of BCS post-kidding and a significant decrease in the milk yield at 2- and 3-weeks postpartum, ignoring the obvious increase at 1-week postpartum. The levels of non-esterified fatty acids (NEFA) peaked at parturition, exhibiting significantly higher levels from 1-week prepartum to the parturition day in the SCHK and SCHC groups. The malondialdehyde (MDA) concentration was increased in the SCHK goats from 1-week antepartum until 3-weeks postpartum, with its concentration being significantly higher in the SCHC goats at parturition. The hydrogen peroxide (H 2 O 2 ) concentration was significantly lower in the SCHK and SCHC goats from 2-weeks antepartum to 1-week post-kidding. The total antioxidant capacity (T-AOC) and the superoxide dismutase (SOD) level were decreased at 1-week antepartum in the SCHK and SCHC goats, respectively. The glutathione peroxidase (GSH-Px) level was increased in the SCHK and SCHC goats during the early lactation period. Conclusions The SCHK and SCHC goats exerted more efforts to maintain their redox homeostasis and to ensure the production performance than the HEAL goats during their periparturient period, probably owing to more intense fat mobilization and lipid peroxidation in the former.

Idiopathic hypocalcemia in Thoroughbred (TB) foals causes tetany and seizures and is invariably fatal. Based upon the similarity of this disease with human familial hypoparathyroidism and occurrence only in the TB breed, we conducted a genetic investigation on two affected TB foals. Familial hypoparathyroidism was identified, and pedigree analysis suggested an autosomal recessive (AR) mode of inheritance. We performed whole-genome sequencing of the two foals, their unaffected dams and four unaffected, unrelated TB horses. Both homozygosity mapping and an association analysis were used to prioritize potential genetic variants. Of the 2,808 variants that significantly associated with the phenotype using an AR mode of inheritance (P<0.02) and located within a region of homozygosity, 1,507 (54%) were located in a 9.7 Mb region on chr4 (44.9-54.6 Mb). Within this region, a nonsense variant (RAPGEF5 c.2624C>A,p.Ser875*) was significantly associated with the hypoparathyroid phenotype (Pallelic = 0.008). Affected foals were homozygous for the variant, with two additional affected foals subsequently confirmed in 2019. Necropsies of all affected foals failed to identify any histologically normal parathyroid glands. Because the nonsense mutation in RAPGEF5 was near the C-terminal end of the protein, the impact on protein function was unclear. Therefore, we tested the variant in our Xenopus overexpression model and demonstrated RAPGEF5 loss-of-function. This RAPGEF5 variant represents the first genetic variant for hypoparathyroidism identified in any domestic animal species.

Abstract Background Ionized calcium (iCa) is the biologically active fraction of total calcium (tCa) with clinical relevance to evaluate calcium homeostasis, but not all primary veterinarians have access to serum iCa. Formulas that adjust tCa to correct for variability in serum protein concentrations were not designed to predict iCa and are considered unreliable surrogates for iCa. Objectives To determine whether adjusted calcium concentration (aCa) can predict ionized hypocalcemia in hypoalbuminemic dogs without hyperphosphatemia. Animals A total of 262 hypoalbuminemic dogs without hyperphosphatemia. Methods Retrospective review of paired tCa and iCa. Patients were included if serum albumin concentration was ≤2.5 g/L and serum phosphorus concentration was ≤5 mg/dL. The aCa was calculated using tCa (mg/dL) − serum albumin concentration (g/dL) + 3.5 (g/dL). Sensitivity, specificity, positive (PPVs) and negative (NPVs) predictive values, and accuracy were determined for tCa and aCa at predicting any (<1.13 mmol/L) and moderate (<1.02 mmol/L) ionized hypocalcemia. Patients also were stratified into mild-to-moderate (2.0-2.5 g/dL) and severe hypoalbuminemia (<2.0 g/dL). Results A total of 4296 dogs had paired results of which 262 met the inclusion criteria. Of these, 35 (13.4%) dogs had iCa < 1.13 mmol/L and 13 dogs (5.0%) had concentrations <1.02 mmol/L. The sensitivity, specificity, NPVs and PPVs of a decreased tCa and aCa for detecting moderate ionized hypocalcemia were 100% and 92.3%, 57.8% and 94.8%, 100% and 99.6%, and 11.0% and 48.2%, respectively, and accuracy was 60.0% and 94.7%, respectively. Conclusions A low aCa was useful to detect ionized hypocalcemia in hypoalbuminemic nonhyperphosphatemic dogs. A normal aCa indicated that moderate ionized hypocalcemia was unlikely.