Ex Vivo Immune Function and Modulatory Effects of Calcitriol in Dogs with Naturally Occurring Diabetes Mellitus.

Human patients with type 1 diabetes mellitus (T1DM) are susceptible to several long-term complications that are related to glycemic control and immune dysregulation. Immune function remains relatively unexplored in dogs with naturally occurring diabetes mellitus (NODM). Calcitriol improves various aspects of immune function in a variety of species, but its effect in diabetic dogs remains unexplored. Therefore, the objectives of this study were to (i) evaluate immune function in dogs with NODM and determine if differences exist based on the level of clinical control and (ii) assess the immunomodulatory effects of calcitriol. Twenty diabetic dogs (clinically controlled, n = ten, not controlled, n = ten) and 20 non-diabetic, healthy control dogs were included in this prospective, case-control study. Whole blood was incubated with calcitriol (10-7 M) or negative control, after which the samples were divided for phagocytosis and leukocyte cytokine response experiments. The phagocytosis of opsonized Escherichia coli (E. coli) was evaluated with flow cytometry. The samples for leukocyte cytokine response evaluations were stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or phosphate buffer solution (PBS; negative control), and tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8, and IL-10 were measured in supernatant using a canine-specific multiplex bead-based assay. The leukocytes from diabetic dogs produced higher concentrations of IL-10 (p = 0.01), IL-6 (p < 0.0001), and IL-8 (p < 0.0001) than the control dogs while controlling for the intervention and stimulant. Calcitriol decreased the supernatant concentrations of TNF-α (p < 0.001) and IL-8 (p = 0.04) with concomitant increases in IL-6 (p = 0.005). Diabetic dogs had a lower percentage of leukocytes undergoing phagocytosis (p < 0.0001) but a higher number of bacteria phagocytized per cell (p = 0.001) when compared to the control dogs. Calcitriol had no effect on phagocytic capacity. Lastly, the status of clinical control in diabetic dogs did not yield differences in immune function. These results support that dogs with NODM exhibit immune dysregulation and warrant additional investigation.

Age-dependent changes in plasma concentrations of 25-hydroxyvitamin D may complicate vitamin D status assessment of immature cats.

Background: Vitamin D deficiency and excess in clinically presented cats conventionally is diagnosed by comparison of patient plasma 25-hydroxyvitamin D (25 (OH)D) concentration with plasma reference intervals determined in healthy adult cats. For immature cats, validity of this vitamin D status assessment method is uncertain. Objective: The overall objective was determination of whether plasma concentration of 25 (OH) D and other vitamin D metabolites in immature cats markedly change with developmental age as has been reported in other species. Methods: Four male and 4 female domestic short-hair kittens from weaning were continuously presented a single nutritionally adequate growth-diet. Concentrations of 25 (OH) D and 24,25-dihydroxyvitamin D (24,25 (OH)2D), and calcitriol were quantified in plasma of jugular venous blood collected at 12, 15, 18, and 21 weeks and 1 year of age. Plasma was liquid and solid-phase extracted and fractionation by normal-phase HPLC, and 25 (OH) D and 24,25 OH)2D quantified by reverse-phase HPLC-UV and calcitriol by RIA. Results: Plasma 3-epi-25 (OH) D and 25 (OH) D concentrations increased (p < 0.001) with age so that by study end the concentrations rose by 1-and 2-fold, respectively. Concentrations of 3-epi-25 (OH) D relative to 25 (OH) D were 30% at 12 weeks and 20% at 1 year. Between ages 12 and 21 weeks, rises in 25 (OH) D concentration were positively correlated with body weight gains (ρ = 0.952, p < 0.001) and 24,25 (OH)2D concentrations were consistently greater than 25 (OH) D concentrations (p < 0.001). At 1 year of age, concentrations of 24,25 (OH)2D declined below those of 25 (OH) D and 3-epi-24,25 (OH)2D consistency occurred in low concentrations. Vitamin D2 metabolites and sex differences in metabolite concentrations were not observed. Conclusion: Reliance on quantification of plasma 25 (OH) D concentration for vitamin D status assessment in kittens may be confounded by developmental changes in 25 (OH) D independent of vitamin D intake. High 24,25 (OH)2D concentration and occurrence of 3-epi-25 (OH) D in plasma additionally may interfere with the quantification.

Evaluation of serum 25-hydroxyvitamin D, C-reactive protein, and haptoglobin as biomarkers in dogs newly diagnosed with histoplasmosis.

BACKGROUND: Serum 25-hydroxyvitamin (OH)D, C-reactive protein (CRP), and haptoglobin are useful biomarkers in various infectious diseases and inflammatory disorders in dogs, but their utility in histoplasmosis is unknown. OBJECTIVE: Determine if serum 25(OH)D, CRP, and haptoglobin concentrations are different in dogs with histoplasmosis compared to healthy controls and whether serum globulin, albumin, CRP, or haptoglobin are associated with 25(OH)D concentration. ANIMALS: Twenty-two client-owned dogs (histoplasmosis, n = 12; controls, n = 10). METHODS: Prospective case-control study. Dogs with histoplasmosis were categorized as pulmonary, disseminated, or gastrointestinal (GI) tract. Serum 25(OH)D was measured using modified high-performance liquid chromatography (HPLC). Serum CRP and haptoglobin were measured with ELISA assays. RESULTS: Dogs with histoplasmosis were grouped as disseminated (n = 8) and GI tract (n = 4). No dogs had pulmonary tract involvement alone. Dogs with histoplasmosis (median, interquartile range [IQR]; 11.6 ng/mL, 16.8) had lower serum 25(OH)D concentrations than controls (35.7 ng/mL, 17.6; P < .001). Serum CRP and haptoglobin concentrations were higher in dogs with histoplasmosis (CRP: median, IQR; 63.5 mg/L, 37.1 and haptoglobin: 459.7 mg/dL, 419.6) than controls (CRP: 1.9 mg/L, 2; P < .001 and haptoglobin: 85.5 mg/dL, 106.7; P = .003). Serum 25(OH)D concentration was positively associated with fold change in serum albumin concentration (ρ = 0.77; P < .001), and negatively associated with fold change in serum globulin (ρ = -0.61; P = .003) and CRP concentrations (ρ = -0.56; P = .01). CONCLUSION AND CLINICAL IMPORTANCE: Assay of serum 25(OH)D, CRP, and haptoglobin could have clinical value in dogs with histoplasmosis.

Serum 25-hydroxyvitamin D concentrations in dogs with coccidioidomycosis and variables associated with extent of clinically evident disease.

BACKGROUND: Clinicopathologic variables predictive of disseminated coccidioidomycosis are known in humans but have not been explored in dogs. Serum 25-hydroxyvitamin (OH)D correlates with severity of disease of various etiologies in dogs but its role in coccidioidomycosis is unknown. OBJECTIVE: Determine whether serum 25(OH)D concentrations are different in dogs with coccidioidomycosis compared with healthy controls and if clinicopathologic variables are associated with extent of disease. ANIMALS: Thirty-five dogs with coccidioidomycosis (pulmonary, n = 13; disseminated, n = 15; uncharacterized, n = 7), and 25 healthy control dogs. METHODS: Prospective cohort study. Serum 25(OH)D and C-reactive protein (CRP) concentrations were measured with modified-HPLC and a commercial ELISA kit, respectively. RESULTS: There was no difference in 25(OH)D concentrations between dogs with coccidioidomycosis (median, interquartile range [IQR]; 31.9 ng/mL, 23.3-49.2) and controls (29.5 ng/mL, 25.6-40.8, P = .73). Serum 25(OH)D concentration was lower in dogs with coccidioidomycosis and IgG titers ≥1:32 than dogs with titers below this cut-off (P = .02). Dogs with IgG titers ≥1:32 were more likely to have disseminated disease (OR, 7.5; 95% CI: 1.1-68; P = .03). Serum CRP concentrations were higher in dogs with IgG titers ≥1:16 (median, IQR; 4474.8 ng/mL, 2885.8-8236.1) than in those below this cut-off (151.2 ng/mL, 30.4-2907.3; P = .02). There was a significant inverse association between serum 25(OH)D and CRP at 25(OH)D concentrations ≤33 ng/mL. CONCLUSION AND CLINICAL IMPORTANCE: Serum 25(OH)D concentration was lower for dogs with IgG titers ≥1:32, indicating a potential association between semi-quantitative titers and 25(OH)D concentrations in dogs with coccidioidomycosis. IgG titers ≥1:32 yielded higher odds of disseminated disease, but was inadequate as a standalone test to determine form of disease.

Plasma and Whole Blood Taurine Concentrations in Dogs May Not Be Sensitive Indicators of Taurine Deficiency When Dietary Sulfur Amino Acid Content Is Reduced.

Background: Taurine status is impacted by dietary supply of methionine and cysteine (SAA) and possibly intestinal microbial activity, where plasma and whole blood taurine concentrations are currently used to evaluate taurine status. Objective: We determined effects of dietary SAA restriction on rate and extent of taurine depletion of blood and skeletal muscle in dogs of two body sizes, and whether oral antibiotic administration affected the taurine depletion and fecal bile acid excretion of the dogs. Methods: Adult, male, Beagles (n = 6; 10.1-13.1 kg) and larger mixed-breed dogs (n = 6; 28.5-41.1 kg) were given four dry-expanded diets, whereby each successive diet contained lower protein and/or SAA concentration. After receiving the final diet for 44 weeks, all dogs were orally administered a mixture of ampicillin, neomycin sulfate, and metronidazole for 12 weeks. Taurine concentrations were determined every 2-4 weeks in venous blood and voided urine and every 4 to 16 weeks in biopsied semimembranosus muscle. Fecal bile acid excretion before and after antibiotics administration were quantified. Results: When given for 36 weeks the lowest SAA diet, 3.4% methionine and 2.9% cystine, taurine concentrations in whole blood were not different between groups, while taurine in plasma declined (P < 0.05) in large but not in small dogs, and taurine in biopsied muscle decreased (P < 0.05) by 50% in large and by 37% in small dogs. Concentrations of taurine in muscle were lower (P < 0.01) and fecal bile acids greater (P = 0.001) in large than small dogs. Antibiotic administration restored plasma and muscle taurine to initial concentrations and halved fecal bile acid excretion by dogs of both groups. Conclusions: Blood taurine concentration may not be a sensitive indictor of taurine depletion caused by low intake of bioavailable SAA in dogs, especially in large dogs. Taurine status and dietary SAA requirements of dogs may substantively depend on taurine loss mediated by intestinal microbiota.

Dietary 25-hydroxyvitamin D3 effects on vitamin D status, plasma metabolites and urine mineral excretion in adult cats.

OBJECTIVES: The study aimed to evaluate the safety and effectiveness of vitamin D supplementation with dietary 25-hydroxyvitamin D3 (25[OH]D3) in adult cats. METHODS: Three levels of dietary 25(OH)D3 concentrations (4.9, 8.4, 11.8 µg/kg as fed) were received by five adult cats for 9 weeks, each in a randomized complete block design. Effects were determined on plasma or serum concentrations of 25(OH)D3, 24,25-dihydroxyvitamin D3, calcitriol, parathyroid hormone, ionized calcium, urinary excretions of phosphorus, calcium and magnesium, and clinical hematology and chemistry panels. RESULTS: The lowest concentration of dietary 25(OH)D3 supported elevation of vitamin D status, with no adverse effects. Supplementation of 8.4 µg/kg 25(OH)D3 had significant effects on the urinary magnesium: creatinine ratio. Increasing supplementation up to 11.8 µg/kg 25(OH)D3 had significant effects on plasma concentrations of calcium and magnesium, and vitamin D metabolites. CONCLUSIONS AND RELEVANCE: Dietary supplementation with approximately 5.0 µg/kg of 25(OH)D3 or the ingested equivalence of 0.09 µg of 25(OH)D3 per metabolic body weight (kg0.67) is a safe, potent and effective means for raising vitamin D status in cats. A higher dose with approximately 11.8 µg/kg of 25(OH)D3 resulted in elevation in C-3 epimers of 25(OH)D3 and slight elevation in plasma magnesium and calcium concentrations above their respective reference intervals.

Investigation of the effects of dietary supplementation with 25-hydroxyvitamin D3 and vitamin D3 on indicators of vitamin D status in healthy dogs.

OBJECTIVE: To compare the effects of short-term dietary supplementation with vitamin D3 and 25-hydroxyvitamin D3 (25[OH]D3) on indicators of vitamin D status in healthy dogs. ANIMALS: 13 purpose-bred adult dogs. PROCEDURES: 20 extruded commercial dog foods were assayed for 25(OH)D3 content. Six dogs received a custom diet containing low vitamin D concentrations and consumed a treat with vitamin D2 (0.33 µg/kg0.75) plus 1 of 3 doses of 25(OH)D3 (0, 0.23, or 0.46 µg/kg0.75) once daily for 8 weeks followed by the alternate treatments in a crossover-design trial. In another crossover-design trial, 7 dogs received a custom diet supplemented with vitamin D3 or 25(OH)D3 (targeted content, 3,250 U/kg [equivalent to 81.3 µg/kg] and 16 µg/kg, respectively, as fed) for 10 weeks followed by the alternate treatment. In washout periods before each trial and between dietary treatments in the second trial, dogs received the trial diet without D-vitamer supplements. Dietary intake was monitored. Serum or plasma concentrations of vitamin D metabolites and biochemical variables were analyzed at predetermined times. RESULTS: 25(OH)D3 concentrations were low or undetected in evaluated commercial diets. In the first trial, vitamin D2 intake resulted in quantifiable circulating concentrations of 25-hydroxyvitamin D2 but not 24R,25-dihydroxyvitamin D2. Circulating 25(OH)D3 concentration appeared to increase linearly with 25(OH)D3 dose. In the second trial, circulating 25(OH)D3 concentration increased with both D vitamer-supplemented diets and did not differ significantly between treatments. No evidence of vitamin D excess was detected in either trial. CONCLUSIONS AND CLINICAL RELEVANCE: Potency of the dietary 25(OH)D3 supplement estimated on the basis of targeted content was 5 times that of vitamin D3 to increase indicators of vitamin D status in the study sample. No adverse effects attributed to treatment were observed in short-term feeding trials.

Effects of Vitamin D2 and 25-Hydroxyvitamin D2 Supplementation on Plasma Vitamin D Epimeric Metabolites in Adult Cats.

Feline vitamin D status is based on dietary consumption but metabolism of this essential nutrient and the efficacy of supplementation forms are poorly described in cats. The aim of this study was to further elucidate the metabolites of vitamin D2 in cats and to compare the effectiveness of vitamin D2 and 25(OH)D2 for increasing feline vitamin D status. Eight adult male castrated domestic shorthair cats received vitamin D2 or 25(OH)D2 in a single crossover design. Vitamin D2 was dosed daily in a molar equivalent dosage to vitamin D3 ingested in the diet while 25(OH)D2 was provided at a daily dose of 20% molar equivalent intake of dietary vitamin D3 based on its expected higher potency. Plasma concentrations of 25-hydroxyvitamin D epimers were evaluated at baseline then every 2 weeks for a total of 10 weeks. Analysis of multiple vitamin D metabolite concentrations was completed at the end of each supplementation period, followed by a washout period preceding the second phase of the crossover trial. Results showed that supplementation with 25(OH)D2 more effectively and rapidly raised circulating 25(OH)D2 levels in cat plasma compared to vitamin D2. Formation of C-3 epimers of 25(OH)D3, 25(OH)D2, and 24,25R(OH)2D3, but not 24,25(OH)2D2, were observed in feline plasma. The abundant concentrations of epimeric forms of vitamin D metabolites found in circulation suggest that these metabolites should be considered during vitamin D analyses in cats. Further studies using 25(OH)D and vitamin D2 forms are needed to conclude safety and efficacy of these vitamers for supplementation in this species.

Rapid improvement in vitamin D status with dietary 25-hydroxycholecalciferol in vitamin D insufficient dogs.

Vitamin D insufficiency is associated with various disease processes. We determined whether consumption of a diet supplemented with HyD®, a 25-hydroxycholecalciferol (25(OH)D3) source, would safely increase plasma 25(OH)D3 concentrations in Golden Retrievers with low vitamin D status. We hypothesised that dietary supplementation with HyD® would rapidly increase and sustain plasma 25(OH)D3 levels in healthy Golden Retrievers with low vitamin D status compared with supplementation with vitamin D3. Of fifty-seven privately owned dogs recruited with written owner consent, eighteen dogs with low vitamin D status were identified and sorted between two groups to have similar initial plasma 25(OH)D3 concentrations, sex distributions, ages and body weights. Dogs of each group were fed a dry dog food supplemented with either 16 µg/kg of 25(OH)D3 as HyD® (n 10) or 81 µg/kg of cholecalciferol (D3) (n 8) for 4 months. Plasma 25(OH)D3 concentrations were determined monthly. A significant time effect (P < 0⋅001) and time by group interaction (P = 0⋅0045) were found for monthly determined plasma 25(OH)D3 concentrations. Dogs fed the HyD®-supplemented diet experienced a 40⋅5 % rise in plasma 25(OH)D3 values after 1 month (P < 0⋅001) and no change thereafter. Plasma 25(OH)D3 values of dogs supplemented with vitamin D3 did not increase (P > 0⋅05) and were less than values of dogs supplemented with HyD® (P = 0⋅044). With few exceptions, average haematologic, biochemical and urinalyses results remained within the reference range for both groups. Dietary supplementation with HyD® is sufficient to safely increase and sustain plasma 25(OH)D3 levels in healthy dogs.

A review of phosphorus homeostasis and the impact of different types and amounts of dietary phosphate on metabolism and renal health in cats.

Elevated concentrations of serum phosphate are linked with progression and increased case fatality rate in animals and humans with chronic kidney disease. Elevated concentrations of serum phosphate can be a risk factor for development of renal and cardiovascular diseases or osteoporosis in previously healthy people. In rodents, an excess intake of dietary phosphorus combined with an inverse dietary calcium : phosphorus ratio (<1 : 1) contributes to renal calcification. Renal injury also has occured in cats fed experimental diets supplemented with highly soluble phosphate salts, especially in diets with inverse calcium : phosphorus ratios. However, not all phosphorus sources contribute similarly to this effect. This review, which focuses on cats, summarizes the published evidence regarding phosphorus metabolism and homeostasis, including the relative impact of different dietary phosphorus sources, and their impact on the kidneys. No data currently shows that commercial cat foods induce renal injury. However, some diets contain high amounts of phosphorus relative to recommendations and some have inverse Ca : P ratios and so could increase the risk for development of kidney disease. While limiting the use of highly soluble phosphates appears to be important, there are insufficient data to support a specific upper limit for phosphate intake. This review also proposes areas where additional research is needed in order to strengthen conclusions and recommendations regarding dietary phosphorus for cats.

Successful Long-Term Management of Canine Superficial Necrolytic Dermatitis With Amino Acid Infusions and Nutritionally Balanced Home-Made Diet Modification.

A 10-year old, castrated male, Bichon Frise with a history of hyperadrenocorticism and intrahepatic portal vein hypoplasia was diagnosed with superficial necrolytic dermatitis (SND). The dog exhibited thick crusts on the chin, muzzle, prepuce, and paws. In addition, the dorsal surfaces of all paws were erythematous while the palmar/plantar surfaces were hyperkeratotic, hardened, and painful. The dog was treated with intravenous amino acid infusions (AAI), raw egg yolks, as well as zinc and omega-3 fatty acid oral supplements. The dog required AAI once every 2-3 weeks because this coincided with recrudescence of painful skin lesions. The dog was subsequently diagnosed with diabetes mellitus. A consult with the Nutrition Service was pursued 220 days after the original SND diagnosis because of concern for feeding raw eggs and for malnutrition since appetite was variable, muscle condition was reduced, and greater than 50% of ingested calories were from foods that were not nutritionally complete. There was also concern regarding the variability of the diet and the impact it would have on the management of diabetes mellitus. The diet was prepared by the dog owner according to a provided recipe and presented twice daily. The diet was rich in high quality protein and fat. All other treatments including medications, supplements, and bathing schedule remained unchanged at the time of diet modification. The dog was subclinical for SND associated clinical signs approximately 3 weeks after the diet modification, which also coincided with the last AAI. The AAI was postponed and was next administered 7 weeks later (i.e., 10 weeks from the previous infusion). The dog remained subclinical for SND related clinical signs and continued to receive AAI once every 10-12 weeks until he was euthanized 718 days later for complications related to severe multi-drug resistant, skin infections. In conclusion, this report highlights a novel role for nutritionally balanced home-made diets designed by a board-certified veterinary nutritionist could substantially increase time interval between AAI and outcome in dogs with SND.

Effects of body fat mass and therapeutic weight loss on vitamin D status in privately owned adult dogs.

More than one-third of humans and companion dogs in Western societies are overweight or obese. In people, vitamin D deficiency is widespread and associated with obesity, a now recognised inflammatory state. Low vitamin D status occurs in dogs with inflammatory conditions, but its relationship with obesity has not been investigated. In otherwise healthy privately owned adult dogs of ideal body condition (control, n 7) and dogs with overweight to obese body condition (treatment, n 8), serum 25-hydroxyvitamin D (25(OH)D) concentration and body composition as inferred from 2H-labelled water dilution space were evaluated. Subsequently, the dogs were transitioned to a commercial canine therapeutic weight-loss diet; control dogs were fed to maintain body weight and treatment dogs were energy-restricted to achieve a safe weight-loss rate. Thereafter, serum 25(OH)D concentration was re-evaluated 8 weeks after diet transition, and at the study end, which was 6 months or when ideal body condition was achieved. At study end, body composition analysis was repeated. Initial body condition scores and percentage body fat were positively correlated (ρ = 0·891; P < 0·001). However, percentage body fat and serum 25(OH)D concentration were not significantly correlated. Final serum 25(OH)D concentrations were greater (P < 0·05) than initial concentrations for control and treatment groups, indicating a diet but not weight-loss effect on vitamin D status. These findings suggest that vitamin D status of dogs is not affected by obesity or loss of body fat with therapeutic weight reduction.

Serum vitamin D concentrations in hospitalized critically ill dogs.

Hypovitaminosis D has been extensively documented in critically ill humans. However, whether or not critically ill dogs have alterations in vitamin D concentrations remains unconfirmed. The primary aims of our study were to compare serum 25-hydroxycholecalciferol [25(OH)D] concentrations in critically ill dogs with healthy control dogs, determine the prognostic utility of serum 25(OH)D concentration as a biomarker in critically ill dogs, and to assess if serum 25(OH)D concentrations in critically ill dogs are associated with length of stay in the intensive care unit or illness severity. Serum concentrations of 25(OH)D together with a range of other clinical, biochemical, and hematological parameters, were measured in 99 dogs within 24 hours of admission to the Intensive Care Unit (ICU). Critically ill dogs (P = 0.001) and dogs with sepsis (P = 0.002) had significantly lower serum 25(OH)D concentrations compared to healthy control dogs. In addition, serum 25(OH)D concentration was an independent predictor of in-hospital and 30 day survival. Using a cut-off of 33 ng/mL, serum 25(OH)D concentrations had excellent sensitivity (0.94; 95% CI, 0.71-1.00), but poor specificity (0.41; 95% CI, 0.31-0.53) for detection of survival. Serum 25(OH)D concentrations were inversely associated with acute patient physiologic and laboratory evaluation (APPLE) fast score but were not associated with ICU length of stay. Hospitalized dogs with critical illness have decreased serum 25(OH)D concentrations compared to healthy dogs and can be used to predict survival in this cohort.

Previously undescribed vitamin D C-3 epimer occurs in substantial amounts in the blood of cats.

Objectives The aim of this report is to describe the identification of a novel vitamin D metabolite, a C-3, alpha-epimer of 25-hydroxycholecalciferol (3-epi-25(OH)D3), in serum and plasma extracts of cat blood and compare its abundance in cat, dog and rat serum to 25-hydroxycholecalciferol (25(OH)D3), a conventional marker of vitamin D status. Methods Serum 25(OH)D3 and 3-epi-25(OH)D3 concentrations were measured in healthy cohorts of cats (n = 8), dogs (n = 8) and rats (n = 17) using validated reverse and normal-phase high-performance liquid chromatography methods. The methods were verified using liquid chromatography tandem mass spectrophotometry. Dietary intake and dietary concentrations of vitamin D were also measured for evaluation of species differences and effect of dietary change on vitamin D metabolite concentrations. Differences between cat serum and plasma metabolite concentrations were determined. Results Detectable concentrations of 3-epi-25(OH)D3 were observed in all cats and rats. No 3-epi-25(OH)D3 was detected in dogs, where our limit of detection was 5 ng/ml. There were significant differences ( P <0.05) in serum concentrations of 25(OH)D3 and 3-epi-25(OH)D3 among species, with cats having the greatest concentrations of both metabolites. Serum and plasma results were not significantly different. A diet change, which resulted in an increase in vitamin D intake among the cats, affected serum concentration with an increase ( P = 0.004) in 3-epi-25(OH)D3 but no significant change in 25(OH)D3. Conclusions and relevance Serum and plasma of cats contain 3-epi-25(OH)D3 in varied and extraordinary concentrations, much greater than in rats and certainly than that of dogs, a species for which the metabolite was not detected. Importantly, this finding indicates a C-3 epimerization pathway is quantitatively significant for vitamin D metabolism in domestic cats, making 3-epi-25(OH)D3 assays essential for the evaluation of vitamin D status in cats and positioning the cat as a novel model for study of this pathway.

Serum 25-hydroxyvitamin D3 and 24R,25-dihydroxyvitamin D3 concentrations in adult dogs are more substantially increased by oral supplementation of 25-hydroxyvitamin D3 than by vitamin D3.

We previously found a weak response in serum 25-hydroxyvitamin D3 (25(OH)D3) concentrations when dogs were supplemented with oral vitamin D3 (D3). In the present study, we determined the relative potency of oral 25(OH)D3 compared with D3 for increasing vitamin D status in dogs with low serum 25(OH)D concentrations. Four male and three female, 4-year-old, intact, lean, genetically related, Chinese-crested/beagle dogs were studied in a randomised, single cross-over trial. After feeding a low-vitamin D diet (<4 IU/100 g) for 30 d, four dogs received daily D3 supplementation at 2·3 µg/kg body weight0·75, while three dogs received a molar equivalency as 25(OH)D3. The supplements, dissolved in ethanol, were applied to a commercial treat for consumption. Serum 25(OH)D3 and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) were analysed weekly using a validated HPLC method. Both supplementations increased (P ≤ 0·01) serum 25(OH)D3 concentrations. However, oral 25(OH)D3 resulted in greater (P < 0·0001) concentrations than D3 by week 1, with a difference of 173 % (P < 0·0001) by week 2. The supplementation period was limited to 14 d after serum 25(OH)D3 concentrations were not appearing to plateau. Thereafter, a washout period of 1 month separated the cross-over. Following 25(OH)D3, but not D3 supplementation, serum 24R,25(OH)2D3 concentrations increased (P ≤ 0·02), 3 to 5 weeks after initiating supplementation. Vitamin D status, as indicated by serum 25(OH)D3 and 24R,25(OH)2D3 concentrations, is more rapidly and efficiently increased in adult dogs by oral supplementation of 25(OH)D3 than D3.

Effects of parenteral fish oil on plasma nonesterified fatty acids and systemic inflammatory mediators in dogs following ovariohysterectomy.

OBJECTIVE: To evaluate the effects of intravenous (IV) infusion of fish oil (FO) emulsion following ovariohysterectomy (OVH) on inflammatory mediators and plasma omega-3 nonesterified fatty acids (NEFA) concentrations in dogs. DESIGN: Prospective clinical study. SETTING: University teaching hospital. ANIMALS: Twenty-nine privately owned dogs undergoing routine OVH. INTERVENTIONS: Postoperative 3-hour IV infusion of saline (n = 9), FO (Omegaven, n = 10), or soybean oil (SO, intralipid, n = 10) emulsion and blood collected before, 5 and 24 hours following OVH for plasma NEFA and RBC membrane fatty acids (FAs) concentrations, leukocyte cytokine production capacity, and C-reactive protein (CRP) measurement. MEASUREMENTS AND MAIN RESULTS: Plasma omega-3 NEFA, eicosapentaenoic acid, docosahexaenoic acid, and total long-chain omega-3 FA significantly increased shortly after FO infusion (8.8 ± 3.3 µM, 13.6 ± 5.6 µM, and 25.1 ± 9.6 µM, respectively) compared to SO (0.7 ± 0.9, 2.3 ± 1.8, and 4.2 ± 3.0 µM, respectively) and saline infusion (1.6 ± 2.5, 2.6 ± 3.1, and 5.9 ± 6.4 µM, respectively). Plasma CRP concentration significantly increased after OVH, but with no significant group differences. A weak negative correlation occurred between post-OVH CRP and postinfusion total long-chain omega-3 FA concentrations (r2 = 0.21, P = 0.014). Stimulated leukocyte interleukin (IL) 6 production capacity increased (P = 0.001) after OVH in all groups; SO infusion resulted in reduced leukocyte IL-6 production capacity (1048.1 ± 277.7 pg/mL) compared to FO (1299.9 ± 302.1 pg/mL, P = 0.048) and saline infusions (1499.0 ± 363.1 pg/mL, P = 0.01). No significant group difference was observed in leukocyte IL-10 and tumor necrosis factor α production capacities. CONCLUSIONS: Postoperative administration of FO emulsion increases plasma omega-3 NEFA concentrations promptly, but does not significantly attenuate CRP production or leukocyte cytokine production capacity. FO infusion at the dosage used in the present study can be safely used in dogs, but it was not clearly beneficial in decreasing post-OVH indices of inflammation.

Bisphenol A (BPA) in the serum of pet dogs following short-term consumption of canned dog food and potential health consequences of exposure to BPA.

Bisphenol A (BPA) is a widely present endocrine disruptor chemical found in many household items. Moreover, this chemical can bioaccumulate in various terrestrial and aquatic sources; thereby ensuring continual exposure of animals and humans. For most species, including humans, diet is considered the primary route of exposure. However, there has been little investigation whether commercial-brands of dog foods contain BPA and potential health ramifications of BPA-dietary exposure in dogs. We sought to determine BPA content within dog food, whether short-term consumption of these diets increases serum concentrations of BPA, and potential health consequences, as assessed by potential hematological, serum chemistry, cortisol, DNA methylation, and gut microbiome changes, in dogs associated with short-term dietary exposure to BPA. Fourteen healthy privately-owned dogs were used in this study. Blood and fecal samples were collected prior to dogs being placed for two-weeks on one of two diets (with one considered to be BPA-free), and blood and fecal samples were collected again. Serum/plasma samples were analyzed for chemistry and hematology profiles, cortisol concentrations, 5-methylcytosine in lymphocytes, and total BPA concentrations. Fecal samples were used for microbiome assessments. Both diets contained BPA, and after two-weeks of being on either diet, dogs had a significant increase in circulating BPA concentrations (pre-samples=0.7±0.15ng/mL, post-samples=2.2±0.15ng/mL, p<0.0001). Elevated BPA concentrations positively correlated with increased plasma bicarbonate concentrations and associated with fecal microbiome alterations. Short-term feeding of canned dog food increased circulating BPA concentrations in dogs comparable to amounts detected in humans, and greater BPA concentrations were associated with serum chemistry and microbiome changes. Dogs, who share our internal and external environments with us, are likely excellent indicators of potential human health concerns to BPA and other environmental chemicals. These findings may also have relevance to aquatic and terrestrial wildlife.

Oral vitamin D supplementation at five times the recommended allowance marginally affects serum 25-hydroxyvitamin D concentrations in dogs.

Little is known regarding optimal vitamin D status in adult dogs. To date no studies on vitamin D supplementation for improving vitamin D status have been reported for adult dogs. The aims of this study were to identify dogs with low vitamin D status and evaluate an oral dosage of cholecalciferol (D3) for effectiveness in increasing vitamin D status. For this, forty-six privately owned dogs were evaluated. Of the dogs, thirty-three (or 71·7 %) had serum 25-hydroxyvitamin D (25(OH)D) concentrations less than 100 ng/ml, a minimum previously suggested for vitamin D sufficiency in dogs. Subsequently, thirteen dogs were enrolled in a supplementation trial. Dogs were given either a D3 supplement (n 7; 2·3 µg/kg(0·75)) or olive oil placebo (n 6) daily with food. Serum concentrations of 25(OH)D were determined at weeks 1, 3 and 6, and at the trial end. Only at the trial end (weeks 9-10) was 25(OH)D significantly greater (P = 0·05) in supplemented v. placebo dogs. Serum concentrations of 24R,25-dihydroxycholecalciferol determined at the trial end were about 40 % of that of 25(OH)D3 and not significantly different between the groups. Concentrations of parathyroid hormone, ionised Ca, P and creatinine measured in initial and final serum samples indicated supplementation caused no toxicity. We conclude that vitamin D3 supplementation at a dosage near the National Research Council recommended safe-upper limit was not effective for rapidly raising serum 25(OH)D concentrations in healthy, adult dogs. Further work is needed in evaluating the metabolism of orally administered D3 in dogs before dosing recommendations can be made.

Development of Obesity: Mechanisms and Physiology.

Normal adult animals living in nonstressful environments that receive nutritionally sound diets balance their energy expenditure with their energy intake over the long-term. Most knowledge of mechanisms underlying the precise balance of energy is derived from research on rodent models and human correlates. This knowledge is believed applicable and pertinent for understanding causes of obesity in dogs and cats. The roles of satiation and adiposity feedback, cognitive input, energy expenditure, and physical activity are reviewed. Dietary and environmental factors especially relevant to promotion of overweight body condition are reviewed. These include dietary fat and palatability, inactive and stressful lifestyle, and obesogenic effects of neutering.