Association of Vitamin D Status and Clinical Outcome in Dogs with a Chronic Enteropathy

Dysregulated serum concentrations of fat-soluble vitamins in dogs with chronic enteropathy

BACKGROUND

In inflammatory bowel disease (IBD) of humans, nutrient malabsorption can result in fat-soluble vitamin deficiency, especially of vitamin D. In veterinary species, decreased concentrations of vitamin D are relatively common in dogs with chronic enteropathy (CE), but data on the status of other fat-soluble vitamins (FSVs) is lacking.

OBJECTIVES

Determine the serum concentrations of retinol, vitamin D, and α-tocopherol in dogs with CE compared with healthy dogs and compare clinical, clinicopathologic variables between CE and healthy dogs to detect associations with decreased FSVs concentrations.

ANIMALS

Eighteen client-owned dogs with CE and 33 healthy dogs.

METHODS

Serum 25-hydroxyvitamin D (25[OH]D), serum retinol and α-tocopherol concentrations were compared between groups. Correlations and multiple regression modeling were used to examine the relationship between serum 25(OH)D, retinol, and α-tocopherol concentrations and clinical and clinicopathological variables.

RESULTS

Dogs with low serum albumin concentrations were more likely to have lower 25(OH)D concentrations than dogs with normal serum albumin concentration. Dogs with CE had higher serum concentrations of retinol, and variable α-tocopherol concentrations. The cause of these dysregulated vitamin concentrations is unclear and requires further study.

CONCLUSION AND CLINICAL IMPORTANCE

Dogs with severe forms of CE should be monitored for decreased concentrations of 25(OH)D. Additional studies are needed to evaluate the clinical relevance and the possible benefit of vitamin D supplementation in these patients.

Association of folate concentrations with clinical signs and laboratory markers of chronic enteropathy in dogs

BACKGROUND

Serum folate is considered a biomarker of chronic enteropathy (CE) in dogs, but few studies have examined associations with markers of CE.

HYPOTHESIS/OBJECTIVES

To evaluate serum folate concentrations in dogs with and without CE and associations with sample hemolysis and selected markers of CE. We hypothesized that hypofolatemia would be more common in dogs with CE and associated with hypocobalaminemia, higher CIBDAI, and hypoalbuminemia.

ANIMALS

Six hundred seventy-three dogs with available serum folate measurements performed at an academic veterinary hospital between January 2016 and December 2019.

METHODS

Medical records were retrospectively reviewed to categorize cases as CE or non-CE and record clinical details and laboratory markers. Relationships between serum folate, cobalamin, and CE variables were assessed using chi-square, Kruskal-Wallis, or Spearman's correlation tests.

RESULTS

Of the 673 dogs, 99 CE were compared to 95 non-CE. In the overall cohort, serum folate concentration did not correlate with sample hemolysis (P = .75). In the CE subset, serum folate and cobalamin concentrations were positively associated (rho = 0.34, FDR = 0.02). However, serum folate concentrations (median [25th, 75th percentiles]) were higher (CE: 12.1 (8.9, 16.1), non-CE: 10.4 (7.2, 15.5); P = .04) and cobalamin concentrations were lower (CE: 343 (240, 597), non-CE: 550 (329, 749); P = .001) in the CE vs non-CE group. Serum folate was not associated with markers of CE, but serum cobalamin was associated with albumin (P = .04) and cholesterol (P = .03).

CONCLUSIONS AND CLINICAL IMPORTANCE

Hypofolatemia is an inferior biomarker of CE compared to hypocobalaminemia.

Relationship between serum magnesium, calcium, and parathyroid concentrations in dogs with abnormally low serum 25-hydroxyvitamin D concentration and chronic or protein-losing enteropathy

BACKGROUND

The relationship between the development of SHPT and ionized magnesium (iMg) concentrations in blood of dogs with chronic gastrointestinal (GI) disease and abnormally low 25(OH)D is undefined.

OBJECTIVES

Evaluate relationships between ionized magnesium (iMg), PTH, ionized calcium (iCa), and 25(OH)D in dogs with chronic enteropathy (CE) with or without protein-losing enteropathy (PLE) and abnormal 25(OH)D. Determine whether dogs with CE or PLE, decreased 25(OH)D and SHPT have differences in iMg, iCa, or 25(OH)D when compared to dogs that do not have SHPT.

ANIMALS

Fifty dogs with CE +/- PLE and abnormally low serum 25(OH)D.

METHODS

Retrospective search of submissions database at a veterinary diagnostic laboratory for vitamin D profiles submitted in years 2017 to 2020. Cases were excluded if supplemented with Ca, Mg, or vitamin D. Spearman correlation was performed to evaluate relationships between iMg, PTH, 25(OH)D, and iCa. Ionized Mg, iCa, and 25(OH)D concentrations were compared between dogs with SHPT and those with normal PTH concentrations.

RESULTS

Concentrations of iMg were weakly negatively correlated with PTH (rho, -.31; P = .03), and weakly positively correlated with serum 25(OH)D (rho, .34, P = .02) and iCa (rho, .42, P = .003). Ionized magnesium concentrations were lower in dogs with abnormally low 25(OH)D and SHPT compared to dogs with abnormally low 25(OH)D and normal parathyroid hormone concentrations (P = .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

Hypomagnesemia might contribute to alterations in iCa and parathyroid hormone in dogs with CE +/- PLE and abnormally low 25(OH)D.

The Nexus of Diet, Gut Microbiota and Inflammatory Bowel Diseases in Dogs

Canine inflammatory bowel diseases (IBD) are of increasing interest in veterinary medicine. They refer to complex and debilitating conditions of dogs' gastrointestinal tract. Although little evidence for causal inferences is currently available, it is believed that IBD pathophysiology entails intricate interactions between environmental factors, the intestinal immune system, and the microbial communities that colonize the gut. To better understand the mechanisms underlying these disorders, leveraging factors associated with the development of these diseases is imperative. Of these factors, emerging evidence supports the role of dietary patterns as key players influencing the composition and function of gut microbes, with subsequent effects on health and disease. In this review, we particularly focus on addressing IBD in dogs and discuss how specific nutrients may elicit or relieve gut inflammation. Gaining mechanistic insights into such interplay and the underpinning mechanisms is key to inferring dietary recommendations, and setting up new and promising therapeutics.

Vitamin D status is heritable and under environment-dependent selection in the wild

Vitamin D has a well-established role in skeletal health and is increasingly linked to chronic disease and mortality in humans and companion animals. Despite the clear significance of vitamin D for health and obvious implications for fitness under natural conditions, no longitudinal study has tested whether the circulating concentration of vitamin D is under natural selection in the wild. Here, we show that concentrations of dietary-derived vitamin D2 and endogenously produced vitamin D3  metabolites are heritable and largely polygenic in a wild population of Soay sheep (Ovis aries). Vitamin D2  status was positively associated with female adult survival, and vitamin D3  status predicted female fecundity in particular, good environment years when sheep density and competition for resources was low. Our study provides evidence that vitamin D status has the potential to respond to selection, and also provides new insights into how vitamin D metabolism is associated with fitness in the wild.

Serum 25-hydroxyvitamin D and C-reactive protein and plasma von Willebrand concentrations in 23 dogs with chronic hepatopathies

BACKGROUND

Serum concentrations of 25-hydroxyvitamin D (25(OH)VD) and C-reactive protein (CRP) and von Willebrand's factor (vWF) concentration correlate with histopathologic disease grade and stage in chronic inflammatory and fibrotic hepatopathies (CH) in humans.

OBJECTIVES

To evaluate serum 25(OH)VD and serum CRP concentrations and plasma vWF concentration and determine if they correlate with histopathologic and biochemical variables in dog with CH.

ANIMALS

Twenty-three client-owned dogs with a histopathologic diagnosis of CH were prospectively enrolled.

METHODS

Blood samples were collected before liver biopsy. Correlations between biomarkers and clinical pathological and histopathologic variables were evaluated using Pearson's or Spearman's test.

RESULTS

Serum 25(OH)VD concentration (median, 213 nmol/L; range, 42-527 nmol/L) was negatively correlated with serum aspartate aminotransferase activity (AST; rho = -0.59, P < .01), polymorphonuclear neutrophil count (PMN; r = -0.46, P < .05), and positively correlated with serum albumin concentration (r = 0.69, P < .001). Serum CRP concentration (median, 7.4 μg/L; range, 1-44.9 μg/L) was positively correlated with overall histopathologic necroinflammatory activity (r = 0.78, P < .001) and fibrosis score (rho = 0.49, P < .05). Plasma vWF concentration (median, 73.3%; range, 15-141%) was positively correlated with fibrosis score (r = 0.53, P < .05) and prothrombin time (rho = 0.67, P < .01), and negatively correlated with serum albumin concentration (r = -0.73, P < .001).

CONCLUSION AND CLINICAL IMPORTANCE

In dogs with CH, serum 25(OH)VD concentration was negatively correlated with disease activity, whereas serum CRP concentration and plasma vWF concentration were positively correlated with histopathologic grade and stage. Our results provide preliminary evidence that these biomarkers may be useful to assess grade and stage of CH in dogs in the absence of liver biopsy.

Dietary management of chronic enteropathy in dogs

Chronic idiopathic enteropathy is a clinical condition defined by the exclusion of infectious, metabolic or neoplastic causes of gastrointestinal signs and is categorised by a response to treatment including management with diet change, immunosuppressant medication or interventions that directly target the microbiome (e.g. antibiotics, faecal transplantation or probiotics). Animals that fail these therapies are categorised as non-responsive or refractory chronic idiopathic enteropathy. This specific categorisation implies that nutritional intervention is only needed for a subset of patients with enteropathy. However, often dogs with chronic idiopathic enteropathy are malnourished, have nutrient malabsorption or have gastrointestinal inflammation that occurs as a result of a breakdown in tolerance to luminal antigens including microorganism or dietary components. Thus, all dogs with chronic idiopathic enteropathy benefit from a nutritional assessment and targeted nutritional intervention. Among dogs presenting for chronic idiopathic enteropathy, the response rate to diet alone is roughly 50% in the referral population giving the impression that the overall response could be even higher especially when more than one nutritional intervention is attempted and strict adherence is maintained. The objectives of this review article are to outline the nutritional approach to a dog with chronic idiopathic enteropathy, including the nutritional assessment, and to highlight areas for nutritional intervention.

Adjusted calcium concentration as a predictor of ionized hypocalcemia in hypoalbuminemic dogs

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.

Vitamin D metabolism and disorders in dogs and cats

Vitamin D plays an important role in regulating calcium metabolism and in the development and maintenance of skeletal health of companion animals. There is also a growing interest in understanding the role vitamin D plays in non-skeletal health in both human and veterinary patients. This review provides an update of our current understanding of vitamin D biology in dogs and cats and gives an overview of how vitamin D metabolism can be assessed in companion animals. Congenital and acquired vitamin D disorders are then summarised before the review concludes with a summary of recent studies which have explored the role of vitamin D in the development and outcomes of non-skeletal diseases of dogs and cats.

Relationship between vitamin D status and clinical outcomes in dogs with a cranial cruciate ligament rupture

Cranial cruciate ligament rupture (CCLR) is one of the most common orthopaedic disorders diagnosed in dogs yet the factors which influence postoperative clinical outcomes are poorly understood. Low vitamin D status has been linked to poorer clinical outcomes in human patients undergoing elective orthopaedic surgery. The aim of this study was to examine the relationship between pre-operative vitamin D status, as defined by serum 25 hydroxyvitamin D (25(OH)D) concentrations, and initial disease severity and clinical outcomes in dogs undergoing surgical treatment for a CCLR. Serum 25(OH)D concentrations were measured in 44 dogs with a CCLR on the day before surgery. C-reactive protein concentrations were measured at a median time of 1 day post-surgery and the patient's clinical and radiographic response to CCLR surgical treatment was assessed at a median timepoint of 60 days post-surgery. Serum 25(OH)D concentrations in dogs with a CCLR was not significantly different to a population of healthy dogs (median 74.1 nmol/L and 88.40 nmol/L, respectively). There was no significant correlation between pre-operative serum 25(OH)D concentrations and length of pre-diagnosis clinical signs, pre-operative lameness scores or day 1 post-operative CRP concentrations. Thirty nine of the 44 dogs were re-examined at a median 60 days post-surgery. There was no relationship between the day 60 lameness scores and pre-operative serum 25(OH)D concentrations. In summary, we discovered that the vitamin D status of dogs with a CCLR was not significantly lower than healthy dogs and pre-operative serum 25(OH)D concentrations were not correlated to either pre-surgical disease severity or post-operative clinical outcomes.

Coagulation status, fibrinolysis, and platelet dynamics in dogs with chronic inflammatory enteropathy

Background

Coagulation status is poorly understood in dogs with chronic inflammatory enteropathy (CIE). Fibrinolytic activity and platelet dynamics have not been evaluated in CIE dogs.

Objectives

To assess coagulation status and fibrinolysis in normoalbuminemic CIE dogs (CIE‐N) and CIE dogs with protein‐losing enteropathy (CIE‐PLE) compared to healthy controls (HC). To evaluate thromboelastography (TEG) variable differences between groups and for correlations with clinicopathologic data. To report platelet dynamics in CIE dogs.

Animals

Twenty‐five client‐owned dogs with CIE (n = 16 CIE‐N; n = 9 CIE‐PLE); 14 HC beagle dogs.

Methods

All dogs had tissue factor + tissue plasminogen activator TEG. Nine of 25 CIE dogs had whole blood impedance platelet aggregometry. The TEG variables and coagulation data were compared between all CIE vs HC dogs, CIE‐N dogs vs HC, and CIE‐PLE dogs vs HC. Clinicopathologic and coagulation data were available for CIE dogs and assessed for correlation to TEG variables.

Results

Dogs with CIE had higher maximum amplitude (MA; P < .001), longer clot lysis times (CLTs; P < .001), lower % lysis after 30 minutes (LY30; P < .001), and % lysis after 60 minutes (LY60; P < .001) compared to HC, suggesting hypercoagulability and hypofibrinolysis. When separated out, both CIE‐N and CIE‐PLE dogs had higher MA, longer CLT, and lower LY30 and LY60 compared to HC. Serum albumin and 25‐hydroxyvitamin D (25[OH]D) concentrations, and plasma antithrombin and fibrinogen concentrations moderately correlated with MA.

Conclusions and Clinical Importance

Normoalbuminemic and hypoalbuminemic CIE dogs were considered hypercoagulable based on TEG compared to HC. Some CIE dogs displayed hypofibrinolytic phenotypes on TEG.

Dysregulation of gastrointestinal RAGE (receptor for advanced glycation end products) expression in dogs with chronic inflammatory enteropathy

The pathogenesis of chronic inflammatory enteropathies (CIE) in dogs involves dysregulated innate immune responses. The receptor for advanced glycation end products (RAGE), a pattern recognition receptor, plays a role in chronic inflammation. Abrogation of proinflammatory RAGE signaling by ligand binding (e.g., S100/calgranulins) to soluble RAGE (sRAGE) might also be a novel therapeutic avenue. Serum sRAGE levels are decreased in canine CIE, but gastrointestinal tissue RAGE expression has not been investigated in dogs. Thus, the study aimed to evaluate the gastrointestinal mucosal RAGE expression in dogs with CIE. Further, the potential binding of RAGE to canine S100/calgranulin ligands was investigated. Epithelial RAGE expression was quantified in gastrointestinal (gastric, duodenal, ileal, and colonic) biopsies from 12 dogs with CIE and 9 healthy control dogs using confocal laser scanning microscopy. RAGE expression was compared between both groups of dogs and was tested for an association with patient characteristics, clinical variables, histologic lesion severity, and biomarkers of extra-gastrointestinal disease, systemic or gastrointestinal inflammation, function, or protein loss. Statistical significance was set at p < 0.05. RAGE:S100/calgranulin binding was assessed by immunoassay and electrophoretic techniques. RAGE expression was detected in all 59 biopsies from diseased and healthy control dogs evaluated. Epithelial RAGE expression in the duodenum and colon was significantly higher in dogs with CIE than in healthy controls (p < 0.04). Compared to healthy controls, RAGE expression in dogs with CIE also tended to be higher in the ileum but lower in the stomach. A slight (statistically not significant) shift towards more basal intestinal epithelial RAGE expression was detected in CIE dogs. Serum sRAGE was proportional to epithelial RAGE expression in the duodenum (p < 0.04), and RAGE expression in the colon inversely correlated with biomarkers of protein loss in serum (both p < 0.04). Several histologic morphologic and inflammatory lesion criteria and markers of inflammation (serum C-reactive protein and fecal calprotectin concentration) were related to epithelial RAGE expression in the duodenum, ileum, and/or colon. in vitro canine RAGE:S100A12 binding appeared more pronounced than RAGE:S100A8/A9 binding. This study showed a dysregulation of epithelial RAGE expression along the gastrointestinal tract in dogs with CIE. Compensatory regulations in the sRAGE/RAGE axis are an alternative explanation for these findings. The results suggest that RAGE signaling plays a role in dogs with CIE, but higher anti-inflammatory decoy receptor sRAGE levels paralleled RAGE overexpression. Canine S100/calgranulins were demonstrated to be ligands for RAGE.

Plasma 25-hydroxyvitamin D and the inflammatory response in canine cancer

Decreased circulating 25-hydroxyvitamin D (25[OH]D) and increased inflammatory marker concentrations have been reported separately in canine cancer. Correlations between the two exist in humans, but little work has examined links in dogs. This study aimed to determine plasma 25(OH)D and inflammatory marker concentrations in healthy dogs and dogs with cancer and to assess correlations in each group. Newly diagnosed dogs with B-cell lymphoma (B-cell, n = 25), T-cell lymphoma (T-cell, n = 9), osteosarcoma (OSA, n = 21), and mast cell tumour (MCT, n = 26) presenting to a tertiary oncology centre, and healthy dogs (n = 25), were enrolled. Plasma samples were analysed for 25(OH)D, C-reactive protein (CRP), haptoglobin (HP), serum amyloid A (SAA), alpha-1-acid glycoprotein (AAG), and 13 chemokines and cytokines. Dogs with B-cell had decreased plasma 25(OH)D (P = .03), and increased plasma CRP, AAG, HP, KC-like and MCP-1 concentrations (P < =.001, .011, <.001, .013 and .009, respectively) compared with healthy dogs. Plasma CRP, HP and SAA concentrations were increased in dogs with OSA compared with healthy dogs (P = .001, .010 and .027, respectively). No differences were noted in dogs with T-cell and MCT. Negative correlations were observed between plasma 25(OH)D concentrations and: AAG concentrations in dogs with T-cell (R_s  = -0.817, P = .007); GM-CSF concentrations (R_s  = -0.569, P = .007) in dogs with OSA; and IL-7 concentrations (R_s  = -0.548, P = .010) in dogs with OSA. Decreased 25(OH)D concentrations and increased concentrations of multiple inflammatory markers were observed in B-cell patients, supporting an association between 25(OH)D and inflammation. The cross-sectional study design meant the timing of changes could not be determined. Prospective cohort studies are warranted.

Prognostic value of small intestinal dilatation in dogs with protein-losing enteropathy

To date, little is known about the prognostic significance of ultrasonographic findings in dogs with protein-losing enteropathy (PLE). The aim of this retrospective study was to examine the prognostic value of ultrasonographic findings in dogs with PLE. A total of 26 dogs with PLE were included: 20 dogs with chronic enteropathy and 6 dogs with gastrointestinal lymphoma. The presence of small intestinal dilatation was associated with shorter survival time in dogs with PLE (P=0.003). The presence of hyperechoic intestinal mucosal striations was associated with longer survival time in dogs with PLE (P=0.0085). The results of the current study indicate that the presence of small intestinal dilatation might be associated with poor prognosis in dogs with PLE.

The Role of Vitamin D in Small Animal Bone Metabolism

Dogs and cats have differences in vitamin D metabolism compared to other mammalian species, as they are unable to perform vitamin D cutaneous synthesis through sun exposure. Therefore, they are dependent on the dietary intake of this nutrient. The classic functions of vitamin D are to stimulate intestinal calcium and phosphate absorption, renal calcium and phosphate reabsorption and regulate bone mineral metabolism. Thus, it is an important nutrient for calcium and phosphorus homeostasis. This review highlights the evidence of the direct and indirect actions of vitamin D on bone mineral metabolism, the consequences of nutritional imbalances of this nutrient in small animals, as well as differences in vitamin D metabolism between different size dogs.

Determinants of vitamin D status in Kenyan calves

Vitamin D plays a critical role in calcium homeostasis and in the maintenance and development of skeletal health. Vitamin D status has increasingly been linked to non-skeletal health outcomes such as all-cause mortality, infectious diseases and reproductive outcomes in both humans and veterinary species. We have previously demonstrated a relationship between vitamin D status, assessed by the measurement of serum concentrations of the major vitamin D metabolite 25 hydroxyvitamin D (25(OH)D), and a wide range of non-skeletal health outcomes in companion and wild animals. The aims of this study were to define the host and environmental factors associated with vitamin D status in a cohort of 527 calves from Western Kenya which were part of the Infectious Disease of East African Livestock (IDEAL) cohort. A secondary aim was to explore the relationship between serum 25(OH)D concentrations measured in 7-day old calves and subsequent health outcomes over the following 12 months. A genome wide association study demonstrated that both dietary and endogenously produced vitamin D metabolites were under polygenic control in African calves. In addition, we found that neonatal vitamin D status was not predictive of the subsequent development of an infectious disease event or mortality over the 12 month follow up period.

Dietary and Nutritional Approaches to the Management of Chronic Enteropathy in Dogs and Cats

Nutrition can influence those functions of the gastrointestinal tract that can be adversely affected in chronic enteropathy, such as microbiota, mucosal immune system, intestinal permeability, and motility. Diet serves as a possible risk factor in disease pathogenesis and as a target for treatment in chronic enteropathy. Malnutrition is prevalent in people with inflammatory bowel disease and negatively affects outcome. Approximately two-thirds of dogs with protein-losing enteropathy due to chronic enteropathy or lymphangiectasia are underweight. Commercial diets and home-prepared diets have been used successfully in the management of chronic enteropathy. Fat restriction is the main dietary strategy for intestinal lymphangiectasia.

Effects of surgery on free and total 25 hydroxyvitamin D concentrations in dogs

Background

It is unclear whether a low total 25(OH)D concentration is a cause or consequence of illnesses. To address this knowledge gap, studies measuring free and total 25(OH)D during the evolution and resolution of an inflammatory process are required.

Objectives

Serum total and free 25(OH)D concentrations would transiently decline after cruciate surgery in dogs.

Animals

Seventeen client‐owned dogs with a spontaneous cranial cruciate ligament rupture (CCLR).

Methods

A longitudinal cohort study involving the measurement of serum concentrations of total and free 25(OH)D, total calcium, creatinine, albumin, phosphate, C‐reactive protein and plasma ionized calcium, at 1 day before and a median time of 1 and 60 days after surgical treatment of CCLR.

Results

Median serum concentrations of total 25(OH)D before surgery (80.3 nmoL/L [range, 43.5‐137.3]) significantly declined immediately after surgery; (64.8 nmoL/L [range, 36.3‐116.5] 1 day after surgery, P < .005) before increasing to become nonsignificantly different from concentrations before surgery at day 60 after surgery (median 78.0 nmoL/L [range, 24.2‐115.8], P = .14). In contrast, median free 25(OH)D concentrations before surgery (7.6 pg/mL [range, 3.8‐12.2]) significantly increased immediately after surgery (9.2 pg/mL [range, 5.2‐15.7], P < .05) before declining to become nonsignificantly different from before surgery concentrations at day 60 after surgery (median 6.2 pg/mL [range, 4.0‐15.8], P = .37).

Conclusion and Clinical Importance

This study reveals the difficulties of assessing vitamin D status in dogs following elective surgery.

Vitamin D Metabolism and Profiling in Veterinary Species

The demand for vitamin D analysis in veterinary species is increasing with the growing knowledge of the extra-skeletal role vitamin D plays in health and disease. The circulating 25-hydroxyvitamin-D (25(OH)D) metabolite is used to assess vitamin D status, and the benefits of analysing other metabolites in the complex vitamin D pathway are being discovered in humans. Profiling of the vitamin D pathway by liquid chromatography tandem mass spectrometry (LC-MS/MS) facilitates simultaneous analysis of multiple metabolites in a single sample and over wide dynamic ranges, and this method is now considered the gold-standard for quantifying vitamin D metabolites. However, very few studies report using LC-MS/MS for the analysis of vitamin D metabolites in veterinary species. Given the complexity of the vitamin D pathway and the similarities in the roles of vitamin D in health and disease between humans and companion animals, there is a clear need to establish a comprehensive, reliable method for veterinary analysis that is comparable to that used in human clinical practice. In this review, we highlight the differences in vitamin D metabolism between veterinary species and the benefits of measuring vitamin D metabolites beyond 25(OH)D. Finally, we discuss the analytical challenges in profiling vitamin D in veterinary species with a focus on LC-MS/MS methods.

Vitamin D status in cats with cardiomyopathy

BACKGROUND

Low vitamin D concentrations have been associated with advanced heart disease and poorer outcomes in people and dogs. Vitamin D status typically is assessed by serum 25(OH)D concentration. However, cats also produce notable amounts of a C-3 epimer of 25(OH)D (3-epi).

HYPOTHESIS/OBJECTIVES

Determine if vitamin D status, estimated by 25(OH)D₃ alone or combined with 3-epi (summation vitD), is lower in cats with cardiomyopathy (CM) compared to clinically normal (N) cats and if indicators of disease severity are associated with vitamin D status.

ANIMALS

Privately owned cats, 44 with CM and 56 N.

METHODS

Cross-sectional observational study using clinical and echocardiographic findings, diet history, and serum 25(OH)D₃ and 3-epi measurements.

RESULTS

Cat age was negatively related to vitamin D status. Summation vitD was lower in CM cats (median = 47.1 ng/mL) compared to N cats (median = 58.65 ng/mL) both before (P = .03) and after (P = .04) accounting for age. However, 25(OH)D₃ became nonsignificant between CM and N cats after age was included. Summation vitD was related positively to survival time and fractional shortening (FS), but negatively to left atrial enlargement (LAE) severity, both before and after accounting for age. For 25(OH)D₃ alone, only survival time and FS remained significant after including age.

CONCLUSIONS AND CLINICAL IMPORTANCE

We report 25(OH)D₃ and 3-epi concentrations in CM and N cats. Age had an important (negative) relationship to vitamin D status. After accounting for age, summation vitD was lower in CM cats. Vitamin D status was related positively to survival time and FS, but negatively to LAE severity.

Vitamin D status is seasonally stable in northern European dogs

BACKGROUND

Numerous studies in veterinary species have recently linked vitamin D status with nonskeletal health disorders. Previous studies have indicated that dogs cannot produce endogenous vitamin D via cutaneous production and rely solely on dietary intake of vitamin D. The seasonal variation of vitamin D seen in humans due to changes in ultraviolet (UV) exposure, therefore, is unlikely to be replicated in these animals.

OBJECTIVES

The objective of this study was to investigate the natural variation in 25-hydroxyvitamin-D concentrations in dogs subject to seasonal UV exposure.

METHODS

This longitudinal study followed 18 healthy dogs fed a standardized diet over 1 year, with blood samples obtained monthly. Two key vitamin D metabolites, 25-hydroxyvitamin-D₂ and 25-hydroxyvitamin-D₃ , were assessed by liquid chromatography-tandem mass spectrometry in serum samples. Various other biochemical parameters were also measured. Seasonality was assessed using cosinor statistical analysis.

RESULTS

Although the dogs were subject to seasonally varying UV radiation, 25-hydroxyvitamin-D and related biomarkers (including calcium and parathyroid hormone) remained stable over time and did not follow a seasonal pattern. 25-hydroxyvitamin-D was not positively correlated with exposure to UV radiation. Nonetheless, variation in 25-hydroxyvitamin-D concentrations between individual dogs was detected.

CONCLUSIONS

Given the standardization of diet, we concluded that the seasonal stability of 25-hydroxyvitamin-D concentration (vitamin D status) was likely a direct result of lack of cutaneous vitamin D production in this species and highlights the importance of dietary intake. The variation in 25-hydroxyvitamin-D concentration between animals warrants further investigation.

Development and application of a LC-MS/MS assay for simultaneous analysis of 25-hydroxyvitamin-D and 3-epi-25-hydroxyvitamin-D metabolites in canine serum

Hypovitaminosis D and hypervitaminosis D are well recognised disorders in dogs. Hypovitaminosis D can occur following consumption of a diet inadequately supplemented with vitamin D or as a sequelae of severe intestinal disease. Hypervitaminosis D may occur as a result of consuming proprietary dog foods over-supplemented with vitamin D or through ingestion of vitamin D containing medicinal products or rodenticides. Consequently, there is a clear need to establish a methodology that can accurately quantify vitamin D metabolites across a broad dynamic range in dogs. The existence of C3-epimers of vitamin D metabolites has yet to be elucidated in dogs, yet are known to interfere with the analysis of vitamin D and have unknown biological activity in other species. Here, we describe the development and validation of a sensitive, specific and robust analytical liquid chromatography tandem mass spectrometry (LC-MS/MS) assay capable of separating and accurately measuring 25-hydroxyvitamin-D_2/3 (25(OH)D_2/3) and 3-epi-25-hydroxyvitamin-D_2/3 (3-epi-25(OH)D_2/3). We describe a simplified workflow utilising supported liquid extraction (SLE) without derivatization that provides good linearity (mean r > 0.996) and accuracy across a broad dynamic range of 4-500 nmol/L for D₃ metabolites and 7.8-500 nmol/L for D₂ metabolites. Upon application of this assay to 117 canine serum samples, 25(OH)D₃ was detectable in all samples with a median concentration of 82.1 nmol/L (inter-quartile range (IQR) 59.7-101.8 nmol/L). 3-epi-25(OH)D₃ could be detected in 87.2 % of the study population, with a median concentration of 5.2 nmol/L (2.4-8.1 nmol/L). However, 3-epi-25(OH)D₃ was quantified below the LLOQ in 40.2 % of these samples. 3-epi-25(OH)D₃ contributed on average 6.3 % to 25(OH)D₃ status (contribution ranges from 0 to 23.8%) and a positive correlation was detected between 25(OH)D₃ and 3-epi-25(OH)D₃ concentrations. Free 25(OH)D was also measured using an immunoassay with a median concentration of 15.2 pmol/L (12.5-23.2 pmol/L), and this metabolite was also positively correlated to both 3-epi-25(OH)D₃ and 25(OH)D₃ concentrations. D₂ metabolites were not detected in canine serum as expected. Vitamin D metabolite concentrations were variable between individuals, and research into the causes of this variation should include factors such as breed, age, sex and neuter status to determine the impact of genetic and hormonal factors. Given the clinical importance of vitamin D in dogs, and the immense potential for utilising this species as a model for human disease, further elucidation of the vitamin D pathway in this species would provide immense clinical and research benefit.

Vitamin D metabolism in dogs and cats and its relation to diseases not associated with bone metabolism

Due to the presence of receptors in the cells of numerous body tissues, vitamin D is associated with several physiological functions that go beyond calcium and phosphorus homoeostasis and control of bone metabolism in the body. In humans, several studies have associated lower vitamin D concentrations with numerous diseases, such as cancer, heart disease, autoimmune diseases and infectious diseases, and also with an increase in the total mortality rate of the population. Recently, this nutrient started to gain importance in veterinary medicine, and several articles have shown a correlation between low vitamin D status and diseases unrelated to bone metabolism. The present review aims to highlight the recent publications that investigated this relationship, bringing the evidence that exists so far in dogs and cats.

Comparison of clinical, clinicopathologic, and histologic variables in dogs with chronic inflammatory enteropathy and low or normal serum 25-hydroxycholecalciferol concentrations

Background

The cause of low serum vitamin D concentrations in dogs with chronic inflammatory enteropathy (CIE) is not well understood.

Objective

Improve understanding of pathogenesis of low serum vitamin D concentrations in dogs with CIE by comparing several clinical, clinicopathologic, and histologic variables between CIE dogs with low and normal serum 25‐hydroxyvitamin D concentrations (25[OH]D).

Animals

Fifteen dogs with CIE and low serum 25[OH]D concentrations; 15 dogs with CIE and normal serum 25(OH)D concentrations.

Methods

Prospective cohort study. Clinical and clinicopathologic variables were compared between groups. Correlations between serum 25(OH)D concentration and histopathologic variables were assessed.

Results

Dogs with CIE and low serum 25(OH)D concentrations had higher canine chronic enteropathy clinical activity index scores (P = .003), lower serum α‐tocopherol (P < .001), cholesterol (P < .001), and albumin (P < .001) concentrations and higher serum C‐reactive protein (P = .004) concentrations compared to CIE dogs with normal serum 25(OH)D concentrations. Serum concentrations of vitamin D‐binding protein (VDBP) were not different between groups (P = .91). Duodenal morphologic and inflammatory histopathological scores (P = .002 and P = .004, respectively) and total histopathological scores in duodenum and combined duodenum and ileum negatively correlated with serum 25(OH)D concentration.

Conclusions and Clinical Importance

The pathogenesis of low serum vitamin D concentrations in dogs with CIE is likely multifactorial. Fat malabsorption deserves further study in dogs with low serum vitamin D concentration and CIE. Loss of VDBP does not appear to be an important cause of low serum vitamin D concentration in dogs with CIE.

Impact of Micronutrients on the Immune Response of Animals

Vitamins and minerals (micronutrients) play an important role in regulating and shaping an immune response. Deficiencies generally result in inadequate or dysregulated cellular activity and cytokine expression, thereby affecting the immune response. Decreased levels of natural killer, granulocyte, and phagocytic cell activity and T and B cell proliferation and trafficking are associated with inadequate levels of micronutrients, as well as increased susceptibility to various adverse health conditions, including inflammatory disorders, infection, and altered vaccine efficacy. In addition, most studies of micronutrient modulation of immune responses have been done in rodents and humans, thus limiting application to the health and well-being of livestock and companion animals. This exploratory review elucidates the role of vitamins and minerals on immune function and inflammatory responses in animals (pigs, dogs, cats, horses, goats, sheep, and cattle), with reference to rodents and humans.

Effects of calcitriol on phagocytic function, toll-like receptor 4 expression, and cytokine production of canine leukocytes

OBJECTIVE To determine the in vitro effects of calcitriol on indicators of immune system function in blood samples collected from healthy dogs. SAMPLE Blood samples from 8 healthy adult dogs. PROCEDURES Blood samples were incubated with calcitriol (10^-7M) or control substance for 24 hours. Afterward, lipopolysaccharide (LPS)-, lipoteichoic acid (LTA)-, and N-acetylmuramyl-l-alanyl-d-isoglutamine hydrate (MDP)-stimulated leukocyte production of tumor necrosis factor (TNF) and interleukin-10 (IL10) were measured with a canine-specific multiplex assay. Phagocytosis of opsonized Escherichia coli and leukocyte expression of constitutive toll-like receptor 4 (TLR4) were evaluated via flow cytometry. Blood samples from 3 dogs were used to create a concentration-response curve to evaluate whether the observed cytokine modulation was concentration dependent. RESULTS Incubation of canine blood samples with calcitriol resulted in significant decreases in LPS-, LTA-, and MDP-stimulated leukocyte production of TNF but not IL10. Blunting of TNF production was concentration dependent. Leukocyte calcitriol exposure had no significant effect on phagocytosis and TLR4 expression. CONCLUSIONS AND CLINICAL RELEVANCE These data indicated that calcitriol induced an anti-inflammatory shift in canine leukocytes exposed to LPS, LTA, and MDP in vitro, without altering phagocytosis or TLR4 expression. Thus, calcitriol could represent a novel candidate immunomodulatory treatment for dogs.

Clinical utility of currently available biomarkers in inflammatory enteropathies of dogs

Chronic inflammatory enteropathies (CIE) in dogs are a group of disorders that are characterized by chronic persistent or recurrent signs of gastrointestinal disease and histologic evidence of mucosal inflammation. These CIEs are classified as either food-responsive, antibiotic-responsive, or immunosuppressant-responsive enteropathy. Patients not clinically responding to immunomodulatory treatment are grouped as nonresponsive enteropathy and dogs with intestinal protein loss as protein-losing enteropathy. Disease-independent clinical scoring systems were established in dogs for assessment of clinical disease severity and patient monitoring during treatment. Histopathologic and routine clinicopathologic findings are usually not able to distinguish the subgroups of CIE. Treatment trials are often lengthy and further diagnostic tests are usually at least minimally invasive. Biomarkers that can aid in defining the presence of disease, site of origin, severity of the disease process, response to treatment, or a combination of these would be clinically useful in dogs with CIE. This article summarizes the following biomarkers that have been evaluated in dogs with CIE during the last decade, and critically evaluates their potential clinical utility in dogs with CIE: functional biomarkers (cobalamin, methylmalonic acid, folate, α1 -proteinase inhibitor, immunoglobulin A), biochemical biomarkers (C-reactive protein, perinuclear anti-neutrophilic cytoplasmic antibodies, 3-bromotyrosine, N-methylhistamine, calprotectin, S100A12, soluble receptor of advanced glycation end products, cytokines and chemokines, alkaline phosphatase), microbiomic biomarkers (microbiome changes, dysbiosis index), metabolomic biomarkers (serum metabolome), genetic biomarkers (genomic markers, gene expression changes), and cellular biomarkers (regulatory T cells). In addition, important performance criteria of diagnostic tests are briefly reviewed.

Determining optimal therapy of dogs with chronic enteropathy by measurement of serum citrulline

Background

Serum concentration of citrulline is a useful biomarker in human intestinal disease and indicates globally reduced enterocyte mass and absorptive function in various disease states.

Objectives

To determine whether serum citrulline concentration is a biomarker in chronic enteropathy (CE) in dogs, to provide useful information regarding optimal treatment or to predict outcome.

Animals

Seventy‐four dogs with CE and 83 breed‐ and age‐matched hospital controls with no clinical signs of intestinal disease.

Methods

Retrospective study. Outcome was determined and dogs were categorized by response to treatment as having food‐responsive enteropathy (FRE), antibiotic‐responsive diarrhea (ARD), or idiopathic inflammatory bowel disease (IBD). Disease severity was quantified by the CIBDAI scoring index.

Results

Serum citrulline concentration did not differ between dogs with CE (median, 8.4 µg/mL, 5th‐95th percentile 2.0‐19.6) and controls (median, 8.1 µg/mL, 5th‐95th percentile 2.2‐19.7, P = .91). Serum citrulline concentration was similar between dogs with FRE (median, 9.1 µg/mL, 5th‐95th percentile 2.0‐18.9), ARD (median, 13.0 µg/mL, 5th‐95th percentile 1.6‐19.2), IBD (median, 8.4 µg/mL, 5th‐95th percentile 2.1‐21.0; P = .91). Serum citrulline did not correlate to CIBDAI or to serum albumin concentration.

Conclusions and Clinical Importance

In our study, serum citrulline concentration was not associated with efficacy of treatment or outcome in dogs with CE.

Chronic Diarrhea in Dogs - Retrospective Study in 136 Cases

Background

Chronic diarrhea (CD) is common in dogs, and information on frequency and distribution of primary and secondary causes is lacking.

Objectives

To evaluate underlying causes and predictors of outcome in dogs with CD.

Animals

One hundred and thirty‐six client‐owned dogs with CD (≥3 weeks duration).

Methods

Retrospective review of medical records (Small Animal Clinic, Freie Universität Berlin, Germany, 09/2009‐07/2011). Quantification of final diagnoses and comparison of clinical aspects including disease severity and clinicopathological abnormalities among dogs with clinical remission (either complete [gastrointestinal signs absent] or partial [clinical improvement of gastrointestinal signs and reduced episodes with shortened duration]), and those without recovery.

Results

Ninety percent of dogs were diagnosed with a primary enteropathy: inflammatory (71%; of those 66% dietary responsive, 23% idiopathic, 11% antibiotic responsive), infectious (13%), neoplastic (4%), and in one dog each mechanical disease or systemic vasculitis. Secondary causes were diagnosed in 10% of dogs: exocrine pancreatic (6%), endocrine (2%), and in one dog each hepatic, renal, and cardiac disease. In total, 87% of dogs had clinical remission, whereas 13% died or did not respond to treatment: Lack of recovery was frequently recorded for dogs with primary inflammatory (idiopathic) or neoplastic disease and was significantly associated with increased disease severity scores (P = .005), anemia (hematocrit < 40%, P < .001), severe hypoalbuminemia (serum albumin <2.0 g/dL, P = .008), and severe hypocobalaminemia (serum cobalamin concentration <200 pg/mL, P = .006).

Conclusions and clinical importance

Inflammatory enteropathies and particularly those of dietary origin were the most common causes of CD in dogs. Findings support the usefulness of hematocrit, and serum albumin and cobalamin concentration as prognostic markers in dogs with CD.

Canine Leishmaniasis Progression is Associated with Vitamin D Deficiency

The relationship between vitamin D deficiency and the risk of suffering from a plethora of health disorders, ranging from autoimmune processes to infectious diseases has been widely described. Nonetheless, the potential role of vitamin D in visceral leishmaniasis remains uncharacterized. In the Mediterranean basin, where the dog is leishmania’s main peri-domestic reservoir, control measures against the canine disease have shown beneficial effects on the incidence of human leishmaniasis. In this study, we measured the vitamin D levels in serum samples from a cohort of 68 healthy and disease dogs from a highly endemic area and we have also studied the relationship of these levels with parasitological and immunological parameters. The sick dogs presented significantly lower (P < 0.001) vitamin D levels (19.6 ng/mL) than their non-infected (31.8 ng/mL) and the asymptomatic counterparts (29.6 ng/mL). In addition, vitamin D deficiency correlated with several parameters linked to leishmaniasis progression. However, there was no correlation between vitamin D levels and the Leishmania-specific cellular immune response. Moreover, both the leishmanin skin test and the IFN-γ levels displayed negative correlations with serological, parasitological and clinical signs. Further studies to determine the functional role of vitamin D on the progression and control of canine leishmaniasis are needed.

Hypovitaminosis D is associated with negative outcome in dogs with protein losing enteropathy: a retrospective study of 43 cases

Background

Hypovitaminosis D has previously been shown to be prevalent amongst dogs with protein losing enteropathy (PLE).

The hypothesis of this study was that Low 25-hydroxyvitamin D (25(OH) D) serum concentrations could be a risk factor for negative outcome in dogs with PLE.

Forty-three dogs diagnosed with PLE (2005–2014) and which serum Vitamin D serum concentrations were collected and archived at −80 Degrees C were analyzed.

Post-diagnostic communication with referring veterinarians was made to determine outcome of PLE dogss: Dogs which died due to PLE within 4 months after diagnosis (negative outcome group, n = 22) and dogs alive or which died due to another disease at the end point of the study (1 year after diagnosis, good outcome group, n = 21). Serum samples taken at the time of diagnosis were analysed for ionized calcium (iCa) concentrations and serum 25(OH) D concentration.

Results

Clinical (CCECAI) scores, age at PLE diagnosis, and iCa concentrations were not significantly different between dog groups. A significantly greater (p < 0.001) number of PLE dogs treated with hydrolyzed or elimination diet alone showed good outcome as compared to the PLE negative outcome group. Median serum 25(OH) D concentration was significantly (p = 0.017) lower in dogs with negative outcome versus PLE dogs with good outcome. Using logistic regression analysis, 25(OH) D serum concentration was shown to be a statistically significant factor for outcome determination. Cox regression analysis yielded a hazard ratio of 0.974 (95% CI 0.949, 0.999) per each one nmol/l increase in serum 25(OH) D concentration.

Conclusions

Low serum 25(OH) D concentration in PLE dogs was significantly associated with poor outcome. Further studies are required to investigate the clinical efficacy of Vitamin D (cholecalciferol) as a potential therapeutic agent for dogs with PLE.

Beyond the skeleton: the role of vitamin D in companion animal health

While the role of vitamin D in the maintenance of skeletal health has been well-established for many years, the discovery that many non-skeletal tissues express the vitamin D receptor stimulated renewed interest in vitamin D and its wider physiological roles. Subsequently, a vast literature has emerged over the past three decades which has linked vitamin D deficiency to the development of many human diseases including cancer, autoimmune, infectious and cardiovascular disorders. In contrast, the role vitamin D plays in the physiology of non-skeletal tissues in cats and dogs has received little attention. The situation is now starting to change with the publication of several studies that have indicated that vitamin D metabolism is deranged in numerous companion animal disorders. This article reviews the biology of vitamin D in companion animals and highlights some of the recent studies which have advanced understanding of vitamin D homeostasis in cats and dogs. Finally, the essay discusses how a "One Health" approach could further the understanding of vitamin D metabolism in mammals. Investigating vitamin D homoeostasis in companion animals offers many advantages compared to human studies in which vitamin D status is influenced by many more variables.