Gregory A. Reinhart’s research while affiliated with Washington State University and other places

Astaxanthin is a potent antioxidant carotenoid and may play a role in modulating immune response in cats. Blood was taken from female domestic shorthair cats (8-9 mo old; 3.2 ± 0.04 kg body weight) fed 0, 1, 5 or 10mg astaxanthin daily for 12 wk to assess peripheral blood mononuclear cell (PBMC) proliferation response, leukocyte subpopulations, natural killer (NK) cell cytotoxic activity, and plasma IgG and IgM concentration. Cutaneous delayed-type hypersensitivity (DTH) response against concanavalin A and an attenuated polyvalent vaccine was assessed on wk 8 (prior to vaccination) and 12 (post-vaccination). There was a dose-related increase in plasma astaxanthin concentrations, with maximum concentrations observed on wk 12. Dietary astaxanthin enhanced DTH response to both the specific (vaccine) and nonspecific (concanavalin A) antigens. In addition, cats fed astaxanthin had heightened PBMC proliferation and NK cell cytotoxic activity. The population of CD3(+) total T and CD4(+) T helper cells were also higher in astaxanthin-fed cats; however, no treatment difference was found with the CD8(+) T cytotoxic and MHC II(+) activated lymphocyte cell populations. Dietary astaxanthin increased concentrations of plasma IgG and IgM. Therefore, dietary astaxanthin heightened cell-mediated and humoral immune responses in cats.

The modulatory activity of dietary n-3 fatty acids on inflammation and immune response in domestic cats is unknown. Mature female cats (n=14/treatment) were fed control, fish oil or flaxseed oil diets with n-6:n-3 fatty acid ratios of 20:1, 5:1 and 5:1, respectively, for 12 wk. Immune response was assessed on wk 0, 6 and 12, and skin hypersensitivity response on wk 6 and 12. Fish oil increased (P<0.01) eicosapentaenoic and docosahexaenoic acids in plasma and skin, whereas flaxseed oil increased α-linolenic acid. Fish and flaxseed oils decreased (P<0.01) skin inflammatory response to histamine. Cats fed fish but not flaxseed oil had higher (P<0.05) skin leukotriene LTB(5), but not LTB(4). Fish and flaxseed oils lowered B, total T and T(h) subset populations, and leukocyte proliferative response to PWM (P<0.05). In contrast, there was no change in ConA- or PHA-induced lymphocyte proliferation, Tc and MHC II cell populations, DTH response, NK cytotoxicity, IL-2 production, or plasma IgG concentrations. Therefore, fish and flaxseed oil can reduce skin inflammatory responses in cats, however, flaxseed oil appears less immunosuppressive than fish oil.

No information is available on the possible role of astaxanthin on immune response in domestic canine. Female Beagle dogs (9-10 mo old; 8.2 ± 0.2 kg body weight) were fed 0, 10, 20 or 40 mg astaxanthin daily and blood sampled on wk 0, 6, 12, and 16 for assessing the following: lymphoproliferation, leukocyte subpopulations, natural killer (NK) cell cytotoxicity, and concentrations of blood astaxanthin, IgG, IgM and acute phase proteins. Delayed-type hypersensitivity (DTH) response was assessed on wk 0, 12 and 16. Plasma astaxanthin increased dose-dependently and reached maximum concentrations on wk 6. Dietary astaxanthin enhanced DTH response to vaccine, concanavalin A-induced lymphocyte proliferation (with the 20mg dose at wk 12) and NK cell cytotoxic activity. In addition, dietary astaxanthin increased concentrations of IgG and IgM, and B cell population. Plasma concentrations of C reactive protein were lower in astaxanthin-fed dogs. Therefore, dietary astaxanthin heightened cell-mediated and humoral immune response and reduced DNA damage and inflammation in dogs.

Research on the uptake and transport of astaxanthin is lacking in most species. We studied the uptake of astaxanthin by plasma, lipoproteins and leukocytes in domestic dogs and cats. Mature female Beagle dogs (18 to 19 mo old; 11 to 14 kg BW) were dosed orally with 0, 0.1, 0.5, 2.5, 10 or 40 mg astaxanthin and blood taken at 0, 3, 6, 9, 12, 18 and 24 h post-administration (n = 8/treatment). Similarly, mature domestic short hair cats (12 mo old; 3 to 3.5 kg body weight) were fed a single dose of 0, 0.02, 0.08, 0.4, 2, 5, or 10 mg astaxanthin and blood taken (n = 8/treatment) at the same interval. Both dogs and cats showed similar biokinetic profiles. Maximal astaxanthin concentration in plasma was approximately 0.14 mumol/L in both species, and was observed at 6 h post-dosing. The plasma astaxanthin elimination half-life was 9 to 18 h. Astaxanthin was still detectable by 24 h in both species. In a subsequent study, dogs and cats were fed similar doses of astaxanthin daily for 15 to 16 d and astaxanthin uptake by plasma, lipoproteins, and leukocytes studied. In both species, plasma astaxanthin concentrations generally continued to increase through d 15 or 16 of supplementation. The astaxanthin was mainly associated with high density lipoprotein (HDL). In blood leukocytes, approximately half of the total astaxanthin was found in the mitochondria, with significant amounts also associated with the microsomes and nuclei. Dogs and cats absorb astaxanthin from the diet. In the blood, the astaxanthin is mainly associated with HDL, and is taken up by blood leukocytes, where it is distributed to all subcellular organelles. Certain aspects of the biokinetic uptake of astaxanthin in dogs and cats are similar to that in humans.

Résumé— Les effets d'alimentations supplémentées avec des ratios croissants decides gras polyinsaturés n — 6/n — 3 sur la synthèse de leucotriènes B dans la peau du chien et les neutrophiles sont présentés. Trente chien Beagles ont reçu pendant 2 mois avec une alimentation ayant un ratio n —6/n —3 de 28:1. Des aliments expérimentaux contenant des ratios de 5:1, 10:1, 25:1, 50:1 et 100:1 (six chiens par groupe) ont été administrés ensuite pendant 12 semaines. A la fin des deux mois d'alimentation témoin et au bout de 6 et 12 semaines d'alimentation expérimentale, les concentrations de LTB4 et LTB5 dans la peau et les neutrophiles ont été déterminées. Les neutrophiles de chiens ayant mangé des aliments de ratio 5:1 et 10:1 ont synthétisé 30–33 pourcent moins de LTB4 ( P <0,05) et 370–500 pourcent plus de LTB5 ( P <0,05) à 6 et 12 semaines, mais le relargage d'anions superoxide était inchangé. La peau des chiens stimulée par un lipopolysaccharide a synthétisé 48 à 62 pourcent moins de LTB4 ( P < 0,05) et 48 à 79 pourcent moins de LTB5 ( P <0,05) à 12 semaines. [Vaughan, D. M., Reinhart, G. A., Swaim, S. F., Lauten, S. D., Garner, C. A., Boudreaux, M. K., Spano, J. S., Hoffman, C. E., Conner, B. Evaluation of effects of dietary n —6 to n — 3 fatty acid ratios on leukotriéne B synthesis in dog skin and neutrophils. (Evaluation de l'effet du ratio d'acides gras n — 6/n — 3 dans l'alimentation sur la synthèse de leucotriènes B dans la peau du chien et les neutrophiles). Resumen— Evaluamos los efectos producidos por el aumento en la proportion de ácidos grasos poli‐insatu‐rados n‐6 a n‐3 en la dieta sobre la sintesis de leucotrienos B en la piel del perro y en los neutrófilos. Se administró durante dos meses una dieta con una proporión 28:1 de ácidos grasos n‐6 a n‐3 a un grupo de treinta Beagles. Se administraron dietas experimentales con proporciones de 5:1, 10:1, 25:1, 50:1 y 100:1 durante 12 semanas (seis perros por grupo). Se cuantificaron los niveles de leucotrienos B 4 y B 5 en la piel y en los neutrófilos al final de los dos meses de dieta control y a las 6 y 12 semanas de la dieta‐tratamiento. Los neutrófilos de perros con dietas 5:1 y 10:1 sintetizaron 30 a 33% menos leucotrieno B 4 ( P < 0.05) y 370 a 500% más leucotrieno B 5 ( P <0.05) a las 6 y 12 semanas pero no alteraron la liberación de aniones superóxido durante la espiracion. La piel de perro estimulada con lipopolisacáridos sintetizó de 48 a 62% menos leucotrieno B 4 ( P < 0.05) y 48 a 79% más leucotrieno B 5 ( P < 0.05) a las 12 semanas. [Evaluation of effects of dietary n‐6 to n‐3 fatty acid ratios on leukotriene B synthesis in dog skin and neutrophils (Effecto de la proporción de ácidos grasos n‐6 a n‐3 en la dieta sobre la sintesis de leucotrienos B en la piel del perro y en los neutrófilos). Abstract— The effects of diets supplemented with increasing ratios of n‐6 to n‐3 polyunsaturated fatty acids on leukotriene B synthesis in dog skin and neutrophils were evaluated. Thirty Beagles were conditioned for 2 months on a diet with an n‐6 to n‐3 fatty acid ratio of 28:1. Experimental diets, containing n‐6 to n‐3 ratios of 5:1, 10:1, 25:1, 50:1 and 100:1 (six dogs/group), were fed for 12 weeks. At the end of the 2 month control diet period, and again at 6 and 12 weeks of treatment feeding, leukotriene B 4 and leukotriene B 5 were quantitated in skin and neutrophils. Neutrophils from dogs fed the 5:1 and 10:1 diets synthesized 30–33 per cent less leukotriene B 4 ( P < 0.05) and 370–500 per cent greater leukotriene B 5 ( P < 0.05) at 6 and 12 weeks, but had no change in the release of superoxide anions during respiratory burst. Lipopolysaccharide‐stimu‐lated dog skin synthesized 48–62 per cent less leukotriene B 4 ( P < 0.05) and 48–79 per cent more leukotriene B 5 ( P <0.05) at 12 weeks.

To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor 1 and parathyroid hormone concentrations, radiography, and blood chemistry analysis results. 32 purebred Great Dane puppies from 4 litters. At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age. Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group. Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age.