Effect of oral or injectable supplementation with cobalamin in dogs with hypocobalaminemia caused by chronic enteropathy or exocrine pancreatic insufficiency.

BACKGROUND: Recent studies have shown similar efficacy of oral supplementation of cobalamin compared to injectable supplementation in dogs, but few prospective, randomized studies have been published. OBJECTIVES: To evaluate efficacy of oral or injectable supplementation with cobalamin in normalizing serum cobalamin and methylmalonic acid (MMA) concentrations in dogs with hypocobalaminemia caused by either chronic enteropathy (CE) or exocrine pancreatic insufficiency (EPI). ANIMALS: Forty-six client owned dogs with hypocobalaminemia. METHODS: Prospective randomized clinical trial. Dogs were divided into 2 groups (CE or EPI), and randomized to receive oral or injectable supplementation of cobalamin. Each dog had 3 visits and serum cobalamin and MMA concentrations were measured at each visit. RESULTS: In dogs with CE, serum cobalamin concentrations increased with oral (P = .02; median 149 [range 149-231] to 733 [166-1467] ng/L, median difference 552 [95% CI: 181-899] ng/L) or injectable (P < .01; 168 [149-233] to 563 [234-965] ng/L, 367 [187-623] ng/L) supplementation. In dogs with EPI, serum cobalamin concentrations increased with oral (P = .01; 162 [149-214] to 919 [643-3863] ng/L, 705 [503-3356] ng/L) or injectable (P = .01; 177 [149-217] to 390 [243-907] ng/L, 192 [89-361] ng/L) supplementation. Serum MMA concentrations decreased with oral or injectable supplementation in dogs with CE, but only with oral supplementation in dogs with EPI. CONCLUSIONS AND CLINICAL IMPORTANCE: Oral supplementation is an alternative for cobalamin supplementation in dogs with hypocobalaminemia caused by CE or EPI.

Oral glucocorticoids diminish the efficacy of allergen-specific immunotherapy in experimental feline asthma.

Allergen-specific rush immunotherapy (RIT) shows promise in treating asthma; however, pet cats will likely require at least initial concurrent glucocorticoids (GCs) to control serious clinical signs. How the immunosuppressive effects of GCs would impact RIT in cats is unknown. The hypothesis of this study was that oral, but not inhaled GCs will diminish the efficacy of RIT in experimental feline asthma. Cats (n=6/group) were sensitized using Bermuda grass allergen (BGA) and randomized to receive BGA-specific RIT for 9 months with an oral GC (prednisolone 10mg daily), inhaled GC (fluticasone 220 µg twice daily), or placebo administered for the first 6 months. Bronchoalveolar lavage fluid (BALF) percent eosinophils and other immunological assays were performed. Eosinophilic airway inflammation was suppressed in all groups at month 6 of RIT (group mean ± SD, 5 ± 2%, 13 ± 4%, and 7 ± 2% for oral GC, inhaled GC, and placebo, respectively; P=0.291). BALF percent eosinophils significantly increased over time only in oral GC/RIT cats between months 6 and 9 (P=0.031). Placebo/RIT cats had significant decreases over time in BGA-specific serum IgE (P=0.031). Concentration of interleukin (IL)-5 in BALF significantly increased over time in inhaled GC/RIT cats (P=0.031). No significant differences were found between groups at month 6 or over time in each group for BGA-specific lymphocyte blastogenesis, percent blood T regulatory cells, or number of IL-10-producing cells. Given the significant increase of airway eosinophilia over time in RIT cats initially treated with an oral GC, inhaled GCs might be better for dampening eosinophilic inflammation until RIT normalizes the dysregulated immune system.

Flow cytometric determination of allergen-specific T lymphocyte proliferation from whole blood in experimentally asthmatic cats.

The ability to quantify feline lymphocyte proliferation, especially to specific antigen or allergen, would be valuable in experimental models and naturally developing disease where activated lymphocytes drive immune responses. Traditional proliferation assays may pose radioactivity hazards, lack the ability to distinguish viable from non-viable cells, and cannot discriminate individual populations of proliferating lymphocytes (e.g., the CD4+ T cell class). We hypothesized that in an experimental model of feline allergic asthma a four-color flow cytometric assay capable of simultaneously detecting division, viability and cell surface markers (pan T cell marker CD5 or CD4) would allow characterization of lymphocytes stimulated ex vivo using the sensitizing allergen, Bermuda grass (BGA). Peripheral blood mononuclear cells were harvested from eight experimentally asthmatic cats to validate and optimize use of a cell proliferation dye or bromodeoxyuridine (BrdU) with BGA-specific stimulation in a lymphocyte proliferation flow cytometric assay. Only the latter reagent was suitable in the cat. After a 3 day incubation, antibodies with different fluorochromes were used to identify BrdU, viable cells, CD5 and CD4 for subsequent flow cytometric analysis. In asthmatic cats, the group mean ± SEM of proliferating CD5+ lymphocytes was 2.3 ± 0.5%. The group mean ± SEM of proliferating CD4+ lymphocytes was 1.2 ± 0.3%. Flow cytometry is a sensitive method for detecting simultaneous proliferation and viability of very minor populations of allergen-specific lymphocytes in experimentally asthmatic cats.

Beneficial cross-protection of allergen-specific immunotherapy on airway eosinophilia using unrelated or a partial repertoire of allergen(s) implicated in experimental feline asthma.

The study hypothesis was that in experimentally asthmatic cats rush immunotherapy (RIT) using allergens not completely matched with sensitizing allergen(s) would at least partially attenuate the asthmatic phenotype and modulate the aberrant immune response. In phase I, cats sensitized to Bermuda grass allergen (BGA), house dust mite allergen (HDMA) or placebo received BGA RIT. In phase II, cats dually sensitized to BGA and HDMA received RIT using BGA, HDMA or placebo. Efficacy of RIT was assessed using percentage bronchoalveolar lavage fluid (BALF) eosinophils. Additionally, a variety of immunologic assays were performed. Eosinophilic airway inflammation significantly decreased over time in asthmatic cats given RIT using sensitizing allergen or unrelated allergen (P<0.001). In dually sensitized cats, single allergen RIT but not placebo reduced airway eosinophilia (P=0.038). Differences in allergen-specific lymphocyte proliferation, in the number of IL-10 producing cells and in the percentage T regulatory cells were detected between asthmatic cats getting RIT and controls. Cross-protection manifested by reduced airway eosinophilia was noted in cats treated with RIT allergens which did not completely match allergen used in asthma induction. However, the mechanism of immunologic tolerance may differ when improperly matched allergens to the sensitizing allergens are used in RIT.