Effect of age, breed and dietary omega-6 (n-6):omega-3 (n-3) fatty acid ratio on immune function, eicosanoid production, and lipid peroxidation in young and aged dogs
ABSTRACT The focus of this study was to examine the influence of age and diet on various parameters of immune function in young and old Fox Terriers and Labrador Retrievers. Eighteen young and old dogs were utilized for this study. Young and old dogs were fed a basal diet containing an (n-6) : (n-3) ratio of 25 : 1 for sixty days (Phase I). Half of the dogs were then switched to a diet with an (n-6) : (n-3) ratio of 5 : 1, and all were maintained on their respective diets for an additional sixty days (Phase II). Results from these studies revealed an age-associated decline in several immune parameters measured. Both these breeds demonstrated a reduction in sheep red blood cell titers, as well as in their ability to respond to different mitogens. Interestingly, this decline was greater in Fox Terriers, suggesting a decrease in cellular proliferative capacity in lymphocytes isolated from the larger breed. Neither cytokine production or DTH response was affected by age. Diet and breed interactions resulted in a significant increase in T- and B-cell mitogen responsiveness. In contrast, supplementation with n-3 fatty acids did not affect IL-1, IL-6 or TNF-α production. Supplementation with n-3 fatty acids resulted in increased PGE3 production from peritoneal macrophages but had no effect on PGE2 production from peripheral blood mononuclear cells or peritoneal macrophages. The n-3 fatty acid supplementation did not influence α-tocopherol status although older dogs had significantly lower serum α-tocopherol concentrations. Oxidative status of these dogs was assessed by serum levels of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE). Feeding an n-3-enriched diet did not affect 4-HNE levels but significantly decreased MDA levels in old dogs. In summary, this study indicates that feeding a diet containing an (n-6) : (n-3) fatty acid ratio of 5 : 1 had a positive, rather than a negative, effect on the immune response of young or geriatric dogs
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ABSTRACT: Canine transmissible venereal tumor (CTVT) is a neoplasm transmitted by transplantation. Monochemotherapy with vincristine is considered to be effective, but treatment time until complete clinical remission may vary. The aim of this study was to determine which clinical data at diagnosis could predict the responsiveness of CTVT to vincristine chemotherapy. One hundred dogs with CTVT entered this prospective study. The animals were treated with vincristine sulfate (0.025 mg/kg) at weekly intervals until the tumor had macroscopically disappeared. The time to complete remission was recorded. A multivariate Cox regression model indicated that larger tumor mass, increased age and therapy during hot and rainy months were independent significant unfavorable predictive factors retarding remission, whereas sex, weight, status as owned dog or breed were of no predictive relevance. Further studies are necessary to investigate whether these results are due to changes in immunological response mechanisms in animals with a diminished immune surveillance, resulting in delays in tumor regression.The Veterinary Journal 03/2010; 183(3-183):362-363. DOI:10.1016/j.tvjl.2008.11.009 · 2.17 Impact Factor
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ABSTRACT: Mode of access: World Wide Web. Title from document title page. Thesis (Ph. D.)--Louisiana State University, Baton Rouge, 2003.
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ABSTRACT: beta-Carotene is a naturally occurring carotenoid reported to have health-promoting effects in several species. Advancing age is known to have a negative impact on various immune variables in several species. This study was conducted in order to assess the effect of age on immune response in dogs and to determine whether beta-carotene is able to reverse this age-associated decline. To test this hypothesis, young and old dogs (n = 36) were fed either a control diet or experimental diets containing supplemental beta-carotene for 2-month periods. Age significantly (P < .05) lowered CD4+ T cell populations (47.2% versus 33.7%; young-control versus old-control, respectively) and beta-carotene restored percent distributions in old dogs to nonsignificance versus younger controls (41.0%). T cell proliferation was lower in old dogs (30,254 +/- 2,248 versus 14,811 +/- 2,497 cCPM; young-control versus old-control, respectively; P < .05), and beta-carotene supplementation significantly improved responses in this age group (21,329 +/- 2,275 cCPM). Although B cell proliferation was depressed with age (17,967 +/- 1,384 versus 7,535 +/- 1,469 cCPM; young-control versus old-control, respectively; P < .05), beta-carotene supplementation improved B cell proliferation in young dogs (23,500 +/- 1,339 cCPM). Old dogs displayed lower delayed-type hypersensitivity test (DTH) responses versus younger controls to both phytohemagglutinin-P (PHA; 11.1 +/- 0.95 versus 7.57 +/- 1.15 mm; young-control versus old-control, respectively; P < .05) and sheep red blood cell (RBC; 9.12 +/- 0.62 versus 8.08 +/- 0.75 mm; young-control versus old-control, respectively; P < .10). beta-Carotene improved these responses, mostly within the first 24-48 hours after injection. In summary, older dogs have lower immunological responses compared with younger controls. beta-Carotene supplementation significantly restored immune responses in older dogs when compared with their age-matched controls and younger counterparts.Journal of Veterinary Internal Medicine 17(6):835-42. · 2.22 Impact Factor