BACKGROUND: Hypovitaminosis D is a risk factor for the development of respiratory infections in humans and repletion can be protective. OBJECTIVES: Determine if serum 25-hydroxyvitamin (OH)D concentrations are lower in shelter dogs and if 25(OH)D concentrations are associated with clinical signs of canine infectious respiratory disease complex (CIRDC) or with time in the shelter. ANIMALS: One hundred forty-six shelter dogs (clinically ill n = 36, apparently healthy n = 110) and 23 nonshelter control dogs. METHODS: Prospective cohort study. Shelter dogs were grouped as clinically ill or apparently healthy based on the presence or absence, respectively, of clinical signs associated with CIRDC. Serum 25(OH)D concentrations were measured with a competitive chemiluminesence immunoassay. Nucleic acids of agents associated with the CIRDC were amplified by polymerase chain reaction assays. RESULTS: The concentration of 25(OH)D was 7.3 ng/mL (4.5-9.9, 95% confidence interval [CI]) lower in dogs with signs of CIRDC than apparently healthy shelter dogs (t(142) = 2.0, P = .04). Dogs positive for DNA of canine herpesvirus (CHV)-1 had serum 25(OH)D concentrations 14.9 ng/mL (-3.7 to 29.6, 95% CI) lower than dogs that were negative (t(137) = 2.0, P = .04). Serum 25(OH)D concentrations in shelter dogs were not different from control dogs (t(45) = -1.4, P = .17). Serum 25(OH)D concentration was not associated with duration of time in the shelter (F(1, 140) = 1.7, P = .2, R2 = 0.01). CONCLUSION AND CLINICAL IMPORTANCE: Vitamin D could have a role in acute respiratory tract infections in shelter dogs.
Dog Diseases , Vitamin D Deficiency , Animals , Dogs , Prospective Studies , Vitamin D/analogs & derivatives , Vitamin D Deficiency/veterinary
BACKGROUND: The active metabolite of vitamin D, calcitriol, has been shown across many different species to augment innate immune responses and dampen aberrant proinflammatory cytokine production. Community acquired infections are common in shelters and consume limited shelter resources, impact adoption rates, and can result in unnecessary euthanasia. Prophylactic oral vitamin D supplementation decreases the incidence and severity of upper and lower respiratory tract infections in humans. Before a clinical trial investigating the clinical benefit of oral vitamin D supplementation in shelter dogs can be pursued, an in vitro study evaluating the immunomodulatory effects of calcitriol in blood from shelter dogs is warranted. Therefore, the objective of this study was to determine if incubation of whole blood obtained from apparently healthy dogs housed in a shelter for ≥7 days with calcitriol would alter granulocyte/monocyte (GM) oxidative burst and phagocytic function as well as pathogen-associated molecular pattern (PAMP)-stimulated leukocyte production of tumor necrosis factor (TNF)-α, and interleukin (IL)-6, and IL-10. RESULTS: Ten dogs housed in a shelter for ≥7 days were enrolled in a prospective cohort study. Whole blood from these dogs was incubated with calcitriol (10- 7 M) or diluent (control) for 24 h. Subsequent to this incubation, phagocytosis of opsonized-Escherichia coli (E. coli) and E. coli-induced oxidative burst were evaluated via flow cytometry. In addition, leukocyte production of TNF-α, IL-6, and IL-10 were measured using a canine-specific multiplex bead assay. Calcitriol significantly decreased leukocyte TNF-α production (p = 0.009) and increased IL-10 production (p = 0.002). Tumor necrosis factor-α-to-IL-10 ratio was significantly decreased with calcitriol (p = 0.017), while IL-6 production as well as GM oxidative burst and phagocytic function were not significantly affected. CONCLUSIONS: These data indicate that calcitriol attenuates proinflammatory immune responses without affecting GM oxidative burst or phagocytic function in vitro in whole blood obtained from apparently healthy shelter dogs.
