Immunoexpression of IL-33 in the different clinical aspects of canine atopic dermatitis.

Canine atopic dermatitis (CAD) is a chronic and inflammatory skin condition with a multifaceted origin, involving genetic factors, skin barrier abnormalities, immune responses, and hypersensitivity to various allergens. Interleukin 33 (IL-33), released by keratinocytes upon cellular injury, plays a crucial role in atopic dermatitis pathogenesis by inducing Th2 lymphocyte-mediated immune responses. This study aimed to evaluate IL-33 expression in dogs with atopic dermatitis and compare it to a control group. Forty-nine dogs were included, with 39 having atopic dermatitis, subdivided into groups based on clinical characteristics, and ten in the control group. Lesion and pruritus scores were assessed, and incisional biopsies were analyzed for dermatopathological characteristics. IL-33 expression was evaluated using immunohistochemistry, the analyses were blinded, based on the measurement of immunostaining areas using Image Pro-Plus software, version 4.5, relying on a semi-automatic color segmentation method, where the tissue immunostaining area for each biomarker was artificially delimited and quantified. Statistically significant differences in IL-33 immunostaining were found among groups (P=0.0005). Lichenified dogs (group 4) exhibited higher immunostaining compared to erythema (group 3) (P=0.0006), alesional pruritus (group 2) (P=0.0261), and the control group (group 1) (P=0.0079). IL-33 immunostaining increased with lesion progression, strongly correlating with lesion scores (P<0.0001), particularly in patients with chronic lesions characterized by erythema and lichenification. These findings suggest IL-33's significant role in canine atopic dermatitis pathogenesis and its association with lesion and inflammation scores during the chronic phase. This suggests potential therapeutic interventions targeting IL-33 or its receptors, though further studies are needed to explore these possibilities.

Cutaneous protothecosis in a dog successfully treated with oral itraconazole in pulse dosing.

BACKGROUND: Protothecosis is a rare infectious disease caused by unicellular, achlorophyllous, microalgae of the genus Prototheca, ubiquitously distributed in nature. The algae are emerging pathogens, whose incidence is increasing in both human and animal populations and serious systemic infections related to this pathogen have been increasingly described in humans in recent years. After mastitis in dairy cows, canine protothecosis is the second most prevalent form of the protothecal disease in animals. Here, we report the first case of chronic cutaneous protothecosis due to P. wickerhamii in a dog in Brazil, successfully treated with a long-term therapy with itraconazole in pulse. CASE PRESENTATION: Upon clinical examination, exudative nasolabial plaque, ulcered, and painful lesions in central and digital pads and lymphadenitis were observed in a 2-year-old mixed-breed dog, with a 4-month history of cutaneous lesions and contact with sewage water. Histopathological examination revealed intense inflammatory reaction, with numerous spherical to oval, encapsulated structures stained with Periodic Acid Schiff, compatible with Prototheca morphology. Tissue culture on Sabouraud agar revealed yeast-like, greyish-white colonies after 48 h of incubation. The isolate was subjected to mass spectrometry profiling and PCR-sequencing of the mitochondrial cytochrome b (CYTB) gene marker, leading to identification of the pathogen as P. wickerhamii. The dog was initially treated with oral itraconazole at a dosage of 10 mg/kg once daily. After six months, the lesions resolved completely, yet recurred shortly after cessation of therapy. The dog was then treated with terbinafine at a dose of 30 mg/kg, once daily for 3 months, with no success. The resolution of clinical signs, with no recurrence over a 36-months follow-up period, was achieved after 3 months of treatment with itraconazole (20 mg/kg) in pulse intermittently on two consecutive days a week. CONCLUSIONS: This report highlights the refractoriness of skin infections by Prototheca wickerhamii with therapies proposed in the literature and suggests a new treatment option with oral itraconazole in pulse dosing for long-term disease control successfully performed in a dog with skin lesions.

Combined prick and patch tests for diagnosis of food hypersensitivity in dogs with chronic pruritus.

BACKGROUND: Previous studies have shown that patch testing with food extracts can assist formulation of elimination diets (ED) in human patients with suspected adverse food reactions (AFR). Little is known about the use of these tests in dogs. OBJECTIVES: To evaluate the effectiveness of a combination of prick and patch testing in current protocols, and food challenge (FC) tests in dogs with AFR. METHODS AND MATERIALS: Prick and patch tests were performed on 21 dogs with chronic, nonseasonal pruritus. Dogs then were fed an ED formulated on the basis of the results. All dogs with improved clinical signs then were challenged with a food to which there had been a positive reaction in the tests. Six dogs subsequently were challenged with a food to which they had been negative on testing. Pruritus Visual Analog Scale (pVAS) and Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) were evaluated on Day (D)0, D30 and D60 of the ED. Sensitivity (SE), specificity (SP), positive (PPV) and negative (NPV) predictive values, and the Kappa (κ)value were calculated. RESULTS: Of the 21 dogs, there was a significant mean improvement in pVAS and CADESI-04 scores in 16 (76%) dogs after D30 (P < 0.01) and D60 (P < 0.01) of the ED. There were no statistical differences between D30 and D60. The combination of tests had SE, SP, PPV, NPV and κ values of 80%, 66.7%, 66.7%, 80% and -0.17, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: The combination of prick and patch testing reached high values of SE and NPV. A diagnosis of AFR was made in 76% of the dogs, and test results were useful for the selection of an ED.