Effect of an omega-3/omega-6 fatty acid-containing commercial lamb and rice diet on pruritus in atopic dogs: results of a single-blinded study.

A commercial, lamb and rice, dog food with an omega-6:omega-3 fatty acid ratio of 5.5:1 was fed in a single-blinded, self-controlled clinical trial to 18 atopic dogs. The pruritus in 8 of these dogs (44.4%) was satisfactorily controlled within 7 to 21 d, returned within 3 to 14 d after the diet was withdrawn, and was again controlled when the diet was reinstated. Plasma and skin levels of examined fatty acids changed in all 18 dogs when their diet was switched to the test diet. Dogs responding to the test diet had a different pattern of fatty acid change as compared to the dogs which failed to respond to the diet, suggesting that there are subsets of atopic dogs with different fatty acid metabolism capabilities.     

P-76 The effect of omega-3 fatty acid supplementation on cutaneous and plasma fatty acid concentrations in dogs with atopic dermatitis

The objectives of this study were to evaluate in vivo tolerance, and antimicrobial and clinical activities of a topical otic preparation containing EDTA tromethamine (Tris) and chlorhexidine digluconate 0.15% solution (Otodine^®) in dogs with chronic bacterial otitis externa. Eleven dogs were included. The affected ears were filled with the solution once daily during a 2-week period. Dogs were evaluated on days 0, 14 and 28. Three clinical parameters (exudate, erythema, pain) and three cytologic parameters ( Malassezia , cocci, rods) were scored (0–4 scale) by otoscopic and cytological examinations of otic exudate. Bacterial cultures were performed at each time point. If there were bacteria on cytological examination on day 14, the dogs were treated with the original product, with the addition of enrofloxacin (5%) applied 10 min after the original product, for a further 2 weeks. All 11 cases yielded isolates of resistant gram-negative bacteria; gram-positive bacteria were also isolated from six of 11 dogs. On day 14, six of 11 dogs were negative on culture examination; on day 28, 10 of 11 were negative and only one case had a positive culture. On day 14, clinical and microbial scores (cytology) were reduced by 54.6 and 71.1%, respectively, and by 85.7 and 94% on day 28. All cases reported good tolerance of the treatment. The results show that this ear solution was helpful in the management of chronic bacterial otitis externa in dogs and was well tolerated. There seems to be a synergistic effect of the combination of Tris-EDTA/chlorhexidine digluconate 0.15% solution, and an antimicrobial agent (enrofloxacin) against resistant gram-positive and gram-negative bacteria.
Funding: Self-funded.     

Electron microscopic observations of stratum corneum intercellular lipids in normal and atopic dogs.

The barrier function of mammalian skin is maintained by intercellular stratum corneum lipids. In human patients with atopic dermatitis, an abnormal lipid barrier results in dry skin and increased transepidermal water loss. At this time, it is not known if a defective lipid barrier is present in atopic dogs. Normal and atopic canine skin were postfixed in ruthenium tetroxide and studied using transmission electron microscopy to determine structural differences within stratum corneum lipids. Intercellular lipid lamellae were graded on a semiquantitative scale. The deposition of stratum corneum lipid lamellae in atopic canine skin appeared markedly heterogeneous compared with that seen in normal canine skin. When present, the lamellae often exhibited an abnormal structure. The continuity and thickness of the intercellular lipid lamellae were significantly less in nonlesional atopic than in normal canine skin. These preliminary observations suggest that the epidermal lipid barrier is defective in atopic canine skin. Additional studies are needed to further characterize the biochemical defect and to possibly correct it with nutritional and/or pharmacologic intervention.     

Plasma and skin concentrations of polyunsaturated fatty acids before and after supplementation with n-3 fatty acids in dogs with atopic dermatitis

OBJECTIVE: To determine essential fatty acid concentrations in plasma and tissue before and after supplementation with n-3 fatty acids in dogs with atopic dermatitis. ANIMALS: 30 dogs with atopic dermatitis. PROCEDURE: Dogs received supplemental flaxseed oil (200 mg/kg/d), eicosapentaenoic acid (EPA; 50 mg/kg/d)-docosahexaenoic acid (DHA; 35 mg/kg/d), or mineral oil as a placebo in a double-blind, placebo-controlled, randomized trial. Clinical scores and plasma and cutaneous concentrations of linoleic acid, arachidonic acid, alpha-linolenic acid (alpha-LLA), EPA, DHA, prostaglandin E2, and leukotriene B4 were determined. RESULTS: Total plasma concentrations of alpha-LLA and EPA increased and those of arachidonic acid decreased significantly with administration of EPA-DHA, and concentrations of alpha-LLA increased with flaxseed oil supplementation; nevertheless, there was no significant change in the concentrations of these fatty acids or eicosanoids in the skin. There was no correlation between clinical scores and plasma or cutaneous concentrations for any of the measured fatty acids or eicosanoids. CONCLUSION AND CLINICAL RELEVANCE: Results indicated that at the dose used, neither the concentrations of fatty acids in skin or plasma nor a decrease in the production of inflammatory eicosanoids was a major factor involved in the mechanism of action in dogs with atopy that responded to fatty acid supplementation.     

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.

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-alpha 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 alpha-tocopherol status although older dogs had significantly lower serum alpha-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.     

Evaluation of plasma aldosterone concentrations before and after ACTH administration in clinically normal dogs and in dogs with various diseases

Plasma aldosterone concentrations were measured in response to adrenocorticotropic hormone (ACTH) gel administration in clinically normal dogs, in dogs with hypoadrenocorticism, and in dogs (with electrolyte abnormalities) that did not have hypoadrenocorticism. Baseline plasma aldosterone concentrations were determined from specimens obtained every 10 minutes for 3 hours from 2 dogs and every 30 minutes for 7.5 hours from 2 other dogs. During the evaluation period, plasma aldosterone concentrations varied by at least 50% in each dog. A randomized crossover design was used to compare changes in plasma aldosterone concentrations after administration of ACTH gel and physiologic NaCl solution. Dogs had significantly (P = 0.002) higher plasma aldosterone concentrations after administration of ACTH gel than after administration of NaCl solution. Plasma cortisol concentrations increased as expected after ACTH gel administration. Analysis of cortisol and aldosterone concentrations in the same specimens obtained at 7 sample collection times did not reveal significant linear correlation, and scatterplots did not indicate a nonlinear association. In addition, plasma aldosterone concentrations were determined in response to ACTH administration alone and to ACTH combined with a high dose of dexamethasone (0.1 mg/kg, IV). The plasma aldosterone response to ACTH alone was not significantly different from the response to ACTH combined with dexamethasone. For both tests, plasma aldosterone concentrations at 60 and 120 minutes after ACTH administration were significantly (P less than 0.0005 and P = 0.0001, respectively, increased, compared with base-line values. Six dogs with adrenocortical hypofunction, as determined by plasma cortisol concentrations before and after ACTH administration, had plasma aldosterone concentrations that were diminished or did not increase after ACTH administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma levels of oxytetracycline, doxycycline, and minocycline in pigs after oral administration in feed.

Steady-state plasma levels were determined for oxytetracycline (OTC), doxycycline (DC), and minocycline (MC) after medication with different in-feed concentrations. Each concentration of the three tetracyclines was examined in six pigs. The animals were housed in individual pens and fed twice daily with an interval of 12 h. All pigs consumed their feed within 1 h after it was provided. Concentrations of 400, 800, 1,600, and 2,400 mg of OTC per kilogram of feed induced steady-state plasma levels ranging from .13 to .22, .19 to .50, .39 to 1.43, and 1.41 to 2.14 micrograms/ml, respectively. On a feed intake basis, pigs received 13, 26, 54 to 81, and 108 mg of OTC per kilogram of BW per day, respectively. Steady-state plasma levels after medication with 200, 400, and 800 mg of DC or MC per kilogram of feed ranged from .37 to .89, .71 to 1.14, and 1.62 to 3.18 micrograms/ml for DC and from .21 to .60, .43 to 1.05, and 1.19 to 2.62 micrograms/ml for MC. Pigs consumed 7, 13, and 26 mg of DC and 9, 18, and 36 mg of MC per kilogram of BW per day, respectively. For all three tetracyclines there was an increase in steady-state plasma levels when concentrations in feed or per kilogram of BW increased. Plasma levels were determined with both a HPLC method and a microbiological method. A good correlation existed between the results obtained by both methods. It was concluded that based on plasma levels and known in vitro activity DC and MC could be good alternatives for OTC to treat respiratory tract infections in pigs.     

Serum-free thyroxine concentrations, measured by chemiluminescence assay before and after thyrotropin administration in healthy dogs, hypothyroid dogs, and euthyroid dogs with dermathopathies.

The purpose of this study was to determine the usefulness of free thyroxine (FT4) measured by chemiluminescence in evaluating thyroid function in dogs. Total thyroxine (TT4) concentration measured by radioimmunoassay (RIA) and FT4 measured by chemiluminescence were evaluated in 30 healthy dogs, 60 euthyroid dogs with concurrent dermatopathies, and 30 hypothyroid dogs before and after intravenous stimulation with 1 or 2 IU of thyrotropin (TSH). Median basal TT4 and median TT4 concentrations at 4 h post-TSH administration were not significantly different (P < 0.0001) between healthy dogs and euthyroid dogs with dermatopathies, but were significantly higher than those in hypothyroid dogs. In healthy dogs, the median TT4 concentrations at 4 and 6 h post-TSH administration were not significantly different. Median basal FT4 and median FT4 concentrations at 4 h post-TSH administration in healthy dogs were significantly lower (P < 0.0001) than those in euthyroid dogs with dermatopathies, but significantly higher than the same parameters in hypothyroid dogs. There was a significant difference between the median FT4 concentrations at 4 h post-TSH administration and median basal FT4 concentrations for healthy dogs and euthyroid dogs with dermatopathies, but not for hypothyroid dogs. Lastly, in healthy dogs, median FT4 concentrations at 4 and 6 h post-TSH administration were not significantly different. Free thyroxine measured by chemiluminescence was highly correlated (P < 0.0001; Spearman r = 0.91) with FT4 measured by the reference method for free hormone analysis, namely, equilibrium dialysis, when sera from 56 dogs were used.     

The combination of antihistamine (chlorpheniramine) and an omega-3/omega-6 fatty acid-containing product for the management of pruritic cats: results of an open clinical trial

Chlorpheniramine maleate (2 mg/cat every 12 h orally) and a fatty acid supplement (0.5 ml/cat every 24 h orally) were administered in combination to 11 pruritic cats. Although none of the cats had responded to the two products when they were administered as single therapeutic agents, six of the cats (54%) had an excellent response to the combination. Adverse effects were not seen. Under the conditions of this study, the combination of antihistamine (chlorpheniramine) and the omega-3/omega-6 fatty acid-containing supplement exhibited a superior antipruritic effect to either product alone.     

Distribution of chloramphenicol in some tissues and extravascular fluids of dogs after oral administration.

Chloramphenicol concentrations were assayed chemically in tissue homogenates, blood, and certain extravascular fluids of Greyhounds killed 1.5, 3, 6, and 12 hours after they were orally given the drug (50 mg/kg). The concentrations of hemoglobin in blood and tissue homogenates were used to estimate "corrected values" to allow for differences in vascularity of the tissues sampled. The distribution of chloramphenicol in the body was not uniform. In all sampled tissues except brain, the initial corrected values were higher than the concentrations in blood. The tissues sampled, in diminishing order of initial corrected value, were lymph node, spleen, pancreas, liver, kidney, lung, muscle, and brain. The persistence of antibiotic in different tissues varied, and in some tissues it was detectable when blood concentrations reached zero. Penetration of chloramphenicol into brain and cerebrospinal fluid was slower than in other tissues and fluids. In aqueous humor and cerebrospinal fluid, concentrations were lower than those in blood, but high concentrations were present in urine. The findings indicated that during chloramphenicol therapy it may be advantageous to select dosage frequencies according to the site of infection.     

Effects of dietary n-6:n-3 fatty acid ratio on feed intake, digestibility, and fatty acid profiles of the ruminal contents, liver, and muscle of growing lambs

This study investigated the effect of modifying the n-6:n-3 fatty acid ratio (FAR) of diets using linseed, soybean, and cottonseed oils on apparent digestibility, ruminal fermentation characteristics, growth performance, key circulating hormones, and the fatty acid profile of ruminal digesta, liver, and fore-shank muscle of growing lambs fed a high concentrate diet. Forty individually housed Katadhin Dorper lambs (average of 20.0 kg of BW) were fed Bermudagrass hay in ad libitum amounts and concentrates at 3.7% of BW daily. The concentrate contained 68.9% corn, 23.8% soybean meal, 3.3% limestone, and 4.0% oil supplements (DM basis). The treatments consisted of dietary n-6:n-3 FAR of 2.3:1, 8.8:1, 12.8:1, and 15.6:1. After feeding for 35 d in metabolism crates, lambs were slaughtered 15 h after feeding, and samples of ruminal digesta, blood, liver, and foreshank tissue were collected. Increasing dietary n-6:n-3 FAR did not affect the intake of DM nor the apparent digestibility of DM, ether extract, NDF, or ADF, but did increase apparent digestibility of CP (linear, P < 0.05). Concentrations of ruminal butyrate increased linearly (P < 0.05) with increasing dietary n-6:n-3 FAR, whereas the valerate concentration decreased linearly (P < 0.001). Concentrations of plasma insulin and IGF-I were not affected by dietary n-6:n-3 FAR. Concentrations of C18:3n-3 increased linearly (P < 0.001), whereas that of C18:2n-6 decreased linearly (P < 0.001) in ruminal digesta with decreasing dietary n-6:n-3 FAR. Concentrations of transisomers of fatty acids in ruminal digesta did not change. Proportions of C18:0 in liver and foreshank muscle were unchanged by diet. The proportion of trans11 C18:1 and cis-9 trans11 CLA decreased (P < 0.05) in liver but increased (P < 0.05) in foreshank muscle as dietary n-6:n-3 FAR decreased. Proportions of all measured n-3 fatty acids were greater in liver when diets contained more C18:3n-3 from linseed oil. By decreasing the dietary n-6:n-3 FAR, the proportions of n-6 fatty acids in foreshank muscle decreased dramatically; specifically, C18:2n-6 decreased linearly (P < 0.001) from 28.0 to 16.5% and C20:4n-6 decreased linearly (P < 0.001) from 14.7 to 8.6%. Although feeding a diet that contained more n-3 fatty acids increased the n-3 fatty acid concentration of muscle, the ratio of PUFA to SFA was decreased.     

Effects of oral sunflower oil and olive oil on serum and cutaneous fatty acid concentrations in dogs.

The effects of dietary fatty acids on serum and cutaneous fatty acids of healthy dogs were evaluated under controlled conditions. Beagle puppies (n = 12) were fed a standard diet supplemented with sunflower oil (group A), olive oil (group B) or no supplementation (group C) for 12 weeks. There were no significant differences in food intake or growth rates between the three groups. Dogs in group A had significant increases (P < 0.05) in serum 18:2n6 (linoleic acid) and 20:3n6 (dihomo-gamma-linolenic acid), and cutaneous 18:2n6 with significant decreases in serum 20:4n6 (arachidonic acid) and cutaneous 18:1n9 (oleic acid) and 18:3n3 (alpha-linolenic acid). Dogs in group B had significant increases in serum 18:1n9, 20:3n6 and cutaneous 18:1n9 with decreases in serum 20:4n6, 22:4n6, 22:5n3 and 22:5n6, and cutaneous 18:2n6, 18:3n3 and 20:4n6. There were no significant changes in serum or cutaneous fatty acids for the dogs in group C. This study demonstrates that fatty acid supplements can be used to alter the serum and cutaneous fatty acid compositions of dogs.     

Variable absorption of clavulanic acid after an oral dose of 25 mg/kg of Clavubactin and Synulox in healthy dogs

The aims of this investigation were to calculate the pharmacokinetic parameters and to identify parameters, based on individual plasma concentration-time curves of amoxicillin and clavulanic acid in dogs, that may govern the observed differences in absorption of both drugs. The evaluation was based on the data from plasma concentration-time curves obtained following a single dose in an open, randomized, two-way crossover study involving 24 male Beagle dogs treated with two Amoxi-Clav formulations (A Clavubactin and B Synulox, each with 200/50 mg). Plasma amoxicillin and clavulanic acid concentrations were determined using validated bioassay methods. The half-life of elimination of amoxicillin was 1.5 h (t1/2 = 1.52 +/- 0.19 h, Cmax = 11.4 +/- 2.74 microg/mL), and that of clavulanic acid 0.76 h (t1/2 = 0.71 +/- 0.23 h, Cmax = 2.06 +/- 1.05 microg/mL). There was a fivefold variation in the AUCt of clavulanic acid for both formulations, while the AUCt of amoxicillin varied by a factor of 2. The mean ratio of the AUCt amoxicillin : clavulanic acid was 12.7 +/- 3.65 for formulation A and 11.8 +/- 5.22 for formulation B (P = 0.51).     

A pilot study on in vitro solubility of phosphorus from mineral sources,feed ingredients and compound feed for pigs,poultry, dogs and cats

Excess phosphorus (P) as seen in cat foods can have a negative effect on health (Dobenecker, Webel, Reese, & Kienzle, 2017 ; Pastoor, Klooster, Mathot, & Beynen, 1995 ). P surpluses may affect the environment, and economics in food producing animals, whereas marginal supply may impair performance and health. P can only be absorbed if it is soluble. Solubility of feed P in water and weak acid solution—as a precondition for absorption—was investigated in feed for dogs, cats, pigs and poultry. Different P containing mineral compounds (Ca(H₂PO₄)₂, CaHPO₄?2H₂O, Ca₄Na(PO₄)₃, KH₂PO₄, K₄P₂O₇, NaH₂PO₄, Na₅P₃O₁₀ (29 samples), as well as eight different ingredients such as wheat or meat, 64 compound feeds for pig and poultry, eight complete dry and 13 complete moist dog foods, 25 complete moist cat foods and 29 experimental diets were analysed for P solubility. Finely ground feeds were soaked in water or hydrochloric acid (0.4%) for 1 and 90 min. The samples were centrifuged and the supernatant was analysed for P (photometric vanadate molybdate method after wet ashing). The solubility of P from inorganic sources reflected the solubility of the main compound of the feed grade material. “organic” ingredients, such as fish meal or meat, showed a lower P solubility than inorganic sources. Most ingredients from animal origin (exception fish meal) had a higher P solubility than those from plant origin. When inorganic and “organic” P sources were mixed, the P solubility of the mixture reflected the P solubility and percentages of its compounds. In chicken, turkey and pig compound feed the percentage of acid soluble P increased with increasing P content. Pet moist food showed high percentages of water‐soluble P. The results show that the method is suitable to obtain data on water and acid solubility of P in feed and ingredients.     

Double-blind pilot study on the effects of ketoconazole on intradermal skin test and leukotriene C4 concentration in the skin of atopic dogs

Abstract The effects of ketoconazole on intradermal skin test results and on leukotriene C₄ (LTC₄) concentration in the skin of atopic dogs were evaluated in a pilot study. Twelve atopic dogs without a detectable Malassezia dermatitis were selected. All dogs had positive immedíate reaction to intradermal injection of house dust mite (HDM) at 25 PNU mL^-1. Six dogs received a control sugar tablet and six dogs received ketoconazole at 5 mg kg^-1 PO b.i.d. for 3 weeks. On days 0 and 21, intradermal injections of saline, lipopolysaccharide (LPS) and house dust mite (HDM) were performed and biopsies of the injection sites were taken at 90 min postinjection to measure the concentration of LTC₄ in the skin. Intradermal skin test results were not affected by ketoconazole therapy. Ketoconazole significantly decreased the concentration of LTC₄ that could be elicited by the intradermal injection of saline and LPS. Ketoconazole also decreased the HDM-induced LTC₄ but differences between the prevalues and postvalues were not statistically significant. The mean decrease of LTC₄ concentration in the ketoconazole group was 37% for the saline injection, 42% for the LPS injection and 26% for HDM injection. In the control group no significant changes in the LTC₄ concentrations were found over the 3-week time of the study. This pilot study showed that ketoconazole has anti-inflammatory properties and suggests that this drug may be effective in decreasing the skin concentrations of LTC₄ in atopic dogs. Résumé— Les effets de kétoconazole sur les résultats des tests intradermiques et la concentration en leucotriène C4 (LTC₄) dans la peau de chiens atopiques ont étéévalués dans une étude en double aveugle. Douze chiens atopiques sans dermite à Malassezia ont été selectionnés. Tous les chiens ont des tests intradermiques positifs aux acariens de la poussière de maison à 25 PNU mL^-1à 20 minutes. Six chiens ont reçu des comprimés de sucre, six autres ont reçu du kétoconazole à 5 mg kg^-1, 2 fois par jour par voie orale pendant 3 semaines. Aux jours 0 et 21, des injections intradermiques de liposaccharides (LPS), d'eau salée et d'aeariens de la poussière de maison sont réalisées et des biopsies des points d'injections sont effectuées 90 minutes après l'injection afin de mesurer la concentration en LTC₄ dans la peau. Les résultats des tests intradermiques ne sont pas modifies par la thérapeutique au kétoconazole. Par contre, le kétoconazole diminue significativement la concentration en LTC₄ induit par les injections intradermiques de LPS et d'eau salee. Le kétoconazole diminue également le LTC₄ induit par les acariens de la poussière de maison, mais il n'existe pas de différence significative entre les valeurs avant et après. La diminution moyenne de LTC₄ dans le groupe traité au kétoconazole est de 37% pour l'injection intradermique d'eau salée, de 42% pour l'injection intradermique de LPS et de 26% pour l'injection intradermique d'acariens de la poussière de maison. Dans le groupe de contrôle, aucune différence significative dans les concentrations en LTC₄ n'est observée durant les 3 semaines de l'étude. Cette étude démontre que le kétoconazole a des propriétés antiinflammatoires et suggèrent qu'il peut être efficace dans la diminution des concentrations en LTC₄ chez les chiens atopiques. [Marsella R, Kunkle, GA, Vaughn, DM, Macdonald, J. Double-blind pilot study in the effects of kétoconazole on intradermal skin test and leukotriene C₄ concentration in the skin of atopic dogs. (Etude en double aveugle sur les effets du kétoconazole sur les tests intradermiques et la concentration en leucotriène C₄ dans la peau de chiens atopiques.) Veterinary Dermatology 1997; 8 : 3–10.] Resumen Se evaluaron en un estudio piloto los efectos del ketoconazol sobre los resultados del test intradérmico cutáneo y sobre las concentraciones de leucotrieno C₄ (LTC₄) en la piel de perros atópicos. Se seleccionaron doce perros atópicos sin Dermatitis por Malassezia detectable. Todos los perros mostraban respuesta positiva inmedíata a la inyección del ácaro del polvo doméstico (HDM) a 25 PNU mL^-1. Seis perros recibieron una tableta control de azúcar y seis recibieron ketoconazol a dosis de 5 mg kg^-1 PO BID durante 3 semanas. En los días 0 y 21 se realizaron inyecciones intradérmicas de suero salino, lipopolisacárido (LPS) y ácaro del polvo doméstico, y se tomaron biopsias de las zonas inyectadas a los 90 minutos postinyección para cuantificar la concentración de LTC₄ en la piel. Los resultados de los tests intradérmicos no se afectaron por la terapia con ketoconazol. El ketoconazol disminuyó significativamente la concentración de LTC₄ que pudo haber provocado la inyección intradérmica de suero salino y LPS. El ketoconazol también disminuyó el LTC₄ inducido por el HDM pero las diferencias entre los valores previos y posteriores no fueron estadisticamente significativos. La disminución en la concentración medía de LTC₄ en el grupo de ketoconazol fue del 37% para la inyección de suero salino, 42% para la de LPS y 26% para la de HDM. En el grupo control no se encontraron alteraciones significativas en las concentraciones de LTC₄ durante las 3 semanas que duró el estudio. Este estudio piloto mostró que el ketoconazol posee propiedades antiinflamatorias y sugiere que este fármaco puede ser efectivo en disminuir las concentraciones cutáneas de LTC₄ en perros atópicos. [Marsella R, Kunkle, GA, Vaughn, DM, Macdonald, J. Double-blind pilot study in the effects of ketoconazole on intradermal skin test and leukotriene C₄ concentration in the skin of atopic dogs. (Estudio doble ciego sobre los efectos del ketoconazol en los tests intradérmicos cutaneos y en la concentración de leucotrieno C₄ en la piel de perros atópicos.) Veterinary Dermatology 1997; 8 : 3–10.] Zusammenfasung In einer Pilotstudie wurden die Wirkung von Ketoconazol auf Ergebnisse des intrakutanen Hauttests und der Leukotrien C₄ (LTC₄)-Konzentration in der Haut atopischer Hunde bewertet. Zwölf atopische Hunde ohne feststellbare Malassezia Dermatitis wurden ausgewählt. Alle Hunde hatten eine positive Sofortreaktion zu Hausstaubmilbenextrakt von 25 PNU mL^-1. Sechs Hunde erhielten eine Zuckertablette als Kontrolle und sechs Hunde erhielten Ketoconazol in einer Dosis von 5 mg kg^-1 oral zweimal täglich für drei Wochen. An den Tagen 0 und 21 wurden intrakutane Injektionen von physiologischer Kochsalzlösung, Lipopolysaccharid (LPS) und Hausstaubmilbenextrakt durchgeführt und 90 Minuten danach Biopsien an den Injektionsstellen entnommen, um die Konzentration von LTC₄ in der Haut zu messen. Ketoconazoltherapie hatte keinen Einfluss auf die Ergebnisse des Intrakutantests. Ketoconazol verminderte die LTC₄ Konzentration in den intrakutanen Injektionsstellen von physiologischer Kochsalzlösung und LPS. Die Konzentrationen des von Hausstaubmilbenextrakt-induzierten LTC₄ waren ebenfalls vermindert, die Unterschiede zwischen den Werten vor und nach der Injektion waren jedoch nicht statistisch significan. Die durchschnittliche Verminderung der LTC₄ Konzentration in der Ketoconazol-Gruppe betrug 37% für die Injektion mit Kochsalzlösung, 42% für die Injektion mit LPS und 26% für die Injektion mit Hausstaubmilbenextrakt. In der Kontrollgrupe wurden während der dreiwöchigen Studie keine signifikanten Veränderungen in der LTC₄ Konzentration festgestellt. Diese Pilotstudie zeigt die entzündungshemmende Wirkung von Ketoconazol und deutet darauf hin, daß dieses Medikament geeignet sein könnte, die Hautkonzentration von LTC₄ in atopischen Hunden zu verringern. [Marsella R, Kunkle, GA, Vaughn, DM, Macdonald, J. Double-blind pilot study in the effects of ketoconazole on intradermal skin test and leukotriene C₄ concentration in the skin of atopic dogs. (Doppelblind-Pilotstudie über die Wirkung von Ketoconazol auf den intrakutanen Hauttest und die Konzentration von Leukotrien C₄ in der Haut atopischer Hunde.) Veterinary Dermatology 1997; 8 : 3–10.]