Effect of omega-3 fatty acids on canine atopic dermatitis

Twenty-nine dogs were included in a double-blinded, placebo-controlled, randomised trial and were orally supplemented for 10 weeks with either flax oil (200 mg/kg/day), eicosapentaenoic acid (50 mg/kg/day) and docosahexaenoic acid (35 mg/kg/day) in a commercial preparation, or mineral oil as a placebo. For each dog, clinical scores were determined based on a scoring system developed prior to the trial. Total omega-6 and omega-3 intake and the ratio of omega-6:omega-3 (omega-6:3) were calculated before and after the trial. The dogs' clinical scores improved in those supplemented with flax oil and the commercial preparation, but not in the placebo group. No correlation was identified between total fatty acid intake or omega-6:3 ratio and clinical scores. Based on the results of this study, the total intake of fatty acids or the omega-6:3 ratio do not seem to be the main factors in determining the clinical response.     

Masitinib decreases signs of canine atopic dermatitis: a multicentre, randomized, double-blind, placebo-controlled phase 3 trial

This study investigated the efficacy and safety of masitinib, a selective tyrosine kinase inhibitor capable of downregulating mast cell functions, for treatment of canine atopic dermatitis (CAD). Dogs with confirmed CAD received masitinib at 12.5 mg/kg/day (n = 202) or control (n = 104) for 12 weeks. A reduction in CAD Extent and Severity Index (CADESI-02) score of ≥ 50% at week 12 was observed in 61% of masitinib-treated dogs versus 35% of control dogs (P < 0.001), according to the modified intent-to-treat population. For dogs resistant to ciclosporin and/or corticosteroids (60% of the study population), CADESI-02 response rates were 60 versus 31%, respectively (P = 0.004). The mean reduction in pruritus score of severely pruritic dogs was 46 versus 29%, respectively (P = 0.045). Furthermore, 65% of owners with severely pruritic dogs assessed masitinib efficacy as good/excellent versus 35% control (P = 0.05). Overall, 63% of investigators assessed masitinib efficacy as good/excellent versus 35% control (P < 0.001). Premature discontinuations from the modified intent-to-treat population (28.2% masitinib versus 26.0% control) were mainly due to adverse events (13.4 versus 4.8%, respectively) or lack of efficacy (12.4 versus 18.3%, respectively). In total, 13.2% dogs presented with severe adverse events (16.0% masitinib versus 7.7% control). Masitinib showed a risk of reversible protein loss, although regular surveillance of blood albumin and proteinuria allowed for discontinuation of treatment while the dog was still clinically asymptomatic. Masitinib proved to be an effective and mostly well-tolerated treatment of CAD, including severe and refractory cases, with medically manageable adverse effects.     

E-cadherin and β-catenin expression in canine colorectal adenocarcinoma

E-cadherin and its associated cytoplasmic proteins, including β-catenin, have been examined as potential oncogenic markers due to the significant correlation between tumour dedifferentiation and the invasive capacity of epithelial tumours. The purpose of this study was to evaluate the expression of E-cadherin and β-catenin in canine colorectal cancer using immunohistochemistry and to examine the relationship between this expression and various clinicopathological variables. The expression pattern of E-cadherin and β-catenin was investigated in 44 colorectal canine carcinomas. In the intestinal mucosa of noncancerous areas, epithelial cells demonstrated equally strong membranous expression of E-cadherin and β-catenin localised to the cell–cell junctions. Reduced expression of E-cadherin and β-catenin was demonstrated in 75% and 81.8% of the colorectal carcinoma cases, respectively. The down-regulation of both E-cadherin and β-catenin was correlated with decreased differentiation and increased tumour grade. In addition, the expression of β-catenin was correlated with tumour size. These results suggest that dysfunction of the E-cadherin–catenin complex starts in the early stages of carcinogenesis and that the disruption of the tissue architecture is progressively associated with the invasion of the tumour.     

The ACVD task force on canine atopic dermatitis (XII): the relationship of cutaneous infections to the pathogenesis and clinical course of canine atopic dermatitis.

Dogs and human beings with atopic dermatitis (AD) frequently exhibit concurrent skin infections with Staphylococcus sp. bacteria or Malassezia yeast, and treatment of such infections is an important facet of managing these patients. Staphylococci appear to colonize atopic skin readily, and bacterial products on the skin could augment cutaneous inflammation via immediate hypersensitivity responses to the bacteria, by superantigen-mediated lymphocyte activation, or other non-specific mechanisms. Similarly, skin colonization by Malassezia yeast could contribute to clinical signs of AD; yeast components could induce inflammation via non-specific mechanisms, such as alteration in mediator release, or via antigen-specific hypersensitivity reactions. Clinical and experimental evidence exists that secondary microbial infections can both initiate and perpetuate episodes of AD in dogs and humans, and could even participate in promotion of pro-allergic immunologic responses. Mechanistic details of these complex interactions are under extensive investigation in human beings; only a few observations have been extended to include dog with AD.     

A prospective study on the clinical features of chronic canine atopic dermatitis and its diagnosis

Canine atopic dermatitis (CAD) is a multifaceted disease associated with exposure to various offending agents such as environmental and food allergens. The diagnosis of this condition is difficult because none of the typical signs are pathognomonic. Sets of criteria have been proposed but are mainly used to include dogs in clinical studies. The goals of the present study were to characterize the clinical features and signs of a large population of dogs with CAD, to identify which of these characteristics could be different in food-induced atopic dermatitis (FIAD) and non–food-induced atopic dermatitis (NFIAD) and to develop criteria for the diagnosis of this condition. Using simulated annealing, selected criteria were tested on a large and geographically widespread population of pruritic dogs. The study first described the signalment, history and clinical features of a large population of CAD dogs, compared FIAD and NFIAD dogs and confirmed that both conditions are clinically indistinguishable. Correlations of numerous clinical features with the diagnosis of CAD are subsequently calculated, and two sets of criteria associated with sensitivity and specificity ranging from 80% to 85% and from 79% to 85%, respectively, are proposed. It is finally demonstrated that these new sets of criteria provide better sensitivity and specificity, when compared to Willemse and Prélaud criteria. These criteria can be applied to both FIAD and NFIAD dogs.     

Expression of fibronectin and its integrin receptor α5β1 in canine mammary tumours

Fibronectin and its integrin receptor α5β1 were studied by immunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the α5β1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of canine mammary neoplasms. The immunostaining of α5β1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of α5 and β1 was diminished in metastatic tumours but there were some α5-positive cells with pronounced features of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epithelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the content of α5β1 and the expression of fibronectin in canine mammary tumours.     

Epidemiology, clinical signs, histopathology and molecular characterization of canine leproid granuloma: a retrospective study of cases from Brazil

Thirty-eight cases of canine leproid granuloma were diagnosed between 2000 and 2008. Diagnosis was based upon clinical and histopathological findings and the presence of acid-fast bacilli in skin sections. The clinical lesions were localized predominantly on the pinnae and included papules, plaques and nodules, with or without ulceration. Boxer dogs were the breed most affected. Histopathological findings included nodular to diffuse pyogranulomatous, lymphoplasmocytic inflammatory infiltrates, with or without necrosis, localized in the dermis or subcutaneous tissue. The bacillary loading and morphology were variable among the lesions analysed. There was no significant correlation between bacterial load and histopathological pattern, dominant type of inflammatory infiltration or the amount of necrosis or giant cells. No correlation was observed between giant cells and histopathological pattern. In the majority of cases where a PCR-based assay was done, a novel mycobacterium species as the main aetiological agent was identified, as reported in previous studies.     

Detection and measurement of canine α-macroglobulins by enzyme immuno-assay

The alpha-macroglobulins are broad-specificity protease inhibitors important in the regulation and clearance from circulation of biologically active proteases. Inappropriate protease activation may be a feature of canine acute pancreatitis and the ability of the animal to clear these proteases may be important in determining survival. An enzyme immunoassay for the detection and measurement of canine alpha-macroglobulins in plasma samples was developed. A reference range for the canine alpha-macroglobulins of 1.20-2.72 mg ml-1 was established from a panel of canine plasma samples, and the stability of the alpha-macroglobulins in plasma samples stored at 4 degrees C was investigated. Changes in the level of the alpha-macroglobulins during disease states involving increased endogenous protease activity can now be investigated using a rapid, repeatable and quantifiable assay.     

A differential interplay between the expression of Th1/Th2/Treg related cytokine genes in Teladorsagia circumcincta infected DRB1*1101 carrier lambs

ABSTRACT: Substantial debate exists on whether the immune response between sheep resistant and susceptible to gastrointestinal nematodes can be differentiated into a Th1 and Th2 phenotype. The present study addresses the hypothesis that variation in resistance to Teladorsagia circumcincta between DRB1*1101 (associated with reduced faecal egg count and worm burden) carriers and non-carriers is due to a differential interplay in the expression of Th1/Th2 and regulatory T (Treg) related cytokine genes. Lambs from each genotype were either slaughtered at day 0 (un-infected control) or infected with 3 × 104 Teladorsagia circumcincta L3 and slaughtered at 3, 7, 21, and 35 days later. Lambs carrying the DRB1*1101 allele had a significantly lower worm burden (P < 0.05) compared to the non-carriers. Abomasal mucosal cytokine gene expression was evaluated by quantitative real-time PCR and comparison made for time and genotype effects. The response generated varied through the course of infection and was affected by genotype. DRB1*1101 carriers had an up-regulated expression of the Th1-related cytokine genes (IL-1β, TNFα, and IFN-γ) at day 3, but this was replaced by an up-regulated expression of Th2-related cytokine genes (IL-10 and IL-13) and Treg-related cytokine genes (IL-2RA-CD25, TGFα, TGFβ, Arg2, MIF and FOXP3) by day 7. Conversely, in the non-carriers these changes in gene expression were delayed until days 7 and 21 post infection (pi), respectively. It is concluded that resistance to Teladorsagia circumcincta in animals carrying the DRB1*1101 allele is influenced by an earlier interplay between Th1, Th2 and T regulatory immune response genes.     

In vitro antimicrobial efficacy of β‐defensin 3 against Staphylococcus pseudintermedius isolates from healthy and atopic canine skin

β‐Defensins (BDs) are highly conserved antimicrobial peptides important in innate defence against bacteria. β‐Defensin 3 has a specific role in protecting the skin. This study quantified the minimal inhibitory concentration (MIC) of human (h)BD3 against Staphylococcus pseudintermedius isolates from atopic and healthy dogs. Single colony isolates (1 × 10⁵ colony‐forming units/mL log phase) were cultured with doubling dilutions of hBD3 in sodium phosphate buffer from 0.8 to 50 μg/mL at 37 °C for 2 h, before adding 100 μL of tryptone soy broth and incubating for a further 20 h. Bacterial growth was assessed as the mean optical density at 540 nm corrected for background. The median MIC was 12.5 μg hBD3/mL (range 3.125–25 μg/mL; n = 22). Forty‐five percent of the isolates were inhibited at ≤6.25 μg hBD3/mL, and 90% were inhibited at ≤12.5 μg hBD3/mL. Bacterial growth was not inhibited at ≤1.6 μg hBD3/mL. There were no significant differences in the inhibition by hBD3 of isolates from atopic (median MIC 12.5 μg/mL, range 6.25–25 μg/mL, n = 14) and healthy dogs (median MIC 9.4 μg/mL, range 3.125–12.5 μg/mL, n = 8); from noninfected colonized sites (median MIC 12.5 μg/mL, range 3.125–25 μg/mL, n = 16) and infected lesions (median MIC 9.4 μg/mL, range 6.25–12.5 μg/mL, n = 6); or between sample sites (nose median MIC 12.5 μg/mL, range 6.25–25 μg/mL, n = 5; perineum median MIC 12.5 μg/mL, range 3.125–25 μg/mL, n = 7; ear median MIC 6.25 μg/mL, range 6.25–12.5 μg/mL, n = 4; lesions median MIC 9.4 μg/mL, range 6.25–12.5 μg/mL, n = 6). In conclusion, hBD3 inhibited the growth of canine S. pseudintermedius isolates in vitro irrespective of origin.     

Expression of VEGFR and PDGFR‐α/‐β in 187 canine nasal carcinomas

Radiotherapy represents the standard of care for intranasal carcinomas. Responses to tyrosine kinase inhibitors (TKIs) have been reported but data on expression of target receptor tyrosine kinases (rTKs) is limited. This study characterizes the expression of vascular endothelial growth factor receptor (VEGFR), platelet‐derived growth factor receptor (PDGFR)‐α and PDGFR‐β in canine intranasal carcinomas. Histological samples from 187 dogs were retrieved. Immunohistochemistry was performed using commercially available antibodies. Expression of rTKs was classified into weak, moderate or intense and additionally recorded as cytoplasmic, membranous, cytoplasmic‐membranous, nuclear or stromal. VEGFR was expressed in 158 dogs with predominantly moderate expression (36.9%) and a cytoplasmic‐membranous expression pattern (70.9%). PDGFR‐α was detected in 133 with predominantly weak expression (57.9%) and cytoplasmic pattern (87.9%). PDGFR‐β was identified in 74 patients with a predominantly moderate expression (17.6%) and cytoplasmic expression pattern (63.5%). Co‐expression of rTKs was common. These results confirm expression of VEGFR, PDGFR‐α and PDGFR‐β in canine intranasal carcinomas and support the utility of TKIs.